Larutia penangensis, Grismer, Lee, Huat, Evan Quah Seng, Siler, Cameron D., Wood, Perry L., Grismer, Jesse L., Sah, Shahrul Anuar Mohd & Ahmad, Norhayati, 2011
|
publication ID |
https://doi.org/ 10.5281/zenodo.202133 |
|
DOI |
https://doi.org/10.5281/zenodo.5619612 |
|
persistent identifier |
https://treatment.plazi.org/id/9F5E87B2-FFEF-FFC9-FF73-9ED0FC1CF9F6 |
|
treatment provided by |
Plazi |
|
scientific name |
Larutia penangensis |
| status |
sp. nov. |
Larutia penangensis sp. nov.
Figures 3 View FIGURE 3 , 4 View FIGURE 4
Holotype. Juvenile of unknown sex ( ZRC 2.6918) collected by Evan Quah, on 13 June 2010 at Penang Hill, Pulau Pinang, Penang (N.05.43825º, E100.28200º, ± 5m; 308m asl.), Peninsular Malaysia.
Diagnosis. Body elongate, snake-like; dorsal scales smooth; limbs absent; lower eyelid bearing large, transparent scales, central scale largest; four supraoculars; nasals separated; frontoparietals paired; prefrontals small, widely separated; supranasals absent; postnasal scale absent; last supralabial horizontally divided (or two post supralabials); large, posterior chinshields not separated from the infralabials by smaller scales; 120 paravertebral scale rows; 132 ventral scale rows; 18 longitudinal scale rows around midbody; caudal and body scales undifferentiated; body unicolor dark brown; no yellow nuchal bands or pale, yellow spot on frontoparietals, supraoculars, or rostrum. These characters are summarized across all species in Table 4.
Description of holotype. Head small, scarcely distinct from neck, rounded, triangular in dorsal profile; head scales smooth; rostral wider than long, in broad contact with frontonasal; frontonasal wider than long; prefrontals small, not contacting on midline; frontal wide, diamond-shaped, in contact with first supraocular; three supraoculars; frontoparietals contacting all supraoculars anteriorly and parietals and interparietal posteriorly; interparietal diamond-shaped, large, slightly projecting posteriorly, no parietal eyespot; parietals large, in medial contact posterior to interparietal, contacting posterior margin of third supraocular anteriorly; enlarged, differentiated nuchals absent; nasals moderately large, separated, trapezoidal, contacting rostral anteriorly, frontonasal dorsally, first loreal posteriorly, first supralabial ventrally; nostril in central portion of nasal scale; supranasals absent; anterior loreal nearly same size as posterior loreal; two preoculars in contact with second loreal; dorsal preocular much smaller than ventral preocular; four supraciliaries, fourth supraciliary enlarged; two pretemporals; five suboculars; single presubocular; four supralabials; first supralabial large and triangular; two postsupralabials; two twmporals; two primary temporals; two secondary temporals, uppermost contacting parietal; granular scales at anterior corners of eye; lower eyelid bearing large, transparent scales, central scale largest; mental wider than long; single large, rectangular postmental contacting first infralabials; two enlarged pairs of chinshields following postmental, anterior pair contacting medially, posterior pair separated posteriorly by two gular scales; all chinshields contacting infralabials; three similarly sized infralabials; no external ear opening.
Body elongate, snake-like; body scales smooth, cycloid, imbricate; flank, ventral, and dorsal scales equal in size; 18 longitudinal scale rows around midbody; 120 paravertebral scale rows; 132 ventral scale rows; two enlarged, medial, preanal scales; limbs absent; tail robust, cylindrical; caudal scales equal in size, indiscernable from body scales. Measurements are SVL 51.4 mm; TL (broken) 17.6 mm.
Coloration. Dorsal surface of head, body, and tail uniform dark brown; nuchal bands absent; no stripping on body; ventral surface slightly lighter than dorsal surface ( Fig. 4 View FIGURE 4 ), rostral, first supralabial, nasal mental, postmental, and first infralabilal scales opaque.
Distribution. Larutia penangensis sp. nov. is known only from the lower elevations of Penang Hill, Pulau Pinang, Peninsular Malaysia ( Fig. 1 View FIGURE 1 ). It is expected to occur much more widely across the island in appropriate habitats.
Natural history. The specimen was found crawling across an open dirt path surrounded by lowland dipterocarp forest ( Fig. 4 View FIGURE 4 ). All other species of Larutia are fossorial to semi-fossorial and found in loose soils beneath surface objects. This species is expected to be no different.
Etymology. The specific epithet penangensis is in reference to the type locality, Penang Island. The suffix ensis is a derivation meaning “from” or “inhabiting.” It renders the specific epithet an adjective that must be in grammatical accord with the gender of Larutia .
Comparisons. Larutia penangensis sp. nov. is clearly separated from all other species of Larutia by its complete lack of limbs ( Fig. 4 View FIGURE 4 ); having fewer supralabials (4 vs. 5–7; Fig. 3 View FIGURE 3 ); having proportionately larger body scales (18 vs. 20–30 scales around midbody); and its unique, unicolor, color pattern (vs. nuchal bands and/or striping on the body; Figs. 4,6). The new species is further separated from all other species except some specimens of L. miodactyla (see J. Grismer et al. 2003), in having fewer infralabials (3 vs. 4 or 5; Fig. 3 View FIGURE 3 ); from all other species except L. larutensis and L. trifasciata , in that the second pair of chin shields is separated by two gular scales (vs. separated by one scale; Fig. 3 View FIGURE 3 ); from L. larutensis and L. miodactyla , in that the first two pairs of chin shields contact two infralabials (vs. contacting only one infralabial; Fig. 3 View FIGURE 3 ); from all other species except L. sumatrensis (Bleeker) in the absence of linearly arranged yellow spots on the body (Figs. 4,6); from L. larutensis (in juveniles only), L. seribuatensis , and L. trifasciata , in the absence of nuchal bands (Figs. 4,6); from L. serbuatensis and some L. trifasciata in the absence of yellow spots on the head (Figs. 4,6); and from all species except L. larutensis , L. sumatrensis , and L. trifasciata in having opaque scales on the snout (vs. the absence of such scales; Figs. 4,7). These character states are summarized across all species in Table 3 View TABLE 3 .
Given the secretive nature of many skinks in general and fossorial skinks in particular, it is not too surprising to find a new species of Larutia in Peninsular Malaysia. Not only does L. penangensis sp. nov. represent a new record of yet another poorly known skink from Pulau Pinang, it is Peninsular Malaysia’s first completely legless lizard ( Grismer 2008). J. Grismer et al. (2003) presented a morphological phylogeny ( Fig. 5 View FIGURE 5 ) of Larutia wherein they hypothesized that the light yellow nuchal bands and opaque scales on the rostrum were derived character states grouping L. larutensis , L. trifasciata , and L. seribuatensis to the exclusion of L. miodactyla , L. sumatrensis , and L. puehensis Grismer, Leong & Norsham. They further hypothesized that L. trifasciata and L. seribuatensis were sister species based on them having three nuchal bands and yellow spots on the head ( Fig. 6 View FIGURE 6 ). J. Grismer et al. (2003) also hypothesized that extreme limb reduction (i.e. complete loss of digits and movable wrist and ankle joints) in L. miodactyla , L. puehensis , and L. sumatrensis was evidence supporting their monophyly. The results of the molecular phylogenetic analyses ( Fig. 2 View FIGURE 2 ) do not completely agree with some of the relationships proposed by J. Grismer et al. (2003). The molecular analyses recover L. larutensis and L. trifasciata as sister species, and places L. miodactyla as the sister lineage to them to the exclusion of L. seribuatensis . Unfortunately tissues of L. sumatrensis and L. puehensis were not available and thus these species can not be evaluated. The molecular analyses also recover L. penangensis sp. nov. basal to all other species.
Our phylogenetic analyses suggest that extreme limb reduction may be occurring independently within different lineages of Larutia ( Fig. 2 View FIGURE 2 ). Unlike the morphological phylogeny that grouped L. miodactyla , L. puehensis , and L. sumatrensis on the basis of extreme limb reduction ( Fig. 5 View FIGURE 5 ), the molecular analysis nests L. miodactyla within a clade containing L. larutensis , L. trifasciata , and L. seribuatensis and does not place it as being closely related to the limbless L. penangensis sp. nov. The degree of limb reduction in L. miodactyla is so variable (individuals having 0–2 digits) that J. Grismer et al. (2003) and Grismer (2011) suggest this species is likely to be a species complex. The specimen used in the molecular analysis had two digits on each limb which is the condition seen in L. larutensis , L. trifasciata , and L. seribuatensis with whom it was shown to be related ( Fig. 2 View FIGURE 2 ). The systematics and relationships of L. miodactyla that lack digits remain to be investigated.
The molecular phylogeny also does not support the hypothesis that the putatively derived (J. Grismer et al. 2003) acquisition of opaque scales on the rostrum ( Fig. 7 View FIGURE 7 ) has utility in delimiting monophyletic subgroups within Larutia being that opaque scales occur in the most basal species L. penangensis sp. nov. and L. seribuatensis as well as the most derived species, L. larutensis and L. trifasciata but are absent in L. miodactyla which is nested between these lineages ( Fig. 2 View FIGURE 2 ). This would suggest that L. miodactyla may have the autapomorphic state of losing opaque scales and that their presence in the other species is plesiomorphic.
J. Grismer et al. (2003) also hypothesized that L. trifasciata and L. seribuatensis were sister species based on the presence of three nuchal bands ( Fig. 5 View FIGURE 5 ) and head spotting whereas the molecular analyses ( Fig. 2 View FIGURE 2 ) place L. larutensis as the sister species to L. trifasciata and L. seribuatensis , all basal to a clade containing L. larutensis , L. trifasciata , and L. miodactyla . The examination of additional specimens of each species indicates that the number of nuchal bands and degree of head spotting can be quite variable, and that these character states may be unreliable as indicators of relationship. What the molecular phylogeny also suggests is that nuchal banding occurred in the ancestor of L. seribuatensis , L. miodactyla , L. larutensis and L. trifasciata and was independently lost in L. miodactyla or that it evolved independently in L. seribuatensis and the ancestor of L. larutensis and L. trifasciata and was never present in the L. miodactyla lineage. We prefer the former hypothesis on the basis that in L. larutensis , nuchal banding only occurs in juveniles and is lost in adulthood, indicating that this is a character that is subject to loss. There are no independent data suggesting this character can evolve independently. With the acquisition of tissues from L. puehensis , L. sumatrensis and especially L. miodactyla , we will be able to more adequately discuss aspects the evolution of limb loss within and among the various lineages of Larutia as well as the historical biogeography of this group within the context of that of other Sundaland taxa.
TABLE 3. Diagnostic scale counts and color pattern characteristics of the species of the genus Larutia. + = character state present; 0 = character state absent.
| larutensis | miodactyla | puehensis | seribuaten- sis | sumatrensis | trifasciata | penangen- sis sp. nov. | |
|---|---|---|---|---|---|---|---|
| Suproculars | 4 | 4 | 4 | 4 | 3 or 4 | 4 | 3 |
| Supralabials | 6 or 7 | 5 | 5 | 5 or 6 | 5 or 6 | 6 | 4 |
| Infralabials | 4 | 3 or 4 | 5 | 5 | 4 | 5 | 3 |
| Midbody scales | 25 or 26 | 20–22 | 23 | 24 or 25 | 22 | 29 or 30 | 18 |
| ZRC |
Zoological Reference Collection, National University of Singapore |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.