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Open AccessArticle
1
CSIRO Australian National Fish Collection, National Research Collections Australia, Hobart, TAS 7001, Australia
2
Elasmobranch Research, Rehaegenstraat 4, 2820 Bonheiden, Belgium
3
Florida Museum of Natural History, Dickinson Hall, University of Florida, 1659 Museum Road, Gainesville, FL 32611, USA
*
Author to whom correspondence should be addressed.
Received: 20 June 2023
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Revised: 10 July 2023
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Accepted: 11 July 2023
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Published: 12 July 2023
Abstract
:
A new species of hornshark is described from northwestern Australia based on six whole specimens and a single egg case. Heterodontus marshallae n. sp. was previously considered to be conspecific with H. zebra from the Western Pacific. The new species differs from H. zebra in the sequence of its NADH2 gene, several morphological characters, egg case morphology and key coloration features. Despite the coloration being similar between H. marshallae n. sp. and H. zebra, i.e., pale background with 22 dark brown bands and saddles, they differ consistently in two key aspects. Firstly, the snout of H. marshallae n. sp. has a dark semicircular bar, usually bifurcated for most of its length vs. a pointed, triangular shaped dark marking in H. zebra. Secondly, H. zebra has a dark bar originating below the posterior gill slits and extending onto anterior pectoral fin, which is absent in H. marshallae n. sp. The Heterodontus marshallae n. sp. is endemic to northwestern Australia and occurs in deeper waters (125–229 m) than H. zebra (0–143 m).
1. Introduction
The Heterodontiformes is a unique shark order comprising a single family (Heterodontidae) and single extant genus (Heterodontus Blainville 1816 [1]). They are also one of the earliest identified modern elasmobranch lineages with distinctly recognisable isolated teeth recorded from the Lower Jurassic, ~175 mya [2]. These horn or bullhead sharks are characterised by their large, blunt heads with prominent crests above the orbits and a small, almost terminal mouth [3]. They also have a large spine in front of both dorsal fins and an anal fin. There are nine currently recognised nominal species of Heterodontus [4]: H. francisci (Girard, 1855) [5] from the Eastern Pacific; H. galeatus (Günther, 1870) [6] from eastern Australia; H. japonicus Miklouho-Maclay & Macleay, 1884 [7] from the Northwest Pacific; H. mexicanus Taylor & Castro-Aguirre, 1972 [8] from the Eastern Pacific; H. omanensis Baldwin, 2005 [9], from the northwestern Indian Ocean; H. portusjacksoni (Meyer, 1793) [10] from southern Australia; H. quoyi (Fréminville, 1840) [11] from the Eastern Pacific; H. ramalheira (Smith, 1949) [12] from the western Indian Ocean; and H. zebra (Gray, 1831) [13] ranging from northern Australia to Japan. No extant Heterodontus species occur in the Atlantic or Central Pacific oceans.
Australia is home to two endemic heterodontid species, i.e., H. galeatus and H. portusjacksoni, which occur in temperate waters. A third species, H. zebra, is found in the Western Central Pacific from tropical northern Australia extending further north to Japan. Naylor et al. [14] found that the sequence of the NADH2 gene of H. zebra from northern Australia was different from H. zebra from Japan and Malaysian Borneo. They suggested that the northern Australian population is probably an undescribed species and is referred to as H. cf. zebra. The fact that H. cf. zebra was genetically closer to H. portusjacksoni (average pairwise difference of 13 nucleotides for NADH2) than it was to the true H. zebra samples (average pairwise difference of 24) provides compelling support for the separation of the northern Australian population as a distinct species. These two populations also occupy different habitats. In the Western Pacific, H. zebra is associated with the insular and continental shelves to depths of about 50 m, whilst the northern Australian population (H. cf. zebra) occur on the lower continental shelf at depths, ranging from 150 to 200 m [15]. This provides further evidence that H. zebra represents a species complex.
Centracion zebra was originally described by Gray (1831) [13] in the Sea of China, presumably a misspelling for the genus Cestracion, based on ‘Les Cestracions’ of Cuvier [16], a junior synonym of Heterodontus Blainville [1]. Bleeker [17] reported on a specimen of H. zebra from off Ambon, Indonesia, and comments on its occurrence in Manado. Günther [6] included H. zebra as synonym of Cestracion philippi Bloch & Schneider, 1801 [18], and stated its range as New Zealand, Australia, East Indies and Japan, thus including the Bleeker specimens from Indonesia in its distribution. The 580 mm TL Bleeker specimen deposited in the Natural History Museum, London, from Ambon was subsequently described as a new species, Cestracion amboinensis by the authors of [19]. Regan [19] differentiated it from H. zebra from China as its dorsal fins less elevated and dark crossbars broader and separated by narrower interspaces. However, Garman [20] subsequently placed C. amboinensis into the synonymy of Cestracion zebra, which was followed by subsequent authors (as Heterodontus zebra), e.g., [21,22].
In this paper, specimens of H. cf. zebra from northern Australia were compared to true H. zebra specimens from the Northwest Pacific and to the type of Cestracion amboinensis to determine whether they refer to a new species. This paper addresses a high priority knowledge gap for this species in the Action Plan for Australian Sharks and Rays 2021 [23].
2. Materials and Methods
2.1. Morphology
The morphometric measurements taken follow those for sharks in general, as detailed by Compagno (2001) [15], although we typically use direct (point-to-point) measurements rather than horizontal measurements, and for those used for sharks with fin spines, i.e., the dogshark genus Squalus by Last et al. [24]. For comparative purposes, we have included both direct and horizontal measurements for some key characters, e.g., pre-first dorsal length, head length, preorbital length and prenarial length. Dorsal fin origins were located using a finger or thumb against the midline to determine the location of the fin origin and a pin used to mark the position. Total length (TL) was taken horizontally from the tip of the snout to the tip of the caudal fin when lowered to be in line with snout, i.e., stretched total length. The holotype (WAM P.35408-007) and five paratypes (CSIRO CA 3286, CSIRO H 6581–01, NTM S.12929-001, WAM P.26193-010 and WAM P.30424-001) of the H. cf. zebra specimens were measured in full. For comparison, eight specimens of H. zebra (AMS I.1366, NMW 85504, NMMB-P 1825, NMMB-P 5040, NMMB-P 8845 (two specimens), NMMB-P 15867 and NMMB-P unregistered) and five specimens of H. portusjacksoni (CSIRO unregistered (two specimens), CSIRO H 6354-09, CSIRO H 6354-10 and CSIRO H 6340-02) were also measured. The holotype of H. zebra (BMNH 1953.5.10.4) is a dry skin and is thus not suitable for measuring or meristics. In the description, the first measurement proportion or ratio is that of the holotype followed in parentheses by the ranges of the paratypes.
2.2. Vertebral Meristics
Vertebral counts were obtained from radiographs of the holotype and five paratypes of the H. cf. zebra specimens and from two specimens of northwest Pacific H. zebra (AMS I.1366 and NMMB-P.5040). Counts were obtained separately for trunk (monospondylous precaudal centra), precaudal (monospondylous precaudal centra + diplospondylous precaudal centra to origin of the caudal fin upper lobe) and diplospondylous caudal centra (centra of the caudal fin) vertebrae following the methods used by Compagno (1988) [25] for carcharhiniform sharks.
2.3. Dentition
The dental formula used, including symphyseal (S), anterior (A), antero-lateral (AL) and (postero-) lateral teeth (L), follows Casier [26]. Tooth file counts were taken in situ from paratype CSIRO H 6581-01 by making short cuts from both mouth corners to expose the entire jaws. All ERB specimens (jaws) were collected following the protocol of Mollen et al. [27].
2.4. Denticles
Dorsal, lateral and ventrolateral skin patches and photographs were taken just posterior to first dorsal fin in H. cf. zebra and H. zebra, that correspond to topological codes B4–B6 of Reif [28].
2.5. Distribution
The distribution map was generated in QGIS 3.30.2 (www.qgis.org (accessed on 14 April 2023) using a Google Satellite layer. Records of the H. zebra complex were included in the distribution map. For H. cf. zebra, the locations of specimens were mapped, as well as additional records from CSIRO demersal trawl surveys (Atlas of Living Australia; www.ala.org.au (accessed on 10 March 2023). While the latter records do not have associated voucher specimens or images for validation, they are included since it is unlikely that the H. zebra complex would be misidentified off the Northwest Shelf of Australia. For H. zebra, the locations of specimens examined and other records with specific localities from reliable literature records were mapped. The literature records used for H. zebra are (from the north of range to the south): Japan [29,30,31,32,33,34,35,36]; Korea [36,37]; China [36,38,39,40,41]; Taiwan [42,43]; Disputed territory—Paracel Islands [44]; Vietnam [45,46]; Philippines [47]; Thailand [48]; Brunei Darussalam [44]; Malaysia [49,50]; and Indonesia [17,51].
2.6. Molecular Analyses
Specimens were sampled for liver or muscle tissue and temporarily stored in 95% alcohol. DNA was extracted using the phenol chloroform extraction [52] or using High Pure PCR Template Preparation Kit by Roche Diagnostics (Indianapolis, IN, USA). Extracted total DNA was stored at −20 °C until used for amplification via a polymerase chain reaction (PCR). Samples were amplified using Takara ExTaq (Clonetech, Mountain View, Ca) with primers designed to target the complete coding sequence for NADH dehydrogenase subunit 2 (NADH2). A single set of new universal primers (ILEM_LY: 5′-AAG GAY CAC TTT GAT AGA GT-3′; ASNM_LY: 5′-AAC RCT TAG CTG TTA AYT AAG AT-3′), designed to bind to the ASN and ILE tRNA regions of the mitochondrial genome, was used to amplify the target fragment. PCR reactions were generally carried out in 25 µL tubes by adding 14.775 µL of PCR grade water, 2.5 µL of PCR buffer, 2.0 µL of MgCL2 (25 mM), 2.0 µL of dNTP mix (2.5 mM each), 0.8 µL of each primer (10 µM), 0.125 µL of Takara ExTaq (5 U/µL) and 2 µL of DNA template. The reaction cocktail was denatured at 94 °C for 3 min, after which it was subjected to 35 cycles of denaturation at 94 °C for 30 s, annealing at 54 °C for 30 s and extension at 72 °C for 90 s. PCR products were sent off to commercial sequencing centres for purification and sequencing (Retrogen Inc., San Diego, CA, USA). Sequence trace files were evaluated for quality, translated to amino acids and aligned using the software package Geneious 11.0.5 (https://www.geneious.com (accessed 20 April 2023)). The aligned amino acid sequences were translated back, in the frame of their original nucleotide sequences, to yield a nucleotide alignment that was 1044 base pairs long.
Partitioned maximum likelihood (ML) analyses were conducted for the ND2 dataset using RAxML v.8.0.26 [53,54]. Based on the results from PartitionFinder v2.1.1 [55], the dataset was partitioned by the three codon positions and the model GTR + I + G model was chosen. A total of 200 distinct runs were performed based on 200 random starting trees. The tree with the best likelihood score was chosen as the final tree. The bootstrap analyses (1000 replicates) were also conducted using RAxML [56,57] with the same partitioning strategy and nucleotide substitution model as above. PAUP 4.0.b10 [58] was then employed to obtain the 50% majority rule consensus tree and bootstrap values (BP). Sequences have been uploaded to GenBank (see Table S2 for accession numbers and collection details).
2.7. Institutional Acronyms
Museum acronyms used: AMS, Australian Museum, Sydney; BMNH, Natural History Museum, London; CSIRO, Australian National Fish Collection, Hobart; ERB, Elasmobranch Research Belgium, Bonheiden; KAUM, Kagoshima University Museum, Korimoto; NMMB-P, National Museum of Marine Biology and Aquarium (Fishes), Checheng; NMW, Naturhistorisches Museum, Vienna; NTM, Museums and Art Galleries of the Northern Territory, Darwin; QM, Queensland Museum, Brisbane; RBINS, Royal Belgian Institute of Natural Sciences, Brussels; RMNH, Naturalis Biodiversity Center, Leiden; WAM, Western Australian Museum, Perth; ZMH, Zoologisches Museum, Universität Hamburg, Hamburg.
2.8. Comparative Material Examined
Heterodontus francisci: CSIRO H 8931-01, juvenile male, 311 mm TL; CSIRO H 8931-02, female 360 mm TL, San Clemente, CA, USA, 19 November 2021; ERB 1172 (jaws only; other skeletal remains as RBINS 25325, female, 388 mm TL, CA, USA, May 2017.
Heterodontus galeatus: AMS I.4781, egg case and embryo (wet), Coogee Bay, New South Wales, 33°55′47″ S, 151°16′12″ E; CSIRO CA 3938, female, 410 mm TL, no location data, 29 November 1904; CSIRO H 904-01, female, 325 mm TL, between Long Reef and Port Hacking, New South Wales, Australia, ~34° S, ~151° E, March 1987; CSIRO H 6354-08, adult male, 700 mm TL, east of Broken Bay, New South Wales, 33°32.8′ S, 151°27′ E, 40–49 m depth, 14 May 2006; QM I 13003, northwest of Cape Moreton, Queensland, 26°55′ S, 153°25′ E, 110 m depth, 27 February 1975.
Heterodontus japonicus: ERB 1151 (jaws only; other skeletal remains as RBINS 25176; tissue accession GN 19549), male, 440 mm TL, Japan, April 2016.
Heterodontus portusjacksoni: CSIRO H 6340-01, adult male; CSIRO H 6340-02, female, 462 mm TL, northwest of Rottnest Island, Western Australia, 31°54.27′ S, 151°38.47′ E, 100–101 m depth, 7 April 2006; CSIRO H 6354-09, juvenile male, 553 mm TL; CSIRO H 6354-10, juvenile male 362 mm TL; CSIRO H 6354-11, juvenile male, 368 mm TL; CSIRO H 6354-12, female, 347 mm TL, east of Broken Bay, New South Wales, Australia, 33°32.8′ S, 151°27′ E, 40–49 m depth, 14 May 2006; CSIRO H 8732-02, egg case from captive female, Seahorse World, Beauty Point, Tasmania, 10 January 2009; CSIRO unregistered, adult male, 630 mm TL, northwest of Rottnest Island, Western Australia, 149–151 m depth, 7 April 2006; CSIRO unregistered, adolescent male, 686 mm TL, south of Betsey Island, Tasmania, 25 m depth; NTM S.00043-001, female, 237 mm TL, York Sound, Western Australia, ~14°50′ S, ~125°05′ E, June 1975; ERB 0500 (jaws only), female, 845 mm TL, off Geraldton, Western Australia, June 2008; ERB 0904 (jaws only), female, 950 mm TL, off Bunbury, Western Australia, August 2010; ERB 1226 (jaws only), male, 670 mm TL; ERB 1227 (jaws only), female 352 mm TL, off Perth, Western Australia, November 2018.
Heterodontus zebra: AMS I.1366, female, 454 mm TL, off Shantou, China, 1887; BMNH 1867.11.28.183 (holotype of Cestracion amboinensis), female ~630 mm TL, Ambon, Moluccas, Indonesia, 1855; ERB 1147 (jaws only; other skeletal remains as RBINS 25173; tissue accession GN 19551), female, 778 mm TL; ERB 1148 (jaws and skin only; other skeletal remains and skin as RBINS 25174), female, 796 mm TL; ERB 1149 (jaws only), female, 666 mm TL; ERB 1150 (jaws only; other skeletal remains as RBINS 25175), male, 630 mm TL, Taiwan, April 2016; KAUM-I. 69456, egg case, off Oton, Panay Island, Philippines, 10°37′ N, 122°14′ E, 1 March 2005; NMMB-P 1825, female, 569 mm TL; NMMB-P 5040 (ex THUP 02957), juvenile male, 360 mm TL, Kaohsiung, Taiwan, 11 October 1965; NMMB-P 8845 (2 specimens), female, 220 mm TL, and juvenile male, 212 mm TL, Penghu, Taiwan, 30 August 2005; NMMB-P 15867, female, 1005 mm TL, no collection data, presumably Taiwan; NMMB-P unregistered, 536 mm TL, no collection data, presumably Taiwan; NMW 85504, juvenile male, 457 mm TL, Asia?, no other data; RMNH PISC.7412 (2 specimens), adult male, 650 mm TL, and juvenile male, 434 mm TL, Indonesia, purchased from Bleeker auction in 1879; not retained, field code BOD-038 (GenBank accession JQ518723), adolescent male, 580 mm TL, Tanjung Manis, Mukah District, Sarawak, Malaysian Borneo, 02°07′07.04″ N, 111°19′37.16″ E, 6 July 2002; ZMH 10104, male, 457 mm TL, Fuzhou, Fujian Province, China, 4 April 1905; ZMH 10105, female, 165 mm TL, Fuzhou, Fujian Province, China, 24 August 1906; ZMH 10106, male, 434 mm TL, Fuzhou, Fujian Province, China, 1 June 1911.
3. Results
3.1. Comparison with Congeners
The Heterodontus zebra complex is easily distinguished from all other Heterodontus species due to the striking colour pattern of dark, narrow bands on a pale background. Despite the northern Australian H. cf. zebra and the H. zebra from Japan and Malaysian Borneo differing on a molecular level [14], their colour patterns are very similar. However, they do have some key differences, i.e., different dark markings on the snout and dorsal surface of pectoral fin. They also have different egg case morphology and vertebral counts (see Section 3.5 for detailed comparisons). The difference in dark markings on the snout and dorsal pectoral fin was consistent across the different size classes and are thus considered a reliable characteristic for separating the two species. An examination of the holotype of Cestracion amboinensis (BMNH 1867.11.28.183) found that it has the same shaped dark snout markings and pectoral fin markings as H. zebra from Japan, Taiwan and Malaysian Borneo. Therefore, Cestracion amboinensis remains in the synonymy of H. zebra, and the northern Australian specimens (H. cf. zebra) are herein formally named and described as a new species.
3.2. Systematic Account
Order Heterodontiformes Berg, 1937 [59].
Family Heterodontidae Gray, 1851 [60].
Heterodontus marshallae n. sp.
urn:lsid:zoobank.org:act:76D37CD9-AB48-4171-BF97-ED268114AFA7.
3.2.1. Synonymy
Heterodontus zebra—[22] (in part): p. 164 (northern Australian range); [61]: p. 22, Figure (northwestern Australia); [62] (in part): p. 115, figs, pl. 2 (Figure 11.3) (northern Australian range); [63]: p. 143 (Western Australia); [64]: p. 11 (Northern Territory); [65]: p. 13 (Western Australia); [15] (in part): p. 48 (northwestern Australian range); [66]: p. 23 (northwestern Australia); [67] (in part): p. 154 (northwestern Australia range); [3]: p. 120, fig., pl. 2 (northern Australian range); [68]: p. 6 (Northern Territory).
Heterodontus cf. zebra—[14]: p. 56, Figure 40 (northern Australia); [69]: 5 (northwestern Australia).
3.2.2. Type Material
Holotype: WAM P.35408-007, adolescent male, 541 mm TL, west of Exmouth Peninsula, Ningaloo Marine Park (Commonwealth waters), Western Australia, 22°22.946′ S, 113°40.308′ E, 210–212 m depth, 23 November 2022.
Paratypes (n = 6): CSIRO CA 3286, juvenile male, 432 mm TL, north of Port Hedland, Western Australia, 18°33′ S, 118°22.3′ E, 150 m depth, 28 March 1982; CSIRO H 6581–01, female, 580 mm TL, northwest of Cape Leveque, Western Australia, 14°58.69′ S, 121°40.18′ E, 191–202 m depth, 28 June 2007; NTM S.12929-001, adult male, 575 mm TL, north of Bathurst Island, Arafura Sea, Northern Territory, 10°10.02′ S, 130°04.02′ E, 125 m depth, 16 November 1990; NTM S.18275-001, egg case (wet), southeast of Evans Shoal, Arafura Sea, Northern Territory, 10°08′ S, 130°05′ E, 131 m depth, 1 October 1998; WAM P.26193-010, female, 355 mm TL, 150 km north-northeast of Rosemary Island, Western Australia, 22°22′ S, 113°29′ E, 170–172 m depth, 16 May 1978; WAM P.30424-001, adult male, 601 mm TL, east of Exmouth Peninsula, Western Australia, 22°22′ S, 113°40′ E, 221–229 m depth, 29 September 1990.
3.2.3. Representative DNA Sequences
OR078587 (holotype—WAM P.35408-007); JQ519052 (paratype—CSIRO H 6581–01).
3.2.4. Etymology
The specific name is in honour of Dr. Lindsay Marshall (www.stickfigurefish.com.au (accessed 10 May 2023)), a scientific illustrator and elasmobranch scientist who expertly painted all the sharks and rays of the world for the Chondrichthyan Tree of Life Project.
The vernacular name proposed is painted hornshark, in allusion to not only the beautiful coloration of the species but also to its namesake, who has painted all the hornsharks in amazing detail.
3.2.5. Diagnosis
A small species of hornshark with the following combination of characters: colour pattern consisting of 22 dark bands and saddles; snout with a semicircular dark bar, usually bifurcated for most of its length; no dark bar below posterior gill slits extending onto anterior pectoral fin; anal fin well separated from caudal fin (anal-caudal space 11.0–13.5% TL); ventral lobe of caudal fin prominent (lower postventral margin 4.7–6.1% TL); dorsal spines long (exposed first dorsal spine length 3.9–4.5% TL); dorsal fins taller in juveniles than adults; symphyseal and anterior teeth pointed, lateral teeth molariform with a longitudinal keel; 20–22 tooth files in upper jaw, 17–19 in lower jaw; total vertebral centra 106–112, precaudal centra 70–76, monospondylous centra 33–37; egg case with narrow, curved, screw-like keels with 1.5 rotations from anterior to posterior margins.
3.2.6. Description
Proportional measurements of the holotype and ranges for the paratypes are provided in Table 1.
Body moderately robust, nape slightly humped; deepest near first dorsal fin spine, trunk height 1.12 (1.07–1.31 in paratypes) times trunk width; tail height 1.05 (0.96–1.13) times tail width (Figure 1 and Figure 2). Head robust, supraorbital ridges prominent but moderately low and broad; trapezoidal in cross-section at eyes, pear-shaped posteriorly; ventral surface of head mostly flat, slightly upturned anteriorly; head short, 22.3 (20.3–24.1)% LT (Figure 3). Supraorbital ridges broadest anteriorly, becoming relatively narrow posteriorly; originating about one eye length anterior to the eye and terminating about one eye length posterior to the eye; distance between ridges smallest anteriorly, widening posteriorly; interorbital space concave, depth less than one-third eye diameter; interorbital space 34.9 (30.7–36.7)% HL. Head width 1.01 (0.99–1.14) times trunk width, 1.06 (0.97–1.20) times abdomen width; length 1.79 (1.78–2.01) in pre-vent length; height 1.05 (0.95–1.08) times width.
Snout short, broadly triangular (moderately rounded in smaller paratypes) in lateral view, apex rounded; moderately rounded in dorsal view, horizontal length 2.13 (1.75–2.40) times eye length, 1.01 (0.88–1.21) times interorbital space; horizontal prenarial length 3.83 (3.28–7.03) in horizontal preorbital length; preoral length 2.24 (2.34–2.91) in horizontal preorbital length. Eye oval, moderately large, length 6.04 (5.44–6.45) in head length, 1.70 (1.52–1.80) times eye height. Spiracle very small, suboval, situated below posterior margin of eye; greatest diameter of spiracle 5.20 (5.53–9.62) in eye length. First gill opening almost vertical, second to fifth angled slightly posteroventrally; first and second gill openings longest, fifth shortest, height of first slit 4.4 (4.1–5.3)% LT, 1.71 (1.62–2.07) times height of fifth slit; gill openings more elevated posteriorly, lower margin of first gill opening slightly below plane of pectoral fin, lower margin of fifth gill opening three quarters eye length above pectoral fin base.
Mouth relatively large, short; lower jaw slightly concave, width 2.57 (2.77–3.53) times preoral length; labial furrows prominent, lower almost twice length of upper; labial flaps thick; no post-oral groove (Figure 4). Nostril incurrent aperture small, pear-shaped, surrounded by a prominent circumnarial groove; circumnarial groove J-shaped, hook wrapping around posterior end of nostril; deep nasoral groove connecting excurrent aperture with mouth; anterior nasal flap long, reaching mouth; internarial width 22.0 (23.0–25.1)% HL; internarial space 4.54 (3.98–4.34) times preoral length.
First dorsal fin large, upright (more so in smallest paratype), narrowly rounded apically; anterior margin strongly convex (moderately convex in smallest paratype) (Figure 1b and Figure 2); posterior margin concave; free rear tip thick basally, moderately long; inner margin of fin almost straight; insertion of base well forward of pelvic fin origin, over posterior third of pectoral fin free rear tip (sometimes level with apex of free rear tip); fin spine origin slightly anterior to pectoral fin insertion; spine robust, broad-based, exposed anteriorly near junction of spine and soft portion of fin; soft portion of fin connected at about half total spine length; spine tapering distally, anterior margin weakly convex to nearly straight; exposed portion of spine almost vertical (directed posterodorsally in WAM P.30424-001), subequal in length to exposed portion of second dorsal fin spine; pre-first dorsal length 4.33 (3.76–4.51) times in TL; first dorsal fin length 1.07 (0.94–1.51) times its height, 1.12 (1.11–1.23) times second dorsal fin length; first dorsal fin height 1.42 (1.35–1.46) times second dorsal fin height; exposed first dorsal spine length 0.48 (0.25–0.45) times height of fin.
Second dorsal fin large, upright; anterior margin convex, apex narrowly rounded (Figure 1b and Figure 2); posterior margin slightly to strongly concave; free rear tip thick basally, moderately long; second dorsal fin length 1.36 (1.14–1.86) times its height; exposed spine length 0.48 (0.35–0.62) in height of fin, 0.93 (0.96–1.06) times exposed first dorsal fin spine length; fin spine origin about level with or slightly anterior to free rear tip of pelvic fin, exposed at about level of junction with spine and soft portion of fin; spine robust, moderately broad-based, tapering distally; exposed portion of spine angled slightly posterodorsally; interdorsal space 1.34 (1.45–1.57) in pre-first dorsal length, 1.29 (1.05–1.31) times first dorsal fin length.
Anal fin relatively small, short based, anterior margin slightly to moderately convex, apex narrowly rounded, posterior margin slightly concave, free rear tip relatively long (Figure 1b and Figure 2); apex well behind insertion, slightly posterior to free rear tip; anal fin origin about level with mid second dorsal fin free rear tip; pre-anal length 58.2 (55.2–62.2)% TL; anal fin base 2.68 (2.32–3.21) in anal–caudal space, anal fin length 0.68 (0.57–0.70) in second dorsal fin length, anal fin height 0.53 (0.34–0.63) in second dorsal fin height.
Pectoral fin large, subtriangular anterior margin slightly convex (moderately convex in smallest paratype), with a slight concavity midway (Figure 3); apex narrowly rounded; posterior margin weakly concave to nearly straight; inner margin moderately convex, free rear tip broadly rounded; anterior margin length 1.05 (0.94–1.25) in pre-pectoral length; base short, 2.60 (2.32–3.03) in anterior margin length.
Pelvic fins small, subtriangular; anterior margin weakly convex, apex subangular; posterior margin slightly concave; inner margin slightly convex, free rear tip subangular; pelvic fin height 2.32 (2.05–2.83) in pectoral fin height. Clasper moderately stout, extending well past pelvic fin free tip; clasper groove long, not enclosed; clasper glans with a large and deep pseudosiphon (clasper glans and pseudosiphon about 52% of clasper outer length), a cover rhipidion, a thin rhipidion and clasper spine; external surface of cover rhipidion with a short, narrow groove; outer clasper length in adolescent male holotype 8.3% TL and in two adult male paratypes 9.2 and 9.9% TL (Figure 5).
Caudal peduncle moderately long, relatively slender, slightly depressed; no lateral keels; pelvic–anal space 14.7 (11.7–15.5)% LT; no interdorsal groove; shallow post-dorsal and post-anal grooves; tapering slightly to caudal fin; broadly oval in cross-section; anal–caudal space 13.2 (11.0–13.5)% LT, 0.94 (0.86–1.34) in pectoral–pelvic space; dorsal–caudal space 1.02 (0.97–1.19) times interdorsal space; no dorsal or ventral caudal pits. Caudal fin short; dorsal caudal margin weakly convex to straight, dorsal apex narrowly rounded; ventral lobe well produced, ventral caudal margin slightly convex, ventral apex narrowly rounded; postdorsal margin moderately concave; terminal lobe large and deep, terminal margin slightly concave, subterminal margin almost straight, its apex angular; dorsal caudal margin 0.89 (0.79–1.09) in head length; length of lower caudal lobe 1.69 (1.51–1.83) in upper lobe length (add in CTR as proportion of DCM).
Dental formula (based on paratype CSIRO H 6581-01, Figure 6) from left to right, in upper jaw 4L–3AL–3A–1S–3A–2AL–4L (20 tooth files in total) and lower jaw 4L–1AL–3A–1S–3A–1AL–4L (17 tooth files in total). Holotype with about 22 files in upper jaw and 19 files in lower jaw; counts difficult to confirm on digital radiographs where jaws overlap. Strong monognathic heterodonty, including clutching and grinding type dentitions (sensu Cappetta [70]). Symphyseal and anterior teeth pointed, consisting of a principal cusp, flanked by one, or sometimes two pairs of cusplets that are hardly individualised. Lateral teeth molariform, lanceolate shaped, relatively broad but not extremely elongated, and with a longitudinal keel. Labial and lingual crown ornamentation present, showing a texture of transverse ridges running perpendicular to keel. Antero-laterals with intermediate tooth morphology. Dignathic heterodonty weak, with a higher number of antero-lateral teeth in the upper jaws, resulting in more upper tooth files compared to lower jaws. In contrast to lower posterior most tooth file, the upper file is much smaller and mesio-distally compressed compared to adjacent files. Ontogenetic dental shifts present and characterized transformation from clutching to grinding type dentition in lateral tooth positions during early maturity stages. The presence of sexual dimorphism was not examined.
Dermal denticles (based on paratype CSIRO H 6581-01, Figure 7a,c,e) vary both in size and density along the shark’s flank. Dermal denticles and squamation fairly large (>1 mm) and dense in the dorsal region (Figure 7a), moderate in the lateral region (Figure 7c), and small (<1 mm) and wide-spaced in the ventrolateral region (Figure 7e),
