Oligosoma kakerakau, Barr & Chapple & Hitchmough & Patterson & Board, 2021

Barr, Benjamin P., Chapple, David G., Hitchmough, Rodney A., Patterson, Geoff B. & Board, Ngātiwai Trust, 2021, A new species of Oligosoma (Squamata: Scincidae) from the northern North Island, New Zealand, Zootaxa 5047 (4), pp. 401-415 : 406-412

Oligosoma kakerakau sp. nov.

( Figure 3 )

Oligosoma “Whirinaki” Hitchmough et al. (2016)

Holotype. NMNZ RE007385 (adult male); Bream Head Scenic Reserve , Whangārei, New Zealand; E1742432 N6031080; 460m; collected by B.P. Barr, 15 January 2014.

Paratypes (3 specimens). NMNZ RE007383; adult male; same collection data as holotype . NMNZ RE007384; adult female; same collection data as holotype . NMNZ RE007386; adult female; same collection data as holotype .

Morphological characters of the type series are presented in Table 2.

Diagnosis. Oligosoma kakerakau sp. nov. can be distinguished from other Oligosoma species by the following combination of characters: the combination of the distinctive teardrop marking under the eye on the supralabials and the distinctive mid-lateral stripe distinguish O. kakerakau sp. nov. from all other Oligosoma except O. zelandicum and O. microlepis (Patterson & Daugherty) . Oligosoma kakerakau sp. nov. can be distinguished from O. microlepis by its speckled ventral surface versus pale cream or white, and by fewer midbody scales (n=4, 26–30) versus O. microlepis (n=9, 38–44). Oligosoma kakerakau sp. nov. can be distinguished from O. zelandicum by: (a) the heavily flecked venter versus uniform or fine flecking in O. zelandicum ; (b) relatively long hindlimb length with no overlap in HLL/SVL ratio; (c) relatively long 4th hind toe length with no overlap in FTL/SVL; (d) subdigital lamellae count usually>20 versus usually <21 in O. zelandicum (e) mid-lateral stripe always broken above forelimb versus infrequently broken in O. zelandicum (f) larger midbody scales with midbody scale rows usually <31 versus usually> 30 in O. zelandicum ; (g) dorsal scale rows always 6 and two half scales versus usually 8 and two half scales in O. zelandicum ; (h) ventral scales usually <76 versus usually> 73 in O. zelandicum ( Table 3).

Although sample sizes are unavoidably small because Oligosoma kakerakau sp. nov. is a threatened species with a very small known population, confidence is greatly increased by the close agreement of the Whirinaki speci- men with the Bream Head individuals in all characters visible in the video of the former. Oligosoma zelandicum is a common, well-known species and the characters used have proven reliable for many specimens handled at various field localities.

Description of Holotype. Body elongate, oval in cross-section; limbs well-developed, pentadactyl; hindlimbs 38% of SVL and 1.5x length of forelimbs; adpressed limbs meeting; digits sub-cylindrical; third front digit shorter than the fourth; ear opening moderately large and rounded.

Lower eyelid with a transparent palpebral disc surrounded either side and below with granules; snout moderately blunt; nostril centred just below middle of nasal, not touching bottom edge of nasal; nasals entire; supranasals absent; rostral broader than deep; frontonasal broader than long, narrow contact with frontal; frontal longer than broad, shorter than frontoparietal and interparietal together, in contact with 2 anteriormost supraoculars; supraoculars 4, the second largest; preoculars 2, the upper one larger; frontoparietals distinct, larger than interparietal; a pair of parietals meeting behind interparietal, the left overlapping the right, and are bordered posteriorly by a pair each of nuchals and temporals, also in broad contact with interparietal, frontoparietal, 2 postoculars, and narrow contact with 4th supraocular; nuchals 2 pairs; loreals 2, similar size; anterior loreal in contact with first and second supralabial, posterior loreal, prefrontal, frontonasal and nasal; posterior loreal in contact with second and third supralabial, first subocular, upper and lower preocular, prefrontal and anterior loreal; supralabials 7, the sixth the largest; fifth supralabial below centre of eye; infralabials 6, 2–4 are similar in size; mental broader but shallower than rostral; subocular row interrupted by 5 th supralabial; postmental larger than mental; chinshields 3 pairs, the second pair the largest; anterior chinshields separated by one scale width, contact 2 nd and 3 rd infralabial; second chinshields separated by one scale width but two scales deep, contact 3 rd and 4 th infralabial; posterior chinshields separated by 4 gular scales, contact 4 th and 5 th infralabials; ear with several moderate triangular projecting lobules on the anterior margin; one primary temporal, dorsal scales largest, weakly striate; ventral scales smooth; subdigital lamellae smooth.

Measurements (in mm; holotype with the variation shown in the type series in parentheses): SVL 58.4 (mean 56.2, range 51.3–60.4), SE 11.4 (mean 10.7, range 10.3–11.4), SF 23.9 (mean 22.6, range 21.5–23.9), HL 9.7 (mean 9.1, range 8.3–9.7), HW 3.9 (mean 3.7, range 3.2–4.1), AG 26.5 (mean 28.4, range 25.5–33.2), EF 13.0 (mean 12.1, range 11.1–13.0), TL 77.0 (mean 77.9, range 74.4–82.5), HLL 22.3 (mean 21.4, range 20.4–22.3), FLL 14.6 (mean 14.1, range 12.6–15.2), and FTL 7.7 (mean 7.3, range 7.0–7.7).

measures

Morphological counts

Meristic Scalation (holotype with the variation shown in the type series in parentheses): Upper ciliaries 8 (mean 8.3, range 8–9); lower ciliaries 12 (mean 11.8, range 10–13); nuchals 2 pairs (mean 2.5 pairs, range 2–3 pairs); midbody scale rows 30 (mean 28.3, range 26–30); ventral scale rows 75 (mean 70.0, range 67–75); subdigital lamellae 26 (mean 23.3, range 20–26); supraciliaries 5 (mean 6.0, range 5–7), anterior suboculars 2 (mean 2.3, range 2–3), posterior suboculars 3 (mean 3, range 3–3). Anterior loreal in contact with first and second supralabial. Posterior loreal in contact with second and usually third supralabial. Supralabials 7. Infralabials 6. One primary temporal. Third front digit usually shorter than the fourth. Maximum SVL 60.4 mm. Ratios for morphological measurements (± SD): SF/AG 0.90 (± 0.09); SE/EF 0.88 (± 0.06); HLL/SVL 0.38 (± 0.01); FTL/SVL 0.13 (± 0.01); HW/HL 0.40 (± 0.02); HW/SVL 0.07 (0.00); HL/SVL 0.17 (± 0.00).

Colouration. Dorsal surface brown with occasional dark brown and light brown flecks, especially on the head. A cream “tear-drop” marking is below the eye, edged in dark brown. No mid-dorsal stripe. A cream dorsolateral stripe with a distinct lower edge that undulates, sometimes strongly. Dorsolateral stripe fades out gradually. A cream mid-lateral stripe, two half-scale rows wide, extends from the eye to the forelimb and sometimes beyond (although it is always broken above the forelimb) breaking posteriorly into irregular blotches that are on the same plane. Top of the mid-lateral stripe passes through ear. A cream dorsoanterior stripe runs down forelimb on brachium and antebrachium and can be broken. Upper lateral zone between the dorsolateral and mid-lateral stripe is dark brown and unmarked and extends from the nostril, through the eye and down the body and tail. Chin grey and speckled. Throat and belly are brown or dark red-orange, heavily speckled with black flecks aligned as broken stripes. Soles of the feet are dark brown to black. There does not appear to be sexual dimorphism in colour patterns. Juvenile colouration similar to that in adults.

Etymology. The specific name is from the te reo Māori words kake, meaning to climb or scale, and rākau, meaning tree. These are in reference to the tree climbing behaviour of this species. This name was gifted by kaumātua of Ngātiwai, the mana whenua of Bream Head Scenic Reserve, where the type locality resides.

Ecology. Currently, O. kakerakau sp. nov. is known only from a small extant population in Bream Head Scenic Reserve in Northland, and a probable single observation in Whirinaki Forest Park, near Minginui (~ 370 km south of Bream Head) in 2003, which is assumed on the basis of examination of photographs to be conspecific. At Bream Head, O. kakerakau sp. nov. occupies a 1.8 ha 100% mimimum convex polygon ( Wiles 2014). Large areas within this MCP are apparently unoccupied, therefore the true area of occupancy is likely to be <1 ha (Hitchmough et al. 2016).

Oligosoma kakerakau sp. nov. is diurnal and strongly heliothermic, and is most often observed basking or foraging in light wells ( Figure 4 ), particularly during humid conditions ( Gillanders 2017). The habitat within its area of occupancy is a mixture of broadleaf forest, low scrub and low groundcover ( Wiles 2014). Oligosoma kakerakau sp. nov. occurs in all of these habitats, but is most common in low scrub and groundcover probably because these habitats provide a greater number of basking opportunities ( Barr 2014; Wiles 2014). Similarly they are known to occur only on the ridgetop and north facing slopes, and have never been detected on the shady south facing slopes at Bream Head ( Wiles 2014).

While most often observed on the ground, O. kakerakau sp. nov. individuals are also frequently observed climbing and basking in trees and vines. This arboreal behaviour is similar to other members of clade 5, O. striatum and O. homalonotum (Hitchmough et al. 2016; Neilson et al. 2004). Indeed their ability and propensity to climb trees and other vegetation is quite remarkable. Individual skinks have been observed actively foraging and chasing cave weta spp. on the trunk of Cyathea dealbata , and foraging and basking up to 4 m high on a variety of other species including: Ripogonum scandens , Freycinetia banksii , Cyathea medullaris and Olearia furfuracea . In addition, O. kakerakau sp. nov. have been observed catching flies (Diptera spp.), native bush cockroaches ( Blattidae spp.), a honeybee ( Apis mellifera Linnaeus ) and a wasp ( Vespula sp. ).

At Bream Head Scenic Reserve O. kakerakau sp. nov. are known to be syntopic with four other skinks: O. aeneum (Girard) , O. ornatum (Gray) , O. moco (Duméril & Bibron) ( Barr 2019; Gillanders 2017, 2018) and as of 2016 the introduced plague skink, Lampropholis delicata (De Vis) ( Gillanders 2017) ; and one gecko: Mokopirirakau granulatus (Gray) . Three other gecko species ( Dactylocnemis pacificus (Gray) , Naultinus elegans Gray and Woodworthia maculata (Gray)) occur in the reserve. Oligosoma kakerakau sp. nov. are the most frequently observed of all the species ( Barr 2019; Gillanders 2017, 2018). Despite having a very similar niche to O. moco and L. delicata , and being syntopic with O. aeneum and O. ornatum , interspecific aggression is observed infrequently (B. Barr unpubl. data). Rather, O. kakerakau sp. nov. is regularly observed in close proximity with the other species sometimes not interacting at all; for example, an O. aeneum was observed walking on top of a basking O. kakerakau sp. nov. which remained motionless (unpubl. data). However, O. kakerakau sp. nov. has been observed ‘snapping’ at L. delicata , and L. delicata has been observed ‘startling’ O. kakerakau sp. nov.. Similarly, intra-specific aggression has been observed, albeit infrequently (Unpubl. data).

The maximum SVL recorded for this species is 67 mm, the most common size category is 51–60 mm ( Wiles 2014). It is viviparous. Young appear to be born in late summer, but the litter size is unknown.

Conservation Status. Oligosoma kakerakau sp. nov. is currently listed under the New Zealand National Threat Classification System as ‘Nationally Critical’ by Hitchmough et al. (2016). This listing uses criterion A(3) on the basis that the total known area of occupancy (AOO) is ≤ 1 ha (0.01 km 2), and the qualifiers Conservation Dependent, Range Restricted, and Sparse ( Townsend et al. 2008) also apply. The species potentially qualifies for listing as Critically Endangered under the IUCN Red List criteria ( IUCN 2012). Its AOO and Extent of Occurrence (EOO) are both <4 km 2, and it has 2 known locations, which are severely fragmented. Invasive mammalian predators are inferred to be a source of past, current and ongoing decline in EOO, AOO, and number of mature individuals. Thus, the species may be listed as Critically Endangered B1ab(i,ii,v)+B2ab(i,ii,v).

Figures

FIGURE 3. Adult male holotype of Oligosoma kakerakau sp. nov. (RE 007385): A.) dorsal, B.) ventral and C.) lateral views. [Photographs: Jean-Claude Stahl].

FIGURE 4. Forested habitat at the type locality Bream Head Scenic Reserve, Whangārei, March 2019 showing typical light wells similar to those frequented by Oligosoma kakerakau sp. nov. [Photograph: Ben Barr].