Epibator, Sadlier & Bauer & Shea & Smith, 2015

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 : 215-217

Epibator gen. nov.

Type species. Lygosoma (Mocoa) nigrofasciolatum Peters, 1869: 435 designated hereby.

Diagnosis. The species are moderately large to large in size (maximum SVL range 61 mm for greeri and 112 mm for nigrofasciolatus ) with a moderately elongate body, long limbs and digits, and a moderately long tail (maximum tail length 145 and 180% of SVL, respectively).

Scalation: *no distinct supranasal; nasal scale with a prominent postnasal suture or crease; frontonasal as broad as long; prefrontals large and narrowly separated or in narrow contact; frontal longer than broad; supraoculars four; frontoparietals paired; interparietal distinct; parietals each bordered by a single nuchal and upper secondary temporal scale; *primary temporals usually two; lower secondary temporal single; tertiary temporals two; loreals two, each contacting the labials broadly; supraciliaries 7 ( greeri ) or 8 ( nigrofasciolatus ); *upper labials 8 or more with the sixth subocular and contacting the lower eyelid, and the *last divided by an oblique suture into an upper and lower scale ( Fig. 4 ); postmental contacting first and second lower labial; *enlarged chinshields 4–5, first pair in broad contact medially, second pair in moderate contact, first pair usually in partial contact with lower labials but *remaining chinshields separated from lower labials by 1–2 rows of smaller scales ( Fig. 4 ); body scales smooth and moderately small (34–42 longitudinal rows at midbody); *basal dorsal scales of the toes divided.

Osteology: premaxillary teeth 11; atlantal arches of first cervical vertebrae and intercentrum present as three separate units; 29 presacral vertebrae; a phalangeal formula of 2.3.4.5.3 for the manus and 2.3.4.5.4 for the pes; two pairs of mesosternal ribs.

The suite of apomorphic character states identified above will distinguish Epibator gen. nov. from all other genera in the Eugongylus group of skinks, including the new genera described here. Within the endemic New Caledonian skink radiation the presence of 8 or more upper labials with the last divided by an oblique suture and the separation of the chinshields from the lower labial scales by 1–2 rows of small intervening scales will distinguish Epibator gen. nov. from all other genera except Phoboscincus . Epibator gen. nov. is distinguished from Phoboscincus in having no distinct supranasal scale whereas the nasal scale of Phoboscincus is distinctly divided into three separate elements, the plesiomorphic condition. Further, Phoboscincus has two apomorphic character states not present in Epibator gen. nov., fused (vs paired) frontoparietal scales and enlarged fang-like (vs peg-like) anterior teeth.

Etymology. From the Greek for climber (epi, upon + bates, one that walks or haunts), alluding to the arboreal habits of the type species. The gender is masculine (Brown, 1956).

Intergeneric relationships. The molecular data presented by Smith et al. (2007) retrieved a phylogeny which placed Epibator gen. nov. (as represented by nigrofasciolatus ) within a subgroup containing Epibator gen. nov. as the sister to Lacertoides + Phoboscincus . This grouping received a moderate to low level of support (BPP 0.94; bootstrap values <50%), and the species Phoboscincus bocourti and Epibator greeri were missing from the analysis. However, there are no obvious shared apomorphies in morphology between these genera, though there is a tendency towards extreme fragmentation of the scales in the temporal region in all genera. However, this trait is also seen in a number of other members of the Eugongylus group, particularly larger taxa e.g. Eugongylus species and Oligosoma grande ( Sadlier, 2010) , and it is possible its occurrence in the subgroup that includes Phoboscincus , Epibator gen. nov. and Lacertoides , could be independently derived.

The genetic grouping of Phoboscincus , Lacertoides , and Epibator gen. nov., or an inference of relationship between any of these genera, has not previously been suggested. Limited support for this grouping comes from the three genera sharing two scalation characters which could be considered as putative apomorphies to define the subgroup: an elevated number of 8 or more upper labial scales; and division of the basal dorsal toe scales, a derived trait that has evolved independently in several groups of endemic New Caledonian skinks (see Sadlier, 2010: appendix 1). Species in all three genera also share an additional apomorphy in having two (rather than a single) primary temporal scales, though this trait is also present in Kanakysaurus and a range of other more distant taxa in the Eugongylus group. A more recent genetic study ( Ineich et al., 2014) that included both Phoboscincus bocourti and Phoboscincus garnieri also recovered a relationship of E. nigrofasciolatus with Phoboscincus , although that study used one less nuclear gene, had lower support values for the relationship of these two taxa (BPP 0.53, bootstrap values <50%), and Lacertoides was not identified as part of this lineage. Rather, the genetic study of Ineich et al. retrieved a relationship for Lacertoides with Kanakysaurus and Marmorosphax , but with no support for relationships between these genera and only low support for the three genera as a subgroup (BPP 0.53, bootstrap values <50%).

Epibator gen. nov. and Phoboscincus share two morphological apomorphies, separation of the chinshields from the lower labial scales by 1–2 rows of small intervening scales and division of the last upper labial obliquely, that argue for a sister taxon relationship between these genera, contrary to the genetic evidence of Smith et al. (2007) which retrieves Lacertoides as the sister to Phoboscincus , but in accordance with the genetic evidence of Ineich et al. (2014). Separation of the chinshields from the lower labials by an intervening row of scales is variable within Phoboscincus , with the chinshields of bocourti completely separated from the lower labials, but only partially (third chinshield only) in garnieri . These traits have only otherwise been recorded from the monotypic Geoscincus ( Sadlier, 1987) , a genus whose phylogenetic affinities are obscure and for which genetic data are unavailable. Geoscincus is readily distinguished from Epibator gen. nov. in having a highly reduced number of premaxillary teeth (6–9 vs 11), and a “scaled” lower eyelid, the homology of which is unclear and is otherwise only seen in the New Caledonian skink radiation in Phoboscincus bocourti . By comparison, Lacertoides has the plesiomorphic condition of all three chinshields fully in contact with the lower labials and an undivided last upper labial.

Recognized species. Two, Epibator nigrofasciolatus (Peters) and Epibator greeri (Böhme) .

Epibator nigrofasciolatus (Peters)

Synonyms. Lygosoma (Mocoa) nigrofasciolatum Peters, 1869: 435 . Lygosoma arborum Bavay, 1869: 19 . Lygosoma deplanchei Bocage, 1873: 229 (non Lygosoma deplanchei Bavay, 1869 = Sigaloseps deplanchei ).

Distribution. Widespread throughout New Caledonia, including large and small offshore islands, and the Loyalty Islands.

Comments. Recorded from a wide range of habitats at all elevations.

Epibator greeri (Böhme)

Synonym. Leiolopisma greeri Böhme, 1979: 140 .

Distribution. Koumac region in the north-west of Grande Terre.

Comments. Böhme described the species from a single individual collected in forest. It has not been seen with certainty since, although live individuals similar in colouration to the type of Epibator greeri have been photographed (by one of us, RS) from southern Grande Terre .

Figures

Figure 4. Head scalation of Epibator as seen in E. nigrofasciolatus (adapted from Sadlier, 1987) showing some of the primary diagnostic features for the genus including a divided primary temporal scale (PT) and the majority of chinshields (CH) separated from lower labials by 1–2 rows of smaller scales, compared to the plesiomorphic condition of a single enlarged primary temporal scale and the enlarged chinshields contacting the lower labials as seen in Epibator (Fig. 4), Phasmasaurus (Fig. 5) and Caesoris novaecaledoniae (Fig. 7).