Meristics (S1 Table).

1. 1) Monospondylous vertebrae counts: minimum = 37, maximum = 53 (CI = 64; RI = 69).

Monospondylous vertebrae are defined as those vertebrae whose centrum corresponds to a single intermuscular septum and a pair of neural spines. Usually, these vertebrae are located between the occipital centrum in the neurocranium to over or posterior to the pelvic girdle [58]. This character has been used to separate taxonomically species of sharks as in [34] and not less obviously in Squalidae (e.g., [59]). In Dalatias and Isistius, total counts of monospondylous vertebrae vary from 37 (minimum) to 44 (maximum). In Squalus species, it varies from 37 (minimum) to 50 (maximum) whereas in Cirrhigaleus species it is 47–53.

1. 2) Diplospondylous vertebrae counts: minimum = 35, maximum = 77 (CI = 100; RI = 100).

Diplospondylous vertebrae are defined as those vertebrae whose centrum corresponds to two subsequent intermuscular septa and a pair of neural spines. These vertebrae are located from the pelvic girdle to the caudal tip [58]. In Dalatias and Isistius, total counts of diplospondylous vertebrae vary from 35 (minimum) to 47 (maximum). In Squalus species, it varies from 60 (minimum) to 77 (maximum) whereas in Cirrhigaleus species the range from 60 to 69.

1. 3) Upper teeth rows: minimum = 16, maximum = 39 (CI = 0; RI = 5).
2. 4) Lower teeth rows: minimum = 15, maximum = 31 (CI = 0; RI = 3).

Total number of tooth rows in the upper and lower jaws are often expressed as a dental formula in taxonomic descriptions. These formulae vary widely within Squaliformes as seen in [60] and rarely are applied in phylogenetic analysis of sharks (e.g., [61, 62]). In Dalatias and Isistius, upper tooth rows range from 16 (minimum) to 39 (maximum) and lower tooth rows varies from 15 (minimum) to 31 (maximum). In Squalus species, the range is 21–28 for upper tooth and 17–25 for lower tooth rows. Cirrhigaleus species show a minimum of 23 and maximum of 30 upper tooth rows and 18–27 for lower tooth rows.

Neurocranium and associated nerves.

1. 5) Innervation of the medial nasal lobe by the buccopharyngeal branch of the facial nerve (VII): character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

In Cirrhigaleus, anterior margin of nostrils has a medial nasal lobe that bears fleshy core and it is innervated by the buccopharyngeal branch of facial nerve (VII) (5,1). The nerve buccopharyngeal branch of facial nerve (VII) arise from the foramen prooticum (V-VII) at the interorbital wall and runs aside the suborbital shelf of the neurocranium and over suborbitalis muscle in the palatoquadrate till it reaches the antorbital cartilage (Fig 1). Then, the branch buccopharyngeal runs ventrally in the subethmoidal region and reaches the nasal capsule in the neurocranium where it splits into two different small branches. The left branch is thicker than the right one and it runs to the origin of the nasal barbel (medial nasal lobe) at the fleshy core. The second branch runs straight to the rostral tip and aside the rostral keel. In S. acanthias, S. suckleyi, S. megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus, buccopharyngeal nerve runs exclusively to the tip of the rostrum with small innervations running to the nasal capsules, although these do not reach the anterior margin of nostrils. Thus, anterior margin of nostrils is not innervated in these species and the medial nasal lobe is internally supported by a thin nasal cartilage only, lacking fleshy core. In Dalatias, Isistius and species of Squalus such innervation is absent (5,0) [22]. Proposed this character as a synapomorphy of Cirrhigaleus.

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Fig 1.

Anterior margin of nostrils in Cirrhigaleus (A–C, left side) and Squalus (D–E, right side), showing its innervation and internal support. A: C. barbifer, HUMZ 95177, juvenile female, 584 mm TL; B: C. australis, CSIRO H 7042–04, juvenile female, 605 mm TL; C: C. asper, SAIAB 6092, neonate female, 275 mm TL; D: Squalus suckleyi, CAS 21971 (cleared and stained), neonate female, 290 mm TL. Abbreviations: buVII: buccopharyngeal branch of facial nerve; cnab: fleshy core; mnl: medial nasal lobe supported by cartilage (in blue); nab: nasal barbel; nc: nasal capsule; r: rostrum; snf: subnasal fenestra. Scale bars: 5 mm (A); 1 mm (B–D).

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1. 6) Fleshy core at the anterior margin of nostrils: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Medial nasal lobe at the anterior margin of nostrils is supported by a fleshy core in Cirrhigaleus (6,1) (Fig 1). This condition is absent in Dalatias, Isistius and Squalus (6,0).

1. 7) Supraethmoidal process in the neurocranium: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Species of Squalus present a paired short and cylindrical process located at the dorsoposterior edge of the prefrontal fontanelle in the neurocranium (7,1) (Fig 2C–2E; Fig 3C–3F). These processes are absent in Dalatias, Isistius and in both C. barbifer and C. australis (7,0) (Fig 2A and 2B; Fig 3A and 3B). In C. asper, these processes are absent in the Indian Ocean population but present in the Western Atlantic population, and thus this terminal was coded as [1].

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Fig 2. Neurocranium of species of Cirrhigaleus and Squalus in dorsal view.

A: C. barbifer, HUMZ 95177, juvenile female, 584 mm TL; B: C. australis, CSIRO H7042-04, juvenile female, 605 mm TL; C: S. suckleyi, HUMZ 87643, adult male, 665mm TL; D: S. megalops, AMS I46093-001, adult male, 650 mm TL; E: S. mitsukurii, NSMT P-44381, juvenile male, 770 mm TL. Abbreviations: ec: ethmoidal canal of ophthalmicus superficialis nerve; elf: endolymphatic foramen; ep: epiphysial pit; foop: profundus canal for the ophthalmicus profundus nerve; nc: nasal capsule; oc: otic capsule; pep: preorbital process; plf: perilymphatic foramen; poc: preorbital canal of superficial ophthalmic nerve; pop: postorbital process; r: rostrum; sep: supraethmoidal process. Scale bars: 10mm.

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Fig 3. Detail of ethmoidal region of the neurocranium in anterior dorsal view.

A: C. australis, CSIRO H7042-04, juvenile female, 605 mm TL; B: C. asper, SAM 38269, adult female, 1045 mm TL; C: C. asper, UFPB 11864, juvenile female, 970 mm TL; D: S. suckleyi, SAM 38346, adult female, 850 mm TL; E: S. albifrons, MZUSP 121272, adult male, 760 mm TL; F: S. montalbani, MZUSP121270, adult male, 713 mm TL. Abbreviations: ep: epiphyseal pit; sep: supraethmoidal process. Scale bars: 2mm (A,E,F), 5mm (B–D).

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1. 8) Rostrum shape: character state 0 –rostrum reduced and not trough-shaped; character state 1 –developed and trough-shaped (CI = 100; RI = 100).

Ethmoidal region of the neurocranium exhibits an anterior process, the rostral cartilage, which varies in shape and length. The rostrum may be developed and trough-shaped. This condition is observed in species of Cirrhigaleus and Squalus (8,1). Dalatias and Isistius show rostrum reduced and not trough-shaped (8,0; see [52]).

1. 9) Rostral keel in the neurocranium: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Rostral keel is a ventral expansion of the rostrum, located between the nasal capsules. Dalatias and Isistius lack rostral keel in the neurocranium (9,0) whereas in all other taxa examined this keel is present (9,1).

1. 10) Rostral keel extension: character state 0 –short, never transcending anterior margin of nasal capsules; character state 1 –elongate, always transcending anterior margin of nasal capsules (CI = 100; RI = 100).

Although Squalus and Cirrhigaleus present a rostral keel, this structure differs in length (Fig 4). Cirrhigaleus has short rostral keel, never transcending anteriorly the nasal capsules (10,0). Squalus has rostral keel very elongate, transcending anteriorly the nasal capsules (10,1).

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Fig 4. Neurocranium of species of Cirrhigaleus and Squalus in ventral view.

A: C. barbifer, HUMZ 95177, juvenile female, 584 mm TL; B: C. australis, CSIRO H7042-04, juvenile female, 605 mm TL; C: S. suckleyi, HUMZ 87643, adult male, 665mm TL; D: S. megalops, AMS I46093-001, adult male, 650 mm TL; E: S. mitsukurii, NSMT P-44381, juvenile male, 770 mm TL. Abbreviations: aoc: antorbital cartilagem; btp: basitrabecular process; nab: nasal barbel; nc: nasal capsule; pop: postorbital process; r: rostrum; rk: rostral keel: sec: subethmoid chamber; snf: subnasal fenestra; lra: lateral rostral appendage; mra: medial rostral appendage. Scale bars: 10mm.

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1. 11) Rostral appendages in the neurocranium: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Rostral appendages may be present laterally and medially as hook-like projections for connecting anterolaterally the nasal capsules to the ventral base of the rostrum by ligaments. Dalatias and Isistius have no rostral appendages. These are also absent in species of Cirrhigaleus (11,0) but present in all Squalus species examined (11,1).

1. 12) Number of rostral appendages: character state 0 –one pair of lateral rostral appendages; character state 1 –one pair of lateral rostral appendages plus one medial rostral appendage (CI = 100; RI = 100).

In S. acanthias, S. suckleyi (Fig 4C), S. megalops (Fig 4D), S. brevirostris, S. albifrons, one pair of hook-like rostral appendages is present laterally at the tip of the rostrum (12,0). In S. mitsukurii (Fig 4E), S. montalbani (Fig 5A) and S. japonicus, one pair of rostral appendages is present and additionally one single hook-like medial rostral appendage is present (12,1). S. acanthias, S. suckleyi, S. megalops, S. brevirostris, S. albifrons (Fig 5B) exhibit a similar medial rostral appendage, herein called median rostral prominence, but this structure is not hook-like.

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Fig 5. Detail of rostral process of Squalus species in ventral view, showing rostral appendages.

A: S. albifrons, MZUSP 121272, adult male, 760 mm TL; B: S. montalbani, MZUSP121270, adult male, 713 mm TL. Abbreviations: lra: lateral rostral appendage; mra: medial rostral appendage; mrp: median rostral prominence. Scale bars: 1 mm.

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1. 13) Dorsal aperture of profundus canal: character state 0 –absent; character 1 –present (CI = 100; RI = 100).

In Cirrhigaleus and Squalus, profundus canal has one ventral aperture placed in the interorbital wall and a second aperture that opens up to the ethmoidal region, called herein dorsal aperture (13,1) [22, 63]. Stated that the profundus nerve runs together with superficial nerves in the preorbital canal in Dalatias and Isistius, thus, profundus canal is absent (13,0).

1. 14) Position of the dorsal aperture of profundus canal: character state 0 –aside the ethmoidal canal; character state 1 –between ethmoidal canal and preorbital canal (CI = 50; RI = 75).

In S. acanthias, S. suckleyi, S. megalops, S. brevirostris, and S. albifrons profundus canal has its dorsal aperture placed aside the ethmoidal canal, at the base of the nasal capsule (14,0). In Cirrhigaleus and S. mitsukurii, S. montalbani, and S. japonicus the dorsal aperture is between the ethmoidal canal and the preorbital canal at the longitudinal sulcus (14,1).

1. 15) Relative width between postorbital processes and nasal capsules of the neurocranium: character state 0 –width of the across postorbital processes greater than to nasal capsules; character state 1 –neurocranium equally wide across nasal capsules and postorbital processes; character state 2 –neurocranium with greatest width across nasal capsules (CI = 50; RI = 71).

Neurocranium has its greatest width at nasal capsules and/or across postorbital processes. In Dalatias and Isistius, neurocranium is wider across postorbital processes (15.0) and the same condition is observed for S. acanthias, S. suckleyi, S. megalops, S. brevirostris, S. albifrons and S. mitsukurii (15,1). Squalus japonicus has neurocranium equally wide at nasal capsules and postorbital processes. Squalus montalbani has its greatest width across nasal capsules and the same is noticed for species of Cirrhigaleus (15,2) (Fig 2A and 2B).

1. 16) Antorbital cartilage in the neurocranium: character state 0 –vestigial; character state 1 –developed and expanded posteriorly (CI = 100; RI = 100).

Antorbital cartilage is an extension of the subethmoidal region that is triangular and directed posteriorly, forming the ventral base of the preorbital wall. It is vestigial in Dalatias and Isistius as well as in Cirrhigaleus (16,0). In Squalus species, the antorbital cartilage is well developed and expanded posteriorly (16,1) (Fig 4). No homology between this character and the one similarly described for non-squalean sharks and batoids in Shirai (1992) is implied in the present study as this requires further investigation. Character codification follows Shirai (1992, 1996).

Pectoral and pelvic skeleton.

1. 17) Number of pectoral basals: character state 0 –three distinct pectoral basals; character state 1 –one single pectoral basal (CI = 100; RI = 100).

Pectoral fins are supported internally by pectoral basal and radials that vary in shape and name across Squaliformes. Dalatias and Isistius have one single basal in the pectoral fin (17,1). Squalus and Cirrhigaleus have three separated pectoral fin basals (17.0) (Fig 6).

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Fig 6. Pectoral skeleton of C. australis (CSIRO H7042-04, juvenile female, 605 mm TL), showing pectoral girdle and pectoral basals.

A: anterior view; B: posterior view; C: lateral view; D: dorsal view. Abbreviations: co: coracoid bar; df: diazonal foramen; mes: mesopterygium; mtp: metapterygium; pcf: pectoral fin; pcr: pectoral fin radials; pro: propterygium; ptp: posterior triangular process; scl: scapula; scp: scapular process. Scale bars: 5mm (A–D); 2mm (E,F).

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1. 18) Number of regions for pectoral articulation: character state 0 –one articular region; character state 1 –two articular regions (CI = 100; RI = 100).

In elasmobranchs, pectoral articular regions between the pectoral basals of the pectoral fin and pectoral girdle vary in number of articular surfaces and the types (condyle or facet) of articular surfaces [32]. This character refers to the number of surfaces in the scapula for articulation between the pectoral basals and pectoral girdle. As Dalatias and Isistius have one pectoral basal the pectoral fins articulate through a single articular region (18,0) while Squalus and Cirrhigaleus have two separate articular regions (18,1).

1. 19) Articular region of pectoral propterygium: character state 0 –condyle; character state 1 –facet (CI = 100; RI = 100).

A condyle for articulation with the pectoral propterygium is found in Cirrhigaleus species (19,0) (Fig 7). In Squalus, a facet articulates with the propterygium (19,1). Since Dalatias and Isistius present one single pectoral basal and thus not homologous to the condition observed in Cirrhigaleus and Squalus, this character and also character 20 were coded as inapplicable for both taxa.

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Fig 7.

Detail of coracoid bar of Cirrhigaleus and Squalus species in anterior (A,D,G,J,M), posterior (B,E,H,K,N) and lateral views (C,F,I,L,O), showing the pectoral articular region between the pectoral girdle and pectoral basals. A–C: C. australis, CSIRO H7042-04, juvenile female, 605 mm TL; D–F: C. asper, SAM 38269, adult female, 1045 mm TL; G–I: S. acanthias, SAM 38276, adult male, 670mmTL; J–L: S. albifrons, MZUSP 121272, adult male, 760 mm TL; M–O: S. montalbani, MZUSP121270, adult male, 713 mm TL. Abbreviations: bse: barrel-shaped elements; df: diazonal foramen; fpr: facet for propterygium; msc: mesocondyle; mtc: metacondyle; pc: procondyle; scl: scapula. Scale bars: 2 mm.

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1. 20) Articular region of pectoral mesopterygium and metapterygium: character state 0 –one condyle for articulation with mesopterygium only; character state 1 –one condyle for articulation with both mesopterygium and metapterygium (CI = 100; RI = 100).

Squalus acanthias and S. suckleyi have a condyle for articulation with mesopterygium and the metapterygium does not have a direct articulation with the scapula in these two species but it articulates lateral-proximally to the mesopterygium (20,0). In Cirrhigaleus, S. megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani, and S. japonicus, one condyle articulates with both mesopterygium and metapterygium (20,1) (Fig 7).

1. 21) Dorsal ridge of scapula: character state 0 –smooth ridge; character state 1 –segmented ridge (CI = 100; RI = 100).

The depressor pectoralis fossa exhibits a smooth and cylindrical dorsal ridge in the scapula in Dalatias, Isistius and Cirrhigaleus (21,0) (Fig 7A–7F). Species of Squalus also show cylindrical ridge in this region with a few exceptions. Squalus acanthias (Fig 7G–7I) and S. suckleyi have scapula with segmented ridge comprised by small barrel-shaped units located lateral-dorsally to the depressor pectoralis fossa (21,1). These barrel-shaped units were observed in [64, 65] for S. acanthias. [66] suggested that this character may be an autapomorphy for this species but our analysis shows that the barrel-shaped elements may or may not be present in S. suckleyi.

1. 22) Articular region for the basipterygium: character state 0 –one facet articulating with the basipterygium; character state 1 –one facet and one condyle articulating with basipterygium (CI = 100; RI = 100).

Puboischiadic bar of the pelvic girdle articulates with the pelvic fin through two different regions, one articular region for the articulation with the anterior pelvic basal (= first enlarged radial as in [66] of the pelvic fin and a second one with the basipterygium of the pelvic fin. The type of surfaces for the articulation with the pelvic fin may vary between facet or condyle. In Dalatias and Isistius, puboischiadic bar has one pelvic condyle posterolaterally on each side articulating with the anterior pelvic basal, and an inner facet posterolaterally on each side and medially to the pelvic condyle for articulating with the basipterygium. Squalus species also exhibit this pattern of pelvic articulation (25,0) as noticed in [66]. Cirrhigaleus species have the same pattern of pelvic articulation between the puboischiadic bar and anterior pelvic basal but the articular region for the basipterygium has two articular surfaces, an inner facet and a condyle (25,1) (Fig 8A–8F). Pelvic facet is placed ventromedially and the condyle more dorsolaterally in relation to the facet. This condition was not noticed for C. barbifer in [66] possibly due to analysis limitations of the dissected specimen.

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Fig 8.

Puboischiadic bar (right side) in dorsal (A,D,G,J), ventral (B,E,H), posterior (C,F,I) and medial (K) views showing the pelvic articular region with the pelvic fin. A–C: C. australis, CSIRO H7042-04, juvenile female, 605 mm TL; D–F: C. asper, SAM 38269, adult female, 1045 mm TL; G–I: S. montalbani, MZUSP121270, adult male, 713 mm TL; J,K: S. albifrons, MZUSP 121272, adult male, 760 mm TL. Abbreviations: abc: condyle for the anterior pelvic basal; abv: anterior pelvic basal; bp: basipterygium; cbp: condyle for the basipterygium; fpb: facet for the basipterygium; fvn: foramen for ventral fin nerve; lpp: lateral prepelvic proces; plp: posterior-lateral process; pub: puboischiadic bar. Scale bars: 1mm.

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1. 23) Number of pelvic foramina: character state 0 –one single foramen; character state 1 –two foramina (CI = 33; RI = 60).

Pubosichiadic bar at the pelvic girdle has one or two foramina for the pelvic nerve, located laterally on each side of the lateral prepelvic process. Dalatias and Isistius have a single pelvic foramen on each side (26,0). Squalus acanthias, S. suckleyi, S. megalops and S. brevirostris present a single foramen as well. Squalus albifrons, S. mitsukurii, S. montalbani, S. japonicus and species of Cirrhigaleus have two pelvic foramina (Fig 8; 26,1).

1. 24) Posterior medial process of the puboischiadic bar: character state 0 –present; character state 1 –absent (CI = 100; RI = 100).

Puboschiadic bar may be convex medially at the posterior margin, herein named posterior medial process as in [65] or posteriormedian projection as in [66]. This process is present in most taxa examined (27,0) except Cirrhigaleus species (27,1).

1. 25) Shape of the posterior medial process of the puboischiadic bar: character state 0 –conspicuously elongate; character state 1 –posterior medial process short (CI = 0; RI = 0).

In Isistius, posterior medial process is conspicuously elongate, extending backwards as a triangular projection (28,0). In Dalatias and Squalus species, posterior medial process is short, not extending backwards as a triangular projection (28,1).

Clasper morphology.

1. 26) Number of intermediate segments between the basipterygium of the pelvic fin and the axial cartilage of the claspers: character state 0 –one single; character state 1 –two (CI = 67; RI = 67).

Dalatias and Isistius have a single intermediate segment articulating the basipterygium of the pelvic fin and the axial cartilage of the claspers (29,0). Squalus acanthias, S. suckleyi, S. megalops, S. brevirostris, Squalus albifrons, S. mitsukurii and S. japonicus also show a single intermediate segment (Fig 9). S. montalbani and Cirrhigaleus have two intermediate segments (26,1) (Fig 10).

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Fig 9.

Detail of cartilages of the clasper in Squalus species in dorsal (A,D,G,J), ventral (B,E,H,K) and terminal dorsal (C,F,I,L) views. A–C: S. acanthias, SAM 38276, adult male, 670mmTL; D–F: S. brevirostris, HUMZ 189762, adult male, 433 mm TL; G–I: S. albifrons, MZUSP 121272, adult male, 760 mm TL; J–L: S. montalbani, MZUSP121270, adult male, 713 mm TL. Abbreviations: ax: axial cartilage; bp: basipterygium; b1: first intermediate segment; b2: second intermediate segment; mp: mesial process; rd: dorsal marginal cartilage; rl: pelvic radials; td: dorsal terminal cartilage; td2: dorsal terminal 2 cartilage; tv: ventral terminal cartilage; t3: accessory terminal 3 cartilage; β: beta cartilage. Scale bars: 1 mm.

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Fig 10.

Cartilages of the clasper (left side) of C. australis, NMNZ P 38074, adult male, 1020 mm TL in dorsal view (A) and detail of terminal cartilages in ventral view (B). Abbreviations: ax: axial cartilage; b1: first intermediate segment; b2: second intermediate segment; rd: dorsal marginal cartilage; rv: ventral marginal cartilage; td: dorsal terminal cartilage; td2: dorsal terminal 2 cartilage; tv: ventral terminal cartilage; tv2: ventral terminal 2 cartilage; t3: accessory terminal 3 cartilage; β: beta cartilage. Scale bar: 10 mm.

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1. 27) Position of beta cartilage in claspers: character state 0 –beta cartilage placed over the intermediate segment and at the proximal edge of the axial cartilage; character state 1 –beta cartilage placed over the distal edge of basipterygium, the first intermediate segment and the proximal edge of the axial cartilage (CI = 33; RI = 60).

Beta cartilage comprises a cylindrical element that connects dorsally the basipetrygium to the axial cartilage. Relative extension of the beta cartilage varies within Squalidae. Dalatias has one beta cartilage placed over the intermediate segment and partially at proximal edge of the axial cartilage of the clasper (27,0). Squalus acanthias, S. suckleyi, S. megalops, S. brevirostris and S. mitsukurii exhibit the same pattern (Fig 10). Isistius, Squalus albifrons, S. montalbani, and S. japonicus as well as species of Cirrhigaleus (Fig 10) show beta cartilage placed over the distal edge of basipterygium of the pelvic fin, intermediate segment and the proximal edge of the axial cartilage (27,1).

1. 28) Number of terminal cartilages of the clasper: character state 0 –three terminal cartilages; character state 1 –four terminal cartilages; character state 2 –five terminal cartilages (CI = 100; RI = 100).

Terminal cartilages vary in number within Squaliformes [27]. Dalatias and Isistius have three terminal cartilages (30,0): accessory terminal 3 cartilage, ventral terminal cartilage and dorsal terminal cartilage. Squalus species show four terminal cartilages (28,1) which include these three cartilages plus dorsal terminal 2 cartilage. Cirrhigaleus species have five terminal cartilages (28,2): accessory terminal 3 cartilage, dorsal terminal cartilage, dorsal terminal 2 cartilage, ventral terminal cartilage, and ventral terminal 2 cartilage (Fig 10).

1. 29) Mesial process in the axial cartilage of the claspers: character state 0 –absent; character state 1 –present (CI = 50; RI = 75).

In claspers, the axial cartilage may be straight or exhibit some sinuousity and/or a mesial expansion at the proximal edge, herein called mesial process. In Dalatias and Isistius, mesial process is absent (29,0). Squalus megalops, S. brevirostris and S. albifrons share the same condition. Squalus acanthias, S. suckleyi, S. mitsukurii, S. montalbani, S. japonicus as well as species of Cirrhigaleus exhibit a conspicuous mesial process in the axial cartilage (29,1).

1. 30) Relative length of ventral terminal cartilage of the claspers: character state 0 –ventral terminal cartilage shorter than one-third the length of axial cartilage; character state 1 –ventral terminal cartilage greater than one-third the length of the axial cartilage; character state 2 –ventral terminal cartilage with length equal to the length of the axial cartilage (CI = 67; RI = 80).

Ventral terminal cartilage of the claspers varies in length in relation to the length of the axial cartilage. Isistius and Dalatias have short ventral terminal cartilage whose length is smaller than one-third the length of the axial cartilage (30,0). Squalus megalops, S. brevirostris, S. albifrons, and S. japonicus show the same condition. Squalus mitsukurii, S. montalbani and species of Cirrhigaleus (Fig 10) have length of ventral terminal cartilage greater than one-third the length of the axial cartilage (30,1). Squalus acanthias and S. suckleyi have elongate ventral terminal cartilage that is equal in length to the length of the axial cartilage (30,2).

1. 31) Accessory terminal 3 cartilage (t3 or spur): character state 0 –blade-like; character state 1 –pin-like (CI = 100; RI = 100).

The accessory terminal 3 cartilage (or spur) is blade-like in Isistius (31,0). The same condition is observed for Squalus megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus as well as species of Cirrhigaleus. In S. acanthias and S. suckleyi, accessory terminal 3 cartilage (or spur) is pin-like (31,1).

External morphology.

1. 32) Dentition: character state 0 –dignathic heterodonty; character state 1 –dignathic homodonty (CI = 100; RI = 100).

Dalatias and Isistius have dignathic heterodonty (32,0). Squalus and Cirrhigaleus have dignathic homodonty (32,1). This was proposed as synapomorphy of Squalidae in [22].

1. 33) Dorsal fin spines: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Dorsal-fin spines may be present or not at the basal cartilage of the dorsal fin. These spines may be located internally thus retained underneath the skin or externally arising above the skin. In Dalatias and Isistius dorsal-fin spines are absent (33,0). In Cirrhigaleus and Squalus, dorsal-fin spines are present (33,1).

1. 34) Subterminal notch of caudal fin: character state 0 –present; character state 1 –absent (CI = 100; RI = 100).

Caudal fin may have a subterminal notch at the postventral caudal margin in Squaliformes. Dalatias and Isistius do have a subterminal notch (34,0). Species of Cirrhigaleus and Squalus do not have subterminal notch (34,1).

1. 35) Support of the anterior margin of nostrils: character state 0 –nasal lobes supported by flesh only; character state 1 –nasal lobes supported by cartilage (CI = 100; RI = 100).

Anterior margin of nostrils has nasal lobes that are supported internally by flesh or cartilage. In Dalatias and Isistius, nasal lobes are supported by flesh (35,0). In Cirrhigaleus, the same condition is observed. In Squalus, nasal lobes are supported internally by thin cartilages (35,1).

1. 36) Number of nasal lobes at anterior margin of nostrils: character state 0 –two; character state 1 –one (CI = 100; RI = 100).

Anterior margin of nostrils may have one or more nasal lobes, one laterally and a second lobe medially. Dalatias and Isistius have a single nasal lobe (36,1). The same condition is observed for S. acanthias and S. suckleyi but a medial nasal lobe may be present in neonates. Cirrhigaleus species have two nasal lobes (36,0) as well as S. megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus.

1. 37) Shape of nasal barbels: character state 0 –non moustache-like; character state 1 –moustache-like (CI = 100; RI = 100).

Cirrhigaleus barbifer (Fig 11A) and C. australis (Fig 11B) have nasal barbels conspicuously moustache-like and conspicuously elongate, with its tips reaching the mouth (37,1). In C. asper (Fig 11C), the nasal barbel is non moustache-like and very short, with its tips never reaching the mouth (37,0). Nasal barbels are absent in Squalus, Isistius and Dalatia and thus these terminal taxa were coded as “?” for this character.

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Fig 11. Ventral view of the head (right side) in Cirrhigaleus species showing nasal barbels and upper labial furrows.

A: C. barbifer, HUMZ 197852 (neotype), adult female, 870 mm TL; B: C. australis, AMS I 27022–001 (paratype), adult female, 1205 mm TL; C: C. asper, uncatalogued specimen, adult female, 1068 mm TL.

https://doi.org/10.1371/journal.pone.0282597.g011

1. 38) Upper labial furrow: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Upper labial furrow is a lateral sulcus formed as a space between the labial cartilage and the quadrate plate. Upper labial furrow is absent in Dalatias and Isistius (38,0) but present in Cirrhigaleus and Squalus (38,1).

1. 39) Relative length of upper and lower labial furrows: character state 0 –short; character state 1 –elongate (CI = 100; RI = 100).

Upper labial furrow length is much shorter than lower labial furrow in Cirrhigaleus species (39,0) whereas upper labial furrow is as elongate as the lower labial furrow in species of Squalus (39,1).

1. 40) Dorsal fin shape: character state 0 –dorsal fins similar in shape; character state 1 –dorsal fins dissimilar in shape (CI = 100; RI = 100).

First and second dorsal fins are similar in shape in Dalatias and Isistius (40,0). Cirrhigaleus and Squalus have dissimilar dorsal fins (40,1).

1. 41) Dorsal fin length: character state 0 –dorsal fins similar in length; character state 1 –dorsal fins dissimilar in length (CI = 50; RI = 80).

First and second dorsal fins may be similar in length. This condition is observed in Dalatias, Isistius, Cirrhigaleus, S. acanthias and S. suckleyi (41,0). Squalus megalops, S brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus have first dorsal fin greater in length than second dorsal fin (41,1).

1. 42) Proportional length of dorsal-fin inner margin and height: character state 0 –dorsal-fin inner margin length equal to dorsal fin height; character state 1 –dorsal-fin inner margin length smaller than dorsal fin height (CI = 50; RI = 67).

Inner margin of dorsal fins may be similar in length to the dorsal fin height. This condition is present in Dalatias, Isistius, S. acanthias and S. suckleyi (42,0). Cirrhigaleus species and Squalus megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus have dorsal-fin inner margin much smaller than dorsal fin height (42,1).

1. 43) Proportional length between pectoral-pelvic fins and pelvic-caudal fins: character state 0 –pectoral-pelvic space equal or greater pelvic-caudal space; character state 1 –pectoral-pelvic space smaller than pelvic-caudal space (CI = 50; RI = 80).

Distance between pectoral and pelvic fins is equal or greater than the distance between pelvic and caudal fins in Dalatias, Isistius, Cirrhigaleus species, S. acanthias and S. suckleyi (43,0). In S. megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus, pectoral-pelvic space is smaller than pelvic-caudal space (43,1).

1. 44) Precaudal pits: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

The caudal penduncle may exhibit an upper precaudal pit which is a small notch or concavity placed just prior the origin of the caudal fin. In Dalatias and Isistius, precaudal pits are absent (44,0). The same condition is observed for Cirrhigaleus. Species of Squalus have precaudal pits (44,1) as it was noticed in [22] for the genus.

1. 45) Precaudal keel: character state 0 –absent; character state 1 –present (CI = 0; RI = 0).

A longitudinal keel may be present laterally at the caudal peduncle, extending beyond the origin of the lower caudal lobe. Precaudal keel is absent in Dalatias (45,0) but present in Isistius, Cirrhigaleus and species of Squalus (45,1).

1. 46) Caudal fin shape: character state 0 –rectangular; character state 1 –triangular (CI = 0; RI = 0).

Dorsal caudal margin is usually more elongate than the ventral caudal margin which confer a rectangular shape to the caudal fin. Sometimes the ventral caudal lobe is as elongate as the dorsal caudal margin and thus the caudal fin is triangular in shape. Isistius has this pattern of caudal fin shape (46,1) whereas Dalatias, Cirrhigaleus and Squalus have rectangular caudal fin (46,0).

Squamation.

1. 47) Cusps at the crown: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Crown of the dermal denticles may exhibit medial and lateral cusps. In Dalatias and Isistius, dermal denticles have no cusps (47,0) while in Cirrhigaleus (Fig 12) and Squalus, cusps are present (47,1).

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Fig 12.

Scanning electron microscopy of dermal denticles of species of Cirrhigaleus in coronal (A–L, except H) and lateral (H) views. C. barbifer (A–C): A: HUMZ 197852 (neotype), adult female, 870 mm TL; B: NMW 98257, adult female, 960 mm TL; C: CSIRO H 5875–09, adult female, 978 mm TL; C. australis (D–H): D: NMNZ P 38074, adult male, 1020 mm TL; E: NMNZ P 42489, juvenile male, 710 mm TL; F: CSIRO H 7048–01, adult male, 993 mm TL; G–H AMS I 45670–001, juvenile male, 630 mm TL. C. asper (I–L): I: SAIAB, 6092, juvenile female, 275 mm TL; J: SAIAB 31890, adult female, 1090 mm TL; K: SAM 39879, adult female, 1023 mm TL; L: NUPEC uncatalogued, adult female, 1270 mm TL. Scale bars: 100 μm (I); 200 μm (A,D,G,J–L); 500 μm (B,C,E,F,H).

https://doi.org/10.1371/journal.pone.0282597.g012

1. 48) Cusplets at the crown: character state 0 –inconspicuous; character state 1 –conspicuous (CI = 100; RI = 100).

Cusplets are structures that are accessory to the main cusp and it is usually smaller in length. The cusplets are located medially to the lateral cusp on either side of the posterior margin of the crown base. In C. asper (Fig 12I–12L) these cusplets are inconspicuous (48,0) as in Squalus. In C. barbifer and C. australis (Fig 12A–12H) these cusplets are conspicuous (48,1).

1. 49) Ridges on the crown surface: character state 0 –absent; character state 1 –present (CI = 100; RI = 100).

Dermal denticles present medial and lateral ridges at the dorsal surface of the crown in most taxa examined (49,1). Dalatias and Isistius do not have medial and lateral ridges (49,0).

1. 50) Number of ridges in the dermal denticles: character state 0 –three ridges; character state 1 –single ridge (CI = 100; RI = 100).

Cirrhigaleus, Squalus megalops, S. brevirostris, S. albifrons, S. mitsukurii, S. montalbani and S. japonicus have three ridges, one medial and two lateral ridges (50,0). Squalus acanthias and S. suckleyi have a single medial ridge in the dermal denticle (50,1).

1. 51) Dermal denticles shape: character state 0 –diamond-shaped; character state 1 –arrow-shaped; character state 2: club-shaped; character state 3: heart-shaped; (CI = 100; RI = 100).

The crown shape of dermal denticles vary in shape. Dalatias and Isistius have crown diamond-shaped (51,0). Cirrhigaleus, S. mitsukurii, S. montalbani and S. japonicus have heart-shaped dermal denticles (51,1). Squalus acanthias and S. suckleyi present dermal denticles arrow-shaped (51,2) whereas S. megalops, S. brevirostris, S. albifrons have club-shaped dermal denticles (51,3).

Taxonomic account.

Family Squalidae Blainville, 1816 [75]

Genus Cirrhigaleus Tanaka, 1912 [1]

Cirrhigaleus Tanaka, 1912: 151–154, 163; pl. XLI, Figs 156–162 (original description, illustrated; Sagami Sea, Japan; type species by original designation and monotypy) [1]; Herre 1936: 59 (cited; Japan) [76]; Bigelow and Schroeder 1948: 451 (cited; Japan) [18]. Bigelow and Schroeder 1957: 18, 19, 24, 37–38 (cited, revision, description; Japan) [19]; Garrick and Paul 1971: 1–13 (revision, description, illustrated; Japan, New Zealand) [4]; Bass et al. 1976: 9, 10 (cited; Japan) [8]; Fourmanoir and Rivaton 1979: 436 (listed; Japan, New Zealand, Vanuatu) [5]; Compagno 1984: 61–62 (description, revision; Japan, New Zealand, Australia, Vanuatu) [14]; Shirai 1992: 1–125 (cited, listed, described; Japan, South Africa) [22]; Compagno and Niem 1998 (in part): 1203–1224 (listed, cited; Japan, New Zealand, Vanuatu, Australia) [77]; Compagno 1999: 472 (listed; West Indian, Central Pacific and North Atlantic Oceans) [78]; Yuanding and Qingwen 2001: 292–293 (listed; Northwest Pacific Ocean) [79]; Nakabo 2002: 155 (listed; Southern Japan, Ryukyu Islands, New Zealand) [80]; Compagno et al. 2005: 71–73 (revision; Pacific, Atlantic and Indian Oceans) [6]; Last et al. 2007: 1 (cited only) [24]; White et al. 2007: 19–30 (description; Japan, New Zealand, Australia, Taiwan, Vanuatu, Indonesia, Seychelles) [3]; Ebert 2013: 52–55 (cited, listed, revised; Japan, New Zealand, Australia, Hawaii, South Africa, Mozambique, Seychelles, St. Paul and Amsterdam Islands, Gulf of Mexico) [12]; Ebert et al. 2013: 74, 80–82 (cited, description; Pacific, Atlantic and Indian Oceans) [10]; Kempster et al. 2013: 1–4 (cited; Japan, Western and Southern Australia, Indonesia) [7]; Nakabo 2013: 194 (listed; Southern Japan, Ryukyu Islands, New Zealand) [81]; Ebert 2015: 54–56 (cited; South Africa) [11]; Duffy and Last 2015: 125–131 (description; New Zealand, Australia, Japan) [82]; Del Moral-Flores et al. 2015: 58 (listed, Seychelles, Mexico) [83].

Squalus (subgenus Cirrhigaleus): Garman 1913: 457 (description; Japan) [16]; Fowler 1941: 262 (description; Japan) [17].

Phaenopogon Herre, 1935: 121–124, Fig 1 (original description, illustrated; type species P. barbulifer by original designation and monotypy; unnecessary replacement name for Cirrhigaleus; Misaki Bay, Japan) [84]; Herre 1936: 59 (cited as synonym of Cirrhigaleus; Japan) [76].

Squalus: Fowler 1936: 69 (cited; Japan) [85]; Bass et al. 1976: 8–20 (revision, description; Japan, New Zealand, South Africa, Mozambique) [8]; Compagno 1984 (in part): 110, 114 (cited, description; Hawaiian Islands, Gulf of Mexico) [14].

Type species: Cirrhigaleus barbifer Tanaka, 1912 [1] by original designation and monotypy.

Diagnosis. A genus of the family Squalidae differing from Squalus by bearing nasal barbel in the anterior margin of nostrils that it is innervated by a branch buccopharyngeal of the facial nerve (VII) and internally supported by fleshy core. Cirrhigaleus is distinct from Squalus on lacking precaudal pits (vs. present in Squalus), spiracles placed dorsally above the eyes (vs. spiracles placed laterally behind the eyes), eyes with both anterior and posterior margins notched (vs. eyes with anterior margin concave and posterior margin notched), upper labial furrow very short with thick fold (vs. upper labial furrow large with thin fold), and origin of second dorsal fin over or just prior a vertical line traced at pelvic-fin free rear tips (vs. origin of second dorsal fin far behind a vertical line traced at pelvic-fin free rear tips). Cirrhigaleus also differs from Squalus by having dorsal-fin spines markedly elongate, transcending greatly dorsal-fin apexes (vs. dorsal-fin spine short, rarely transcending dorsal-fin apexes). Caudal fin of Cirrhigaleus exhibits continuous transition between upper and lower lobes at level of caudal fork, a condition distinct from Squalus (vs. discontinuous transition between upper and lower lobes). Cirrhigaleus body trihedral in cross-section, conspicuously arched dorsally and humped at belly, tail fusiform and short dorsal-caudal space (vs. body entirely fusiform from head to tail, inconspicuously arched dorsal and ventrally at belly, elongate dorsal-caudal space in Squalus). Cirrhigaleus species also show higher values of monospondylous vertebrae counts than Squalus species (47–53 for Cirrhigaleus vs. 37–50 for Squalus).

Geographical distribution. Cirrhigaleus occurs from the North to Southwestern Pacific Oceans, including waters off Japan, Indonesia, New Zealand and New Caledonia, and in the Western Indian Ocean from the Seychelles to South Africa and St. Paul Islands, as well as in the North and South Western Atlantic Oceans from the USA to Brazil (Fig 15).

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Fig 15. Map of the geographical distribution of Cirrhigaleus species.

Stars: type material; dots: other material; red symbols: C. barbifer; green symbols: C. australis; yellow symbols: C. asper.

https://doi.org/10.1371/journal.pone.0282597.g015

Remarks. Three valid species of barbel-bearing dogfishes of the genus Cirrhigaleus are here recognized: C. barbifer, C. asper and C. australis. They comprise benthic species that are often found on or near bottom of the outer continental shelves and mid-continental slopes in depths between 91–1103 meters. According to [6, 12], species are rarely caught off bays and river mouths.

Remarks.

Designation of the neotype of C. barbifer. Tanaka (1912) [1] described both genus and species based in a single mature male collected at the Tokyo Fish Market in Japan that was designated originally as type and deposited under the catalogue number 3397 in the Science College Museum in Tokyo (currently ZUMT). It is possible that the holotype came from the fish collection of Mr. A. Owston because Dr. S. Tanaka used to work on specimens collected or donated by him as it is provided in [1, 90–93]. Some authors (e.g., [17, 19]) made references to the illustration of the holotype provided in [1] rather than to the specimen itself. According to Dr. K. Sakamoto (ZUMT), the holotype is lost. No other specimen of C. barbifer exists at the ZUMT fish collection, according to verifications achieved personally by the first author of this manuscript, suggesting that the holotype no longer exists. Interestingly, there is no other specimen in the fish collections from Japan collected from the same locality as the type locality of C. barbifer, the Sagami Sea, provided in [1], which reject the possibility of the holotype to have been transferred to another collection in the past. A specimen of C. barbifer (SU 14171) that was also collected by Mr. A. Owston is available at CAS and it has same collecting data of those of the holotype of C. barbifer including collecting site and total length. However, this specimen is a mature female (not a mature male), according to D. Catania (CAS), which discards the possibility of being a missing holotype that ended up at CAS and received a new catalogue number by mistake on the accession and assignment of the specimen.

Cirrhigaleus barbifer has been regularly confused with C. australis in the South Pacific Ocean due to their morphological similarities regarding body size and shape, length of nasal barbels and dorsal-fin spines, and shape of dorsal and caudal fins as well as shape and size of dermal denticles. The characteristics provided in [1] for C. barbifer may also be applied to C. australis. [3] tentatively provided morphological diagnostic characters for separating these two nominal species but many of these (e.g., eye length, dorsal-caudal space, and vertebral counts) exhibited continuous range of values. These studies indicate clearly the difficulty to properly separate C. barbifer and C. australis. Moreover, instraspecific variations (ontogenetic and regional) observed here within C. barbifer reveal a more complex scenario behind the taxonomy of this nominal species because it obscures its morphological differentiation with congeners. Here, the neotype of C. barbifer (HUMZ 197852) is designated to clarify the taxonomic status of this species for better defining morphologically its local form and separating it effectively from C. australis. The neotype is held at Hokkaido University and it was collected off Kanaya, Gulf of Tokyo in Japan, which it is the locality nearest to the original type locality of C. barbifer. Following the requirements of International Code of Zoological Nomenclature (ICZN), diagnosis and description of this species are efficiently provided in our study, and the differentiation with closest related species (C. australis) are provided below based on characters of shape of dermal denticles, number of intermediate teeth, body colour, and length of nasal barbels.

Synonymy of C. barbifer. [84] described Phaenopogon Herre, 1935 [84] as a new genus and monotypic to include P. barbulifer Herre, 1935 [84]. This species was described based on a single specimen collected from Misaki Bay (Sagami Sea), Japan in 1906 by Mr. Alan Owston. This author did not take into account the previous study of [1] as he himself mentioned later in [76]. The characteristics provided in [84] are congruent with those observed for C. barbifer, including length and shape of nasal barbels, shape of dermal denticles, body colour, shape of fins and proportional external measurements. These observations indicate that P. barbulifer is junior synonym of C. barbifer, which is in agreement with [3, 14, 76].

Intraspecific variations. Origin of first dorsal fin is anterior or over a vertical line traced at pectoral-fin free rear tips in juveniles of C. barbifer while it is behind it in adults. First dorsal-fin spine length reaches up to half of first dorsal-fin height and never transcends first dorsal-fin apex in juveniles while first dorsal-fin spine length is over half of first dorsal-fin height and conspicuously transcends first-dorsal fin apex in adults. Second dorsal-fin spine is also smaller in juveniles (7.1%–7.5% TL) than in adults (7.6%–8.0% TL), reaching or mostly often transcending its second dorsal-fin apex in adults but not so often in juveniles. Nasal barbels exceed posterior margin of mouth in juveniles while in adults it reaches anterior margin of mouth or just before it, which it is in agreement with [4]. Height of first and second dorsal fins increases with growth (first dorsal-fin height 8.9%–10.0% TL in juveniles vs. 10.0%–10.8% TL in adults; second dorsal-fin height 8.8%–9.6% TL vs. 9.3%–10.5% TL, respectively). Other measurements that vary ontogenetically in the Japanese species are: pre-second dorsal length (60.8%–61.0% in juveniles vs. 62.0%–66.5% TL in adults); pre-vent length (52.5%–54.8% TL in juveniles vs. 54.4%–56.3% TL in adults; prespiracular length (9.5%–9.8% TL in juveniles vs. 9.7%–11.3% TL in adults); length of pelvic fin (12.2%–13.3% TL in juveniles vs. 13.1%–14.4% TL in adults).

External morphology of C. barbifer also varies regionally. Indonesian specimen has pectoral fins very narrow on its posterior margin (vs. broad in other specimens) and first dorsal fin conspicuously slender on its upper half (vs. conspicuously broad in other specimens). Indonesia/NC specimens show first dorsal-fin posterior margin straight (vs. concave in other specimens). Specimens from Japan have dorsal fins with posterior margin markedly concave (vs. mostly straight in Indonesia/NC). Regional variations are also observed for: length of pectoral fin (pectoral-fin inner margin length 8.3%–8.5% TL in Japan vs. 9.4%–9.5% TL in Indonesia/NC); head width at nostrils (6.4%–7.6% TL in Japan vs. 7.8%–7.9% TL Indonesia/NC); pre-branchial length (14.8%–16.2% TL in Japan vs. 18.9%–19.6% TL in Indonesia/NC); length of first dorsal-fin posterior margin (9.0%–10.9% TL in Japan vs. 12.1%–12.2% TL in Indonesia/NC). Other morphometric variations are noticed between specimens from Japan and Indonesia/NC, respectively: interdorsal space (21.9%–22.6% TL vs. 23.1%–24.5% TL); head length (18.8%–19.5% TL vs. 23.0% TL); length of first dorsal-fin anterior margin (13.5%–14.3% TL vs. 12.7%–12.9% TL); length of second dorsal-fin spine (7.1%–7.6% TL vs. 7.9%–8.0% TL); pelvic-fin length (12.2%–13.3% TL vs. 13.5%–14.4% TL) and inner margin length (5.4%–6.2% TL vs. 6.5%–6.9% TL). These variations may be due to the preservation conditions of the Indonesia/NC material but a more throughout taxonomic investigation should be considered in the future in order to clarify existing morphotypes in the region.

Cirrhigaleus asper (Merrett, 1973) [2].

Roughskin spurdog

Squalus asper Merrett, 1973: 93–110, Figs 1–6, pl. Ib (original description, illustrated; type by original designation; Seychelles) [2]; Bass et al. 1976: 2, 9–11, 18–20, 65, 59, Figs 8 and 12 (description; South Africa, Mozambique) [8]; Compagno 1984: 110, 114 (description; Seychelles, South Africa, Mozambique, Gulf of Mexico, Hawaiian islands) [14]; Bass et al. 1986: 60–61 (cited; South Africa) [94]; Shirai 1992: 8, 35, 106, 121 (listed, cited; South Africa) [22]; Baranes 2003: 42, 46, 48 (cited, Comores) [95]; Manilo and Bogorodsky 2003: 93, 128 (listed, cited; Arabian Sea) [96].

Cirrhigaleus asper Shirai, 1992: 121–122 (cited, listed; South Africa) [22]; Compagno 1999: 472 (listed) [78]; Soto 2001: 66 (listed; Brazil) [97]; Compagno 2002: 381–382 (listed, cited; North and Central Atlantic, West Indian Ocean) [98]; Gadig and Gomes 2003: 27 (listed; West Indian and Western Atlantic Oceans) [99]; Kiraly et al. 2003: 2, 12 (listed, cited; North Carolina to Florida, U.S.A., Puerto Rico, Virgin islands) [100]; Heemstra and Heemstra 2004: 54 (cited; Western Indian Ocean) [101]; Soto and Mincarone 2004: 73 (listed; Brazil) [102]; Mundy 2005: 24, 103 (listed, cited; Hawaii, USA) [103]; Compagno et al. 2005: 72, pl. 2 (description; Pacific, Atlantic and Indian Oceans) [6]; Fischer et al. 2006: 495–501 (cited, reproductive biology; Brazil) [104]; Nunan and Senna 2007: 169 (listed; Brazil) [105]; White et al. 2007: 19, 27 (cited; Western Indian Ocean) [3]; Gomes et al. 2010: 42, 43 (cited, description; Brazil) [9]; Naylor et al. 2012: 59, 148 (cited, listed; off Florida, USA) [15]; Ebert 2013: 53–55, 243 (listed, cited, described; South-western Indian Ocean) [12]; Ebert et al. 2013: 74, 81 (cited, description; Indian and Western Atlantic Oceans) [10]; Rosa and Gadig 2014: 93 (listed; Brazil) [106]; Ebert 2015: 55, 56 (cited, listed; South-eastern Atlantic Ocean) [11]; Del Moral-Flores et al. 2015: 58 (listed, Seychelles, Mexico) [83]; Compagno 2016: 1157 (cited only; North Atlantic and Western Indian Oceans) [107]; Weigmann 2016: 902 (cited, Western Indian, North-eastern Pacific, Western Atlantic Oceans) [88]; Ehemann et al. 2019: 4,7,9,12,13, (cited; Venezuela) [108]; Ebert et al 2021: 20–21 (listed; South Africa and Mozambique) [109]; Blanco-Parra and Niño-Torres 2022: 155, 161 (listed; Mexican Caribbean) [110].

Cyrrhigaleus asper: Menezes 2011: 4 (listed, misspelling; Brazil) [111].

Type material: BMNH 1972.10.10.1 (holotype), adult male, 880 mm TL, off Aldabra Island, Seychelles, Western Indian Ocean, 09°27’S,46°23.5’E, 219 meters depth; Collected by Royal Society Indian Ocean Deep Slope Fishing Expedition, 1969 on 10 February, 1969; BMNH 1972.10.10.2 (paratype), adult male, 847 mm TL, off Astove Island, Seychelles, Western Indian Ocean, 10°04’S,47°43’E, 329 meters depth, collected on 19 January, 1969; BMNH 1972.10.10.3 (paratype),adult female, 865 mm TL, off Farquhar Island, Seychelles, Western Indian Ocean, 10°10’S,51°12’E, 274 meters depth, collected on 24 January, 1969; BMNH 1972.10.10.4 (paratype), adult female, 1002 mm TL, off Assumption Island, Seychelles, Western Indian Ocean, 09°43’S,46°29’E, 600 meters depth, collected on 9 January, 1969. Paratypes with collector data same as holotype.

Type locality: Aldabra Island, Seychelles, Western Indian Ocean.

Other material examined (53 specimens): MNHN 1884–0149, two neonate males, 138–144 mm TL, St. Paul Island, 38°40’1"S,77°30’0"E; MNHN 1884–0151, embryos, less than 90 mm TL, same locality as MNHN 1884–0149; MNHN 1959–0067, embryo male, 107 mm TL, same locality as MNHN 1884–0149; MNHN 1964–0001, neonate male, 207 mm TL, Amsterdam Island, 37°55’1"S,77°40’1"E; MNHN 1964–0003, neonate male, 253 mm TL, same locality as MNHN 1964–0001; MNHN 1986–0722, adult female, 760 mm TL, Comores, 12°0’0"S,43°25’1"E; MNRJ 30227, adult male, 970 mm TL, off Bahia coast, Brazil, 13°40’45"S,38°25’36"W; MNRJ 30228, adult male, 970 mm TL, same locality as MNRJ 30227; NUPEC uncatalogued, two adult females, 1270–1300 mm TL, unknown locality, Brazil; SAIAB 6036, juvenile male, 390 mm TL, unknown locality, South Africa; SAIAB 6037, juvenile female, 380 mm TL, off Kwazulu-Natal, South Africa, 29°53’36.58"S,31°29’46.68"E; SAIAB 6038, juvenile female, 320 mm TL, same locality as SAIAB 6037; SAIAB 6040, adult female, 1120 mm TL, Amatikulu, South Africa, 29.04°S,31.53°E; SAIAB 6092, juvenile female, 275 mm TL; neonate male, 270 mm TL, unknown locality, South Africa; SAIAB 25423, adult female, 1110 mm TL, off Coffee Bay, South Africa, 31.98°S,29.14°E; SAIAB 27027, adult female, 1090 mm TL, Kowie River mouth, Port Alfred, South Africa, 33°36’9.83"S,26°54’6.37"E; SAIAB 31890, adult female, 1090 mm TL, off Gonubie, South Africa, 32°57’25.29"S,28°01’46.26"E; SAIAB 186460, juvenile female, 456 mm TL, off Durban, South Africa, 30.00°S,31.15°E; SAM 38268, nine neonate females, 132–145 mm TL, seven neonate males, 130–137 mm TL, off Coffee Bay, Transkei, South Africa, 31°59’2.59"S,29°09’42.48"E; SAM 39879, adult female, 1023 mm TL, Gulf of Mexico, 27°6’16.12"N,88°8’36.41"W; UERJ 1641, adult male, 990 mm TL, off Rio de Janeiro, Brazil, 23°9’55.29"S,43°1’16.34"W; USNM 220585, juvenile male, 245 mm TL, off Venezuela coast, 11°9.8’N,69°5’W; USNM 217364, adult female, 1000 mm TL, Texas, U.S.A., 27.7°N,94.27°W; NMNZ P 39849, adult female, 1140 mm TL, Desoto Canyon, Louisiana, USA, 28°17’N,92°11’W; NMNZ P 39850, adult female, 1100 mm TL, Desoto Canyon, Louisiana, USA, 27°13’N,91°42’W; Uncatalogued specimen (field number 227CAS0218), adult female, 1068mm TL, Pernambuco coast, Brazil, 8°10’19.4"S, 34°33’57.7"W, 233m depth; Uncatalogued specimen (field number 161CAS1016), juvenile female, 578 mm TL, Pernambuco coast, Brazil, 8°35’52.2"S, 34°42’50.8"W, 411m depth; Uncatalogued specimen (field number 114CAS1115), juvenile male, 945 mm TL, Pernambuco coast, Brazil, 7°49’30.2"S, 34°27’33.0"W, 338m depth; Uncatalogued specimen (field number 121CAS0716), juvenile male, 880mm TL, Pernambuco coast, Brazil, 8°51’15.6"S, 34°46’45.0"W, 500m depth; Uncatalogued specimen (not retained, field number 230CAS0218), juvenile female, 851mm TL, Pernambuco coast, Brazil, 8°10’9.7"S, 34°33’54.1"W, 229m depth; Uncatalogued specimen (not retained, field number 210CAS0118), juvenile female, 880mm TL, Pernambuco coast, Brazil, 8°12’20.9"S, 34°34’42.4"W, 313m depth; Uncatalogued specimen (not retained, field number 213CAS0118), juvenile male, 842mm TL, Pernambuco coast, Brazil, 8°12’20.9"S, 34°34’42.4"W, 313m depth; Uncatalogued specimen (not retained, field number 229CAS0218), adult male, 964mm TL, Pernambuco coast, Brazil, 8°10’19.4"S, 34°33’57.7"W, 233m depth; Uncatalogued specimen (not retained, field number 208CAS0118), adult male, 985mm TL, Pernambuco coast, Brazil, 8°12’20.9"S, 34°34’42.4"W, 313m depth.

Diagnosis. Cirrhigaleus asper is easily distinguished from its congeners by having anterior margin of nostrils conspicuously short, its length 1.0%–1.5% TL and non moustache-like, never reaching the mouth (vs. 5.4%–6.4% TL in C. barbifer vs. 4.4%–6.2% TL in C. australis, moustache-like and reaching the mouth), and body brown in colour when preserved (vs. dark grey in C. barbifer vs. light grey in C. australis). It differs from C. barbifer and C. australis by larger upper labial furrow, its length 1.4%–2.1% TL (vs. 1.1%-1.5% TL for C. barbifer vs. 0.9%–1.4% TL for C. australis), shorter pelvic fins, its length 10.8%–12.7% TL (vs. 13.1%–14.4% TL in C. barbifer vs. 11.9%–14.8% TL in C. australis), and lower second dorsal fin, its height 3.9%–9.3% TL (vs. 9.3%–10.5% TL in C. barbifer vs. 8.4%–9.9% TL for C. australis). It is also separated from its congeners by having dermal denticles heart-shaped (vs. bat-like), median ridge conspicuously broad (vs. median ridge very narrow) and lateral cusps inconspicuous at posterior margin of crown (vs. lateral cusps conspicuous) (Fig 21).

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Fig 21. Specimens of C. asper in lateral view.

A: BMNH 1972.10.10.1 (holotype), adult male, 880 mm TL, Seychelles; B: SAIAB 6092, juvenile female, 275 mm TL, South Africa; C: USNM 220585, juvenile male, 245 mm TL, the U.S.A. Scale bars: 50 mm.

https://doi.org/10.1371/journal.pone.0282597.g021

Description. Morphometric and meristic data are shown in Table 2 and S3 and S4 Tables.

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Table 2. External measurements of C. asper expressed as percentage of total length (%TL).

https://doi.org/10.1371/journal.pone.0282597.t002

External morphology. Body trihedral, stout and robust, conspicuously arched dorsally from anterior margin of spiracle to pelvic fin insertion, turning more slender to the tail (Fig 21); body with greatest width at head than at trunk and abdomen; head width 1.5 (0.6–1.5) times greater than trunk width and 1.8 (0.7–1.8) times wider than abdomen width; body equally deep from head to abdomen with head height 0.9 (0.7–1.2) times trunk height and 0.9 (0.6–1.3) times abdomen height. Head flattened anteriorly and elongate, its length 22.4% (19.7%–24.3%) TL; head narrower at nostrils than at mouth (its width at nostrils 7.7%, 6.0%–10.2% TL; width at mouth 12.5%, 10.8%–13.4% TL). Eyes markedly elliptical with anterior and posterior margins notched; eyes conspicuously large, its length 4.5% (2.0%–6.0%) TL, corresponding to 5.8 (1.7–6.0) times greater than its height. Prespiracular length 0.5 (0.5–07) times prepectoral length and 1.7 (1.5–1.8) times preorbital length. Spiracles crescent, located posteriorly and above the eyes; spiracles conspicuously large, its length 0.3 (0.2–0.7) times eye length. Gill slit somewhat concave, vertical and markedly tall with fifth gill slit 1.1 (0.8–1.4) times higher than first gill slit.

Snout rounded and short with preorbital length 6.5% (5.9%–8.4%) TL; nostrils equally distant to snout tip and mouth with prenarial length 0.9 (0.8–1.2) times distance from nostrils to upper labial furrow and 0.5 (0.5–0.6) times preoral length; nostrils with anterior margin bilobate and markedly broad; medial lobe of anterior margin larger than lateral one, although not moustache-like and elongate; anterior nasal flap with its length 1.5% (1.0%–2.4%) TL, corresponding to 14.7 (9.6–22.5) times smaller than head length. Mouth arched and broad (its width 8.1%, 7.4%–9.2% TL); upper labial furrow markedly small, its length 1.6% (1.0%–2.8%) TL with a small and thick fold; lower labial furrow also small, without fold. Teeth similar in both jaws, labial-lingually flattened, very broad but low at the crown (Fig 22); lower teeth larger than upper teeth; teeth unicuspid with cusp thick and large, somewhat upright and lateral; mesial cutting edge straight and diagonal; distal heel rounded; mesial heel pointed; apron very short and narrow. Three series of functional teeth on both jaws; upper jaw with 14–14 (13–13) teeth rows; lower jaw with 12–12 (12–11) teeth rows.

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Fig 22. Upper teeth (labial view) of the paratype of C. asper, BMNH 1972.10.10.2, adult male, 847 mm TL.

https://doi.org/10.1371/journal.pone.0282597.g022

Dorsal fins conspicuously upright and vertical (Fig 23), both equally tall with first dorsal fin height 1.0 (0.9–2.1) times height of second dorsal fin; first dorsal fin as large as second dorsal fin, its length 1.0 (0.9–1.5) times length of second dorsal fin. Origin of the first dorsal fin located behind the vertical traced at pectoral free rear tips, although near to it in most specimens. First dorsal fin with anterior margin convex and large, its length 13.7% (10.8%–14.5%) TL; first dorsal-fin posterior margin straight and large, its length 10.1% (6.9%–11.8%) TL; first dorsal-fin apex narrow and free rear tip pointed; first dorsal fin conspicuously tall, its height 1.3 (1.0–1.5) times greater than preorbital length and 1.6 (1.4–2.1) times greater than inner margin length of first dorsal fin. First dorsal-fin spine thick (its base width 1.1%, 0.6%–1.5% TL) and markedly elongate, its length 5.7% (1.9%–7.6%) of TL; first dorsal-fin spine not reaching the fin apex, its length 0.7 (0.2–0.8) times height of first dorsal.

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Fig 23.

First (A) and second (B) dorsal fins of C. asper. A,B: BMNH 1972.10.10.1, adult male, 880 mm TL. Scale bars: 20 mm.

https://doi.org/10.1371/journal.pone.0282597.g023

Interdorsal space almost equal to prepectoral length, corresponding to 1.1 (0.8–1.6) times the latter and 2.4 (2.0–3.0) times larger than dorsal-caudal space. Origin of second dorsal fin over vertical traced at free rear tips of pelvic fins. Second dorsal fin with anterior margin convex and large, its length 13.9% (7.8%–14.5%) TL; second dorsal-fin posterior margin markedly falcate and elongate, its length 6.9% (3.9%–8.0%) TL; second dorsal-fin apex conspicuously slender and lobe-like, and free rear tip pointed. Second dorsal-fin spine thick (its base width 1.0%, 0.8%–1.2% TL), and elongate, its length 7.3% (3.4%–7.6%) TL and not reaching second dorsal-fin apex with its length 0.9 (0.4–1.4) times height of second dorsal fin; second dorsal-fin spine slightly larger than first one (its length 1.3, 0.6–2.2 times length of first dorsal spine).

Pectoral fin conspicuously wide distally and square-like (Fig 24A); pectoral-fin anterior margin convex and elongate, its length 1.7 (1.2–1.9) times larger than pectoral-fin inner margin length, and corresponding at least to one-half the distance between pectoral and pelvic fins; pectoral-fin inner margin markedly convex; pectoral-fin posterior margin straight and large, its length 10.5% (8.7%–12.9%) TL; apex and free rear tip of pectoral fins conspicuously rounded and broad, not lobe-like and almost reaching the same length. Pectoral-pelvic distance 1.1 (0.7–1.5) times pelvic-caudal space; the latter 1.0 (0.8–1.3) times interdorsal space. Pelvic fins in the midline between first and second dorsal fin, although nearest to second dorsal fin in some paratypes and non-type specimens. Pelvic fins markedly broad with anterior margin somewhat convex (Fig 24B), posterior margin straight; pelvic-fin apex rounded and conspicuously wide, and free rear tips rounded and lobulated, although more slender in males.

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Fig 24.

Pectoral (A), pelvic (B) and caudal (C) fins of the paratype of C. asper in ventral (A,B) and lateral views (C). A,B: BMNH 1972.10.10.3, adult female, 865 mm TL; C: BMNH 1972.10.10.1, adult male, 880 mm TL. Scale bars: 20 mm.

https://doi.org/10.1371/journal.pone.0282597.g024

Claspers in adults slender and flattened ventrally (Fig 25); claspers very short its inner length 1.1, (0.4–1.2) times pelvic inner margin length, transcending pelvic free rear tips; clasper groove very large, vertical, placed dorsally; apopyle and hypopyle with narrow apertures, located proximal and distally in the clasper groove, respectively; rhipidion flap-like, markedly narrow and short (not reaches distal end of clasper), attached mediodistally to clasper.

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Fig 25. Clasper (right side) of the paratype of C. asper, BMNH 1972.10.10.2, adult male, 847 mm TL in dorsal view.

Abbreviations: ap: apopyle; cg: clasper groove; hp: hypopyle; p2: pelvic fin; rh: rhipidion.

https://doi.org/10.1371/journal.pone.0282597.g025

Caudal peduncle very short with dorsal-caudal space 9.5% (7.4%–10.8%) TL with lateral keel prominent and thick since insertion of second dorsal fin to behind origin of caudal fin; upper and lower precaudal pits absent. Caudal fin (Fig 24C) rather rectangular with dorsal caudal margin convex anteriorly and turning straight until the dorsal caudal tip; length of dorsal caudal margin 0.9 (0.8–1.0) times head length and 1.7 (1.7–3.2) times larger than length of preventral caudal margin; dorsal caudal tip pointed; upper post-ventral caudal margin concave, although straight near the dorsal caudal tip; lower post-ventral caudal margin straight; preventral caudal margin convex and short, its length 1.8 (1.4–3.1) times larger than inner length of pelvic fin; caudal fin slightly continuous between lobes and markedly broad at fork, its width 7.8% (6.8%–13.0%) TL.

Dermal denticles. Dermal denticles tricuspid and heart-shaped (Fig 12I–12L), conspicuously broad at the crown and imbricated; denticles with its width as large as its length; median cusp prominent, pointed and elongate; lateral cusps very short to inconspicuous; median ridge straight, tall, short, markedly thick anteriorly and thin posteriorly; conspicuous anterior furrow and often two small ridges on each side; median ridge projecting anteriorly beyond the crown base; one or two lateral ridges on each side, straight to slightly convex, tall and short, reaching the tip of crown edge; lateral furrow very profound and wide, placed aside each lateral ridge.

Colouration. In fresh material (Fig 26), body light grey dorsally and laterally up to the origin of pectoral fin, light grey laterally, and white ventrally. Pectoral and pelvic fins grey dorsally and whitish ventrally with light grey blotches at the edges and posterior margins white. Dorsal fins light grey and dark grey at the base of the dorsal-fin spines; dorsal-fin posterior margin broadly white from apex to free rear tips; submarginal bar broadly black. Dorsal-fin spines brownish grey, whitish at the tip. Caudal fin light grey, whitish at the vertebral column region; postventral caudal margins white with ventral caudal tip broadly white; upper caudal blotch broadly black; lower subterminal bar broadly black at the lower caudal lobe. In preserved specimens, body brownish-grey dorsally and white ventrally; pectoral, pelvic, dorsal and caudal fins darker than the rest of the body. Pectoral fins with inner and posterior margins homogenously white. Pelvic fins pale ventrally with inner and posterior margins broadly white. Dorsal fins with posterior margins broadly white from apex to free rear tips; dorsal fins lighter at the fin base near the dorsal-fin spine. Dorsal-fin spines brown, whitish at its base and tip. Caudal fin also brown with white postventral caudal margins, except at the dorsal caudal tip; ventral caudal tip broadly white; dorsal caudal margin white, except near the dorsal caudal tip; ventral caudal lobe with white basal marking; caudal stripe light brown.

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Fig 26.

Fresh specimen of C. asper in lateral (A) and ventral (B) views, SAIAB 186460, juvenile female, 456 mm TL, South Africa. Reprinted from NRF-SAIAB under a CC BY license, with permission NRF-SAIAB, 2010.

https://doi.org/10.1371/journal.pone.0282597.g026

Vertebral counts. Monospondylous vertebrae 52 (49–52); precaudal vertebrae 87 (85–90); total vertebrae 116 (115–119).

Geographical distribution. It occurs in the Western Indian Ocean (Seychelles to South Africa and south to St. Paul Islands) and Western Atlantic Ocean (Texas, USA to Rio de Janeiro, Brazil), including the Caribbean Sea (Venezuela [108] and Mexico [110]). Cirrhigaleus asper is often caught between 91–750 meters depth. Its occurrence in Hawaii, USA is not confirmed as material from this region was not assessed in the present study (Fig 15).

Cirrhigaleus australis White, Last & Stevens, 2007 [3].

Southern Mandarin dogfish

Cirrhigaleus barbifer: Garrick and Paul 1971 (in part): 1–13 (revision, description, illustrated; New Zealand) [4]; Last and Stevens 1994 (in part): 48, 68 (cited, description; New Zealand) [112]; Compagno and Niem 1998 (in part): 1203–1224 (listed, cited, illustrated; New Zealand) [77]; Nakabo 2002: 155 (listed; Southern Japan, Ryukyu Islands) [80]; Compagno et al. 2005 (in part): 73 (description; New Zealand) [6]; White et al. 2006: 66, 319 (cited, listed, illustrated; New Zealand) [86]; Nakabo 2013: 194 (listed; New Zealand) [81].

Squalus barbifer: Fourmanoir and Rivaton 1979 (in part): 436 (listed; New Zealand) [5].

Cirrhigaleus australis White, Last and Stevens, 2007: 19–30 (original description, illustrated; type by original designation; off Bicheno, Tasmania, Australia, New Zealand) [3]; Ebert 2013: 53–54 (listed, cited; Australia, New Zealand) [12]; Naylor et al. 2012: 59 (cited; Australia, New Zealand) [15]; Ebert et al. 2013: 74, 81 (cited, description; Southwest Pacific Ocean) [10]; Kempster et al. 2013: 1–4 (cited; Southern Australia) [7]; Yang et al. 2014: 1–2 (cited; Australia, New Zealand) [113]; Duffy and Last 2015: 125, 127 (listed, description; Australia, New Zealand) [82]; Weigmann 2016: 902 (listed; South-western Pacific Ocean) [88].

Type material. CSIRO H 5789–01 (holotype), adult female, 970 mm TL, East of Bicheno, Tasmania, Australia, 41°55’S,148°37’E, 360–414 meters depth. Collected on 18 May 2002 by unknown commercial fishermen; AMS I 19154–001 (paratype), juvenile female, 705 mm TL, off Brush Island, New South Wales, Australia, 35°34’S,150°45’E, 493 meters depth, collected on 6 July 1976 aboard F.R.V. Kapala; AMS I 27022–001 (paratype), adult female, 1205 mm TL, Northeast of Sydney, New South Wales, Australia, 33°00’S,152°00’E, 640 meters depth, collected on March 1986 by Ian Ross aboard R/V Vincenzann; AMS I 42891–001 (paratype), adult female, 1085 mm TL, Southeast of Green Cape, New South Wales, Australia, 37°30’S,150°30’E, 400 meters depth, collected on 3 November 2003 by R. “Smokey” Fanthan aboard R/V Catherine J.

Type locality: Bicheno, Tasmania, Australia.

Other material examined (27 specimens): AMS I 45670–001, juvenile male, 630 mm TL, Britannia Seamount, New South Wales, Australia, 28°22’S,155°37’E; CSIRO H 7042–01, juvenile male, 510 mm TL, Browns Mount, New South Wales, Australia, 34°02’S,151°39’E; CSIRO H 7042–02, juvenile female, 639 mm TL, locality same as CSIRO 7042–01; CSIRO H 7042–03, juvenile female, 634 mm TL, locality same as CSIRO 7042–01; CSIRO H 7042–04, juvenile female, 605 mm TL, locality same as CSIRO 7042–01; CSIRO H 7048–01, adult male, 993 mm TL, east of Tweed Heads, New South Wales, Australia, 28°17’S,153°53’E; CSIRO H 7064–01, juvenile female, 705 mm TL, Northeast of Yamba, New South Wales, Australia, 29°11’S,153°52’E; NMNZ P 5105, juvenile female, 930 mm TL, between Mayor and White Islands, North Island, New Zealand, 37°25’S,176°40’E; NMNZ P 5163, adult female, 1045 mm TL, 10 miles off White Island, North Island, New Zealand, 37°22.32’S,177°12.83’E; NMNZ P 5204, adult female, 1195 mm TL, off Mayor Island, North Island, New Zealand, 37°35’S,176°40’E; NMNZ P 5205, five neonate females, 80–87 mm TL; four neonate males, 83–85 mm TL, same locality as NMNZ P 5204; NMNZ P 7366, adult female, 1272 mm TL, Mayor Island, North Island, New Zealand, 37°20’S,176°20’E; NMNZ P 7367, adult female, 1230 mm TL, Mayor Island, North Island, New Zealand, 37°19’S,176°15’E; NMNZ P 7681, adult male, 1040 mm TL, Tauranga, North Island, New Zealand, 37°41’S,176°10’E; NMNZ P 8030, adult male, 980 mm TL, South Auckland, North Island, New Zealand, 37°39’S,176°13.5’E; NMNZ P 17635, adult female, 866 mm TL, Hikurangi Trough, Hawke’s Bay, North Island, New Zealand, 39°58.65’S,178°8.20’E; NMNZ P 28732, two adult females, 1128–1189 mm TL, New Zealand; NMNZ P 34452, adult male, 990 mm TL, Kermadec Islands, New Zealand, 28°50.80’S,177°50.400’W; NMNZ P 34817, juvenile male, 790 mm TL, Kermadec Islands, New Zealand, 33°4.900’S,179°34.300’W; NMNZ P 34821, adult male, 971 mm TL, Kermadec Islands, New Zealand, 32°23.40’S,179°13.60’W; NMNZ P 38074, adult male, 1020 mm TL, Southern Norfolk Ridge, New Zealand, 32°40’S,167°37’W; NMNZ P 42489, juvenile male, 710 mm TL, Tony B Seamount, West of Norfolk Ridge, New Zealand, 34°31.850’S,168°47.500’E; NMNZ P 42734, adult female, 1110 mm TL, off “The Faces”, Kaikoura, New Zealand, 42°28’S,173°46’E; NMNZ P 43052, neonate female, 77 mm TL, same locality as NMNZ P 5204; NMNZ P 46806, juvenile female, 760 mm TL, Three King Islands, Southwest Norfolk Ridge, New Zealand, 34°36.700’S,168°56.300’E.

Diagnosis. Cirrhigaleus australis is distinguished from its congeners by having body light grey dorsally in preserved material (vs. dark grey in C. barbifer vs. brown in C. asper). It is clearly distinct from C. asper by having nasal barbel moustache-like and conspicuously elongate, its length 4.4%–6.2% TL, usually reaching the mouth (vs. nasal barbel non moustache-like and conspicuously short, its length 1.0%–1.5% TL, never reaching the mouth in C. asper), and dermal denticles bat-like with narrow median ridge (vs. heart-shaped with broad median ridge in C. asper). It further differs from C. asper by smaller length of upper labial furrow, its length 0.9%–1.4% TL (vs. 1.4%–2.1% TL). Cirrhigaleus australis is separated from C. barbifer by having teeth with narrow apron (vs. broad in C. barbifer), and dermal denticles with one cusplet lateral-posteriorly on each side (vs. two cusplets in C. barbifer) (Fig 27).

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Fig 27. Cirrhigaleus australis in lateral view.

A: CSIRO H 7042–04, juvenile female, 605 mm TL, Australia; B: NMNZ P 34821, adult male, 971 mm TL, New Zealand.

https://doi.org/10.1371/journal.pone.0282597.g027

Description. Morphometric and meristic data are shown in Table 3 and S3 and S4 Tables.

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Table 3. External measurements of C. australis expressed as percentage of total length (%TL).

https://doi.org/10.1371/journal.pone.0282597.t003

External morphology. Body trihedral, strongly robust and humped in all its extension, conspicuously arched from posterior margin of the eye to pelvic fin insertion with belly noticeable ventrally (more slender when juveniles than in adults); body equally wide from head to abdomen with head width 1.0 (0.9–1.2) times trunk width, and 1.0 (1.0–2.1) times abdomen width; body deepest at trunk and abdomen with head height 0.7 (0.6–1.5) times trunk height, and 0.7 (0.7–1.5) times abdomen height. Head very small, its length 20.0% (18.2%–23.1%) TL, flattened and narrow anteriorly, humped and broader posteriorly near the mouth; head width at nostrils 7.1% (6.4%–7.7%) TL, and at mouth 11.8% (10.4%–13.6%) TL. Eyes oval and elongate, its length 3.3% (3.1%–4.6%) TL and corresponding to 2.1 (2.1–5.5) times its height; anterior margin of eye convex, posterior margin slightly notched, prominent dorsally. Spiracles crescent and wide, its length 0.8 (0.8–1.8) times eyes height, placed lateral-posteriorly and above the eyes. Gill slits vertical and slightly concave, tall with height of fifth gill slit 2.3% (1.9%–2.7%) TL, corresponding to 1.3 (0.9–1.4) times first gill slit height. Snout very short, preorbital length 6.5% (5.8%–7.2%) TL and conspicuously rounded at the tip; nostrils equally near to snout tip and upper labial furrow, its prenarial length 0.9 (0.9–1.4) times distance from nostrils to upper labial furrow; anterior nasal flap bilobate with second lobe markedly elongate and moustache-like as nasal barbels, reaching anterior margin of mouth in adults (young specimens have nasal barbels markedly beyond posterior margin of the mouth); anterior nasal flap length 5.0% (4.4%–7.1%) TL, corresponding to 4.0 (2.6–5.1) times in head length.

Short distance from mouth to snout tip, preoral length 7.3% (6.9%–8.6%) TL. Mouth strongly arched and wide, its width 1.9 (1.6–2.0) times prenarial length, and 2.2 (1.8–2.3) times broader than internarial space. Upper labial furrow markedly short, its length 0.9% (0.9%–1.6%) TL, with thick fold; lower labial furrow elongate, lacking a fold. Teeth similar in both jaws, compressed labial-lingually, conspicuously broad and low (Fig 28); teeth of upper jaw much smaller than those of lower jaw; teeth unicuspid with cusp pointed, thin, cylindrical and short, directed laterally; mesial cutting edge somewhat convex, although diagonally; mesial and distal heels rounded; apron narrow and short, larger on lower teeth than upper teeth. Three series of functional teeth on both jaws; upper jaw with 12–12 (13–13) teeth rows; lower jaw with 10–10 (11–11) teeth rows.

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Fig 28.

Upper (A) and lower (B) teeth (labial view) of C. australis, AMS I 45670–001, juvenile male, 630 mm TL. Scale bars: 1 mm.

https://doi.org/10.1371/journal.pone.0282597.g028

Dorsal fins conspicuously upright and vertical, both equally tall with first dorsal fin height 1.0 (0.9–1.2) times height of second dorsal fin; first dorsal fin as large as second dorsal fin, its length 1.0 (0.9–1.2) times length of second dorsal fin. Origin of first dorsal fin beyond vertical traced at the pectoral-fin free rear tips in adults. First dorsal fin markedly slender at fin web, apex rounded, and broad on its base, base length 8.4% (7.7%–9.8%) TL; first dorsal-fin anterior margin convex, raked and large, its length 12.2% (11.7%–14.6%) TL; first dorsal-fin posterior margin concave and elongate, its length 10.6% (9.0%–11.9%) TL; first dorsal-fin inner margin short, its length 6.3% (4.9%–6.8%) TL with pointed free rear tip; first dorsal fin height 1.6 (1.4–2.0) times greater than first dorsal-fin inner margin length, and 1.5 (1.3–1.9) times preorbital length (Fig 29). First dorsal-fin spine straight, markedly elongate, although never reaching the fin apex, its length 5.7% (3.1%–6.8%) TL, corresponding to two-fourth the height of first dorsal fin. Interdorsal distance 1.2 (1.0–1.3) times pre-pectoral length, and 3.0 (2.3–3.5) times greater than dorsal-caudal space.

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Fig 29.

First (A,B) and second (C,D) dorsal fins of C. australis. A,C: AMS I 42891–001 (paratype), adult female, 1085 mm TL, Australia; B,D: NMNZ P 28732, adult female, 1189 mm TL, New Zealand. Scale bars: 20 mm.

https://doi.org/10.1371/journal.pone.0282597.g029

Origin of second dorsal fin posterior to vertical traced at pelvic-fin free rear tips. Second dorsal fin slender at the fin web, apex rounded and lobulate, broad at its base, base length 9.6% (9.0%–10.5%) TL; second dorsal-fin anterior margin convex and large, its length 14.2% (13.5%–14.9%) TL; second dorsal-fin posterior margin strongly concave, falcate (half-moon shaped in juveniles); second dorsal-fin height 1.7 (1.5–2.2) times greater than second dorsal-fin inner margin length; second dorsal-fin inner margin also short, its length 5.5% (4.4%–6.3%) TL. Second dorsal-fin spine convex and broad, its base width 1.1% (0.8%–1.3%) TL, conspicuously elongate, its length 6.4% (4.4%–9.3%) TL; second dorsal-fin spine corresponding to 1.1 (0.7–2.1) times length of first dorsal-fin spine and three-forth the height of second dorsal fin, exceeding the fin apex in juveniles only.

Pectoral fins narrow (Fig 30A), although broader posteriorly than anteriorly, its base length 5.0%, (4.4%–5.8%) TL; pectoral-fin anterior and inner margins markedly convex; pectoral-fin posterior margin slightly concave, its length never greater than the trunk height when adpressed laterally, corresponding to 0.6 (0.6–1.7) times trunk height; pectoral-fin apex and free rear tips rounded and wide (sometimes lobulate in paratypes) with apex transcending horizontal line traced at pectoral-fin free rear tip; pectoral-fin anterior margin length 1.5 (1.2–1.9) times pectoral-fin posterior margin length, and 1.8 (1.6–2.0) times pectoral-fin inner margin length.

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Fig 30.

Pectoral (A), pelvic (B) and caudal (C) fins of C. australis (NMNZ P 28732, adult female, 1189 mm TL) in ventral (A,B) and lateral (C) views. Scale bars: 20 mm.

https://doi.org/10.1371/journal.pone.0282597.g030

Pelvic fins (Fig 30B) nearest to second dorsal fin than first dorsal fin; length of pelvic fin 1.7 (1.6–2.1) times interdorsal space. Pelvic fins conspicuously broad and pentagonal; pelvic-fin anterior margin slightly convex; pelvic-fin inner margin straight; pelvic-fin posterior margin somewhat concave; pelvic-fin apex markedly rounded; pelvic-fin free rear tips triangular and lobe-like; pelvic length 1.1 (1.0–1.5) times length of preventral caudal margin. Claspers (Fig 31) in adults flattened ventrally and markedly wide, narrower distally; claspers very short its inner length 0.5–1.3 times pelvic inner margin length, exceeding pelvic-fin free rear tips; clasper groove elongate, vertical, placed dorsally; apopyle with narrow aperture, located anteriorly in the clasper groove; hypopyle with broad aperture, placed distally in the clasper groove, prior to the rhipidion; rhipidion flap-like, slender and large, attached mediodistally to clasper.

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Fig 31. Clasper (left side) of C. australis, NMNZ P 38074, adult male, 1020 mm TL in dorsal view.

Abbreviations: ap: apopyle; cg: clasper groove; hp: hypopyle; p2: pelvic fin; rh: rhipidion. Scale bar: 20 mm.

https://doi.org/10.1371/journal.pone.0282597.g031

Pelvic-caudal space 0.9 (0.8–1.0) times interdorsal space. Caudal peduncle thick in cross-section and conspicuously short with dorsal-caudal distance 7.5% (6.9%–9.1%) TL, corresponding to 3.0 (2.3–3.5) times smaller than interdorsal space; lateral precaudal keel prominent almost as a fold, since second dorsal fin insertion to backwards origin of caudal fin; upper and lower precaudal pits absent. Caudal fin (Fig 30C) conspicuously rectangular; dorsal caudal margin straight and elongate, its length 1.1 (0.9–1.2) times head length and 1.8 (1.7–2.2) times greater than length of preventral caudal margin; dorsal caudal tip rounded; upper post-ventral caudal margin convex, although evidently straight proximally; lower post-ventral caudal margin convex; preventral caudal margin somewhat straight and small, its length 2.0 (1.3–2.3) times greater than length of pelvic-fin inner margin; ventral caudal tip rounded; transition between upper and lower caudal lobes continuous; caudal fork markedly broad, its width 7.6% (7.2%–8.6%) TL.

Dermal denticles. Dermal denticles (Fig 12D–12H) tricuspid and bat-like, imbricate, large and conspicuously broad at the crown; dermal denticles with its width equivalent to its length; cusps pointed and located posteriorly at the crown margin; median cusp much larger than lateral ones; median ridge elongate, thin, tall and straight, slightly transcending anterior base of crown; lateral ridges thin, short and low, markedly convex proximally; median furrow small and shallow, placed proximally over median ridge; lateral furrow short and deep, located aside each lateral ridge; one secondary cusp (or cusplet) sometimes present on each side of posterior margin of the crown; cusplets much smaller than median cusp.

Colouration. Body light grey dorsal and laterally, white ventrally (Fig 27). Nasal barbels white, and slightly grey lateral-proximally. First dorsal fin dark grey with posterior margin broadly white from its apex to free rear tip, submarginal bar light grey, white spots in the anterior margin near its apex. Second dorsal fin dark grey with posterior margin broadly white until its midline, and submarginal bar light grey. Dorsal-fin spines white, greyish proximal and distally, although whitish at the tips. Pectoral fins grey dorsally and light grey ventrally, with both inner and posterior margins discreetly whitish at the edge. Pelvic fins also grey, lighter ventrally, with posterior margin sparsely whitish. Caudal fin dark grey, whitish medially; post-ventral caudal margins white but not uniform, broadly white in the dorsal and ventral caudal tips; subterminal bar blackish; black caudal stripe absent. In recent collected specimens, large dark grey blotches are observed ventrally in both pectoral and pelvic fins.

Vertebral counts. Monospondylous vertebrae 51 (49–53); precaudal vertebrae 85 (85–90); total vertebrae 117 (113–119).

Geographical distribution. Cirrhigaleus australis occurs in the South-western Pacific Ocean and it is endemic to New Zealand and Southern Australia from Tweed Heads in New South Wales to Tasmania. It is caught between 91–1103 meters depth, and more often between 540–580 meters (Fig 15).

Remarks.

Intraspecific variations. Snout and nasal barbels are smaller in adults than in juveniles of C. australis from Australia (AUS) but not in the New Zealand (NZ) population (prenarial length 3.9%–4.2% TL for adults vs. 4.5%–4.9% TL for juveniles; length of anterior margin of nostrils 4.4%–5.3% TL for adults vs. 5.9%–7.1% TL for juveniles). Clasper length also varies with maturity in both populations (clasper outer length 1.2%–1.5% TL for juveniles vs. 4.4% in adults for AUS; 3.7%–10.0% and 1.2%–1.7% for NZ, respectively; clasper inner length 3.5%–3.9% TL in juveniles vs. 7.2% TL in adults for AUS; 4.3%–8.8% and 3.2%–3.6% for NZ). Other variations are observed here for the first time, including position of origin of first dorsal fin varies from over or just anterior to the vertical traced at the pectoral-fin free rear tips in juveniles while it is behind it in adults.

C. australis exhibits morphometric and morphological variations between the New Zealand (NZ) and Australian (AUS) populations, such as: head longer and flattened dorsally in the NZ specimens (vs. shorter and arched in the AUS specimens); snout more obtuse (vs. snout rounded); dorsal fins broad at the fin web with straight posterior margin (vs. dorsal fins thin at fin web with strongly concave posterior margins); second dorsal-fin spine transcending second dorsal-fin apex (vs. not transcending second dorsal-fin apex); narrower abdomen when adults (7.3%–12.6% TL for NZ vs. 13.1%–16.1% TL for AUS, respectively).

It is also noticed that specimens from New Zealand exhibit intermediary characteristics, concerning body colour, dentition and shape of dermal denticles, shape of dorsal fins, length of dorsal-fin spines related to dorsal-fin apex, and origin of first dorsal fin related to pectoral-fin free rear tips, suggesting that more than one morphological group of Cirrhigaleus occurs in this region. One group has greyish body, origin of first dorsal fin prior to a vertical line traced at pectoral-fin free rear tips, first dorsal-fin spine never reaching first dorsal-fin apex, and caudal fin with posterior caudal tip narrow. The second group has dark brown body, origin of first dorsal fin behind a vertical line traced at pectoral-fin free rear tips, first dorsal-fin spine transcending first dorsal-fin apex, and caudal fin with posterior caudal tip broad. These specimens also have greater range of values of external measurements (e.g., precaudal length; pre-first and pre-second dorsal length; interdorsal space; dorsal-caudal distance; pectoral-pelvic distance; pelvic-caudal distance; size of first and second dorsal fins; length of dorsal-fin spines) and vertebral counts, which give additional support for this hypothesis.