Bythaelurus bachi


Bach’s Catshark
Classification: Elasmobranchii Carcharhiniformes Pentanchidae

Reference of the original description
Bythaelurus bachi n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the southwestern Indian Ocean, with a review of Bythaelurus species and a key to their identification. Zootaxa, 4208 (5): 401–432

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Description :

Citation: Bythaelurus bachi WEIGMANN, EBERT, CLERKIN, STEHMANN & NAYLOR, 2016: In: Database of modern sharks, rays and chimaeras,, World Wide Web electronic publication, Version 02/2019

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Bythaelurus bachi WEIGMANN, EBERT, CLERKIN, STEHMANN & NAYLOR, 2016, paratype, ZMH 26189, adult female 407 mm TL fresh, 400 mm TL 70% ethanol preserved, RV ‘Vityaz’, cruise 17, station 2735, Walters Shoals, 33°36’ S, 44°32’ E – 33°38’ S, 44°34’ E, 930–950 m depth, 29 m shrimp trawl, trawl # 68, on the bottom for 75 minutes, 19 Dec 1988 © Dr. Simon Weigmann, Elasmobranch Research Laboratory, Lüneburg

Common names
eng Bach’s Catshark

Short Description
Original Diagnosis of WEIGMANN, EBERT, CLERKIN, STEHMANN & NAYLOR, 2016 [24789]: A small scyliorhinid and a medium-sized Bythaelurus species with the following characteristics: body firm and stout (slender in juveniles); snout long (preorbital length 4.7–7.6% TL) and broad, bell-shaped in dorsoventral view with distinct lateral indention; pre-outer nostril length 1.1–1.9 times internarial space; preorbital snout length 0.7–1.0 times interorbital space; preoral snout length 1.0–1.9 times in mouth width; eye length 9.0– 13.0 times in predorsal distance, 3.6–5.4 times in head length and 1.4–4.1 times eye height; head length 1.8–2.7 times width at level of maximum outer extent of anterior nostrils; head width at level of maximum outer extent of anterior nostrils 1.1–1.5 times width at level of lateral indention of head, 1.1–1.8 times preorbital length, and 7.2– 10.0% TL; tongue and roof of mouth densely set with oral papillae of distinct size, which are partially very large and conglomerated from several single papillae; pelvic anterior margin 1.1–2.1 times in pectoral-fin anterior margin; first dorsal-fin base 1.0–1.8 times in interdorsal space; length of second dorsal-fin inner margin 0.5–1.9 times in second dorsal-fin height; second dorsal-fin base length 6.7–9.7% TL; anal-fin base 0.7–1.3 times interdorsal space. Coloration: body and fins plain beige to light grayish-brown, slightly brighter on ventral side. monospondylous trunk vertebrae centra 38–43, diplospondylous precaudal centra 33–43, total centra 124–132. Dermal denticle morphology highly diverse in different body areas and post-embryonic specimens with very characteristic double row each of about 20 distinctly enlarged, blunt, spatulate, cross-based dermal denticles along dorsal trunk. Claspers rather long and very thick, inner margin length 10.6–11.3% TL, base width 2.3–3.1% TL; no clasper hooks, cover rhipidion and pseudosiphon very large, envelope elongated. The new species is easily distinguished from all congeners by the plain beige to light gray-brown coloration, high diversity in dermal denticle morphology, and presence of composite oral papillae. In the western Indian Ocean, it is the only stout-bodied species of Bythaelurus with oral papillae.

Madagascar Ridge at Walters Shoals [24789]

Oviparous [24789]

Size / Weight / Age
120 mm TL (hatching) - 445 mm TL [24789]

bathydemersal; marine; depth range 910–1365 m [24789]

Upper jaw with 70–84 and lower jaw with 60–76 rows of small tri- to pentacuspidate teeth with outer surface of crown furrowed by strong longitudinal ridges and structured by reticulations in basal areas [24789]

shark-references Species-ID=14806;