Lioscincus Bocage, 1993

Sadlier, Ross A., Bauer, Aaron M., Shea, Glenn M. & Smith, Sarah A., 2015, Taxonomic Resolution to the Problem of Polyphyly in the New Caledonian Scincid Lizard Genus Lioscincus (Squamata: Scincidae), Records of the Australian Museum 67 (7), pp. 207-224 : 212-215

Genus Lioscincus Bocage

Lioscincus Bocage, 1873: 228 .

Type species. Lioscincus steindachneri Bocage, 1873: 228 . Diagnosis. The species of Lioscincus s.s. are moderately large in size (maximum snout vent length [SVL]: L. vivae 55 mm; L. steindachneri 88.5 mm) with a stout body, moderately well-developed limbs and digits, and a relatively long tail (maximum tail length: L. steindachneri 180% SVL; L. vivae 210% SVL). The ear opening is large and lacks obviously enlarged lobules around the anterior edge.

Scalation ( Fig. 3 ): *distinct supranasal scales absent; nasal scale lacking a postnasal suture (a crease is sometimes present in steindachneri ); frontonasal broader than long; prefrontals large and narrowly to moderately separated; frontal elongate, longer than broad; supraoculars four; *frontoparietals fused to form a single scale; interparietal distinct; *nuchal scales divided so that the parietals are each bordered by three scales comprising a divided nuchal (two similar sized scales) and the upper secondary temporal scale; primary temporal single; lower secondary temporal single; tertiary temporals two; postlabials two; *anterior loreal reduced to a semilunar scale positioned on the anterodorsal margin of the nasal and either failing to, or only narrowly contacting, the labials; supraciliaries usually seven; upper labials seven with the fifth subocular and either contacting the lower eyelid ( steindachneri ) or separated by a complete row of subocular scales ( vivae ); postmental contacting first and second lower labial; transversely enlarged chinshields three, first pair in broad contact, second pair separated by one scale, third pair separated by three scales, all chinshields contacting the lower labials; dorsal scales of body smooth.

Osteology: premaxillary teeth 11; atlantal arches and intercentrum of first cervical vertebrae present as three separate units but showing some degree of partial ( vivae ) or superficial ( steindachneri ) fusion; presacral vertebrae usually 29; phalangeal formula for the manus 2.3.4.5.3 and for the pes 2.3.4.5.4; two pairs of mesosternal ribs.

The suite of apomorphic character states identified above will distinguish a redefined Lioscincus from all other genera in the Eugongylus group of skinks, including the new genera described here. In particular the combination of fused frontoparietal scales and division of the nuchal scale (such that three scales border each of the parietal scales) serves to distinguish Lioscincus from all genera outside the endemic New Caledonian skink radiation. Within the endemic New Caledonian skink radiation only Celatiscincus , Kanakysaurus and Phoboscincus bocourti also share this pair of scalation apomorphies ( Sadlier, 2010), although division of the nuchal scale occurs variably in Simiscincus . The nuchal scale division in Kanakysaurus is regular but part of a more extensive pattern of fragmentation of scales in the temporal and nuchal region, and fragmentation of the nuchal and temporal scales in Phoboscincus bocourti is extreme and irregular and also part of a pattern of fragmentation of scales in the temporal and nuchal region. By contrast division of the nuchal scale in Lioscincus and Celatiscincus is regular and not associated with a more extensive pattern of head shield fragmentation.As such, division of the nuchal scales to varying degrees has likely evolved independently in several of the major groups of endemic New Caledonian skinks, with its presence in Lioscincus and Celatiscincus a putative synapomorphy for a sister relationship between these genera. Celatiscincus has two morphological apomorphies not shared with Lioscincus , an elevated number of premaxillary teeth (13 vs 11) and the body scales with weak keels (vs smooth).

Etymology. Bocage (1873) does not give the origin of the name Lioscincus , but it is presumably derived from the Greek leios (smooth), and in allusion to the unkeeled scalation of the type species steindachneri .

Intergeneric relationships. The sister group relationship between Lioscincus s.s. and Celatiscincus inferred by the genetic data ( Smith et al., 2007) is supported by these taxa sharing the apomorphic condition for three scalation characters, the combination of which is unique within the Eugongylus group of skinks: fusion of the frontoparietal scales; parietals each bordered by at least three scales, two of which are a divided nuchal scale and one the upper secondary temporal; and a narrowing of the anterior loreal basally to the point where it can be occluded from contact with the labials. Celatiscincus is distinguished from Lioscincus s.s. in having an elevated number of premaxillary teeth (13 vs 11). The relationships of Geoscincus , an unusual monotypic genus of skink known only from the two type specimens collected in 1975 ( Böhme, 1976), are not available from any of the genetic analyses and its relationships to other Eugongylus group skink remain obscure. Regardless, Geoscincus is readily distinguished from Lioscincus s.s. in having highly fragmented posterior head shields, including division of the upper secondary temporal scale, a greatly reduced number of premaxillary teeth (6–9 vs 11), and in having the plesiomorphic condition of divided (vs fused) frontoparietal scales.

Recognized species. Two, Lioscincus steindachneri Bocage and Lioscincus vivae Sadlier, Bauer, Whitaker & Smith.

Lioscincus steindachneri Bocage, 1873: 228

Distribution. Panié Range in the far north-east, and central

metamorphic ranges as far south as Mé Adéo.

Comments. Recorded only from humid forest habitat.

Lioscincus vivae Sadlier, Bauer,

Whitaker & Smith, 2004: 211 Distribution. The central-west ultramafic massifs of Kopéto and Paéoua.

Comments. Recorded from the edge of high elevation closed forest and throughout maquis shrubland to as low as 500m elevation ( Whitaker, 2006).

Intrageneric relationships. There is a high level of support for L. steindachneri and L. vivae as sister taxa (BPP 0.95) in the combined mitochondrial ND2 and nuclear RAG1 + c- mos molecular phylogeny ( Smith et al., 2007), but with substantial nucleotide sequence divergence between these taxa for the mitochondrial ND2 gene of around 12.5% (a similar level of sequence divergence was found between the two species of the sister-genus Celatiscincus ). Ineich et al. (2014) similarly found a high level of support (BPP 1.0) for the sister-species relationship. The high level of genetic differentiation between the two taxa is complemented by the differences in morphology previously identified, and clearly supports their recognition as divergent and independent evolutionary entities. The differences in morphology are substantial, such that their sister relationship was not immediately obvious. The two species differ markedly in overall appearance, most notably in the absence of sexual dichromatism in L. steindachneri , whereas adult male L. vivae have a different coloration to adult females and juveniles of that species. They also differ significantly in distribution and habitat preferences. Lioscincus steindachneri is restricted to moist habitat in humid forests on non-ultramafic soils of the north-east and east-central ranges, whereas Lioscincus vivae occurs primarily in maquis shrubland on the west coast ultramafic ranges of Massif de Kopéto and Paéoua (Whitaker et al., 2004).

Figures

Figure 3. Head scalation of Lioscincus s.s. as seen inL. steindachneri (adapted from Sadlier, 1987) showing some of the primary diagnostic features for the genus including fused frontoparietal scales (FP), a narrow-based and semilunar anterior loreal scale (AL) which contacts the upper labial scales narrowly or not at all, and divided nuchal scales (N), compared to the plesiomorphic condition of a broad-based anterior loreal and single transversely elongate nuchal either side of the neck as seen in Epibator (Fig. 4), Phasmasaurus (Fig. 5) and Caesoris novaecaledoniae (Fig. 7), and paired frontoparietals seen in Epibator (Fig. 4).