102 



A. REDSTED RASMUSSEN 



Species assignment. The material examined is separated 

 into three geographical regions: Andaman Sea and Malacca 

 Strait, India and Sri Lanka, and Persian Gulf and Gulf of 

 Oman (Tables 2 and 3, Figs. 6 and 7). When comparing 

 specimens from the three areas mentioned above, geographi- 

 cal variation is found in general body form (specimens from 

 the Persian Gulf look more robust than specimens from 

 Andaman Sea and Malacca Strait), in scale rows on neck in 

 relation to scale rows on body (Fig. 6), in number of 

 vertebrae (Table 3), and in number of vertebrae in relation to 

 VB heart (Table 3, Fig. 7). However, it is difficult to decide 

 whether the variation indicates a cline or distinct geographic 

 forms, as material is still missing from Bangladesh and 

 Burma, and so are representative samples from Pakistan, 

 India, and Sri Lanka. 



Both Boulenger (1896), Wall (1909) and Smith (1926) 

 referred the type specimen described by Anderson in 1872 

 under the name H. stewartii to H. lapemoides. Having 

 examined the specimen, I have serious doubt about its 

 assignment. 52 Scale rows on body in relation to 30 scale rows 

 on neck (Fig. 6), and 182 vertebrae in relation to 94 VB heart 

 (Fig. 7) indicate that the specimen belongs to a distinct taxon. 

 But as representative material is lacking from India and Sri 

 Lanka, I tentatively assign it to H. lapemoides. Further mate- 

 rial may show whether it is a valid taxon. 



Dunson & Minton (1978) caught some sea snakes in the 

 Philippines, during the Visayan Sea Expedition of R/V Alpha 

 Helix, and identified them as H. ornatus. In 1983 Tamiya et 

 al. reclassified the specimens as H. lapemoides, and later 

 Rasmussen (1989) reexamined the specimens and identified 

 them as H. lamberti. Comparison of the above mentioned 

 specimens with H. lapemoides from Andaman Sea and Mal- 

 acca Strait, shows that they differ in following characters: 

 Scale rows on neck (H. lamberti, 37-45), VS heart tip (H. 

 lamberti, 87-109), and VS liver (H. lamberti, 86-108), VB 

 heart tip (H. lamberti, 65-71), and color pattern (Rasmussen, 

 1989). Comparing the skull, H. lamberti shows a more robust 

 parietal, with a longer ridge (from 1/2 to 2/3 of the total 

 length of parietal bone in midline), and with a less globular 

 form than H. lapemoides. A single specimen of H. lamberti 

 (FMNH 313058) was collected sympatrically with H. 

 lapemoides (ZMUC 66101) in the area of Singapore, and also 

 here the two species are distinct on the characters mentioned 

 above. 



McCarthy & Warrell (1991) referred to a specimen 

 (BMNH 1987.172) from the Gulf of Siam (Samut Sakhon) as 

 '//. sp near H. lapemoides'. I have examined this specimen 

 and agree that it is very similar to H. lapemoides, however, it 

 differs in number of scale rows around body in relation to 

 scale rows on neck (Fig. 6) and in number of vertebrae in 

 relation to VB heart (Fig. 7). Compared to H. lapemoides 

 from Malacca Strait and Andaman Sea it is very long (1.1m) 

 and very robust in body and head form. In general shape it is 

 much closer to H. ornatus and H. lamberti, although the 

 characters differ here, too. Accordingly I think H. sp. near 

 H. lapemoides' should be separated from H. lapemoides, but 

 further studies are needed to find out whether the specimen 

 belongs to some of the more robust species in the Gulf of 

 Siam or is an unknown species. 



Generic assignment 



H. lapemoides has a combination of characters which places it 

 in the genus Hydrophis as defined by Smith (1926): maxillary 

 bone not extending forward beyond the palatine; poison-fang 

 followed, after a diastema, by from 1 to 18 teeth; palatine 

 straight; nostrils superior; nasal shields in contact with one 

 another; head shields large, regular; and ventrals small, 

 distinct throughout and normally entire. 



McDowells subgeneric assignment. In 1972 McDowell 

 recognized three subgenera in the genus Hydrophis, how- 

 ever, making a cladistic analysis (Rasmussen, in press) of the 

 subgenus Chitulia (formerly Aturia, see Williams & Wallach, 

 1989), the results indicated that the group was paraphyletic, 

 held together by plesiomorphic character states. Neverthe- 

 less, many of McDowell's character states are most useful in 

 making a congeneric comparison. 



Comparison with sympatric species 



In the genus Hydrophis the following species are sympatric with 

 H. lapemoides: H. bituberculatiis , H. brookii, H. caerulescens , 

 H. cantoris, H. cyanocinctus , H. fasciatus, H. gracilis, H. 

 inornatus, H. klossi, H. lamberti, H. mamillaris, H. melano- 

 soma, H. obscurus, H. ornatus, H. spiralis, H. stricticollis, and 

 H. torquatus. (Bussarawit et al., 1989; De Silva, 1980; Gasper- 

 etti, 1988; McCarthy & Warrell, 1991; Minton, 1966; Murthy, 



Table 2 Geographic variation of external and internal characters in H. lapemoides. 





Sex 



n 



Ventrals 



VS-heart 



% VS-heart 



VS-liver 



% VS-liver 



Andaman 



M 



28 



288-347 



106-131 



34.2-40.6 



110-133 



35.7-41.3 



Sea and 





jc±SD 



317±13 



118±6.7 



37.5±1.4 



120±6.2 



38.1 + 1.3 



Malacca 



F 



23 



299-378 



106-140 



33.8-38.5 



107-143 



34.4-39.1 



Str. 





Jt+SD 



341 ±20 



122±7.7 



35.7±1.2 



124+7.7 



36.3+1.2 



India 



M 



2 



313-318 



114-119 



36.4-37.4 



114-120 



34.4-37.7 



and Sri 





x±SD 



315±3.5 



116±35 



36.9±0.7 



117+4.2 



37.1+0.9 



Lanka 



F 



5 



313-376 



117-145 



35.1-39.0 



117-146 



35.1-39.3 







x±SD 



347±24 



127±12 



37.3+1.8 



129+13 



37.8±1.8 



Persian 



M 



45 



293-369 



111-141 



35.0-41.5 



113-144 



36.3-41.5 



Gulf and 





x±SD 



320±16 



123±7.2 



38.5+1.4 



124+7.1 



38.8±1.4 



Gulf of 



F 



25 



300-395 



114-155 



34.6-40.9 



114-157 



34.6-41.2 



Oman 





x±SD 



347±23 



129±10 



37.5+1.6 



130+10 



37.7±1.6 



VS-heart, VS-liver = position of tip of the heart and anterior tip of liver in relation to the number of the adjacent ventral scales, respectively. %VS-heart, 



% VS-liver = relative position of tip of the heart and anterior tip of the liver in number of ventral scales, expressed as percentage of total number of ventral scales. 



