Rentapia hosii ( Boulenger, 1892 )

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 : 600-602

Rentapia hosii ( Boulenger, 1892)

Brown Tree Toad ( Figs. 4 , 7C )

Nectophryne hosii Boulenger, 1892: 508 .

Pedostibes hosii Barbour, 1938: 192 .

Material examined. FMNH 156344–45 , 156354 , 156394 , adult females, collected by W. Hosmer at Tubau camp on Sungai Pesu (3°06′N 113°38′E), Bintulu , Sarawak, Malaysia on 27 May 1964, 15 April 1964, 7 June 1964, and 7 August 1964 respectively ; FMNH 119897 , 134217 , adult females, collected by Lord Medway and Tom Harrisson respectively, at Sungai Sekaloh, Niah, Sarawak, Malaysia on 31 August 1959 and 6 September 1960, respectively ; FMNH 134219 , adult female, collected by Tom Harrisson at Pengkalan Lobang, Niah, Sarawak, Malaysia in 1960 .

Description of female. Body 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 slightly 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; basal subarticular tubercles distinct, others 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 2.5–3 IV 2.5–3 1 V; subarticular tubercles distinct, round; inner metatarsal tubercle large, oval; outer metatarsal tubercle distinct, half the size of inner.

Skin on back, flanks and upper surfaces of limbs covered with indistinct, low tubercles; tubercles on upper eyelids, and lateral and dorsal aspects of nuchal and scapular region more pronounced; parotoid gland D-shaped in dorsal profile, continuous with upper eyelid; scapular swelling indistinct; venter finely granulate; tarsal ridge present.

In preservative, dorsal base colour dark grey, venter brownish-grey; entire dorsal surface covered with yellowish reticulations that are relatively evenly distributed; entire ventral surface lacks distinct markings. Measurements of specimens are provided in Table 2.

Diagnosis. Rentapia hosii can be differentiated from other congeners by the following combination of characters: adult females large (up to 105 mm SVL); skin on back, flanks and upper surfaces of limbs covered with indistinct, low tubercles; tubercles on upper eyelids, and lateral and dorsal aspects of nuchal and scapular region more pronounced; in life and preservative, dorsal base colour dark grey, venter brownish-grey; entire dorsal surface covered with yellowish reticulations that are relatively evenly distributed; entire ventral surface lacks distinct markings. 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. The amount and density of dorsal reticulations vary among individuals ( Fig. 4 ). Base dorsal colouration also varies from brownish to dark grey. However, females of this species group are known to exhibit drastic changes in dorsal colouration in response to stress, such as during handling and euthanisation (pers. obs.). A series of female specimens from Kapit district in Sarawak had light brown dorsal colouration with no distinct markings, which are similar to males. However, these individuals were confirmed to be females by their large size (90–100 mm SVL; Table 2) and examination of internal reproductive organs. At present, we are unable to determine if the preserved colour-pattern of these individuals is reflective of that in life, or whether it is a result of the preservation process. Because the Kapit population cannot be morphometrically differentiated from other populations in Sarawak, we provisionally consider it as Rentapia hosii s.s., pending the acquisition of fresh material.

Distribution. Rentapia hosii occurs in the state of Sarawak, Malaysia, the country of Brunei Darussalam, as well as in Kalimantan, and provisionally also in Sumatra, Indonesia (see Discussion).

Figures

Fig. 4. Dorsal and ventral representations of preserved adult female Rentapia hosii from Sarawak. A–C, FMNH 156354, 156344–45 respectively, from Bintulu; D, FMNH 119897 from Niah.

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).