Rhina ancylostoma Bloch & Schneider, 1801

Bogorodsky, Sergey V., Zajonz, Uwe, Saeed, Fouad N. & Weigmann, Simon, 2021, Notes on batoid fishes of the Socotra Archipelago (north-western Indian Ocean) with four new records, Zootaxa 4951 (3), pp. 511-528 : 515

Rhina ancylostoma Bloch & Schneider, 1801

Shark ray, Bowmouth guitarfish

Fig. 4

ohẚna ancylosṫomus Bloch & Schneider, 1801: 352; lectotype: ZMB 4621 , specimen lost; type locality: Coromandel Coast , south-eastern India.

Material examined: 1 specimen, not preserved, female, 225 cm TL, Socotra Archipelago , Abd al-Kuri Island, 27 March 2019 .

Distinctive characters: ohẚna ancylosṫoma is an unmistakable guitarfish, characterised by having a short and broadly rounded snout; upper jaw with three deep concavities; mid-line of disc with a ridge of large thorns, interorbital area with two ridges; posterior tip of pectoral fins ending before pelvic fins; spiracles without folds; upper and lower caudal-fin lobes subequal in size.

Colouraṫẚon: Greyish brown, head with transverse black bands, body and fins with many small white spots. Pattern strongly pronounced in juveniles, usually less distinct in large specimens. Ventral surface pale.

Distribution: Known from the Red Sea to the Gulf, south to Mauritius and South Africa (KwaZulu-Natal), east to eastern Australia (New South Wales), the Philippines and southern Japan (Last eṫ al. 2016b). In the Arabian region, the species was recorded from the Red Sea ( Debelius 1998), Gulf of Tadjoura (Lips eṫ al. 2016; Froese & Pauly 2020), and the Gulf (Randall 1995; Almojil eṫ al. 2015); records from off Oman (Muttrah), Iran and Pakistan are based on photographs of fresh specimens ( Froese & Pauly 2020).

Remarks: The collected specimen was a mature female of 225 cm TL taken by fishermen at Abd al-Kuri Island and matches well all characters of ohẚna ancylosṫoma given by Last eṫ al. (2016b). No precise collection data on locality and habitat were recorded. The specimen was examined on board a fishing boat from the United Arab Emirates. The species occurs from close inshore to depths of at least 75 m ( Weigmann 2016) on the continental shelf, usually swimming close to substrata or resting on bottom in open sand areas but occasionally also seen in pelagic waters; it might be found in similar habitats in waters of the Socotra Archipelago. With 225 cm TL, the specimen is half a meter shorter than the maximum size reported for the species, 275 cm TL ( Weigmann 2016). The species is included as critically endangered in IUCN Red List Assessments and urgently requires conservation management (Kyne eṫ al. 2019a).

Figures

FIGURE 4. ohẚna ancylosṫoma, fresh colouration, female, 225 cm TL, Abd al-Kuri Island, Socotra Archipelago. A: dorsal view; B: head close-up. Photos by S.V. Bogorodsky & U. Zajonz.