Oligosoma robinsoni ( Wells & Wellington 1985

Melzer, Sabine, Hitchmough, Rod A., Bell, Trent, Chapple, David G. & Patterson, Geoff B., 2019, Lost and Found: Taxonomic revision of the speckled skink (Oligosoma infrapunctatum; Reptilia; Scincidae) species complex from New Zealand reveals a potential cryptic extinction, resurrection of two species, and description of three new species, Zootaxa 4623 (3), pp. 441-484 : 464-467

Oligosoma robinsoni ( Wells & Wellington 1985 )

Figures 6a, b

Synonyms

Leiolopisma infrapunctatum

(Boulenger): HARDY 1977; OWEN 1997

Oligosoma robinsoni

WELLS & WELLINGTON 1985; JEWELL & MORRIS 2011

Oligosoma infrapunctatum

GREAVES et al. 2008; CHAPPLE et al. 2009; PERROTT et al. 2011; SCHRAGEN et al. 2011; SCHRAGEN & PER- ROTT 2011; TOWNS et al. 2002

Oligosoma aff. infrapunctatum “crenulate”

HITCHMOUGH, R., BULL, L. & CROMARTY, P. 2007; HITCHMOUGH et al. 2010; HITCHMOUGH et al. 2013; BELL 2014; HITCHMOUGH et al. 2016a; HITCHMOUGH et al. 2016b; VAN WINKEL et al. 2018.

Leiolopisma “Ngahinapouri”

DEPARTMENT OF CONSERVATION BIOWEB HERPETOFAUNA DATABASE (1968) [Amphibian & Reptile Distribution Scheme card number 867, observation record number 483057]

Holotype. Moutohorā (Whale Island) (37º 52’S, 176º 58’E), RE004443 (S801) (coll. M. Imber, 01 Sep 1970).

Paratypes (13 specimens). Moutohorā (Whale Island) (37º 52’S, 176º 58’E), 2 specimens: NMNZ RE004120 (S442), male ; NMNZ RE004120 (S477), male (coll. L. Moran, 04 Sep 1969) ; Moutohorā (Whale Island) (37º 52’S, 176º 58’E), 2 specimens: NMNZ RE005412, female ; NMNZ RE005413, female (coll. K. Owen, 03 Apr 1992) ; Western Taupo (38º 51’S, 175º 40’E), NMNZ RE000824, male (coll. R. Dell, 03 Nov 1953) ; N of Tihoi , western Taupo (- 38º 37’S, 175º 40’E), 2 specimens: NMNZ RE000820, female ; NMNZ RE000822, immature (coll. R. Dell, P. Bull, 06 Nov 1953) ; Ngongataha , Rotorua (38º 05’S, 175º 13’E), NMNZ RE005404, female (coll. Unknown, 20 Mar 1987) ; Taumaranui , NI (38º 05’S, 175º 13’E), 2 specimens: NMNZ RE005405 (organs removed) ; NMNZ RE005406 (organs removed) (coll. Unknown, unknown date) ; Miller Road , Lake Okereka, Rotorua (38º 10’S, 175º 20’E), NMNZ RE005247, male (coll. K. Owen, 1997) ; Hamilton (37º 54’S, 175º 11’E), NMNZ RE003881, male (coll. B. Thomas, 02 Apr 1968) ; Tokoroa (( 38º 12’S, 175º 52’E), NMNZ RE008540, unknown (coll. G. Sutherland, 19 Feb 2011).

Diagnosis. O. robinsoni can be distinguished from other species in the O. infrapunctatum species complex by a combination of characters ( Figure 4 a–j). In O. salmo sp. nov. subdigital lamellae usually <20 versus usually 20 or above in O. robinsoni . The VS count is 69 or below in O. salmo sp. nov. versus usually 69 or greater; supraciliaries 5 only ( O. salmo sp. nov.) versus usually>5; ventral speckling much more pronounced in O. robinsoni than O. salmo sp. nov. There are statistical differences between O. newmani and O. robinsoni (AG/SF). Subdigital lamellae are usually 20 or below in O. newmani versus 20 or above in O. robinsoni . O. robinsoni has a longer tail relative to SVL compared with O. newmani . O. robinsoni differs from O. albornense sp. nov. in having a VS count usually 69 or greater versus 69 or below ( O. albornense sp. nov.); upper ciliaries 6 or less ( O. albornense sp. nov.) versus usually 6 or more; ventral speckling much more pronounced in O. robinsoni than O. albornense sp. nov. It differs from O. auroraensis sp. nov. i n having subdigital lamellae usually 21 or above ( O. auroraensis sp. nov.) versus usually 21 or below; VS usually 75 or less in O. robinsoni versus usually 75 or greater in O. auroraensis sp. nov.; mid-dorsal stripe to base of tail in O. robinsoni , past base of tail in O. auroraensis sp. nov.

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 blunt. Nostril centred in lower middle of nasal, not touching bottom edge of nasal, pointing up and back. Supranasals absent. Rostral broader than deep. Frontonasal broader than long, not separated from frontal by prefrontals meeting in midline. Frontal longer than broad, shorter than frontoparietal and interparietal together, in contact with 2 anteriormost supraoculars. Supraoculars 4, 2 nd largest. Preoculars, 2, upper one 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, 4 th supraocular, and 2 postoculars. Loreals 2, anterior one the larger; anterior loreal in contact with 1 st and 2 nd supralabial, posterior loreal, prefrontal, frontonasal, and nasal; posterior loreal in contact with 2 nd and 3 rd supralabial, 1 st subocular, upper and lower preocular, prefrontal, and anterior loreal. Supralabials 7, 6 th largest. Infralabials 6, several equally largest. Fifth supralabial below centre of the eye. Temporals: 1 primary; 2 secondary. Ear opening round, moderately large (1.6% as percentage of SVL), with several small projecting granules on anterior margin. Suboculars 8, 4 th and 5 th separated by 5 th supralabial. Mental broader but shallower than rostral. Postmental larger than mental. Chinshields 3 pairs. Dorsal scales largest, weakly striate. Ventral scales and subdigital lamellae smooth. Adpressed limbs barely meeting. Digits moderately long, subcylindrical. Third front digit shorter than the 4 th.

Measurements (in mm; holotype with the variation shown in the specimens examined in parentheses). SVL 70.1 (mean 62.2, range 40.0–84.3), HL 11.1 (mean 9.8, range 7.3–12.1), HW 7.0 (mean 5.9, range 4.2–8.3), AG 36.5 (mean 32.4, range 19.3–45.1), SF 28.5 (mean 24.5, range 16.5–30.4), S-Ear 14.3 (mean 12.3, range 8.5– 15.2), EF 14.7 (mean 12.8, range 8.3–16.4), HLL 26.5 (mean 20.6, range 12.3–26.5), D-Ear 1.1 (mean 1.2, range 0.9–1.6).

Variation (holotype with the variation shown in the paratypes /specimens examined in parentheses). Upper ciliaries 5 (mean 7, range 5–8); lower ciliaries 8 (mean 9, range 7–12); nuchals 4 pair (mean 3 pairs, range 1–4 pairs); midbody scale rows 30 (mean 32, range 30–35); ventral scale rows 78 (mean 73, range 64–84); subdigital lamellae 20 (mean 20, range 17–23); supraciliaries 6 (mean 6, range 5–7); suboculars 6 (mean 6, range 6–8). Frontonasal usually not 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 84.3 mm. Only 2 of the specimens examined had an intact tail, tail length of intact specimens ranging between 55–92 mm. Mean TL/ SVL = 1.34. Ratios for morphological measurements (+ SD): AG/SF 1.32 + 0.12; S-Ear/EF 0.99 + 0.08; HL/HW 1.72 + 0.11 (N=14).

Colouration. This is variable among specimens, but the most common colouration is as follows: Mid-dorsal stripe either broken or continuous. If continuous, only to base of tail. Dorsal surface mid to dark brown, usually with light and dark flecking, 6 scale rows wide, grading into pale dorsolateral stripe extending from behind head to base of tail, becoming indistinct thereafter. This pale stripe is bordered below by a ½ scale row wide dark brown band, below that a 1–2 scale wide lighter brown row, notched on upper and lower edges, running from behind nostril through eye towards base of tail becoming indistinct thereafter. This band sometimes has paler speckles in it. Then a darker brown band 1–2 half-scales wide. This lower dark brown band is bordered below by a pale stripe, 1 to 2 half-scale rows wide running from below the eye, through the ear, above the limbs to become indistinct after the hindlimbs. This band is broken above forelimbs and bounded below by a very broken light brown band breaking up into a ventral speckling. Soles of feet grey/black. Belly yellow or cream, usually speckled with darker flecks. Throat pale. Outer surface of forelimbs brown, speckled with light and dark.

Etymology. Named for Professor E.S. Robinson of the School of Biological Sciences, Macquarie University, Sydney in recognition of his herpetological research ( Wells & Wellington 1985). The history of common and tag names for this species is complex. A.H. Whitaker and Bruce Thomas in the 1960s and 1970s used the tag name Leiolopisma “Ngahinapouri”, but also included specimens from the Wairarapa under this tag name. Jewell & Morris (2008) coined the name “crenulate skink” for the larger of the two entities found in sympatry at Granity. This population, now known to be part of the widespread O. newmani , was then thought in error to represent Clade 2a of Greaves et al. (2008). The common name “crenulate skink” then expanded in use to include all populations of Clade 2a plus 2b. More recently South Island members (Clade 2a) have been known by the names “cobble skink” and “Hokitika skink”. Crenulate skink has continued in use for the North Island populations described here as O. robinsoni .

Distribution. The species is recorded in several locations and ecological districts across central North Island, from the King Country, Waikato, Taupo, Rotorua and Bay of Plenty (11.04 Hamilton, 13.04 Rotorua, 13.05 White Island, 15.03 Tokoroa, 16.02 Taupo and 23.02 Taumarunui Ecological Districts). This distribution is approximately north of what is termed as the ‘Taupo Line biogeographic barrier’ ( Chapple & Hitchmough 2016). Environments include warm mild and cool, humid lowlands / swampland / rolling hill country up to 630 m ASL, that is—or wasoriginally scrubland / fernland or forested, including coastal or lake islands in a central North Island region with a very frequent and recent volcanic history. These skinks are found in dense grassland, scrub, shrublands, fernland and forest edge habitats; the species can also be found on the coast on boulder beaches, and beneath rocks and logs in grasses above high tide mark ( van Winkel et al. 2018).

Natural History. Diurnal, heliothermic, terrestrial. A medium-to-large coastal and lowland species (up to 90 mm SVL, c. 8.2 g), animals heavy-bodied with broad heads and robust limbs in the Central North Island, and island animals smaller and more slender ( van Winkel et al. 2018). This species is found in scattered populations in the central North Island; not all have had genetic analyses undertaken. Two populations are known from islands free of predatory mammals, Moturoa / Whale Island in the Bay of Plenty and Mokoia Island in Lake Rotorua. The Mokoia Island population was discovered only after removal of Norway rats ( Rattus norvegicus ), although weka ( Gallirallus australis ), an efficient native predator of lizards, were introduced to the island in the 1950s and are still present ( Owen 1997, Towns et al. 2002). Subsequently, Perrott et al. (2011), Schragen et al. 2011 and Schragen & Perrott 2011 studied this population, investigating population, genetics, individual health and bait preferences. Similarly, another population of what is assumed to be O. robinsoni was discovered in the Pureora Forest, Waikato, after the commencement of extensive predatory mammal control ( Towns et al. 2002). These skinks appear to be social, avid but cryptic sunbaskers; animals are noticeably gravid in November with births between December–March, 6–9 young (DOC BioWeb Herpetofauna database observation record number 487553, van Winkel et al. 2018). Findings from recent scientific research on O. robinsoni on Mokoia Island include: SVL range was 45 mm – 88 mm, weight range is 1 g– 15 g; females were noticeably pregnant in November–December, with the smallest pregnant female at 61 mm SVL; the birthing period is likely between December and March; caudal autotomy rates were high (increasing from 23% to 100% across four progressive size classes); the parasitic mite Neotrombicula sphenodonti is present on these skinks, with parasitism possibly seasonal (December), as 44.8% of trapped skinks were parasitized during that month, but not other months; the population had low genetic variation, suggestive of a small founder population; and bracken fern ( Pteridium esculentum ) is a major habitat for these skinks, possibly as a refugia from predation pressure by weka ( Perrott et al. 2011, Schragen et al. 2011, Schragen & Perrott 2011, J. Perrott & S. Darke, unpub. data).

Discussion. The larger-bodied Granity population included in this species by Jewell & Morris (2011) belongs to Clade 1 ( Figure 2 ), so is not conspecific with the North Island “crenulate skink” populations which we here identify as O. robinsoni . Greaves’ (2008) Clade 2a specimens from Granity appear to correspond to the smaller-bodied taxon that Jewell & Morris (2008, 2011) called the “cobble skink”. However, this population contains multiple mitochondrial lineages and requires further taxonomic research. The other population contained in Clade 2a of Greaves et al. (2008) was from Hokitika, and was substantially divergent from the Granity population, and the sampled animals are much larger.

Figures

FIGURE 2. Maximum Likelihood (ML) phylogenetic tree, with 1,000 bootstraps, for the Oligosoma infrapunctatum species complex. Well-supported nodes (i.e. bootstrap support>70) are indicated with an asterisk.

FIGURE 4. a–j. Notched boxplots comparing the morphological characteristics of the species in the Oligosoma infrapunctatum species group (O. albornense, n=4; O. auroraensis, n=6; O. newmani, n=50; O. robinsoni, n=14; O. salmo, n=5). a) snout-ear (SE)/ear-axilla (EF), b) midbody scales, c) ventral scales, d) upper ciliaries, e) supraciliaries, f) supralabials, g) snout-vent length (SVL)/ hindlimb length (HLL), h) subdigital lamellae, i) axilla-groin (AG)/snout-forelimb (SF), j) head-length (HL)/ head-width (HW). If there is no overlap between two medians, then the medians are significantly different at a 95% confidence interval.

FIGURE 6. a) O. robinsoni holotype, Moutohorā (Whale Island) (photo: Jean-Claude Stahl). b) Live specimen of O. robinsoni, Moutohorā (Whale Island) (photo: Dylan van Winkel).