Galeus corriganae, White, William T., Mana, Ralph R. & Naylor, Gavin J. P., 2016

White, William T., Mana, Ralph R. & Naylor, Gavin J. P., 2016, Galeus corriganae sp. nov., a new species of deepwater catshark (Carcharhiniformes: Pentanchidae) from Papua New Guinea, Zootaxa 4205 (3), pp. 255-264 : 256-261

Galeus corriganae sp. nov.

Corrigan’s Catshark

( Figs 1–4 , Table 1 )

Galeus gracilis— Fricke et al., 2014: 12 (Madang, based on NTUM 10171 )

Holotype. NTUM 10171 (tissue accession GN 17185), adolescent male 306 mm TL, west of Sek Island, Madang , Papua New Guinea, 05°04' S, 145°51' E, 582–587 m depth, 28 Nov 2012.

Paratypes. 6 specimens: NTUM 10321 (tissue accession GN 17204), adolescent male 282 mm TL, north of Taviltae , Madang Province, Papua New Guinea, 04°30' S, 145°34' E, 600–660 m depth, 17 Dec 2012 ; NTUM 10322 (tissue accession GN 17207), juvenile male 203 mm TL, north of Taviltae , Madang Province, Papua New Guinea, 04°29' S, 145°31' E, 500–510 m depth, 17 Dec 2012 ; NTUM 11492 (tissue accession GN 17225), adolescent male 372 mm TL, southeast of Murien , West New Britain, Papua New Guinea, 06°10' S, 149°18' E, 510–743 m depth, 7 May 2014 ; NTUM 11493 (tissue accession GN 17224), juvenile male 271 mm TL, south of Murien , West New Britain, Papua New Guinea, 06°08' S, 149°10' E, 430–620 m depth, 6 May 2014 ; ASIZ unregistered (field code CP 3708-5), 2 specimens, female 278 mm TL and juvenile male 247 mm TL, off Madang, Papua New Guinea, 05°01.270' S, 145°50.210' E, 502–529 m depth, 2 Oct 2010 .

Diagnosis. A small, slender Galeus with the following combination of characters: relatively broad head, interorbital space 7.2–7.8% TL; pelvic–anal space 12.2–13.0% TL; anal fin relatively small, base length 7.8–8.6% TL; anal-fin posterior margin 5.2–6.3% TL; prepectoral length relatively short, about 18.4–21.5% TL; labial furrows moderately long, not confined to mouth corners, uppers 2.2–2.9% TL; enlarged denticle crest of upper caudal fin originating anterior to origin of ventral caudal lobe; denticles on elevated portion of supracaudal crest forming 2–4 central rows of denticles between much larger obliquely positioned lateral rows; no subcaudal crest; anterior margin of pectoral fins black; anterior half of dorsal fins almost entirely dark or dusky; precaudal centra 83–86.

Description. Body very slender, head height 8.0 in holotype (6.2–6.8 in paratypes)% TL; abdomen long, pectoral–pelvic space 14.2 (12.9–14.3)% TL, 1.43 (1.42–1.76) in head length; pelvic–anal space long, 1.51 (1.42– 1.60) times anal-fin base; caudal peduncle elongate, anal–caudal space 0.74 (0.76–0.79) times anal-fin base; peduncle moderately compressed. Snout moderately long, parabolic, tip narrowly rounded; preoral length 7.3 (7.1– 8.5)% TL, 0.90 (0.78–0.95) times mouth width; prenarial snout 1.28 (1.18–1.37) times eye length. Eyes small, length 4.3 (4.0–4.6)% TL, 4.74 (4.36–5.03) in head length; eyes slightly dorsolateral on head, with well-developed subocular ridges and nictitating lower eyelids. Spiracles small and subcircular, close to but well separated from eyes; dorsolateral on head. Gill slits moderately long, upper ends about level with lower edges of eyes, fifth gill slit shortest and above pectoral-fin origins; gill filaments not visible externally.

Mouth large, moderately long, arched, width 8.2 (7.7–9.1)% TL, 2.18 (2.31–3.18) times its length; labial furrows well developed, lower furrows only slightly shorter than mouth length, uppers not extending forward to symphysis ( Fig. 2 ). Teeth with mainly 5 cusps (rarely 3); cusps adjacent central cusp well developed, almost half length of central cusp; in 60 (63–69) rows in upper jaw; 60 (54–64) rows in lower jaw.

Denticles on sides of trunk below first dorsal fin tricuspidate, semi-erect, slightly imbricated; crown broadly parabolic with a long, broad-based central cusp and short but distinct lateral cusps; pronounced longitudinal ridge along midline of crown including central cusp. Supracaudal crest well developed, about equal in length to interdorsal space; origin of crest posterior to second dorsal-fin free rear tip, anteriorly pre-crest denticles progressively increasing in size and becoming more oblique on crest; crest becoming elevated anterior to level of origin of lower lobe, elevated portion demarcated by strip of naked skin; denticles in mainly 3 or 4 central rows (2 or 3 in smallest type), rows bordered by larger, more posterolaterally directed lateral denticles (about 2 or 3 times size of central denticles); subcaudal crest absent.

Claspers of adults not available; outer length of partially calcified clasper in largest adolescent male 8.4% TL, inner length 10.7% TL.

Dorsal fins low, strongly raked, anterior margins slightly to moderately convex, apex moderately round, posterior margins almost straight, free rear tips angular, first slightly larger than second, first dorsal-fin height 1.15 (1.10–1.44) times second dorsal-fin height; first dorsal-fin origin over pelvic-fin insertions; second dorsal-fin origin above midbase of anal fin, its insertion well behind insertion of anal fin. Pectoral fins moderately large, broad, anterior margin 10.8 (10.1–11.7)% TL. Pelvic fins small, low, angular, length 10.6 (10.3–11.5)% TL. Anal fin relatively short, base 8.4 (7.8–8.6)% TL, 1.31 (1.36–1.50) in interdorsal space; origin slightly posterior to midinterdorsal space; anal-fin height 2.48 (1.97–2.29) in base length. Caudal fin slender, moderately long, asymmetrical; dorsal caudal margin biconvex, mesially weakly concave to level with subterminal notch; postventral margin weakly concave, ventral lobe barely evident; subterminal margin straight; terminal caudal margin convex.

Monospondylous centra 39 (38–39); precaudal centra 86 (83–85); caudal 55 (50–54); total 141 (135–138).

Colour. Dark to medium grey above; paler ventrally; four distinct (less distinct once preserved), darker dorsal saddles situated beneath each dorsal fin and on tail ( Fig. 1 ); saddle below first dorsal fin commencing near fin origin, its width slightly narrower than fin base, extending ventrally almost to lateral midline; saddle below second dorsal fin similar, subequal in width to fin base; saddle above apex of lower lobe of caudal fin also of similar size and extends just below lateral midline of fin; broad saddle before terminal lobe of caudal fin, width subequal to length of second dorsal fin, extending across entire width of fin. Dorsal fins with extensions of dark body saddles above base, narrow whitish posterior margins, remaining fin pale grey. Anal fin mostly grey with a narrow (sometimes indistinct) blackish anterior margin, posterior margin whitish. Pectoral fins with a strikingly distinct, narrow black anterior margin ( Fig. 2 ) and a narrow whitish posterior margin; fins darker dorsally than ventrally. Pelvic fins and claspers pale grey, naked skin along dorsal surface of clasper and near cloaca pale. Head distinctly paler ventrally than dorsally, cheek mostly pale; roof of mouth and tongue dark grey to blackish, floor beneath tongue and jaws whitish.

Size. Only known from the type specimens, 203–372 mm TL. Three are juveniles, 203–271 mm TL, four are adolescent males, 282–372 mm TL, and a single female 278 mm TL.

Distribution. Known only from the type specimens collected off the Madang Province and southwestern West New Britain Province of Papua New Guinea in depths of 500 to 742 m ( Fig. 3 ).

Holotype Paratypes

Min. Max. ......continued on the next page Holotype Paratypes

Min. Max. Interdorsal space 11.01 11.69 12.74 First dorsal origin to second dorsal origin 16.69 16.64 18.59 First dorsal insertion to second dorsal insertion 16.84 16.98 18.18 Etymology. Named for Dr Shannon Corrigan whose extensive molecular population and phylogenetic work on sharks has contributed toward an improved understanding of their alpha taxonomy and phylogenetic relationships.

Molecular analysis. The analysis of the NADH2 data ( Fig. 4 ) suggest that Galeus corriganae represents a monophyletic lineage that is distinct from, but most closely related to Galeus priapus Séret & Last, 2008 from New Caledonia. These two species are, in turn, sister to G. nipponensis Nakaya, 1975 , G. longirostris Tachikawa & Taniuchi, 1987 and G. eastmani ( Jordan & Snyder, 1904) from the Northwest Pacific ( Fig. 4 ). No tissue samples are available for Galeus gracilis Compagno & Stevens, 1993 from northwestern Australia, but this species likely belongs within this complex due to its morphological similarities to G. priapus and the new species. It should be noted that this inference is based on a single mitochondrial marker. Inclusion of multiple nuclear markers could affect the presented inference.

Comparisons. Comparisons of the new species with its congeners is restricted to the two most similar species, G. priapus and G. gracilis , which are also the two closest congeners from a geographical sense. Galeus corriganae sp. nov. is almost identical in appearance to Galeus priapus from New Caledonia but differs from this species in the following characters: broader head (head width 10.4–13.2 vs. 8.3–9.9% TL in G. priapus ; interorbital width 7.2–7.8 vs. 6.0–7.0% TL), larger eyes (orbit length 4.0–4.6 vs. 2.6–3.5% TL), longer upper labial furrows (2.2–2.9 vs. 1.4–2.1% TL), slightly larger nostrils (nostril width 25–3.0 vs. 2.2–2.3% TL), pelvic and anal fins further apart (pelvic–anal space 12.2–13.0 vs. 10.0–11.7% TL), shorter pelvic-fin base (base length 6.3–7.2 vs. 7.6–9.3% TL) and longer pelvic-fin inner margin (4.2–4.7 vs. 2.8–4.2% TL), shorter anal-fin inner margin (2.0–2.5 vs. 1.3–1.9% TL)

Galeus corriganae sp. nov. is also similar to Galeus gracilis from northwestern Australia but differs in the following characters: more vertebrae (monospondylous centra 38–39 vs. 33–36 in G. gracilis ; precaudal centra 83– 86 vs. 74–78; total centra 130–134 vs. 135–141), smaller anal fin (posterior margin length 5.2–6.3 vs. 6.4–7.3% TL), pelvic–anal space much longer (12.2–13.0 vs. 8.0–10.3% TL), claspers of adults likely to be much longer (outer length of adolescent male 8.4 vs. 5.2–7.3% TL in adult males of G. gracilis ).

Figures

FIGURE 1. Lateral view of the holotype of Galeus corriganae sp. nov., NTUM 10171, adolescent male 306 mm TL: (A) fresh; (B) preserved.

FIGURE 2. Ventral view of the head of the holotype of Galeus corriganae sp. nov., NTUM 10171, adolescent male 306 mm TL (fresh).

FIGURE 3. Map showing the capture locations of the type specimens of Galeus corriganae sp. nov. in Papua New Guinea. Green star denotes the holotype and red circles denote the paratypes (Image © NASA, TerraMetrics, Google Earth).

FIGURE 4. Maximum Likelihood tree estimated under the General Time Reversible model (GTR) with model terms to accommodate both Invariant site (I) and Gamma Distributed rates (G). Bootstrap support values are shown from a separate ML bootstrap analysis. Sequences used in this tree are part of the Chondrichthyan Tree of Life project (http: // sharksrays. org /).

Tables

TABLE 1. Morphometrical measurements of the holotype (NTUM 10171) of Galeus corriganae sp. nov. and ranges for the 4 measured paratypes, expressed as a percentage of total length.

Total length (mm)	306	203	372
Pre-first dorsal length	44.77	40.39	43.82
Snout to first dorsal-fin insertion	50.00	46.31	50.18
Pre-second dorsal length	62.09	58.13	61.83
Snout to second dorsal-fin insertion	67.32	64.53	67.20
Head length	20.26	19.59	22.75
Prebranchial length	16.29	15.93	18.35
Prespiracular length (horizontal)	12.11	11.27	13.19
Preorbital length (horizontal)	7.05	7.25	7.91
Prenarial length (horizontal to outer margin)	4.56	3.47	4.27
Prenarial length (horizontal to inner margin)	5.48	5.27	5.97
Preoral length	7.31	7.09	8.46
Prepectoral length	18.71	18.36	21.52
Prepelvic length	37.58	35.96	39.25
Snout-vent length	40.85	38.42	41.94
Preanal length	56.86	53.69	59.14
Precaudal length (dorsal)	70.59	70.43	71.22
Head height	8.01	6.17	6.78
Head width at mouth corners	10.14	10.53	11.97
Head width	10.39	10.93	13.23
Mouth width	8.17	7.71	9.09
Mouth length	3.75	2.26	3.40
Internarial width	3.05	2.65	2.74
Upper labial furrow length	2.22	2.18	2.94
Lower labial furrow length	2.24	2.58	2.72
Orbit length	4.27	4.01	4.64
Orbit height	0.89	0.87	1.10
Nostril width	2.42	2.45	2.95
Nostril to mouth distance	2.04	1.82	2.33
Interorbital width	7.32	7.15	7.78
First gill slit height	2.01	2.15	2.66
Third gill slit height	1.64	1.80	2.89
Fifth gill slit height	1.23	1.13	1.95
Intergill width	3.97	3.38	5.19