A REVISION OF Eutropis rudis (BOULENGER, 1887), RESURRECTION OF E. lewisi (BARTLETT, 1895) AND DESCRIPTION OF A NEW SPECIES (REPTILIA : SCINCIDAE) FROM GREAT NICOBAR

We examined the syntype series of Eutropis rudis (6 specimens) collected from Sumatra and Borneo, currently deposited at the Natural History Museum, London. We observed that the type series is composed of two species. In order to stabilize application of the name, we designate a lectotype for E. rudis from Sumatra. Mabuya lewisi, described based on a specimen from Borneo, is resurrected as a valid species of Eutropis and redescribed. Based on morphology and geographic distribution, we describe a new species of this complex from Great Nicobar Island with two specimens deposited at the Zoological Survey of India (ZSI), Kolkata.

Currently, the Eutropis multifasciata complex consists of three recognised taxa [fide Amarasinghe et al. 2017Amarasinghe et al. : 105-106, 2018): E. multifasciata (Kuhl, 1820), E. rudis (Boulenger, 1887) and E. macrophthalma (Mausfeld & Böhme, 2002). In this study we examined the type material (including synonym types) and several other voucher specimens of E. rudis in several museums. In the collections of the Zoological Survey of India, Kolkata (ZSI) we found two Eutropis specimens collected from Great Nicobar (ZSI 23483, 25118) identified as E. rudis, but differing in several respects. These are described here as new species. Examination of the extant M. lewisi (presently a synonym of E. rudis) syntype revealed clear differences from the specimens of M. rudis s. str., and we regard the differences to be distinct enough to consider it a valid species of the genus Eutropis.

Material and methods
We compared specimens (including types), original descriptions, and synonymised species types of the Eutropis rudis complex (Appendix I). Museum acronyms are those of Uetz et al. (2019). We examined the external morphology of specimens by using a Wild M3Z stereomicroscope. Sex was not determined from specimens unless the hemipenes in males were everted. All locality records are based on our personal observations and data recorded in museums. Altitudes are given in metres above mean sea level. The following measurements were taken to the nearest 0.1 mm on the left side of the body with a Mitutoyo digital caliper: snout-vent length (SVL, from tip of snout to anterior margin of vent), head length (HL, from posterior edge of the retro-articular process of the mandible to tip of snout), head width (HW, width of head at the temporo-mandibular articulation / angle of the jaws), snout length (ES, from anterior border of orbit to tip of snout), eye-nostril length (EN, from anterior border of orbit to the posterior border of nostril), orbit diameter (ED, the greatest horizontal diameter of the orbit), tympanum-eye length (TYE, from posterior border of orbit to anterior border of tympanum), thigh length (FEL, from the anterior margin of the hind limb at its insertion point on the body to the knee while flexed 90 degree), shank length (TBL, from the posterior surface of the knee while flexed 90 degree to the base of the heel), and toe lengths (from tip of finger, to the junction with the adjacent digit, excluding the claw). Supralabial and infralabial scales were counted from the gape of the lips to the rostral and mental scales respectively. Ventrals included all scales from the scale posterior to the postmental to the last scale bordering the vent, counted along the ventral midline. Paravertebral scales are between postparietal / nuchal (included) to the level of the posterior margin of the thigh in a straight line immediately left of the vertebral column. Subdigital lamellae on toe IV from the first proximal enlarged lamellae wider than the width of the largest palm scale to the distal-most lamella at the base of the claw. Total number of longitudinal scale rows was counted around the midbody.
We conducted both univariate and multivariate analyses on three morphometric ratios (TYE/SVL, ED/SVL and TBL/SVL) covering keel-scaled skinks of the E. rudis complex: Eutropis rudis and E. lewisi from Borneo, E. macrophthalma from Sulawesi, and the new species from Great Nicobar, to explore morphometric differences among putative species. We excluded the smooth-scaled E. multifasciata from our comparisons. The univariate analyses for each ratio were conducted by separate one-way ANOVAs considering morphometric ratio as the response variable and the species as the predictor variable. Post-hoc analyses were conducted by performing a Tukey HSD test when necessary. Multivariate analyses were conducted using Nonmetric multidimensional scaling (NMDS) to reduce the morphometric ratio matrix of seven to two dimensions using the metaMDS function in the R package -vegan‖ (Oksanen et al. 2012). The ordination was based on a Bray-Curtis distance measure. The ordination plot was based on the Pearson Correlation Coefficient for each ratio against the two NMDS axes. We considered stress less than 0.20 as an adequate solution (McCune & Grace 2002). All statistical analyses were conducted using the R statistical software program.

Results
The syntype series of Mabuia rudis (BMNH 1946(BMNH .8.15.26, 1946 is composed of two morphospecies originating from the islands of Sumatra and Borneo. In order to stabilize the name with a recognized type specimen and to solve the complex taxonomic problem, it is essential to designate a lectotype. Although Boulenger (1887) examined six specimens (one adult and five juveniles) for his original description, he provided the measurement for only the adult (largest specimen) he had at hand, which was collected from Sumatra. Therefore, we designate that specimen, BMNH 1946.8.15.26 as the lectotype of Mabuia rudis. One of the Bornean paralectotypes of M. rudis, BMNH 1946.9.7.46 is clearly identified, following examination, as Eutropis rudis.
Mabuia lewisi (Bartlett, 1895) has been considered a junior subjective synonym of Mabuia rudis since Smith (1935). However a critical comparison of the designated lectotype of Mabuia rudis and the available type specimen of Mabuia lewisi at BMNH revealed that the latter is morphologically distinct enough to be regarded as a separate species. Therefore we recognise and redescribe Mabuia lewisi as a valid species of the genus Eutropis. The number of specimens comprising the syntype series of Mabuia lewisi is unclear, though the original description implies the possibility of having at least two specimens because the author described the morphology of both sexes. Therefore, in order to stabilize the name with a recognized type specimen and to solve the complex taxonomical problem, we hereby designate the available type specimen BMNH 1946.8.3.57 as the lectotype. The paralectotypes of Mabuia rudis, BMNH 1946.9.7.47-50 also represent Eutropis lewisi. Furthermore, the original description of Mabuia rudis and Mabuia lewisi were very concise, lacking most of the important diagnostic characters, so here we provide comprehensive redescriptions based on their lectotypes. We present diagnostic morphological, morphometric, and meristic data taken from the type specimens and other specimens examined (Tables 1-3).    , slightly convex in lateral profile; rostral shield large, hemispherical, slightly visible from above, posterior margin of midpoint curved; frontonasal slightly in contact with rostral; frontonasal wide, lateral border touching first loreal; prefrontals widely in contact separating the frontal and frontonasal, largest distance along the longitudinal axis of frontonasal equal to the prefrontals in length, lower border touching both loreal scales, the posterior border touching the first supraocular, and frontal; frontal large, elongate, subtriangular, bluntly pointed posteriorly, equal in length to the frontoparietals and interparietal combined; frontoparietals two, in contact, distinct, slightly larger than interparietal; parietals large and completely separated by interparietal, touching pretemporal scales laterally; nuchals single pair, overlapping mid-dorsally behind interparietal. Nostril large and placed in the middle of nasal; single supranasal; loreals two, anterior loreal touching nasal, supranasal, frontonasal, prefrontal, posterior loreal, and 2 nd and 3 rd supralabials; posterior loreal longer than the anterior loreal in the longitudinal axis, touching prefrontal and first supraciliary; two presuboculars; eye large (ED 18.7% of HL), orbit diameter smaller than tympanum-eye length, pupil rounded; interorbital distance broad; three small postoculars; supraoculars wide, four, second is the longest in the longitudinal axis and the widest in the transverse axis and fully contacts the frontal; first supraocular in contact with prefrontal and frontal, 2 nd in contact with frontal, 3 rd in contact with frontoparietals, and 4 th in contact with both frontoparietal and parietal; supraciliaries five; eyelid moveable, scaly window separated into several scales. Six supralabials, fifth largest and at the mid orbit position (5 th and 6 th touching orbit); three pretemporals; three primary temporals, three secondary temporals; infralabials five; ear opening deep, small, near spherical and approximately one quarter of eye diameter. Mental large; a single large postmental followed by two chin shield pairs, the first pair meeting in midline, the first chin shield in contact with first and second infralabial scales, the second pair in contact with second and third infralabials.
With the exception of head shields and nuchals pair all body scales are tricarinate; all scales imbricate and lack apical pits; scales on the dorsal surface of thigh moderately tricarinate; body slender, elongate (AG 49.2% of SVL); midbody scale rows 33; paravertebral scales 45; five enlarged preanal scales.
Forelimbs short, hind limbs relatively long (FEL 15.8% of SVL, TBL 15.2% of SVL); shank slightly short and 96.3% of thigh length; dorsal surfaces of fore and hind limbs moderately carinate; subdigital lamellae on toes I, 9; II, 12; III, 16; IV, 19; and V, 12; relative length of digits those of fingers: IV > III > II > V > I; those of toes: IV > III > V > II > I. Tail complete, median scale row of subcaudals of original tail subequal with the scales beside.
Coloration. Dorsal head and body light copper brown, limbs more reddish dorsally; brown untidy band commencing from posterior eye passing through tympanum until shoulder, bordered above by a white stripe. Venter white. (Bartlett, 1895) comb. nov. (Figs. 1, 2,  , slightly convex in lateral profile; rostral shield large, hemispherical, distinctly visible from above, posterior margin of midpoint curved; frontonasal in contact with rostral; frontonasal wide, lateral border touching first loreal; prefrontals widely in contact separating the frontal and frontonasal, largest distance along the longitudinal axis of frontonasal longer than length of prefrontals, lower border touching both loreal scales, the posterior border touching the first supraocular, and frontal; frontal large, elongate, subtriangular, bluntly pointed posteriorly, equal in length to frontoparietals and interparietal combined; frontoparietals two, in contact, distinct, larger than interparietal; parietals large and completely separated by interparietal, touching pretemporal scales laterally; nuchals single pair, overlapping middorsally behind interparietal. Nostril large and placed in the middle of nasal; single supranasal; loreals two, anterior loreal touching nasal, supranasal, frontonasal, prefrontal, posterior loreal, and 2 nd supralabial; posterior loreal longer than the anterior loreal in the longitudinal axis, touching prefrontal and first supraciliary; two presuboculars; eye large (ED 24.1% of HL), orbit diameter and the tympanum-eye length equal in length, pupil rounded; interorbital distance broad; three small postoculars; supraoculars wide, four, second is the longest in the longitudinal axis and the widest in the transverse axis and fully contacts the frontal; first supraocular in contact with prefrontal and not in contact with frontal, 2 nd in contact with frontal and frontoparietal, 3 rd in contact with frontoparietal, and 4 th in contact with both frontoparietal and parietal; supraciliaries six; eyelid moveable, scaly window separated into several scales.

Eutropis lewisi
Six supralabials, fifth largest and at the mid orbit position (5 th touching orbit); three pretemporals; three primary temporals, three secondary temporals; infralabials five; ear opening deep, small, near spherical and approximately one quarter of eye diameter. Mental large; a single large postmental followed by two chin shield pairs, the first pair meeting in midline, the first chin shield in contact with first and second infralabial scales, the second pair in contact with second and third infralabials.
With the inclusion of head shields and nuchals pair all body scales are strongly carinate, body scales tricarinate; all scales imbricate and lack apical pits; scales on the dorsal surface of thigh strongly tricarinate; body slender, elongate (AG 52.5% of SVL); midbody scale rows 28; paravertebral scales 33; five enlarged preanal scales.
Variation. See Table 2. Coloration. Dorsal head, body and limbs uniform dark copper brown. Venter white, throat greyish.
Diagnosis. E. dattaroyi sp. nov. is diagnosed by the following combination of morphological characters: moderate body size (SVL 99.3-123.1 mm); tricarinate dorsal scales; scaly lower eyelid; 52-53 paravertebrals; 65-70 ventrals; 20-21 subdigital lamellae under toe IV; 36-38 midbody scale rows; temporals smooth; scales on dorsal surface of the thigh keeled; only the supraocular II in contact with the frontal and the absence of dark lateral or longitudinal bands along the body (Table 3).

Description of holotype.
Male, SVL 123.1 mm. Head moderately large (HL 25.9% of SVL), narrow (HW 61.1% of HL, HW 15.8% of SVL), indistinct from neck; snout short (ES 36.0% of HL, ES 59.0% of HW), slightly concave in lateral profile; rostral shield large, hemispherical, visible from above, posterior margin of midpoint concave; frontonasal in broad contact with rostral; frontonasal wide, lateral border touching first loreal; prefrontals in broad contact, separating frontal and frontonasal, length equals maximum frontonasal length, laterally contacting both loreal scales, posterior border contacting first supraciliary, first two supraoculars and frontal; frontal large, elongate, subtriangular, bluntly pointed posteriorly, length equal to frontoparietals and interparietal combined; frontoparietals two, in contact, larger than interparietal; parietals large and completely separated by interparietal, contacting pretemporal scales anterolaterally; single pair of nuchals, overlapping mid-dorsally behind interparietal. Nostril large and placed in centre of nasal; supranasal single; loreals two, anterior contacting nasal, supranasal, frontonasal, TAPROBANICA VOL. 09: NO. 01 prefrontal, posterior loreal, and first two supralabials; posterior longer than anterior loreal in the longitudinal axis, contacting prefrontal, first supraciliary, and third supralabial; presuboculars two; eye large (ED 25.7% of HL; slightly smaller than TYE), pupil rounded; interorbital distance broad; postoculars three, small; supraoculars four, all wide, second longest in the longitudinal axis and widest in the transverse axis, 1 st supraocular in contact with prefrontal, 2 nd in contact with prefrontal, frontal, and frontoparietal, 3 rd in contact with frontoparietal, 4 th in contact with frontoparietal and parietal; supraciliaries seven; eyelid moveable, window divided into several tall rectangular scales. Supralabials six, fifth largest, at the mid orbit position, and contacting granular scales of lower eyelid; pretemporals three; primary temporals three, secondary temporals three; infralabials six; ear opening small (approximately one quarter ED), deep, near round. Mental large; postmental single, large; two pairs of chin shields, first pair meeting in midline, first chin shield in contact with first and second infralabial scales, the second pair in contact with second and third infralabials.
Variation. See Table 2. Coloration. Dorsal head, body and limbs light uniform copper brown, limbs darker. Venter cream.
Etymology. The specific epithet is an eponym latinised as a noun in the genitive singular, honouring Dr. Aniruddha Datta-Roy for his remarkable contributions to the field of herpetology, especially on skinks (Reptilia: Scincidae) of the Indian subcontinent. Aniruddha Datta-Roy is an Indian herpetologist, and the sectional editor for skinks of the journal Zootaxa.