Tytthoscincus temasekensis, Grismer & Wood & Jr & Lim & Liang, 2017

Grismer, L. Lee, Wood, Perry L., Jr, Lim, Kelvin K. P. & Liang, Lim J., 2017, A new species of swamp-dwelling skink (Tytthoscincus) from Singapore and Peninsular Malaysia, Raffles Bulletin of Zoology 65, pp. 574-584 : 578-582

Tytthoscincus temasekensis , new species Singapore swamp skink

( Fig. 2 )

Tytthoscincus cf. sibuensis — Grismer et al., 2017: in press.

Holotype. ZRC 2.6490 (adult female) collected from Pasir Laba Road , Singapore (N 01°19.526′, E 103°40.212′; 24 m elevation) by B. Y. H. Lee on 21 June 2014.

Paratypes. ZRC 2.2557 (juvenile) collected from the Nee Soon Swamp , Singapore (approximately N 01°24.051′, E 103°48.537′; 20 m elevation) by K. P. K. Lim on 28 December 1989 . ZRC 2.667 (adult male) collected from the Nee Soon Swamp , Singapore (approximately N 01°24.051′, E 103°48.537′; 20 m elevation) by K. Young and P. K. L. Ng on 30 April 1990 . ZRC 2.3959 (adult male) at Lorong Banir off Upper Thomson Road, Singapore (approximately N 01°23.427′, E 103°50.220′; 9 m elevation) by K. P. K. Lim on 24 May 1994 . ZRC 2.7111 (juvenile) collected at Upper Seletar Reservoir Park , Singapore (approximately N 01°22.376′, E 103°48.434′; 37 m elevation) by N. Baker on 12 September 2015 .

Non-types. Tytthoscincus temasekensis . ZRC 2.3277 (juvenile) from North Selangor Peat Swamp kilometer marker 34 on road to Tanjung Malim, Selangor, Peninsular Malaysia (approximately N 03°42.383′, E 101°09.115′; 20 m elevation) collected by NUS 1991–92 Zoology Honours Class on 17 June 1991 . ZRC 2.3377 (juvenile) from North Selangor Peat Swamp kilometer marker 47 at Sungai Besar Road on road to Tanjung Malim, Selangor, Peninsular Malaysia (approximately N 03°41.472′, E 101°14.062′; 15 m elevation) collected by D. S. L. Chung in April 1993 . ZRC 2.7152 from the Nee Soon swamp-forest, Singapore collected by H. H. Tan and others on 23 October 1999 .

Diagnosis. Tytthoscincus temasekensis sp. nov. can be differentiated from all other species of Tytthoscincus in Peninsular Malaysia by having the combination of two loreals, two postsupralabials, 9`1 or 10`2 superciliaries, four supraoculars; interparietal contacting 2 nd –4 th supraoculars, a shallow, pigmented tympanum, slightly enlarged pectoral scales, 27–29 midbody scale rows, 55–65 paravertebral scales, 54–63 ventral scales, 9–11 subdigital lamellae on the fourth toe, keeled, subdigital lamellae, and a dorsal pattern of light-coloured stripes and/or linearly arranged spots. All characters are scored across all other Tytthoscincus and species of Sphenomorphus suspected of being Tytthoscinus in Grismer et al. (2016a: 237) and Karin et al. (2016: 416). Description of holotype. Adult female, SVL 34.9 mm; tail length 40.8 mm, 2 mm of tip removed; axilla-groin length 18.4 mm; head length 5.8 mm; head width 4.1 mm; snout to anterior margin of foreleg 11.5 mm; rostral wider than long, in broad contact with frontonasal; frontonasal wider than long; prefrontals large, contacting on midline; frontal elongate, diamond-shaped, in contact with first two supraoculars; four supraoculars; interparietal in contact posterior to frontal, contacting second, third, and fourth, supraoculars anterolaterally and parietals and interparietal posteriorly; frontoparietals non-overlapping; interparietal diamond-shaped, large, slightly projecting posteriorly, eyespot in posterior projection; parietals large, in medial contact posterior to interparietal, contacting fourth supraocular anteriorly; enlarged nuchal scales absent; nasals small, widely separated, trapezoidal, contacting rostral anteriorly, frontonasal dorsally, first loreal posteriorly, first supralabial ventrally; nostril in center of nasal; supranasals absent; two loreals taller than wide, posterior loreal largest; upper and lower preocular present; 10 superciliaries, posterior two superciliaries elongate and projecting dorsomedially; seven supralabials, third, fourth, and fifth below eye; two postsupralabials; two primary temporals; two pretemporals; two secondary temporals, uppermost not contacting parietals; lower eyelid transparent, scaly, no enlarged central window; mental twice as wide as long; single, large postmental, contacting first infralabials on each side; two enlarged pairs of chinshields posterior to postmental, anterior pair contacting medially, posterior pair separated posteriorly by a single scale; chinshields contacting infralabials; seven infralabials; external ear opening 0.8 mm wide, approximately one-half diameter of eyeball, subcircular, lacking anterior lobules; and tympanum shallow, pigmented.

Body scales smooth, cycloid, imbricate; ventral scales slightly larger than dorsal scales; some pectoral scales slightly enlarged; 29 longitudinal scale rows around midbody; 65 paravertebral scale rows; 63 ventral scale rows; slightly enlarged precloacal scales, inner precloacals overlap outer precloacals; and tail slightly compressed laterally.

Limbs well-developed, short, contacting but not overlapping when adpressed; scales of dorsal surface slightly larger than those of ventral surface; palmar and plantar scales slightly raised; and digits short, scales of dorsal surface of fourth toe in multiple rows, subdigital keeled, 10 on fourth toe; and rank of toe length I, II, IV, III, V.

Colouration in alcohol ( Fig. 2 ). Overall dorsal ground colour of head, body, limbs, and tail dark-brown; head speckled with light-coloured markings; labials distinctly barred; labials bearing a central light-coloured spot; anterior of flanks and venter to posterior margin of jaws dull-orange; light-coloured, lineate, paravertebral markings extending from postorbital region to groin becoming more of a series of spots closer to the groin and bordered below anteriorly by a thick, dark-coloured stripe; mid-dorsal region bearing a lineate series of light-coloured, paravertebral spots extending from occiput to anterior portion of tail; dorsal surface of limbs and tail speckled; ventral surfaces beige; and plantar and palmar regions dark.

Variation ( Fig. 2 ). Paratypes closely approach the holotype in all aspects of colouration except for the dorsal pattern of ZRC 2.2557 is generally more spotted than lineate. The dorsal patterns of ZRC 2.2667 and 2.3959 are very faded but the same general lineate characteristics are still visible. Colour photos of living ZRC 2.2711 show its dorsal pattern to be much less bold than that of the holotype and nearly unicolour. Both ZRC 2.3277 and 2.3377 from the vicinity of Tanjung Malim bear the same lineate dorsal characteristics of the Singapore specimens. Meristic variation is presented in Table 4 .

Distribution. Tytthoscincus temasekensis , new species, is known from lowland areas in Singapore and near Tanjung Malim, Perak, Peninsular Malaysia ( Fig. 1 ).

Natural history. Tytthoscincus temasekensis has been found in lowland dipterocarp forests but is far more common along stream banks in peat and freshwater swamp forests up to at least 37 m in elevation ( Lim, 1998; Serin, 2015; Fig. 3 ). Specimens near Tanjung Malim were inadvertently collected while hand-netting for fishes in small streams which may indicate semi-aquatic proclivities as noted by Baker (2013) who states “An example of about 5 cm was seen among forest leaf litter at the edge of a shallow stream. It swam in a sinuous motion across the stream, coming to rest on the opposite side partly submerged, with only the front part of its head including the eyes and nostrils emerged.” ZRC 2.7111 was collected while crossing a paved road running through lowland forest. A juvenile (ZRC 2.6859) was taken from the gut of an Aheatulla mycterizans found dead on Old Upper Thomson Road.

Etymology. The specific epithet temasekensis is derived from the word Temasek meaning ‘Sea Town’ in Old Javanese and represents the earliest recorded name of a settlement in Singapore. The suffix -ensis is Latin meaning ‘of or from a place.’ The specific epithet is in reference to the type locality being on the island of Singapore. The suggested common name is the Singapore swamp skink.

Comparisons. Tytthoscincus temasekensis , new species, can be differentiated from all other species of the Tytthoscincus of the montane clade by having stripes or longitudinally arranged spots. Tytthoscincus temasekensis sp. nov. can be differentiated from all other species of the Tytthoscincus of the swamp clade by having two versus one loreal scale, slightly enlarged pectoral scales versus no enlarged pectoral scales, and adpressed limbs making contact versus being separated. Tytthoscincus temasekensis sp. nov. can be further differentiated from T. panchorensis by the interparietal contacting the 2 nd –4 th supraoculars versus the 3 rd –5 th supraoculars and having four versus five supraoculars (these two characters are linked); having 55–65 versus 68 paravertebral scales rows, having 9–11 versus eight subdigital lamellae on the 4 th toe; and having white lineate markings in its dorsal pattern ( Tables 4, 5). Tytthoscincus temasekensis sp. nov. is further differentiated from T. sibuensis by having 54–63 versus 52 ventral scale rows.

Remarks. Because the morphology and colour pattern of the Tanjung Malim specimens from Peninsular Malaysia (ZRC 2.3277, 2.3377) are completely subsumed within the variation of those from specimens of the Singapore population, we elect to consider them conspecific given there is no intrinsic evidence to suggest otherwise. However, we do not include the Tanjung Malim specimens as part of the type series. Crypsis within the genus Tytthoscincus , has been well-documented and can potentially create taxonomic problems when new species are described in the absence of molecular data ( Grismer et al., 2017). If molecular evidence eventually indicates that the Tanjung Malim population is not conspecific with the Singapore population, the type series of T. temasekensis sp. nov. will remain intact. This was not the case with the type series of T. bukitenis ( Grismer, 2007a) that was eventually shown to be composed of two unrelated species ( Grismer et al., 2017).

Figures

Fig. 2. Tytthoscincus temasekensis sp. nov. Upper: adult holotype (ZRC 2.6490) from Pasir Laba Road, Singapore. Middle: juvenile paratype (ZRC 2.7111) from Upper Seletar Reservoir Park, Singapore (Photograph by Nick Baker). Lower: uncataloged specimen from 3 km south of the Nee Soon Swamp, Singapore (Photograph by Noel Thomas).

Fig. 1. Upper: Maximum Likelihood phylogram depicting the relationships of species within the swamp clade of Tytthoscincus (brown highlight) and their relationship to other Tytthoscincus lineages. Bayesian posterior probabilities and ultrafast bootstrap values, respectively, are listed at the nodes. Lower left: Distribution map of the species of the swamp clade of Tytthoscincus. Lower right: Principal Component Analysis of the species of the swamp clade of Tytthoscincus.

Fig. 3. Microhabitat of Tytthoscincus temasekensis sp. nov. in the Nee Soon Swamp, Singapore.