Pliotrema kajae

Weigmann, Gon, Leeney & Temple, 2020


Kaja’s sixgill sawshark
Classification: Elasmobranchii Pristiophoriformes Pristiophoridae

Reference of the original description
Weigmann, S. & Gon, O. & Leeney, R.H. & Barrowclift, E. & Berggren, P. & Jiddawi, N. & Temple, A.J. (2020)
Revision of the sixgill sawsharks, genus Pliotrema (Chondrichthyes, Pristiophoriformes), with descriptions of two new species and a redescription of P. warreni Regan. PLoS ONE, 15(3), Article e0228791


Images of types

Description :


Citation: Pliotrema kajae Weigmann, Gon, Leeney & Temple, 2020: In: Database of modern sharks, rays and chimaeras, www.shark-references.com, World Wide Web electronic publication, Version 03/2024

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Pliotrema kajae Weigmann, Gon, Leeney & Temple, 2020, holotype, MNHN 1987–1266, juvenile female, 560 mm TL, scale bar: 5 cm © Dr. Simon Weigmann, Elasmobranch Research Laboratory, Hamburg, Germany
Common names
deu \(T\) Kajas Sechskiemer-Sägehai, eng Kaja’s sixgill sawshark

Short Description
Diagnosis after WEIGMANN et al., 2020 [28258]: A large six-gilled sawshark with the following characters: barbel origin to anterior nostrils 1.4–2.3 times anterior nostrils to symphysis upper jaw; prenarial length 1.5–1.7 times prebarbel length; preoral length 2.0–2.7 times interdorsal space; pectoral-fin anterior margin 1.2–1.6 times dorsal–caudal space; mouth width 2.8–6.6 times spiracle length. First dorsal fin originates about opposite pectoral-fin free rear tips. Lateral trunk dermal denticles tricuspidate, rather flat and imbricated. Color pale to light brown dorsally with two thin yellowish longitudinal stripes; uniform white ventrally; fins with rather indistinct white posterior fin margins; dorsal rostrum surface with two distinct longitudinal dark stripes, lateral rostral teeth dark-edged. Monospondylous centra 52–57; precaudal diplospondylous centra 48– 56; total vertebral centra 151–164. This new species is distinguished from its two congeners, Pliotrema warreni and the second new species, by a combination of characteristics, including most notably, a rostrum that is clearly constricted between barbel origin and nostrils. Furthermore, P. kajae has sharp folds in both upper and lower jaw teeth, as well as a posteriorly notched, teardrop-shaped dorsal fenestra of the precerebral fossa. Pliotrema kajae is further distinguished from P. warreni by barbels that are situated about half way from rostral tip to mouth, with prebarbel length about equidistant from barbel origin to symphysis of upper jaw (vs. barbels about two thirds way from rostral tip to mouth, with prebarbel length about twice distance from barbel origin to symphysis of upper jaw) and the presence of two indistinct, yellowish longitudinal stripes on the dorsal surface (vs. one pronounced yellowish longitudinal stripe). Pliotrema kajae also clearly differs from the second new species in a generally longer snout, more upper and lower jaw tooth rows, higher total large lateral rostral tooth and ventral rostral spine counts, and a pale to light brown dorsal coloration with two indistinct yellowish stripes, uniform white ventral coloration, and posterior fin margins with narrow white edges (vs. uniform medium to dark brown dorsally without longitudinal stripes, white ventrally but with few indistinct dark blotches on belly, posterior fin margins conspicuously white-edged).

Distribution
off Madagascar and the Mascarene Ridge [28258]

Size / Weight / Age
TL (max): 143 cm; TL (birth): around 35 cm [28258]

Habitat
demersal; marine; depth range 214-320 m [28258]

Dentition
Teeth unicuspidate, in well-defined series, bases oval and flattened with short but pronounced, narrow median cusp near middle of jaw, no lateral cusps (cusps similar in paratypes except for adult male SAIAB 84096, which has distinctly longer cusps); cusps diminishing in height towards jaw angles, indistinct near jaw corners; about 4–5 series of functional teeth. Median cusp with labial face slightly convex and with both mesial and distal cutting edges weakly bent mesially and distally in occlusal view, respectively. The mesial and distal crown base parts somewhat curve apically. A pronounced and broad, irregularly shaped apron overlaps the junction of crown and root, building a notch at the junction with both mesial and distal crown base parts. Basal ornamentation, striae or reticulations absent, but sharp folds present in both upper and lower jaw teeth. The lingual face of the cusp is strongly convex, a well-developed uvula is present at the central crown base. The mesial/distal latero-lingual crown faces curve strongly towards the apex of the crown, partially forming a sharp notch with the uvula. The root is anaulacorhizid and slightly arched without lobation. The outer surface of the root shows up to five large basal foramina, which are mostly oval-shaped. The inner face of the root shows up to six well-developed foramina along the crown-root junction at each side of the uvula. The basal face of the root is flat, partly showing some outer foramina. [28258]

Remarks
shark-references Species-ID=15841;