Morphology Data of Bythaelurus vivaldii
Identification keys
Main Ref. Weigmann, S. and C.J. Kaschner, 2017
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral other (see remarks)
Cross section flattened
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales placoid scales

This species is distinguished by the following characters: body firm and stout (of the presumably adult holotype and slender in supposedly juvenile paratype); snout is long (preorbital length 6.1-6.6% TL) and broad, bell-shaped in dorsoventral view with a distinct lateral indention; the pre-outer nostril length is subequal to internarial space; preorbital snout length is subequal to interorbital space; preoral snout length 1.4–1.8 times in mouth width; eye length 13.9-15.0 times in predorsal distance, 6.8-6.9 times in head length and 1.6-2.3 times eye height; head length 2.6-2.8 times width at level of maximum outer extent of anterior nostrils; head width at the level of maximum outer extent of anterior nostrils, 1.2 times width at level of lateral indention of head, 1.3–1.4 times preorbital length, and 8.5–8.6% TL; the roof of the mouth is loosely set with rather small, knob-like to elongated oral papillae, oral papillae on tongue hardly detectable; pelvic-fin anterior margin 2.0-2.1 times in pectoral-fin anterior margin; first dorsal-fin base 2.2-2.3 times in interdorsal space; length of second dorsal-fin inner margin 1.3-2.3 times in second dorsal-fin height; second dorsal-fin base length 5.3% TL; anal-fin base 0.7-0.8 times interdorsal space; upper jaw with 68-75 and lower jaw with 64 rows of small tri- to pentacuspidate teeth with outer surface of crown furrowed by strong longitudinal ridges from base of cusps to tip and strongly structured by reticulations from basal areas to well into cusps; monospondylous trunk vertebrae centra 38, diplospondylous precaudal centra 43-44, total centra about 135-140; dermal denticles leaf-like to teardrop-shaped on snout and tricuspidate on trunk and tail; reported to have 8–9 dark, broad but inconspicuous transverse bars on the back (preserved coloration plain beige with scattered remains of dark brown); .

Description: The new species is distinguished from all congeners in the western Indian Ocean by having a larger pre-second dorsal fin length, a longer head, a larger interdorsal space, a larger intergill length, a longer pectoral-fin posterior margin, a shorter caudal fin, an intermediate caudal fin preventral margin, and a larger internarial width (Ref. 114990).

Ease of Identification

Meristic characteristics of Bythaelurus vivaldii

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb


Dorsal fin(s)

Fins number
Finlets No. Dorsal   
Spines total
Soft-rays total
Adipose fin

Caudal fin


Anal fin(s)

Fins number
Spines total
Soft-rays total

Paired fins

Pectoral Attributes  
Pelvics Attributes  
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17