Oligosoma elium, Melzer & Bell & Patterson, 2017

Melzer, Sabine, Bell, Trent & Patterson, Geoff B., 2017, Hidden conservation vulnerability within a cryptic species complex: taxonomic revision of the spotted skink (Oligosoma lineoocellatum; Reptilia: Scincidae) from New Zealand, Zootaxa 4300 (3), pp. 355-379 : 365-366

Oligosoma elium sp. nov.

Figure 4a , b

Oligosoma aff. lineoocellatum “South Marlborough”

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

Holotype. Motunau Island, Canterbury (43° 04’S, 173° 04’E), NMNZ RE003737 (S 92), female (coll. A. Whitaker, 20 Feb 1967).

Paratypes (9 specimens). Motunau Island , Canterbury (43° 04’S, 173° 04’E), 2 specimens ( NMNZ RE001745 (2/2/8.33), female ; NMNZ RE001745 (2/2/8.34), male) (coll. A. Whitaker, unknown date); Motunau Island , Canterbury (43° 04’S, 173° 04’E), 3 specimens ( NMNZ RE003736 (S 91), male ; NMNZ RE003738 (S 93), male; NMNZ RE003820 (S 178), male) (coll. A. Whitaker, 20 Feb 1967); Waipapa Bay (42° 15’S, 173° 49’E), NMNZ RE004192 (S550), female (coll. A. Whitaker, 0 3 Dec 1969) ; Montrose Stream , Waiau River (42° 46’S, 172° 43’E), NMNZ RE004191 (S549), male (coll. A. Whitaker, 27 Nov 1969) ; Jack Taylor’s farm, Ward (41° 48’S, 174° 03’E), NMNZ RE005463, OR (coll. R. Ainsworth, 0 8 Feb 1988) .

Diagnosis. Oligosoma elium 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. elium sp. nov. and O. kokowai sp. nov. (lower ciliary count, AG/SF), O. lineoocellatum (midbody scales), and O. prasinum sp. nov. (midbody scales, upper ciliary count) ( Figure 6 a-e). Adpressed limbs always meet in O. elium sp. nov., whereas in O. lineoocellatum they usually do not. In O. elium sp. nov. the lateral brown stripe is 2 or 3 scale rows wide, whereas in the other species it is 3 or 4 scale rows wide. The pale dorsolateral strip is pronounced, particularly anteriorly, compared with O. prasinum sp. nov. where this stripe is usually indistinct.

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 in length 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, anterior one the larger; 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 preocular, prefrontal, and anterior loreal. Supralabials 7, 5th largest. Infralabials 6, several equally largest. Fifth supralabial below centre of the eye. Temporals: 1 primary; 2 secondary. Ear opening round, moderately large, with no projecting granules on anterior margin. Suboculars 4, 2nd and 3rd separated by 5th supralabial. Mental broader but shallower than rostral. Postmental larger than mental. Chinshields 3 pairs. Dorsal scales similar in size to ventral scales, weakly striate. Ventral scales and subdigital lamellae smooth.

Adpressed limbs barely 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 78.3 (mean 78.8, range 67.0–89.2), HL 12.3 (mean 12.2, range 10.6–13.6), HW 6.5 (mean 6.9, range 5.8–7.7), AG 41.6 (mean 40.4, range 32.1–49.3), SF 29.3 (mean 29.5, range 25.7–33.4), S-Ear 14.9 (mean 15.2, range 12.8– 16.9), EF 15.8 (mean 15.6, range 13.1–18.4), HLL 26.4 (mean 26.4, range 22.9–29.0).

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

Upper ciliaries 7 (mean 7, range 6–8); lower ciliaries 8 (mean 9, range 7–10); nuchals 5 pairs (mean 2 pairs, range 1–5 pairs); midbody scale rows 34 (mean 34, range 34–36); ventral scale rows 97 (mean 85, range 76–97); subdigital lamellae 24 (mean 25, range 23–29); supraciliaries 5 (mean 5, range 5–5); suboculars 4 (mean 4, range 4–4). Frontonasal never separated from frontal by prefrontals meeting in midline. Anterior loreal always in contact with first and second supralabial, posterior loreal always in contact with second and third supralabial. Supralabials 7, fifth or sixth (usual) the largest. Infralabials 6 (usual) or 7. Projecting scales often present in ear opening. Maximum SVL 89.2 mm. Three of the specimens examined had an intact tail, tail length of intact specimens ranging between 84 - 99 mm. Mean TL/SVL = 1.18. Ratios for morphological measurements (± SD): AG/SF 1.36 ± 0.17; S-Ear/EF 0.98 ± 0.06; HL/HW 1.77 ± 0.07 (N=9).

Colouration. This is quite variable among specimens, but the most common colouration is as follows: Middorsal stripe lacking. Dorsal surface pale green, usually with light and dark flecking (ocelli), 5-6 scale rows wide, bordered by cream dorsolateral stripe 2 scale rows wide extending from behind head to base of tail, becoming indistinct thereafter. This pale stripe bordered below by a brown lateral stripe two or three scale rows wide, notched on upper and lower edges, running from behind eye towards tip of tail. This brown band is heavily flecked with white and often bordered below by another pale band that breaks up into irregular cream and dark brown mottling. Ventral region occasionally suffused with pink, except on the throat which is pale. Soles of feet light grey/cream. Outer surface of forelimbs speckled with light and dark, sometimes orange and green. Tail may be either marked or unmarked. Throat and vent sometimes speckled, occasionally heavily.

They do not appear to be sexually dichromatic. Juvenile colouration similar to adult.

Etymology. The specific name means “olive” in Greek. The accepted vernacular name is ‘Marlborough spotted skink’ (Bell 2014).

Figures

FIGURE 4. a) O. elium holotype, RE 003737 (photo: Jean-Claude Stahl), Motunau Island. b) Live specimen of O. elium, Motunau Island (photo: Marieke Lettink).

FIGURE 6. a – e. Notched boxplots comparing the morphological characteristics of the species in the Oligosoma lineoocellatum species group (O. elium, O. kokowai, O. lineoocellatum, O. prasinum). a) snout-vent length (SVL) / head width (HW), b) midbody scales, c) lower ciliaries, d) axilla-groin (AG) / snout-forelimb (SF), e) upper ciliaries. If there is no overlap between two medians, then the medians are significantly different at a 95 % confidence interval.