Microcephalophis gracilis (Shaw, 1802)

Rezaie-Atagholipour, Mohsen, Ghezellou, Parviz, Hesni, Majid Askari, Dakhteh, Seyyed Mohammad Hashem, Ahmadian, Hooman & Vidal, Nicolas, 2016, Sea snakes (Elapidae, Hydrophiinae) in their westernmost extent: an updated and illustrated checklist and key to the species in the Persian Gulf and Gulf of Oman, ZooKeys 622, pp. 129-164 : 150-151

Taxon classification Animalia Squamata Elapidae

Microcephalophis gracilis (Shaw, 1802) Figures 23, 24

Hydrus gracilis Shaw, 1802: 560.

Microcephalophis gracilis gracilis - Smith 1926: 121. - Kennedy 1937: 748. - Volsøe 1939: 25. - Corkill and Cochrane 1965: 494. - Joger 1984: 35. - Gasperetti 1988: 320.

Microcephalophis gracilis - Corkill 1932: 51. - Carpenter et al. 1997: 248. - Baldwin and Gardner 2005: 251. - Egan 2007: 160. - Safaei and Esmaili 2009: 45.

Hydrophis gracilis gracilis - Leviton and Aldrich 1984: XXIV. - Firouz 2005: 209.

Hydrophis gracilis - Leviton et al. 1992: 122. - Firouz 1999: 192. - Latifi 2000: 339. - Rastegar-Pouyani et al. 2008: 20. - Soorae et al. 2010: 535. - Kamali 2013: 239. - Safaei-Mahroo et al. 2015: 282.

Material examined.

Gulf of Oman: 11 specimens, Beris and Pasa-Bandar, depth 20-40m [(ZMSBUK.HD.31), TL 968, SVL 878, HL 13.1, HW 5.3, GL 7.7, SNL 3.1, NEL 1.1, ND 24, GBD 66, NSL 5, NSR 19, BSR 33, NV 237, NB 21; (ZMSBUK.HD.32), TL 830, SVL 757, HL 116, HW 4.4, GL 7, SNL 2.7, NEL 1.2, ND 19, GBD 66, NSL 6, NSR 18, BSR 31, NV 269, NB 43; (ZMSBUK.HD.33), TL 978, SVL 893, HL 13.1, HW 5.9, GL 7.8, SNL 3.4, NEL 1.9, ND 20, GBD 54, NSL 6, NSR 15, BSR 29, NV245, NB 59; (ZMSBUK.HD.34), TL 900, SVL 821, HL 12.3, HW 5.2, GL 7.9, SNL 2.8, NEL 1.4, ND 23, GBD 67, NSL 6, NSR 18, BSR 29, NV 253, NB 55; (ZMSBUK.HD.35), TL 893, SVL 821, HL 12.1, HW 6.3, GL 9, SNL 3, NEL 1.8, ND 20, GBD 55, NSL 6, NSR 17, BSR 31, NV 223, NB 20; (ZMSBUK.HD.36), TL 900, SVL 820, HL 12.2, HW 5.1, GL 9, SNL 3.6, NEL 1.7, ND 22, GBD 58, NSL 6, NSR 18, BSR 31, NV 231, NB 51; (ZMSBUK.HD.37), TL 957, SVL 870, HL 12.5, HW 5.7, GL 8.5, SNL 3.5, NEL 1.4, ND 20, GBD 50, NSL 6, NSR 19, BSR 32, NV 264, NB 46; (ZMSBUK.HD.38), TL860, SVL 787, HL 12.3, HW 5.4, GL 7.7, SNL 3, NEL 1.5, ND 20, GBD 60, NSL 6, NSR 19, BSR 29, NV 229, NB 27; (ZMSBUK.HD.39), TL 935, SVL 847, HL 12.8, HW 5.7, GL 8, SNL 3.4, NEL 2.2, ND 22, GBD 78, NSL 6, NSR 19, BSR 30, NV 229, NB 41; (ZMSBUK.HD.46), TL 827, SVL 752, HL 12.7, HW 5.6, GL 9, SNL 3.4, NEL 1.5, ND 18, GBD 62, NSL 6, NSR 19, BSR 30, NV 242, NB 48; (ZMSBUK.HD.54), TL 922, SVL 837, HL 13.2, HW 5.9, GL 8.9, SNL 3.2, NEL 1.4, ND 20, GBD 67, NSL 6, NSR 19, BSR 31, NV 246, NB 53], August 2013, collector: M. Rezaie-Atagholipour.

Diagnosis.

Head extremely small (Figure 24); 5-6 supralabials, second usually in contact with prefrontal, third and fourth touch eye (Figure 23a); neck markedly slender; body elongate, markedly slender anteriorly (Figure 24d); 15-20 scale rows on neck, 20-33 on body [18-19 and 31 ( Volsøe 1939)]; 223-269 ventrals [232-269 ( Volsøe 1939)].

Coloration.

Gray to dark gray dorsally, gray-whitish ventrally, darker anteriorly than posteriorly; 20-59 black bands broader dorsally; bands on necks and anterior part of body are black and merge each other only ventrally or ventrally and dorsally (Figure 24d); bands on the posterior part of the body are paler, or sometimes absent.

Size.

Mean TL 906 mm, maximum 978 mm (n = 11); [n = 9, mean TL 865.5 mm, maximum TL 1030 mm ( Volsøe 1939)].

General distribution.

Indo- West Pacific, from the Persian Gulf to Australia ( David and Ineich 1999).

IUCN Red List Category.

Least concern ( IUCN 2016).

Remarks.

Microcephalophis gracilis and the other Small-headed Sea Snake, Microcephalophis cantoris , recorded here for the first time in the area (see below), are easily distinguishable from other species in the region by having an extremely small head and slender neck. However, these two species may be confused with each other at a glance. Microcephalophis gracilis is distinguishable from Microcephalophis cantoris by having less number of ventrals (223-269 versus 404-468 in Microcephalophis cantoris ). All material examined in this study was collected from eastern Gulf of Oman. Volsøe (1939) however recorded material from the western Gulf of Oman and western Persian Gulf.