Rhinobatos borneensis Last, Séret & Naylor, 2016
Borneo guitarfish
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Family:  Rhinobatidae (Guitarfishes)
Max. size:  68.6 cm TL (male/unsexed); 90 cm TL (female)
Environment:  benthopelagic; marine
Distribution:  Northwest Pacific: South China Sea, off Borneo.
Diagnosis:  This species is distinguished by the following characters in adults: a wedge-shaped disc, its width 29-31% TL and length 1.30-1.42 times width; snout length 2.5-3.3 times the interspiracular distance, 3.8-5.6 times the interorbital width; medium-sized orbit, 1.5-2.2 times the spiracle length; nostrils weakly oblique, length 1.5-1.7 times internarial distance; preoral length 7.4-8.1 times the internarial distance; anterior nasal flaps are penetrating slightly into internarial space but well separated at their insertion (not reaching level of inner corner of nostril); posterior nasal flaps are broad; spiracular folds 2, the outermost fold distinctly taller than inner fold; ridges of rostral cartilage almost parallel, converging slightly anteriorly but not constricted medially; anterior cartilage sickle-shaped, pointed or blunt posteriorly; distance between fifth gill slits 2.7-3.3 times in ventral head length; prebranchial sensory pore patch obvious, extending to just behind first gill slit; postscapular sensory canal apparent with exposed lateral pores, grooved; thorn patches present on supraorbit, scapular region, and dorsal midline rudimentary, not evident; in males pelvic-fin inner margin subequal to its base, shorter in females; interdorsal distance 2.5-3.3 times first dorsal-fin base; dorsal caudal margin 1.9-2.3 times preventral margin; upper jaw with ca. 90 tooth rows; post-synarcual centra 176-180; nasal lamellae 50-53; dorsal fin usually with a large, often faint, central dusky blotches; in adults dorsal disc yellowish or brownish, often with diffuse pale yellowish blotches, without white spots; young with ocellate markings (Ref. 108568).
Biology:  This species is probably benthic on continental shelf. Biology of the species is poorly known, but for finding a pregnant female with 6 pups (Ref. 108568). Matures at ca. 63 cm TL (Ref. 114953).
IUCN Red List Status: Not Evaluated (N.E.) Ref. (123251)
Threat to humans:  harmless
Country info:   
 

Entered by: Capuli, Estelita Emily - 16.05.17
Modified by: Abucay, Luisa - 08.08.19

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