Redescription of sexually dimorphic of Andaman leg-skate

Dorsal view of Cruriraja andamanica, (a) adult male and (b) adult female

Phylum: Chordata

Class: Elasmobranchii

Order: Rajiformes

Family: Crurirajidae Hulley, 1972

Cruriraja andamanica (Lloyd, 1909)

Collection: Andaman sea-7°52’ N, 93° 47’ E, 601 m, 24.09.2010 (FORV SS 280, St. 38); 8° 21’N, 93°20’E, 613 m, 14.11.2011 (FORV SS 292, St. 13); 8°23’ N, 93°20’ E, 622 m, 29.01.2015 (FORV SS 334LII, St. 7A). HSDT

Voucher No.: CMLRE R. C. No. 2803807a, 2803807b, 2929113a, 334LII7A1

Description: Disc markedly quadrangular, maximum angle anterior to spiracles 80–90°, with greatest width posterior to horizontal midline; disc width 1·1–1·3 times its length. Teeth of adult males strongly pointed, unicuspid, caniniform; posteriorly directed in middle of upper jaw; cusps much shorter and slightly oblique towards jaw angle; similar in lower jaw but with relatively shorter cusps; arranged in longitudinal rows; 50 rows in the upper jaw and 42 rows in the lower jaw. Teeth of adult female with oval bases, having low subtriangular cusps; arranged in definite longitudinal rows. Teeth of immature males and females with short, subtriangular cusps and similar patterns of arrangement as that of adult female. Pelvic fin separated into two morphologically distinct lobes. Anterior lobe limb-like, slender and greatly elongated; distally spatulate, extending up to the level of posterior lobe. Tail elongate, tapered and relatively slender; length about 1·5 times distance from snout tip to rear of cloaca. Single series of enlarged thorns on mid-dorsal region, becoming multiple rows towards middle of tail. Inter-dorsal space very short, less than length of first dorsal base. Dorsal surface of disc closely packed with numerous denticles, except the dorsal surface of pelvic fin and posterior mid-dorsal region of the disc, where they are widely scattered. Entire lower surface of disc smooth, devoid of denticles. Disc dorsally slate-grey in life, lacking blotches; ventrally light grey; snout, tail-tip including second dorsal fin and distal portion of first dorsal fin white.

Biological association: None

Remarks: The species was known only from a few specimen and holotype (ZSI) is very damaged. Present samples are the only intact specimen of this species in the world.

Distribution: Eastern Indian Ocean off Great Nicobar Island (510–622 m), Andaman Sea.

Distribution map:

Map showing locations of present record from Indian waters (square) of Cruriraja andamanica

Identified by: Vinu Jacob

Publication: Vinu, J., Rajeeshkumar, M. P., Parmeswaran, U. V., Sumod, K. S., Akhilesh, K. V., Manjebrayakath, H., & Sanjeevan, V. N. (2017). Redescription and sexual dimorphism of Andaman leg‐skate Cruriraja andamanica (Chondrichthyes: Rajiformes) with comments on the zoogeography of the genus Cruriraja. Journal of fish biology91(2), 587-602.

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