Hydrophis dayanus Stoliczka, 1872

Mondal, Sonia, Ganesh, S. R., Sethy, P. G. S., Raghunathan, C., Raha, Sujoy & Sarkar, Sagnik, 2022, Redescriptions of the type specimens of synonymous nominal taxa of sea snakes (Serpentes: Elapidae: Hydrophis, Laticauda) at the Zoological Survey of India, Zootaxa 5169 (4), pp. 301-321 : 309

Hydrophis dayanus Stoliczka, 1872

synonym of Hydrophis cyanocinctus Daudin, 1803

( Table 1 ; Fig. 5 )

Material Examined. ZSI 8278 Holotype from Karachi (in Sindh, Southern Pakistan).

Description. Head robust, short, head shield large, regular; Rostral broader than high; Nasal superior, nasal shield in contact with each other; Prefrontal small, 2 nd supralabial touching prefrontal; Frontal shorter than the distance from the tip of the rostral; Parietal longer than wide; Temporals 1+2; One Supraocular on each side of head; One Preocular on each sides of head; Two Postoculars on each sides of head; Eight Supralabials on each sides of head; 2 nd touching the prefrontal; 3 rd, 4 th and 5 th touching the eye; 6 th broken; Eight infralabials on right and nine on left side of head; 3 infralabials touching the chin shield, small cuneate scales present; Chinshield well developed; both the pair not in contact with each other; Scales around neck 33; Scales around Midbody 40; Ventrals 327, very small but distinct from adjacent dorsal scales; Preanal small; Two white dots present on prefrontal, Head width 7.2 mm; Head depth 7.4 mm; Head length 14.9 mm; Snout to Vent length 550.0 mm; Tail length 54.0 mm. Head dark brown dorsally and ventrally with a weak light brown dots present on prefrontal, two lateral light brown C-shaped marks extending from eye to temporals. Entire body light brown, encircled by dark brown bands; interspaces light brown, broad dorsally and on flank, disappearing ventrally. All ventral scales light brown. Tail with dark brown bands both dorsally and ventrally. Number of bands 57 around body till vent; Seven bands on tail.

Remarks. Wall (1906) stated its scale counts to be scale rows 33:39:40 and ventrals as 342, whereas Smith (1926) stated it to be a young male, with scale rows 33:43 and ventrals 343. Sclater (1891) listed H. dayanus in the synonymy of H. lapemoides (Gray, 1849) and this was also followed by Boulenger (1896). But Wall (1906) synonymized H. dayanus with H. cyanocinctus where it now rests (see Wall 1909; Smith 1926; Wallach et al. 2014; Ganesh et al. 2019). Hydrophis lapemoides is a species originally described based on two specimens, a juvenile from Madras and a subadult from Sri Lanka ( Stoliczka 1872). Rasmussen (1993) while redescribing this species illustrated and redescribed the type specimens of H. lapemoides . Wallach et al. (2014) designated BMNH 1946.1.7.2 the subadult specimen from Sri Lanka as the lectotype and thus BMNH 1946.1.6.91 the juvenile from Madras became a paralectotype. Because the type of H. dayanus is also a subadult, this probable confusion of H. dayanus being conspecific with H. lapemoides (see Sclater 1891; Boulenger 1896) had risen (see Wallach et al. 2014; Ganesh et al. 2019). Hydrophis cyanocinctus young ones and subadults to certain extent, have much thicker and bolder bands, compared to the usual adult pattern in that species ( Smith 1926, 1943; SRG pers. obs.). Rasmussen (1993) did not list H. dayanus in the synonymy of H. lapemoides . The unsettled opinions were also stated by Das et al. (1998). However, Das et al. (1998) reported ZSI 8278 as holotype and still remarked that another syntype is in the Naturhistorisches Museum Wien (NMW), Wienna, Austria. Stoliczka’s (1872) description clearly mentions two specimens (one 23 inches and the larger one 27 inches), and hence ZSI 8278 is a syntype, not holotype as reported by Das et al. (1998). Our perusal suggests that the 604 mm long specimen is the 23 inch long (total length) one dealt with by Stoliczka (1872). Similarly, Das et al. (1998) stated ZSI 8266 as a syntype that goes well with Smith’s (1926) remark of the same specimen as being one of the types of H. trachyceps .

Figures

FIGURE 5. Holotype of Hydrophis dayanus ZSI 8278, dorsal (top), ventral (middle) and lateral (bottom) aspects. Photograph by Zoological Survey of India, Kolkata.