Oligosoma prasinum Melzer & Bell & Patterson 2017, sp. nov.

Oligosoma prasinum sp. nov.

Figure 5a, b

Oligosoma aff. lineoocellatum “Mackenzie Basin”

HITCHMOUGH, R., BULL, L. & CROMARTY, P. 2007; HITCHMOUGH et al. 2010; HITCHMOUGH et al. 2013; HITCHMOUGH et al. 2016 b

Holotype. Tekapo, Mt Hay (43° 59’S, 170° 28’E), NMNZ RE005462, male (coll. G. Patterson, 0 1 Nov 1990);

Paratypes (9 specimens). Tekapo, Mt Hay (43° 00’S, 170° 34’E), 2 specimens (NMNZ RE005447, OR; NMNZ RE005448, organs removed) (coll. G. Patterson, 30 Nov 1984); Tekapo (44° 01’S, 170° 29’E), 3 specimens (NMNZ RE005464, male; NMNZ RE005465, OR; NMNZ RE005466, OR) (coll. G. Patterson, 0 1 Jan 1990); Tekapo (-44° 00’S, 170° 48’E), 4 specimens (NMNZ RE006222, OR; NMNZ RE006223, organs removed; NMNZ RE006224, organs removed; NMNZ RE006225, organs removed) (coll. C. Daugherty, 26 Nov 1985).

Diagnosis. Oligosoma prasinum can be distinguished from other species in the O. lineoocellatum species complex by a combination of characters. The subdigital lamellae count is usually above 24, compared with O. kokowai sp. nov. and O.lineoocellatum where it is usually below 24. There are significant differences between O. prasinum sp. nov. and O. kokowai sp. nov. and O. elium sp. nov. (midbody scales; Figure 6b). The lower ciliary count is usually below 9, whereas in O. lineoocellatum it is usually 9 or above. In O. elium sp. nov. the UC count usually higher than 6, whereas in O. prasinum sp. nov. it can be lower than 6. This species always has more than 1 nuchal pairs, compared with O. kokowai sp. nov. that always has 1 pair. The pale dorsolateral stripe is usually not as pronounced as in the other species. Unlike Hardy’s (1977) observation, we did not find the VS useful in differentiating the species, as there was a big range in counts, e.g. 76 to 102 in O. lineoocellatum. Oligosoma prasinum sp. nov. seems to be less heavily built than the other species, in particular O. elium sp. nov. (Figures 2, 3, 4, 5).

Description of Holotype. Habit lacertiform, body elongate, oval in cross-section; limbs well developed, pentadactyl. Lower eyelid with a transparent palpebral disc, bordered on sides and below by small, oblong granules. Snout moderately sharp. Nostril centred in lower middle of nasal, not touching bottom edge of nasal, pointing up and back. Supranasals absent. Rostral narrower than deep. Frontonasal broader than long, not separated from frontal by prefrontals meeting in midline. Frontal longer than broad, similar to frontoparietal and interparietal together, in contact with 2 anteriormost supraoculars. Supraoculars 4, 2nd largest. Preoculars, 2, upper one the larger. Frontoparietals distinct, larger than the interparietal. A pair of parietals meeting behind interparietal and bordered posteriorly by a pair of nuchals and temporals, also in contact with interparietal, frontoparietal, 4th supraocular, and 2 postoculars. Loreals 2, similar size; anterior loreal in contact with 1st and 2nd supralabial, posterior loreal, prefrontal, frontonasal, and nasal; posterior loreal in contact with 2nd and 3rd supralabial, 1st subocular, upper and lower preocular, prefrontal, and anterior loreal. Supralabials 7, 6th and 7th largest. Infralabials 6, several equally largest. Fifth supralabial below centre of the eye. Temporals: 1 primary; 2 secondary. Ear opening round, moderately large, with several small projecting granules on anterior margin. Suboculars 5, 2nd and 3rd separated by 5th supralabial. Mental broader but shallower than rostral. Postmental smaller than mental. Chinshields 3 pairs. Dorsal scales larger than ventral scales, weakly striate. Ventral scales and subdigital lamellae smooth. Adpressed limbs not meeting. Digits long, subcylindrical. Third front digit similar in length to 4th.

Measurements (in mm; holotype with the variation shown in the specimens examined in parentheses). SVL 71.0 (mean 72.5, range 47.3–94.0), HL 11.3 (mean 11.0, range 7.7–13.1), HW 6.2 (mean 6.3, range 4.7–7.8), AG 34.7 (mean 38.2, range 24.8–55.8), SF 27.0 (mean 26.9, range 19.4–30.3), S-Ear 13.7 (mean 13.3, range 9.4– 16.0), EF 14.0 (mean 14.1, range 9.9–16.3), HLL 23.1 (mean 22.7, range 16.1–27.2).

Variation (holotype with the variation shown in the paratypes in parentheses).

Upper ciliaries 6 (mean 6, range 5–6); lower ciliaries 8 (mean 8, range 8–9); nuchals 3 pairs (mean 3 pair, range 2–4 pair); midbody scale rows 34 (mean 32, range 30–34); ventral scale rows 94 (mean 86, range 78–94); subdigital lamellae 28 (mean 25, range 23–28); supraciliaries 5 (mean 5, range 4–5); suboculars 5 (mean 5, range 4–6). Frontonasal never separated from frontal by prefrontals meeting in midline. Anterior loreal usually in contact with first and second supralabial, posterior loreal usually in contact with second and third supralabial. Supralabials 7 (usual) or 8, the sixth or seventh the largest. Infralabials 5, 6 (usual) or 7. Projecting scales usually present in ear opening. Maximum SVL 94.0 mm. None of the specimens examined had an intact tail, however from records tail length of intact specimens ranged between 89–91 mm. Mean TL/SVL = 1.14. Ratios for morphological measurements (± SD): AG/SF 1.41 ± 0.18; S-Ear/EF 0.95 ± 0.06; HL/HW 1.77 ± 0.11 (N=10).

Colouration. This is very variable among specimens, but the most common colouration is as follows: No middorsal stripe. Dorsal surface olive green, with regular light and dark flecking, 6 scale rows wide, grading into pale dorsolateral stripe extending from behind eye towards base of tail, becoming indistinct thereafter. This pale stripe extends into brown lateral stripe three or more scale rows wide, running from behind eye to base of tail, becoming indistinct thereafter. This brown band is speckled with light and dark along its length. Grading into a grey unmarked belly, sometimes with traces of pink. Soles of feet dark grey. Throat unmarked. Outer surface of forelimbs olive green, speckled with light and dark. Dorsal surface of tail either marked with dark speckling or (more usually) unmarked. They do not appear to be sexually dichromatic. Juvenile colouration similar to adult.

Etymology. The specific name means “green” in Greek. It has been latinized. The accepted vernacular name is ‘Mackenzie skink’ (Bell 2014).