Rhinobatos lionotus Norman 1926

• Main Authors: Last, Peter R., Séret, Bernard, Naylor, Gavin J. P.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2019
• Subjects: Biodiversity; Taxonomy; Animalia; Chordata; Elasmobranchii; Rajiformes; Rhinobatidae; Rhinobatos; Rhinobatos lionotus; Fridtjof Nansen
• Online Access: https://doi.org/10.5281/zenodo.5926017; http://treatment.plazi.org/id/C06087AC0E065501FF68C250FE1A0AB0

Rhinobatos lionotus Norman 1926 Smoothback Guitarfish (Figs 4, 5, 10–12; Table 2) Rhinobatis schlegelii ( nec Muller & Henle): Annandale, 1909, Memoirs Indian Museum 2, 15. Rhinobatus lionotus Norman, 1926, Proc. Zool. Soc. London 1926 (62): 961, fig. 14. Rhinobatos lionotus : Fowler, 1941, 310; Akhilesh et al. 2014, Checklist Chondrichthyans India: 115-118 (listed). Material examined. Holotype, BMNH 1909.7.12.3 [ex ZSI], female 495 mm TL, mouth of Hooghly River, India, ~ 70 m depth; CSIRO H 7867-01, female 760 mm TL, Bay of Bengal, N of Andaman Is, Myanmar, 15°01.63’ N, 93°45.55’ E, bottom trawl, 76 m depth, RV Dr Fridtjof Nansen station 60, specimen 247, collected P. Psomadakis, 9 May 2015. Diagnosis. A medium-sized species of the genus Rhinobatos (attaining at least 760 mm TL) distinguished by the following combination of characters: disc wedge-shaped, rather large, width 35–37% TL, length 1.2–1.3 times width; snout relatively short, length 2.5–2.7 times interspiracular distance, ~3.4 times interorbital width; orbit diameter 1.2–1.4 times spiracle length; nostrils moderately oblique, their length 1.3–1.5 times internarial distance; mouth width 6.3–6.9% TL; preoral length 5.5–5.9 times internarial distance; posterior nasal flaps broad; two spiracular folds, outermost fold subequal to marginally taller than inner fold; ridges of rostral cartilage almost parallel, widely separated, converging slightly anteriorly but not constricted medially; anterior cartilage weakly sickle shaped, almost truncate posteriorly; distance between fifth gill slits 2.5–2.7 times in ventral head length; prebranchial sensory pore system obvious, extending posteriorly to margin of first gill slit; postscapular sensory canal notched, with exposed lateral pores; weak thorn patches on supraorbit and scapular region, and row of rudimentary thorns (not conspicuous) along dorsal midline; denticles on dorsal fins densest anteriorly, more sparse posteriorly; dorsal fins small, height of first 7.7–8.1% TL; pelvic-fin inner margin subequal to ...