Pulchrana sundabarat, Chan & Abraham & Grismer & Brown, 2020

Chan, Kin Onn, Abraham, Robin K., Grismer, L. Lee & Brown, Rafe M., 2020, A systematic review of the Pulchrana picturata complex, with the description of a new species from Peninsular Malaysia, Sumatra, and southern Thailand, Raffles Bulletin of Zoology 68, pp. 880-890 : 882-887

Pulchrana sundabarat , new species

Western Sunda Spotted Stream Frog ( Fig. 5 )

Holotype. ZRC 1.10388 , adult male, collected by Leong Tzi Ming and Tan Heok Hui from Bunker Trail, Panti Forest Reserve , Johor, Malaysia, on 17 January 2003.

Paratypes. ZRC 1.10226 – 27 (adult males), same collection information as holotype ; ZRC 1.9752 – 53 , 1.10771 (adult males) collected by LZM from the base of Gunung Berlumut , Johor, Malaysia on 22 May 2002 ; ZRC 1.10538 – 39 (adult males) and ZRC 1.10540 (adult female), collected by Lim C. C. from Lakum Forest Reserve , Pahang, Malaysia on 18 May 2003 ; ZRC 1.10789 , adult female, collected by Lim Boo Liat from Ulu Muda Forest Reserve , Kedah, Malaysia on 8 April 2003 .

Other paratypes. KU 335661–70 (adult males), collected 2002–2003 by J. Sukumaran from Sungai Tupah, Gunung Jerai, Kedah, Malaysia (5.7489 E, 100.4428 N; 525–550 m elevation) .

Description of holotype. Adult male; medium-sized (SVL 37.4 mm); head longer than wide; snout pointed in dorsal profile, rounded in lateral profile, projecting beyond lower jaw; nostrils located laterally, close to tip of snout; lores slanting, slightly concave; canthus rostralis absent; tympanum circular, relatively large, smaller than eye diameter; vomerine teeth indistinct; left dentigerous process of vomer oval and protruding, right low and ridgelike; shape of tongue spatulated, tapering to a point posteriorly; choanae oval.

Forelimbs slender; length of fingers II <I = IV <III; no webbing on fingers; fingertips slightly expanded, flat, bearing horizontal supradigital notch above the ultimatepenultimate phalangeal articulation; circummarginal groove present; subarticular tubercles distinct, raised, numbering one under fingers I and II, two beneath fingers III and IV; one supernumerary tubercle present at base of each digit; inner (thenar) metacarpal tubercle large, elongated; outer metacarpal tubercle irregularly shaped, smaller than inner, in contact with smaller palmar tubercle ( Fig. 5C ).

Hindlimbs long, slender; toetips expanded, flat, slightly pointed, horizontal supradigital notch above the ultimatepenultimate phalangeal articulation indistinct; toe webbing formula: I 2 – 3 II 1 – 3 III 1 – 3.5 IV 3.5 – 1 V; subarticular tubercles distinct, raised, numbering one on toes I and II, two on toes III and V, three on toe IV; supernumerary tubercles present, randomly scattered across digits and webbing; inner metatarsal tubercle large, elongated; outer metatarsal tubercle small, rounded ( Fig. 5D ).

Skin on dorsum smooth, indistinctly glandular; glandules on flanks and cloacal region more prominent; supratympanic and dorsolateral folds absent; rictal tubercle present but indistinct; brachial (humeral) gland small and indistinct on the left, larger on the right; tarsal fold absent; small tubercles irregularly scattered on dorsal and ventral side of foot including web; nuptial pad distinct, consisting of two lobes that are connected on the left thumb but separated on the right, located venteromedially on the first metacarpal and dorsomedially on the proximal phalanx of the first finger; paired subgular vocal sac present; vocal sac aperture oval, located on both sides of the buccal floor.

In preservative, dorsal base colour dark brown; continuous white stripe encircles tip of snout, canthus, and outer margins of palpebrae; semi-continuous white dorsolateral stripe from back of eyes to groin; top of snout without markings; top and side of head, dorsum, flanks, and posterodorsal side of thighs scattered with round spots; spots coalesce to form irregular bars on dorsal side of front and hindlimbs; venter cream with dense dark brown stippling that is sparser on the belly, underside of thighs, brachium, and hands; stippling most dense on underside of feet; webbing dark brown; small, sparsely spaced white spots on throat and chest; spots become more sparse and indistinct on belly; tubercles on underside of hands and feet opague; nuptial pad cream. Holotype measurements (in mm): SVL = 37.40, HL = 14.78, HW = 12.19, SNL = 5.90, IOD = 3.40, TYD = 3.05, FAL = 9.40, FML = 19.14, TBL = 20.25.

Diagnosis. Pulchrana sundabarat , new species, can be differentiated from all other congeners by the following combination of characters: adult males relatively small (SVL <40 mm); dorsum smooth with low, indistinct glandules; in life, base colour of dorsal surfaces brown to black, welldefined orange to red dorsolateral stripe (continuous or partially broken), dorsum and flanks covered with orange spots, irregularly shaped orange bars on front and hindlimbs, dorsal pigmentation fades towards flanks and venter, ventral surfaces with or without spots; vomerine teeth and paired subgular vocal sac present.

Comparison. Pulchrana sundabarat , new species, differs from the name-bearing P. picturata lineage from Borneo (Ranau [including Mount Kinabalu], Tawau, and Lahad Datu districts) by having a more conspicuous and defined dorsolateral stripe (vs. poorly defined, interrupted, or dorsolateral stripes indistinct), bright orange to red dorsolateral stripe and dorsal spots (vs. brown to pale orange spots), and smaller body size in males ( Figs. 2 , 3 ). Certain genetically admixed populations of P. picturata from central and western Borneo may possess colour pattern characteristics that are similar to P. sundabarat which precludes their distinction using colour pattern (see Discussion). Pulchrana sundabarat , new species, differs from P. signata by having more variable, jagged, interrupted, and/or less continuous dorsolateral stripes (vs. smooth and continuous) and brighter. Compared to P. banjarana and P. fantastica , P. sundabarat has smooth skin on the dorsum and flanks (vs. bearing apical glandules and peripheral subglandules. Pulchrana sundabarat , new species, differs from P. centropeninsularis , P. fantastica , and P. siberu by having more jagged and interrupted dorsolateral stripes (vs. smooth and continuous) and denser dorsal spots (vs. sparse spots or immaculate dorsum).

Variation. The paratypes vary in the size and density of dorsal and ventral spotting, continuity of the dorsolateral stripe, and tubercles on the foot webbing. Some specimens lack vomerine teeth and a dentigerous process. When present, the state of the dentigerous process varies from being protruding and oval-shaped, to low and ridge-like. As in the holotype, the same individual may exhibit a different state on each side of the vomer. The size of the humeral gland and degree of separation between nuptial pad lobes also varies within (as in the holotype) and between individuals.

Distribution. Pulchrana sundabarat , new species, is known from southern Thailand (south of the Isthmus of Kra), Peninsular Malaysia, and Sumatra.

Natural History. Pulchrana sundabarat , new species, is associated with small to moderately sized forest streams/ rivers in lowland and hill dipterocarp forests up to ~ 850 m a.s.l. ( Berry, 1975; Chan et al., 2009, 2010, 2019; Nurulhuda et al., 2014; Sumarli et al., 2015) [reported therein as Rana / Hylarana / Pulchrana picturata or signata ]. Males begin calling singly at dusk from river banks, rocks, low vegetation, or hidden among thick debris within, along, or not far from the water’s edge.

Etymology. The specific epithet is constructed from the words Sunda , in reference to the region of Sundaland where the new species resides; and the Malay word barat (= west), in reference to the distribution range of the new species that is restricted to western Sundaland.

Figures

Fig. 5. Dorsal (A), ventral (B), left hand (C), and left foot (D) of Pulchrana sundabarat, new species, holotype.

Fig. 2. Boxplots and p-values of the t-test comparing adjusted measurements of various populations across Borneo and Peninsular Malaysia.

Fig. 3. PCA (A, C) and DAPC plots (B, D) of males and females. Populations from Peninsular Malaysia are represented by triangles, whereas Bornean populations are represented by circles. PC = principal component, followed by the proportion of variance in parentheses; LD = linear discriminant.