Rentapia flavomaculata, Chan & Abraham & Badli-Sham, 2020

Chan, Kin Onn, Abraham, Robin K. & Badli-Sham, Baizul Hafsyam, 2020, A revision of the Asian tree toad complex Rentapia hosii (Anura: Bufonidae) with the description of a new species from Peninsular Malaysia, Raffles Bulletin of Zoology 68, pp. 595-607 : 602-606

Rentapia flavomaculata , new species

Yellow-spotted Tree Toad ( Figs. 5 , 6 , 7A, B )

Nectophryne hosii Boulenger, 1892: 508 .

Pedostibes hosii Barbour, 1938: 192 .

Rentapia hosii Chan et al., 2016: 9 .

Holotype ( Fig. 5 ). ZRC 1.13264 , adult female, collected by Baizul Hafsyam at Sungai Peres (4°57′44.45″N 102°57′13.77″E; 64 m a.s.l.), Sekayu Recreational Park , Terengganu, Malaysia on 7 April 2016 (1000 hours).

Paratypes ( Fig. 6 ). UMTZC 1404 , adult female, collected by Baizul Hafsyam at Sungai Bubu (4°58′1.41″N 102°57′20.71″E, 47 m a.s.l.), adjacent to Sekayu Recreational Park , Terengganu, Malaysia on 14 February 2015 (2300 hours) ; BBM 7252, adult female, collected by J. A. LeDoux and J. R. Hendrickson at Kota Tinggi, Johor, Malaysia on 20 October 1956 .

Description of holotype. Adult female; large, habitus robust; head wider than long; top of head flat; interorbital space concave; snout angular, truncate in dorsal profile, slightly projecting beyond lower jaw in lateral profile; nostrils elongated, diagonally oriented, located laterally at tip of snout; canthus rostralis distinct, rounded; lores distinctly concave; eyes large; tympanum distinct, oval, higher than wide, tympanic rim slightly elevated; vomerine teeth absent.

Forelimbs relatively long, robust; relative length of fingers, I <II <IV <III; all fingers webbed at base; finger tips expanded into large discs not bearing circummarginal groves; subarticular tubercles indistinct, numbering one on fingers I and II, two on fingers III and IV; large palmar tubercle at base of manus; supernumerary tubercles absent.

Hind limbs robust; toe tips expanded into small discs not bearing circummarginal grooves; toe webbing formula I 0–1 II 0–2 III 0–3 IV 3–1 V; subarticular tubercles indistinct; inner metatarsal tubercle large, oval; outer metatarsal tubercle indistinct.

Skin on dorsal surfaces smooth except for a small tubercle slightly above the jaw articulation and a series of indistinct tubercles on the posterolateral aspect of head level with the scapula; no tubercles on dorsal aspect of nuchal region; cranial ridge absent; parotoid gland D-shaped, continuous with upper eyelid; scapular swelling present; venter finely granulate; tarsal ridge present ( Fig. 5 ).

In preservative, dorsal base colour dark grey, venter brownish-grey; irregularly-sized cream spots on back, side of head and snout, flanks, dorsal surface of limbs (including the manus, pes, and digits), gular, ventrolateral region, and chest; spots absent on top of head; spots fuse together to form stripes on front limbs; belly with indistinct creamy, irregular patches ( Fig. 5 ). Measurements of type material are provided in Table 2.

Diagnosis. Rentapia flavomaculata , new species, can be differentiated from other congeners by the following combination of characters: adult females large (up to 105 mm SVL); dorsum relatively smooth; no distinct tubercles on dorsal aspect of nuchal region; in life, dorsal colour light green, ventral colour greyish-green; bright yellow spots on back, side of head, flanks, dorsal surface of limbs, gular, ventrolateral region, and chest; spots absent on top of head and sparser (sometimes absent) on back. In males, dorsal colouration uniform brown to reddish-brown with no distinct markings; venter light grey with no distinct markings; gular sac blackish; nuptial pad present on dorsal surface of thumb; single, internal subgular vocal sac.

Variation. In females, the amount and density of spots vary among individuals. Some lack spots on the back, while others have spots on the belly. Some specimens have slightly more tuberculation on the lateral aspect of the scapular/nuchal region ( Fig. 6 ). Males are uniform brown to orangish with no distinct pattern, but have a higher degree of tuberculation, especially at the flanks, supraocular, sacral, and femoral region.

Comparison. Because males are morphologically similar, all comparisons are based on females. Rentapia flavomaculata , new species, can be differentiated from R. hosii s.s. by having a smoother dorsum and lacking prominent tubercles on the upper eyelids and dorsal part of the nuchal and scapular region; dorsal colouration light green (vs. dark brown to grey); dorsum and parts of venter (gular and sometimes chest and belly region) covered with bright yellow spots (vs. dorsum covered with yellowish to light brown reticulations and venter lacking distinct markings). Although our morphometric analyses revealed significant differences in a number of mensural characters ( Fig. 2 ; Table 3), those characters are non-discrete and do not adequately represent the full range of intrapopulational variation due to limited sampling size. Therefore, dorsal tuberculation and discrete differences in female colour-pattern should be used as primary diagnostic characters.

Phylogenetic definition. Rentapia flavomaculata , new species, is a crown clade name that is reciprocally monophyletic with R. hosii ( Chan et al., 2016) . Due to the unavailability of molecular data from the type material, we provisionally designate a 12S + 16S rRNA mitochondrial gene sequence from an individual from Krau Wildlife Reserve, Pahang (GenBank accession number AY325993 ) that was used in Chan et al. (2016) to serve as a representative genetic barcode.

Distribution. Rentapia flavomaculata , new species, is confirmed to occur throughout Peninsular Malaysia and southern Thailand (south of the Isthmus of Kra).

Natural history. All species in the Rentapia hosii group are typically arboreal and occur in lowland forests from 20–525 m a.s.l. ( Inger, 1966). Females are encountered much less frequently than males and are usually observed during breeding, where they descend from treetops to breed in pools of water along small to moderately sized forest streams. Females have been observed perched on branches up to 25 m above ground in the forest canopy near fastflowing rivers. Males call from elevated perches and multiple individuals can usually be heard along a single stretch of stream. In females, base colour changes relatively rapidly from light green to dark grey when handled, stressed, and preserved ( Fig. 7A, B ). Males can change from light to a darker shade of brown.

Etymology. The specific epithet is constructed from the Latin adjectives flavo (= yellow) and maculata (= spotted) in reference to the species’ diagnostic yellow spots.

Figures

Fig. 5. Dorsal (A) and ventral (B) images of the adult female holotype (ZRC 1.13264) of Rentapia flavomaculata, new species, including close-ups of the head (C, D).

Fig. 6. Dorsal and ventral images of Rentapia flavomaculata, new species, paratype UMTZC 1404 (A, B) from Sungai Bubu, Terengganu, Malaysia and BBM 7252 (C, D) from Kota Tinggi, Johor, Malaysia.

Fig. 7. Live photographs of: amplecting Rentapia flavomaculata, new species, displaying (A) normal and (B) stressed colouration; (C) female R. hosii s.s. from Sarawak (Photo by Alexander Haas); (D) female R. cf. hosii from Tawau, Sabah (Photo by Robert F. Inger; ©Field Museum of Natural History. FMNH 248199. Created by Field Museum of Natural History, Amphibian and Reptile Collection and licensed under CC-BY-SA 4.0); and (E) uncollected female from Tawau, Sabah (Photo by A. Haas).

Fig. 2. Clustering of populations in morphospace as inferred from the first three principal components of the PCA analysis (A–C; E–G) and the discriminant analysis of principal components (D, H).