Hydrophis donaldi, Ukuwela, Kanishka D. B., Sanders, Kate L. & Fry, Bryan G., 2012

Ukuwela, Kanishka D. B., Sanders, Kate L. & Fry, Bryan G., 2012, Hydrophis donaldi (Elapidae, Hydrophiinae), a highly distinctive new species of sea snake from northern Australia, Zootaxa 3201, pp. 45-57 : 48-52

Hydrophis donaldi sp. nov.

( Figs. 1 and 2 , Table 2)

Holotype. QM J90700 ( Figs. 1 A–C and 2A–B), an adult male from the Gulf of Carpentaria, Weipa, Queensland, Australia (12°35'10.88" S, 141°57'47.21" E) by B. G. Fry on 15th October, 2000. Liver tissue stored in ethanol in the QM (Accession no: 007903).

Paratypes (n = 7). SAMA R65215 (juvenile), SAMA R65216 adult male and SAMA R66274 adult male, all collected from the Gulf of Carpentaria, Weipa, Queensland, Australia (12°35'10.88" S, 141°57'47.21" E) collected by B. G. Fry between the 15-20 October, 2000. Tail tissue stored in ethanol in the ABTC-SAM. QM J63802 , QM J63803 , QM J63809 and QM J63810 (all adults, sex undetermined), all collected from the Gulf of Carpentaria, Weipa, Queensland, Australia (12°45'4.03" S, 141°53'58.10" E) by B. G. Fry on 1st March, 1997.

Diagnosis. Hydrophis donaldi sp. nov. is distinguished from all other Hydrophis species except H. coggeri , H. sibauensis and H. torquatus diadema by the following combination of characters: ventrals not divided by a longitudinal furrow, 29–30 costal scale rows around neck, 33–35 costal scales around body, 6–7 maxillary teeth behind fang on each side, 246–288 ventrals (Rasmussen et al. 2001; Smith 1926). The new species differs from H. coggeri by having 47–56 (vs 30–42) bands on the body and tail, strongly spinous (vs feebly carinate) body scales, 246–288 (vs 280–360) ventrals, relatively larger and rounded (vs smaller, elongate) head, and anterior part of the maxilla not arched upwards and the tip of the fang projecting below the level of the maxillary teeth ( Fig 1 D) (vs anterior part of the maxilla arched upwards and tip of fang not projecting below the level of the maxillary teeth) ( Cogger 2000). The new species differs from H. sibauensis by a higher number of scale rows around the neck 29–30 (vs 25–26 in H. sibauensis ) and strongly spinous (vs feebly carinate) body scales (Rasmussen et al. 2001). Hydrophis donaldi sp. nov. differs from H. torquatus diadema by a lower midbody scale count (33–35 vs 35–42 in H. torquatus diadema ) and strongly spinous (vs feebly carinate) body scales ( Smith 1926).

Description of the Holotype. Six maxillary teeth are present behind the poison fang. One pre-ocular and postocular scale on each side. Seven supra-labials on each side. First and second supralabials touch the nasal scale and the 3rd and 4th touch the eye. Two anterior and posterior temporals on each side. Seven infralabials on each side. The 1st, 2nd and 3rd infralabials are in contact with the anterior chin-shield and the 4th contacts the posterior chin-shield. Costal scale rows around neck 29; around midbody 33. Dorsal scales strongly spinous. Ventral scales bear two strong spines. Ventrals 269; subcaudals 48; ventrals 1.5 times as wide as adjacent scales. SVL 756 mm; TAL 105 mm; TH 16.71 mm. The dorsal head scales have a rough and warty appearance.

Variation (n = 7). Only differences to the holotype are noted. The number of maxillary teeth behind the poison fang is 6 or 7. Two anterior temporals are present in most of the paratypes, but some specimens have one anterior temporal (Table 2) and SAMA R66274 has one anterior temporal on the left and two on the right. Costal scale rows around the neck 29–30 and around midbody range 33–35. Ventral scales bear two strong spines in all paratypes except in the juvenile SAMA R65215. Ventrals range from 246–288; subcaudals +42–51. SVL in mature individuals 649–777 mm; TL 92-101 mm; TH 13.02–16.69 mm (see Table 2).

Gene/Locus Marker type Size Substitution Total polymor- Min. fixed Max. fixed (bp) Model phic sites nucleotide nucleotide differences differences Colour pattern. Before preservation in the holotype, the background colour was yellowish brown with 56 brownish bands from neck to tail. Bands are broader dorsally, narrow laterally and taper without connecting ventrally. They are wider than the paler interspaces. Bands in first third of body are darker in colour than rest of the body. Head is pale brown in colour. In preserved specimens bands are brownish grey with paler interspaces. The single juvenile specimen (SAMA R65215) has a brighter colouration with a blackish head and bands with turquoise blue interspaces. Number of bands on body and tail in the type series range from 47 (SAMA R65216) to 64 (holotype). See Fig 1 A and B.

Etymology. The species is named to honour Dave Donald, the skipper of the boat who worked tirelessly with us and whose local knowledge facilitated the discovery of this species. We propose the common name ‘rough scaled sea snake’ for this species due to its strongly keeled body scales.

Distribution. Collection localities for H. donaldi sp. nov. are restricted to coastal regions of Weipa, Queensland, northern Australia. The specimens were collected from shallow (<10 m) estuarine habitats (with shale, mud and sea-grass on the bottom) at the mouths of the Mission River and Hey Creek where they connect to Albatross Bay in Weipa, Queensland.

Remarks. Hydrophis donaldi sp. nov. can be assigned to the genus Hydrophis ( Smith 1926; McDowell 1972; Cogger 2000) based on the following characters: fewer than 73 scale rows around body, single rostral shield, nasals not separated from internasals, more than four supralabials, ventrals small and not broader anteriorly than posteriorly, mental shield broader than long, shorter head without a bill like snout, shorter gape, ventrals entire, no spines on head shields, preocular scales present, maxillary bone not extending forward beyond the palatine, fang followed by a diastema (see Fig 1 D), ventrals distinct throughout the body and not enlarged compared to the dorsal scale rows, ventral scales not broader than twice the adjacent body scales and more than 24 scales around the thickest part of the body.

Genetics. The final concatenated mitochondrial alignment consisted of 2704 bp for 25 individuals. Under AIC GTR+i+g is the best-fit model for each partition. There were 1237 invariable, 571 polymorphic and 362 parsimony informative sites and 599 sites with alignment gaps or missing data. The phased G1888 nuclear DNA alignment contained 367 invariable, 12 polymorphic, six parsimony informative sites and 49 sites with alignment gaps/missing data. In the phased G1894 nuclear DNA alignment, 385 sites were invariable, 14 polymorphic, 9 parsimony informative and 23 sites with alignment gaps/missing data.

Maximum likelihood and Bayesian analysis of the mitochondrial alignment yielded similar branch lengths and topologies that differed only in the position of Astrotia stokesii (sister to a Hydrophis caerulescens + H. brooki clade under ML; sister to H. elegans under Bayesian analysis). In the results of both analyses, H. donaldi sp. nov. forms a well-supported monophyletic sister lineage to all the other sampled ingroup taxa except Hydrelaps darwiniensis and Parahydrophis mertonii , which formed successive sister lineages to the Hydrophis clade ( Fig. 3 ). Hydrophis donaldi sp. nov. was closest to H. czeblukovi , with a mean pairwise corrected (Hasegawa-Kishino-Yano (HKY) correction method) mitochondrial distance of 4.46% and 13 fixed substitutions separating these taxa. The greatest distance among ingroup taxa was between H. donaldi sp. nov. and P. mertoni (14.64%), with 140 fixed nucleotide differences. Pairwise distances between H. donaldi sp. nov. and H. coggeri (the species it most closely resembles morphologically) ranged from 7.1–8.0% with 71 fixed substitutions.

For each nuclear locus Hydrophis donaldi sp. nov. is represented by a single haplotype that is not shared with any other sampled taxon (parsimony trees are shown in Fig. 4 A and B). For G1888 there was one fixed nucleotide difference between H. donaldi sp. nov. and both H. coggeri and Lapemis curtus , and 7 fixed nucleotide differences between H. donaldi sp. nov and Parahydrophis mertoni . For G1894 there was one fixed difference between H. donaldi sp. nov. and Acalyptophis peronii , three between H. donaldi sp. nov. and H. coggeri , and 9 between H. donaldi sp. nov. and P. mertoni . The summary of genetic data from the analysis is shown in Table 3 .

Figures

FIGURE 1. Hydrophis donaldi sp. nov. (A) Dorsal aspect of holotype QM J 90700 (before preservation), (B) Ventral aspect of holotype QM J 90700 (before preservation), (C) strongly spinous dorsal scales, (D) micro-CT scan of the lateral view of the head of SAMA R 65216 (Scale = 10 mm). Note that the maxillary bone does not extend forward far beyond the palatine and that the fang is followed by a diastema. both character states were used by Smith (1926) to diagnose Hydrophis.

FIGURE 2. Hydrophis donaldi sp. nov., holotype QM J 90700 (A) lateral aspect of head, (B) Dorsal aspect of head. Scale = 10 mm.

FIGURE 3. Bayesian majority rule consensus tree of the sea snakes sampled in this study based on the concatenated mitochondrial alignment. Hydrophis donaldi sp. nov. forms a highly divergent lineage although its phylogentic position remains poorly resolved. Nodes with maximum likelihood bootstrap support> 70 (below) and Bayesian posterior probability> 0.8 (above) are indicated. The outgroup Aipysurus laevis is not shown. Scale bar indicates the number of nucleotide substitutions per site.

FIGURE 4. The single most parsimonious trees for phased haplotypes of the nuclear loci (A) G 1888 (B) G 1894. Scale bars indicate branch lengths corresponding to 1 step.

Tables

TABLE 3. Summary of genetic data. The minimum and maximum fixed nucleotide differences were calculated between Hydrophis donaldi sp. nov. and the species with which it shares the lowest and highest number of nucleotide differences, respectively.

Concatenated mtDNA mt.DNA 2407 HKY	316	13	151
G1888 anon. nuclear 409 HKY	19	1	7
G1894 anon. nuclear 431 HKY	17	3	9