Aipysurus mosaicus, Sanders, Kate L., Rasmussen, Arne R., Elmberg, Johan, Guinea, Michael, Blias, Peter, Lee, Michael S. Y. & Fry, Bryan G., 2012

Sanders, Kate L., Rasmussen, Arne R., Elmberg, Johan, Guinea, Michael, Blias, Peter, Lee, Michael S. Y. & Fry, Bryan G., 2012, Aipysurus mosaicus, a new species of egg-eating sea snake (Elapidae: Hydrophiinae), with a redescription of Aipysurus eydouxii (Gray, 1849), Zootaxa 3431, pp. 1-18 : 7-12

Aipysurus mosaicus sp. nov.

Figs. 1–3 , 4 a, 5a–c, 6a–c

Aipysurus eydouxii ( Gray, 1849) (part): Smith (1926) (part); MacPherson (1933); Cogger (1975); Limpus (1975); Minton (1975) (part); Reidfield et al. (1978); Cogger et al. (1983) (part); Cogger (1992); Golay et al. (1993) (part); Heatwole & Cogger (1994); Greer (1997); Porter et al. (1997); David & Ineich (1999) (part); Heatwole (1999); Ward (2000); Fry et al. (2001); Li et al. (2005a, b); Lukoschek & Keogh (2006); Cogger (2007).

Tomogaster eydouxii Gray, 1849 (specimens collected from Java and therefore not referable to A. mosaicus ): Wells (2007).

Holotype. SAMA R65222. A small adult male collected in the Gulf of Carpentaria near Weipa, Australia, in October 2000 by B.F. Fry. Tail tissue stored in ethanol in the ABTC-SAM.

Paratype. SAMA R23493. An adult female collected in the Gulf of Carpentaria, Australia. Tissue stored frozen in the ABTC-SAM.

Referred specimens. An additional 26 specimens (9 adult males, 17 adult females), see Appendix 2 for details.

TABLE 2. Mean, range, standard deviation, and t-tests of morphological characters comparing Asian ( Aipysurus eydouxii ) and Australian ( A. mosaicus sp. nov.) specimens. Australian data and t-tests include counts from holotype (H) and paratype (P) when available. T-test probabilities are two-tailed, with significant contrasts given in bold type. See Methods for explanation of characters. Note that sample sizes for some characters differ from the gross sample size per origin and sex.

Males

Females Generic assignment. Aipysurus mosaicus has a combination of characters (see type description and variation below) that place it in the genus Aipysurus as defined by Smith (1926: 13): “Maxillary bone as long as or longer than the ectopterygoid, extending forwards beyond the palatine; poison-fangs followed after an interval by from 5 to 11 teeth. Nostrils superior, nasal shields in contact; head-shields regular or broken up; scales imbricate in regular rows, 17–25; ventrals large, one-third to half the breadth of the body, a median keel usually present at least in the posterior part of the body.”

Diagnosis. Aipysurus mosaicus is distinct from seven of the eight species (except A. eydouxii ) of Aipysurus using external characters. Aipysurus apraefrontalis and A. foliosquama have ventrals with a deep median notch on the posterior edge, A. mosaicus has ventrals lacking a median notch. Aipysurus tenuis has more than 170 ventrals, A. mosaicus has 140–154. Aipysurus duboisii , A. fuscus , A. laevis , and A. pooleorum have more than 17 scale rows around midbody and at least some of the head shields are usually broken up into smaller plates, A. mosaicus has 17 scale rows around body and head shields that are normally symmetrical and not broken up.

Aipysurus mosaicus is clearly distinct from A. eydouxii in a number of external and internal characters. Aipysurus eydouxii has 29 or more bands on body, A. mosaicus has 22 body bands or fewer. In our sample, the following characters differ significantly between A. eydouxii and A. mosaicus when compared intrasexually: number of body bands, tail bands, ventrals, subcaudals, as well as heart and liver positions (absolute and relative) (Table 2). Compared to A. eydouxii , A. mosaicus has a larger premaxilla, a smaller maxilla, a cresent-shaped (rather than triangular) nasal, an anteriorly concave (rather than straight) frontoparietal suture, and dorsally-expanded caudal neural spines ( Fig. 5 ).

Description of holotype. Male. Snout-vent length 46.3 cm, tail 8.6 cm. One pre- and two postoculars on both sides. Six supralabials and six infralabials on both sides. First and second supralabials in contact with nasal. Second and third supralabials in contact with preocular on right side, second, third and fourth on left side. Fourth and fifth supralabial in contact with eye. Two anterior temporals on both sides. Sublinguals are well-developed and in contact with one another. First, second, third and fourth infralabials in contact with anterior pair of sublinguals. Fourth infralabial touching posterior pair of sublinguals. Seventeen scale rows on neck, 17 scale rows on body, 15 scale rows ten ventrals before vent. Ventrals 144, distinct throughout, about three to four times as broad as adjacent scales. Preanals enlarged and divided into paired scales. Subcaudals cannot be counted reliably due to a tail biopsy but probably number between 29 and 32. Head dark brown above and below. Body dark brown above, paler below. Twenty-one irregular brown bands on body and five on tail.

Description of paratype (R23493). Female. Snout-vent length 73.0 cm, tail 11.5 cm. One pre- and two postoculars on both sides. Six supralabials and six infralabials on both sides. First and second supralabials in contact with nasal. Second, third and fourth supralabials in contact with preocular on both sides. Fourth and fifth supralabial in contact with eye. Two anterior temporals on both sides. Sublinguals are well-developed and in contact with one another. First, second and third infralabial in contact with anterior pair of sublinguals. Third and fourth infralabial touching posterior pair of sublinguals. Seventeen scale rows on neck, 17 scale rows on body, 13 scale rows ten ventrals before vent. Ventrals 154, distinct throughout, about three to four times as broad as adjacent scales. Preanals enlarged and split up into two scales. Twenty-nine subcaudals. Head dark brown above and below. Body dark brown above, lighter below. Seventeen white/cream irregular brown bands on body and five on tail.

Variation in Aipysurus mosaicus sp. nov. The following description refers to all 28 A. mosaicus specimens examined (10 adult males, 18 adult females), including the holotype and paratype: see Table 2 and Appendix 2.

External morphological characters. One pre- and two postoculars on both sides in 25 specimens, 1-2/1- 1 in two specimens, and 1-3/ 1-2 in one specimen. Six/six supralabials in 26 specimens, 7/ 6 in two specimens. First and second supralabials in contact with nasal in 26 specimens, first, second and third in two specimens. Second, third and fourth supralabial in contact with preocular in 22 specimens, second and third in six specimens. Fourth supralabial in contact with eye in 22 specimens, third and fourth in one specimen, fourth and fifth in four specimens, and third, fourth and fifth in one specimen. Two anterior temporals on both sides in 22 specimens, 1/ 1 in one specimen, 1/ 2 in one specimen, 2/ 3 in three specimens and 3/ 3 in one specimen. Six infralabials on both sides in 26 specimens, 7/ 7 in two specimens. Sublinguals well-developed and in contact with one another in all specimens. First, second and third infralabial in contact with anterior pair of sublinguals in 24 specimens, first through fourth in four specimens. Third and fourth infralabials touching posterior pair of sublinguals in 22 specimens, only the fourth in six specimens. Sixteen to seventeen scale rows on neck in males, 16–17 in females, 17 scale rows on body in males, 17 in females. Thirteen to seventeen scale rows ten ventrals before vent in males, 13–17 in females. Ventrals 140–147 in males, 140–154 in females, distinct throughout, about three to four times as broad as adjacent scales. Preanals enlarged and split up into two scales. Subcaudals 28–38 in males, 25–33 in females. Snout-vent length of largest male 68 cm, tail 14 cm; largest female 95 cm, tail 15 cm.

Internal morphological characters. Tip of heart extending to ventral scale number 44–51 in males, 45–52 in females. %VS-heart 30.8–35.2% in males, 30.0–35.7% in females. Anterior end of liver situated at ventral scale number 47–53 in males, 47–54 in females. %VS-liver 32.9–36.6% in males, 32.0–36.7% in females. Heart and liver separated by 1–4 ventral scales in males, 1–5 in females.

Colouration. Head dark brown above and below. Body usually cream, salmon or yellowish with brown to olive green irregular cross-bands. Bands are often incomplete with some forming staggered half-bands on either side of the body. Number of bands on body 17–22 in males and 15–21 in females (when distinct enough to be counted). Number of bands on tail 5–7 in males and 4–6 in females.

Distribution. The new species is found along the coasts of northern Australia and southern New Guinea. We have examined specimens (Appendix 2) belonging to this species from the following localities in northern and north-eastern Australia: Coburg Peninsula (Arafura Sea), the Gulf of Carpentaria (southeast and northeast areas), Thursday Island (Torres Strait), Townsville (northeast Queensland), and Swain Reefs and Shoal Water Bay (southeast Queensland). A single specimen was examined from Kaap Valsch (= Tanjung Vals) on the south coast of West Papua. Limpus (1975) reports this species as breeding as far south as 26o S in subtropical Queensland.

Etymology. Named from the Latin mosaicus in reference to the mosaic-like pattern of dark and light scales arranged in irregularly staggered cross-bands. We suggest the common name mosaic sea snake for this species.

Natural history. All collection records suggest that Aipysurus mosaicus (mentioned as A. eydouxii ) inhabits offshore waters, estuaries and tidal rivers, where it is associated with soft sand and mud bottom substrates. Most records are from depths between 2m ( Heatwole 1975) and 22m ( Redfield et al. 1978) and there are no records from waters exceeding 50m. Limpus (1975) examined the guts of>100 A. mosaicus specimens from southern Queensland; 38% contained diet items, all of which were clumps of benthic fish eggs. A similarly specialist diet of fish eggs (and occasionally squid and cuttlefish) was reported for A. eydouxii in Malaysia ( Voris 1966; Glodek & Voris 1982). In northern Australia, females of A. mosaicus are gravid between May and August but not in October ( Fry et al. 2001).

Figures

FIGURE 1. MrBayes all compatible consensus of 4000 post burn-in trees for the Aipysurus and Emydocephalus specimens sampled in this study based on the concatenated mitochondrial data (Hydrophis caerulescens outgroup not shown). Scale bar indicates the number of nucleotide substitutions per site. Node support values (posterior probabilities) above 0.95 are shown.

FIGURE 2. The single most parsimonious tree for phased haplotypes of the nuclear G 1894 fragment. Scale bar indicates branch lengths corresponding to 1 step.

FIGURE 3. The single most parsimonious tree for phased haplotypes of the nuclear G 1888 fragment. Scale bar indicates branch lengths corresponding to 1 step.

FIGURE 4. Full body photographs of A) the holotype of Aipysurus mosaicus sp. nov. from northern Australia (SAMA R 65222) and B) A. eydouxii from Singapore (SAMA R 22569). Grid scale represents 1 x 1 cm. Note that A. mosaicus has fewer bands on the body and tail and that these are less distinct.

FIGURE 5. Micro-CT images of Aipysurus mosaicus sp. nov. from (A) left lateral and (B) dorsal view of skull, and (C) left lateral view of mid-caudal vertebrae; and Aipysurus eydouxii from (D) left lateral and (E) dorsal view of skull, and (F) left lateral view of mid-caudal vertebrae. Note the differences in the morphology of the premaxilla, maxilla, nasal, frontoparietal suture, and neural spine; see text for fuller discussion. Specimens illustrated are as follows: (A, B) SAMA R 65222 holotype, (C) SAMA R 23493 paratype, (D, E) MZB Ophi 4184, (F) SAMA R 22569.