Uperodon obscurus

Garg, Sonali, Senevirathne, Gayani, Wijayathilaka, Nayana, Phuge, Samadhan, Deuti, Kaushik, Manamendra-Arachchi, Kelum, Meegaskumbura, Madhava & Biju, Sd, 2018, An integrative taxonomic review of the South Asian microhylid genus Uperodon, Zootaxa 4384 (1), pp. 1-88 : 33-35

Uperodon obscurus ( Günther, 1864 “1863”)

Sri Lankan Globular Frog

( Figs. 1 , 2A, 2D , 3H , 5G , 9H–K , 10A–D ; Tables 1–4)

Original name and description. Callula obscura Günther, 1864 “1863”. The Reptiles of British India. London: Ray Society by R. Hardwicke: 438. Holotype. By monotypy, NHM 58.11.28.42 (ex. BMNH 1947.2.11.20), an adult female, SVL 32.2 mm. Type locality. “Ceylon” (Sri Lanka). Current status of specific name. Valid name, as Uperodon obscurus ( Günther, 1864 “1863”).

Comparison. For comparison of Uperodon obscurus with U. globulosus , U. systoma , U. taprobanicus , U. anamalaiensis , U. montanus , U. mormorata and U. nagaoi see ‘comparison’ section of those species. Uperodon obscurus is closely related to U. palmatus , both genetically and morphologically. However, it differs from the latter by its snout length longer than horizontal diameter of eye, male: EL/SL ratio 0.6–0.9, N = 17; female: EL/SL ratio 0.6–0.9, N = 5 (vs. equal, male: EL/SL ratio 1.0, N = 4, female: EL/SL ratio 1.0, N = 2) ( Table 4 ), snout nearly acute in lateral view (vs. vertical), relatively less webbing, I1–2II1 1/2–3– III2–3 + IV3 +– 2V (vs. more, I1–2II1–3 – III1– 3IV2 2/3– 1V) ( Fig. 10D ), and dorsal skin shagreened to sparsely granular (vs. distinctly granular with warty projections). It differs from U. triangularis by its fourth toe webbing extending close up to second subarticular tubercle: I1–2II1 1/2–3– III2–3 + IV3 +– 2V (vs. toes completely free of webbing). Uperodon obscurus cannot be confused with three other species, U. nagaoi , U. rohani sp. nov. and U. variegatus , due to its relatively extensive foot webbing, I1–2II1 1/2–3– III2–3 + IV3 +– 2V (vs. rudimentary or absent), and ventral skin being light to dark brown with distinct blotches or spots (vs. brown without prominent mottling in U. nagaoi , and white without any blotches or spots in U. rohani sp. nov. and U. variegatus ).

Genetic divergence. For 16S mitochondrial gene sequences, intraspecific variation was not observed between the sampled populations of Uperodon obscurus (N = 3). Genetically, U. obscurus is closely related to U. palmatus , from which it was found to differ by an average uncorrected genetic distance of 2.4% (range 2.4–2.6%, N = 12). For interspecific genetic distances with all other members of the genus, see Table 3.

Remarks. The original description by Günther (1864 “1863”) was very brief. Subsequently Parker (1934) provided a general description based on the types, without a comparison with other closely related members. Hence, a detailed description and comparison of this species with all its congeners is provided here.

Redescription of holotype (measurements in mm) ( Figs. 3H , 10A–D ). Small-sized (SVL 32.2), slender adult female; head small (HW 9.3, HL 8.8, IFE 4.9, IBE 8.6), less than one-third (27.3%) of body length, wider than long (HW/HL ratio 1.1); snout truncate in dorsal and ventral view, nearly acute in lateral view, its length (SL 4.2) longer than horizontal diameter of eye (EL 3.9); loreal region acute with rounded canthus rostralis; interorbital space more than twice as wide (IUE 3.3) as upper eyelid width (UEW 1.4), and wider than internarial distance (IN 2.7); nostril much closer to tip of snout (NS 0.7) than to eye (EN 2.4); supratympanic fold distinct, extending from posterior corner of upper eyelid to insertion of forelimb at axilla; eye diameter (EL 3.9); vomerine odontophores present on the palate, without teeth; weakly-developed neopalatinal ridges on posterior side of each choana, appear fused with the vomerine odontophores; tongue moderately large, oval, slightly emarginate. Forelimbs (FAL 8.8) shorter than hand length (HAL 9.5); finger length formula I<II<IV<III, tips of all fingers with oval discs, moderately wide compared to finger width (FD I 0.8, FW I 0.4; FD II 1.1, FW II 0.5; FD III 1.0, FW III 0.5; FD IV 0.9, FW IV 0.4); subarticular tubercles prominent, oval, all present; two well-developed palmar tubercles, oval. Hind limbs relatively long and thin, thigh length (TL 13.5) longer than shank (SHL 13.3), and shorter than foot (FOL 14.9); relative digit lengths I<II<V<III<IV, tips of all toes with small truncate to rounded discs, rather wide compared to toe width (TD I 0.7, TW I 0.5; TD II 0.8, TW II 0.5; TD III 0.7, TW III 0.5; TD IV 0.7, TW IV 0.5; TD V 0.5, TW V 0.5); foot webbing present, I1– 2II1 1/2–3– III2–3 + IV3 +– 2V; well-developed dermal fringes present on all toes; subarticular tubercles prominent, oval; two smooth metatarsal tubercles, oval, outer one slightly larger than the inner.

Skin of snout, between eyes, sides of head, and anterior part of dorsum, shagreened to granular; posterior parts of back, and upper and lower parts of flank, granular; dorsal surfaces of forelimb, thigh, tibia and tarsus, shagreened to sparsely granular; throat, chest and abdomen, shagreened; ventral surfaces of forelimb and hind limb, shagreened ( Figs. 3H , 10A ).

Colouration. In preservation: Dorsum greyish-brown with dark brown median patch; flanks light greyishbrown; dorsal surfaces of forelimbs, thigh, shank and foot, light brown; chest and belly, dark grey with faint grey spots; ventral surfaces of thigh, tibia and foot, greyish-brown with faint grey spots ( Fig. 3H ). Colour in life (DZ 1366): Dorsum light orangish-brown with irregular blackish-brown spots, prominent blackish-brown band extending from behind the eye up to vent where it becomes wider; lower parts of flank brown with light bluish-grey spots; dorsal surfaces of forelimb, thigh, shank and foot, orangish-brown with dark brown cross bands; throat light brown; chest greyish-brown; belly and ventral surfaces of forelimb, thigh, tibia and foot, brown with light bluishgrey spots ( Figs. 9H–I ).

Variations. Morphometric measurements of 17 males and five females, including the holotype, are given in Table 4 . DZ 1408: dorsal skin bright orange and more prominently granular compared to DZ 1366; DZ 1369: dorsum orangish-grey with a dark grey median band, and ventral surfaces coffee brown with light bluish-grey spots, except on the throat.

Secondary sexual characters. Male (DZ 1366): vocal sac externally visible on the lower jaw; female (NHM 1982.1290): ova white, pigmented on pole (diameter 0.7–1.0 mm, N = 20).

Geographical distribution and habitat. Uperodon obscurus is endemic to Sri Lanka and known to occur in Central, North Western, Sabaragamuwa, Southern and Uva Provinces ( Fig. 2D ; Tables 1, S1). In the present study, we confirmed the occurrence of this species in Kandy district (Kandy, Peradeniya, Panwila, Pussellawa and Udawatta Kele), Kegalle district (Babilapitiya estate), Kurunegala district (Kurunegala), Matale district (Gammaduwa), Nuwara Eliya district (Bogawantalawa and Laxapana) and Ratnapura district (Sinharaja and Morningside), from elevations of 100 m up to 1220 m asl. It was collected either from tree hollows in disturbed forests adjacent to urban areas (Peradeniya and Panwila), or temporary ponds surrounded with vegetation (Laxapana).

Figures

FIGURE 1. Maximum Likelihood phylogram based on 511 bp of mitochondrial 16S rRNA gene sequences from 73 individuals representing all known members of the genus Uperodon. Three samples representing taxon under synonymy are shown inquotationmarks.Outgroup not shown for graphical purposes.BayesianPosterior Probabilities and bootstrap values of>50 are shown above and below the branches, respectively. Values towards the species labels represent mean uncorrected genetic distances between the species with range values in parentheses.

FIGURE 2. A. Geographic distribution of the genus Uperodon in Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka; B. Distributionof Uperodon globulosus, U. systomaand U.taprobanicus; C. Distribution of four endemic Uperodon species of the Western Ghats (excluding the widely distributed Indian member U. variegatus, shown in Fig.12A); D. Distribution of four endemic Uperdodon species of Sri Lanka. Details of localities reported in the present study are provided in Table 1. Records from literature are listed in supplementary Table S1 and indicated here based onapproximate coordinates.

FIGURE 3. Preserved type specimens of Uperodon species in dorsal and ventral view. A. Uperodon systoma, Syntype, ZMB 3551 (female); B. Uperodon globulosus, Syntype, NHM 62.12.29.4 (ex. BMNH 1947.2.10.97) (female); C. Kaloula pulchra taprobanica, Holotype, NHM 1905.3.25.138 (ex. BMNH 1947.2.10.62) (female); D. Ramanella anamalaiensis, Neotype, ZSI/ WGRC/V/A/956 (male); E. Hylaedactylus montanus, Holotype, NHM 72.4.17.212 (ex. BMNH 1947.2.11.19) (female); F. Ramanella mormorata, Neotype, ZSI/WGRC/V/A/958, (female); G. Ramanella nagaoi, Holotype, WHT 2826 (male); H. Callula obscura, Holotype, NHM 58.11.28.42 (ex. BMNH 1947.2.11.20) (female); I. Ramanella palmata, Holotype, NHM 90.11.8.62 (ex.BMNH 1947.2.11.21); J. Callula triangularis, Lectotype, NHM 74.4.29.897 (ex.BMNH 1947.2.11.15) (male); K.Hylaedactylus carnaticus, Lectotype, ZSI 2761(female); L. Uperodonrohani sp. nov., Holotype, DZ1449 (male).(Images: SD Biju and Sonali Garg).

FIGURE 5. Ventral surface of the palate in Uperodon species showing vomerine odontophores separated or fused with dermal projectionsand/or neopalatinalridgeson posterior sides ofthe choanae (indicated witharrows).A. Uperodon systoma, SDBDU 2005.2787 (female) and SDBDU 2005.2806 (male); B. Uperodon globulosus, SDBDU 2014.2673 (female) and SDBDU 2005.4762 (female); C. Uperodon taprobanicus, SDBDU 2007.6364 (female) and SDBDU 2005.4732A (male); D. Uperodon anamalaiensis, SDBDU 2013.2302 (female) and SDBDU 2002.3050 (male); E. Uperodon montanus, SDBDU 2002.24B (female) and SDBDU 2003.40115 (male); F. Uperodon mormorata, SDBDU 2011.507 (male) and SDBDU 2012.43 (male); G. Uperodon obscurus, DZ 1366 (male); H. Uperodon palmatus, DZ 1331 (male); I. Uperodon triangularis, SDBDU 2007.6400 (female) and ZSI/WGRC/V/A/959 (male); J. Uperodon variegatus, SDBDU 2005.4726 (female) and SDBDU 2005.4727 (male); K.Uperodon rohani sp. nov., DZ 1521 (male).(Images:SD Biju).

FIGURE 10. Head, hand, foot and foot webbing in Uperodon obscurus, U. palmatus, U. triangularis and U.variegatus. A–D. Holotype ofUperodon obscurus(NHM58.11.28.42 ex.BMNH 1947.2.11.20, female):A. Lateralview of head; B. ventral view of hand; C. ventral view of foot; D. schematic illustration of foot webbing; E–H. Holotype of Uperodon palmatus (NHM 90.11.8.62 ex. BMNH 1947.2.11.21, female): E. Lateral view of head; F. ventral view of hand; G. ventral view of foot; H. schematic illustration of foot webbing; I–L. Lectotype of Uperodon triangularis (NHM 74.4.29.897 ex. BMNH 1947.2.11.15, male): I. Lateral view of head; J. ventral view of hand; K. ventral view of foot; L. schematic illustration of foot webbing; M. Lectotype of Uperodon variegatus (ZSI 2761, female), lateral view of head; N–P. Referred specimen of Uperodon variegatus (ZSI 4726, female): N. ventral view of hand; O. ventral view of foot; P. schematic illustration of foot webbing. (Illustrations: SD Biju).

FIGURE9. Uperodon mormorata, U. nagaoi and U.obscurus inlife.A–C. Uperodonmormorata (SDBDU 2016.3404,male): A. Dorsolateral view; B. dorsal view; C. ventral view; D. Uperodon mormorata (SDBDU 2011.835, male), dorsolateral view; E–G. Uperodon nagaoi (DZ 1367, male): E. Dorsolateral view; F. dorsal view; G. frontal view; H–K. Uperodon obscurus: H. Dorsolateral view (DZ 1366, male); I. Dorsal view (DZ 1366, male); J. dorsolateral view (DZ 1408, male); K. dorsolateral view (DZ 1369, male); L. ventral view (DZ 1369, male). (Images: SD Biju and E–G Madhava Meegaskumbura).