Elasmobranchii (sharks and rays) >
Carcharhiniformes (Ground sharks) >
Pentanchidae (Deepwater catsharks)
Etymology: Bythaelurus: bythos (Gr.), depths of the sea, referring to its deepwater habitat; ailouros (Gr.), cat, probably an allusion to the vernacular “catshark,” so named for its cat-like eyes (See ETYFish); bachi: In honor of Johann Sebastian Bach (1685-1750), a “musical genius and one of the greatest composers of all time” (so named because the senior author admires Bach and not for any Bach-like feature the shark might possess, Simon Weigmann, pers. comm.) [see also B. vivaldii] (See ETYFish).
Eponymy: Johann Sebastian Bach (1685–1750) was described in the etymology as: “…a musical genius and one of the greatest composers of all time.” There is no further need here for a lengthy biography. (Ref. 128868), visit book page.
Environment: milieu / climate zone / depth range / distribution range
Ecology
Marine; pelagic-oceanic; depth range 910 - 1365 m (Ref. 113731). Tropical
Distribution
Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | Faunafri
Western Indian Ocean: Madagascar Ridge at Walters Shoals.
Size / Weight / Age
Maturity: Lm ? range ? - ? cm
Max length : 42.2 cm TL male/unsexed; (Ref. 113731); 44.5 cm TL (female)
Short description
Identification keys | Morphology | Morphometrics
This species is distinguished by the following characters: body firm and stout (slender in juveniles); snout long, preorbital length 4.7-7.6% TL and has a 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; its 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; length of second dorsal-fin base 6.7-9.7% TL; anal-fin base 0.7-1.3 times interdorsal space; 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; 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. Colouration: body and fins plain beige to light grayish-brown, slightly brighter on ventral side (Ref. 113731)
The females of this species based on total length are mature at 39.2 cm and immature at 36.1 cm, while males are mature at 40.0 cm and immature at 37.6 cm . The size at hatching based on the three post-embryonic specimens is estimated at around 12.0 cm TL (Ref. 113731).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Weigmann, S., D.A. Ebert, P.J. Clerkin, M.F.W. Stehmann and G.J.P. Naylor, 2016. 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. (Ref. 113731)
IUCN Red List Status (Ref. 130435: Version 2024-1)
Threat to humans
Harmless
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Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5001 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00355 (0.00175 - 0.00721), b=3.08 (2.90 - 3.26), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref.
93245).
Trophic level (Ref.
69278): 4.3 ±0.5 se; based on size and trophs of closest relatives
Resilience (Ref.
120179): Low, minimum population doubling time 4.5 - 14 years (Preliminary low fecundity).
Fishing Vulnerability (Ref.
59153): Low to moderate vulnerability (35 of 100).
![Image of Bythaelurus bachi (Bach\](/images/thumbnails/jpg/tn_Bybac_f0.jpg "Image of Bythaelurus bachi (Bach\")
