Laticauda frontalis (de Vis, 1905)

Laticauda frontalis (de Vis, 1905) View in CoL

Platurus frontalis de Vis, 1905. A new genus of lizards. Annals of the Queensland Museum, 6:48. Holotype: Queensland Museum (QM) J202 (Fig. 1). Type locality: New Guinea. Date of collection, donor and/or collector unknown.

Diagnosis. A banded sea krait of the genus Laticauda characterized by the possession of a yellow upper lip, an undivided rostral scale, an almost invariate 21 mid-body scale rows in both sexes, fewer than 209 (males) and 212 (females) ventral scales, and a maximum snout-vent length (SVL) of 654 mm (males) and 783 mm (females). It can be distinguished from L. laticaudata and L. crockeri by its yellow upper lip (black in laticaudata and crockeri) and from L. semifasciata and L. schistorhyncha by its undivided rostral. From L. colubrina it may be distinguished by the following combination of characters: a lower modal midbody scale row count of 21, lower ventral scale counts in both sexes (Table 1, Fig. 9 View Fig ), smaller size (Table 1) and, throughout the known area of sympatry, by the absence of a lower lateral connection between the black head band and the first black band on the neck ( Fig. 2 View Fig ), and the failure of the dark body bands, at least anteriorly, to extend to the middle of the venter (Fig. 1).

Description of the holotype. A member of the Laticauda colubrina complex in shape; the mid-body diameter is contained 40.7 times in its snout-vent length and the head is scarcely wider than the neck. Head width (widest point) 7.3 mm, head length (snout tip to rear edge of quadrate) 8.9 mm, the latter representing 3.0% of snout-vent length. Rostral undivided, as broad as deep, and separating the nasals. Internasals narrowly in contact behind the rostral, while there is a large azygous scale, almost as large as a prefrontal, separating the prefrontals. Frontal 2.25 times longer than broad, while each supraocular is about the same width as the frontal. Seven supralabials on each side, the second and third contacting the eye. Nine infralabials on each side, the count being confused by a series of splintlike marginal scales separating the anterior infralabials from the lip margins. Temporals 1 + 3 on each side. Postmental scale (sensu McCarthy, 1986) absent.

Number of scale rows around the body (excluding the ventrals) at the 20th, 50th, 100th, 150th and 200th ventrals respectively are 21, 21, 21, 21, and 19. There are 203 ventral scales (gastrosteges) and 31 divided subcaudal scales, indicating that it is a female (specimen not dissected). The snout-vent length is c. 293 mm (several counts; the specimen is badly kinked in preservation) while the tail length is 34 mm.

Thirty-one dark body bands and 3 dark caudal bands; the first body band is not connected laterally to the nuchal band (see Fig. 2 View Fig , upper). This is the smallest specimen of this species seen by the authors, and possesses the characteristic juvenile condition of ventrally incomplete dark cross-bands, the latter generally extending only to the middle or lower parts of the flanks.

Variation. Variation in a number of phenotypic character states in Laticauda frontalis is compared in Table 1 with variation in the same characters for syntopic Laticauda colubrina (from Vanuatu), for Laticauda colubrina from the Fiji Islands to the east, and from Laticauda saintgironsi from New Caledonia to the south.

The extent to which the dark bands fail to meet ventrally varies ontogenetically. All dark bands are usually incomplete in juveniles and subadults, while in large adults usually only those bands on the anterior part of the body may remain incomplete.

The centre of the heart is located between ventrals 67 and 75 (mean = 70.6, SD = 2.37, n = 10).

Distribution. The holotype of Laticauda frontalis is said to have come from “New Guinea”; if this provenance is correct then it is the only specimen currently known outside the region encompassing Vanuatu and the Loyalty Islands. P. Couper (in litt.) of the Queensland Museum advises that there is no additional documentation associated with the holotype’s original acquisition that might provide more accurate information about its provenance (including any doubt or uncertainty) or the unknown donor/collector. All of our fieldacquired specimens were collected on two island complexes— Efate and Espiritu Santo—in the Republic of Vanuatu (formerly the British-French condominion of the New Hebrides).

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There is a single specimen in the Macleay Museum, University of Sydney (MM 633) and another in the Muséum national d’Histoire naturelle, Paris (HFH) from the Loyalty Islands (the easternmost islands of New Caledonia located about one-third of the distance between New Caledonia’s main island (Grande Terre) and the southernmost islands of Vanuatu). The species has not been recorded from the Solomon Islands to the northwest of Vanuatu, nor from New Caledonia’s main island complex. Consequently we regard the current distribution of the species to be confined to the Loyalty Islands and the islands of Vanuatu, at least as far north as the island of Espiritu Santo. And in the absence of any records of this species from New Guinea since it was described in 1905, and without secondary sources to confirm the original type locality, we regard either the type locality of “New Guinea” to be erroneous or the holotype to be a waif individual originating from the Vanuatu region. In all of the features used above to characterize this species, the holotype falls within the range of variation recorded in specimens from Vanuatu.

Ecology. Like other members of the Laticauda colubrina species complex, Laticauda frontalis feeds exclusively on eels belonging to several families—most commonly those in the families Muraenidae and Congridae (Reed et al., 2002).

This species was long confused with juveniles and subadults of the sympatric and syntopic Laticauda colubrina, not only because of their morphological similarity but in large part because the two species could be found together, both in terrestrial aggregations and in aquatic feeding sites. On some small coral islets within the lagoon at Panangisu on the northern side of Efate Island in Vanuatu, individuals of both species were found coiled up together under the same rock or pile of decaying vegetation, or in wave-eroded cavities and crevices in the exposed perimeter calcarenitic rock above high tide level but well within the splash zone.

Other individuals were found in cavities in the wide, flat calcarinite platforms that make up the supralittoral zone around many parts of the larger islands, even close to major urban centres such as the national capital of Port Vila, on Efate Island. At night the snakes could be found emerging from the sea onto these platforms, or moving across them 100 m or more from the sea.

Maximum prey size is broadly correlated with body size in anguillophagous sea kraits, and so the dwarf frontalis competes for prey with similar-sized (generally sub-adult) members of the larger syntopic Laticauda colubrina (Shine et al., 2002b).

Material examined. Numerous live specimens captured for venom extraction were examined for a variety of mensurable and meristic characters before being released back into the wild. Heatwole et al. (2005) list additional specimens examined by only one of us (HFH) in other museum collections, but the following specimens assigned by us to this species were preserved and lodged in the herpetological collections of the Australian Museum, Sydney: R164858–68♂♂, R164869– 70♀♀, R164871♂, R144025♀, R144026–28♂♂, R144055♂ from Pango Point at Pango (Etang) Village, near Port Vila, Efate Island, Vanuatu; R164872–79♂♂, R144020♀, R144021–22♂♂ from Niogoriki Island, off Paunangisu Village, N. coast of Efate Island, Vanuatu; R164880–81♂♂, from W. side of Mele Bay, Port Vila, Efate Island, Vanuatu; 144023♀, 144024♂, from Tukutuku Plantation, Tukutuku Bay, Efate Island, Vanuatu.