Hydrophis sibauensis RASMUSSEN, AULIYA & BÖHME, 2001
Can you confirm these amateur observations of Hydrophis sibauensis?
|Higher Taxa||Elapidae (Hydrophiinae), Colubroidea, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||E: Kalimantan Sea Snake|
|Synonym||Hydrophis sibauensis RASMUSSEN, AULIYA & BÖHME, 2001|
Hydrophis sibauensis — AULIYA 2006
Chitulia sibauensis — KHARIN 2005
Chitulia sibauensis — KHARIN & DOTSENKO 2012
Hydrophis sibauensis — SANDERS et al. 2012 (by implication)
Chitulia sibauensis — WALLACH et al. 2014: 167
|Distribution||West Kalimantan (Indonesia, Borneo: River Sibau, an affluent of the River Kapuas)|
Type locality: Sibau Kecil, Putussibau.
|Types||Holotype: ZMUC 661199; Paratypes: ZFMK 64889 male|
Habitat: freshwater; this species was found in a river 1000 km up-river from the coast.
Diagnosis: Hydrophis sibauensis has a combination of characters that place it in the genus Hydrophis as defined by Smith (1926): maxillary bone not extending for- ward beyond the palatine; poison-fang followed, after a diastema, by 1-18 teeth; pal- atine straight; nostrils superior; nasal shields in contact with each other; head shields large, regular (Fig. 3); and ventrals small, distinct throughout and normally entire [except H. cantoris and H. gracilis, which have the ventrals divided posteriorly (McDowell, 1972)]. Hydrophis sibauensis is clearly distinct from 25 of the 33 species in the genus us- ing only three external characters: number of ventrals, number of scale rows around neck, and number of scale rows around body. Hydrophis sibauensis is distinct from the following 18 species in having lower number of ventrals (Table 1): H. atriceps, H. brookii, H. cantoris, H. cyanocinctus, H. elegans, H. fasciatus, H. kingii, H. klos- si, H. mamillaris, H. nigrocinctus, H. ob- scurus, H. pacificus, H. parviceps, H. semper, H. spiralis, H. stricticollis, H. vorisi, and H. walli (Bussarawit et al., 1989; Cog- ger, 1975, 1992; Cogger et al., 1983; Kharin, 1984a, 1989; McDowell, 1972; Smith, 1926, 1935, 1943; Taylor, 1963, 1965; our data). Hydrophis sibauensis is distinct from the following seven species in having lower number of scale rows around the neck and/or lower number of scale rows around the body (Table 2): H. bituberculatus, H. cacrulescens, H. czeblukovi, H. inornatus, H. lamberti, H. major, and H. ornatus (Rasmussen, 1989, 1992; Rasmussen and Smith, 1997; Smith, 1926; Toriba, 1994; our data). The remaining eight species in Hydro- phis can be separated from H. sibauensis using a combination of external and inter- nal characters. Hydrophis gracilis is easily distinguished from H. sibauensis in having the ventrals divided by a longitudinal fur- row posteriorly, this furrow is absent in H. sibauensis. The following six species can be separated from H. sibauensis using a combination of number of ventrals, VS- heart, VB-body, and color pattern (Table 3): H. belcheri (as redefined by McCarthy and Warrell, 1991), H. coggeri, H. lape- moides, H. rnacdotvelli, H. melanocephal- us, and H. melanosoma (Cogger, 1975, 1992; Greer, 1997; Heatwole and Cogger, 1994; Kharin, 1983, 1984b; Mao and Chin, 1980; McCarthy and Warrell, 1991; Ras- mussen, 1993; Smith, 1926; Taylor, 1965; our data). In addition to Table 3, H. sibauiensis can be separated from H. belcheri and H. coggeri in having 20 ptery- goid teeth (14-17 in H. belcheri and 14- 15 in H. coggeri), from H. lapemoides in having one postocular (two or three in H. lapemoides), and from H. melanosoma in having seven maxillary teeth (5-6 in H. melanosoma). The last species, Hydrophis torquatus, is currently divided into three subspecies (Smith, 1926). Hydrophis sibauensis is dis- tinct from the three subspecies of H. torquatus using a combination of number of scale rows around neck, number of scale rows around body, number of ventrals, VS- heart, and VB-body (Table 4) (Smith, 1926; our data). The only specimen of H. torquatus taken from Borneo belongs to H. t. aagaardi (BMNH 18.104.22.168) (Smith, 1926; Stuebing, 1991), and is distinct in having 35 scale rows around the neck (25- 26 in H. sibauensis), 46 scale rows around the body (35-37 in H. sibauensis), 145 VS- heart (108-109 in H. sibauensis), and 317 ventrals (257-264 in H. sibauensis).