A new species of the genus Hoplobatrachus Peters, 1863 (Anura, Dicroglossidae) from northwestern Thailand

Abstract

Importance of the work: Northwestern Thailand lacks any intensive survey of amphibian fauna; thus, this area is suspected to have undiscovered populations of amphibians. Therefore, conducting field surveys in such areas is essential to fill knowledge gaps about species richness in this animal group. Objectives: To describe a new species of frog genus Hoplobatrachus as new to science. Materials & Methods: A new species was described based on specimens collected from Salawin National Park, Mae Sariang District, Mae Hong Son province, northwestern Thailand. The new species was separated from its congeners inferred from molecular (16S and Cytb genes) and morphological information. Results: The new species was distinguished from its congeners based on mitochondrial DNA sequence analyses and morphological comparisons. The species was characterized by the following characters: pointed snout; large size (snout-vent length [SVL] of adult males = 94.8-102.4 mm, SVL of females = 93.2-96.3 mm); presence of mid-dorsal stripe; absence of thin stripe on inner side of tibia; presence of sexual dichromatism; yellow external vocal sac; presence of nuptial pad on base of first finger in adult males; relative length of finger II < IV < I < III, toe I < II < V < III < IV. Main finding: A new frog species was described based on specimens from Thailand.

Larval description of Salween Frog Hoplobatrachus salween (Anura: Dicroglossidae) from Northwestern Thailand

“…Forests surrounding the collection site included dry evergreen, mixed deciduous and dry dipterocarp forests. Identification followed Thongproh et al (2022) who assigned these tadpoles to H. salween based on their morphological details, similar to tadpoles of genus Hoplobatrachus and only H. salween was found in the type locality. The developmental stage was assigned according to Gosner (1960).…”

“…Two Hoplobatrachus species have been reported in Thailand (Frost, 2023): H. chinensis (as H. rugulosus) and H. salween. Hoplobatrachus chinensis distributes throughout the country (Chuaynkern and Chuauynkern, 2012) while H. salween is restricted to only its type locality (Thongproh et al, 2022).…”

It's not easy being green: Comparing typical skin colouration among amphibians with colour abnormalities associated with chromatophore deficits

“…Few amphibians have blue skin colours or patterns that are considered typical. Exceptions include some morphs of the poison dart frog ( Dendrobates tinctorius ), where both sexes are almost entirely blue (d'Orgeix et al., 2019 ), the moor frog ( Rana arvalis ), which shows dynamic sexual dichromatism as males turn blue during breeding periods (Rojas, 2017 ), and the Indian bullfrog ( Hoplobatrachus tigerinus ) in which breeding males exhibit blue vocal sacs (AmphibiaWeb, 2010 ; Thongproh et al., 2022 ). For these species, the blue colouring may be used as a visual cue for sex recognition (Sztatecsny et al., 2012 ), or as a warning sign (aposematism) to prevent predation (Caro & Ruxton, 2019 ; Rojas & Endler, 2013 ).…”