A taxonomic revision of the Ingerophrynus parvus species complex (Amphibia, Anura, Bufonidae) with the description of a new species from Thailand

Abstract

A review of the taxonomic status of the Ingerophrynus parvus species complex, based on morphological, bioacoustic, and molecular data, revealed a new species from southern Thailand, which we describe as Ingerophrynus сhrysolophus sp. nov. The new species is distinguished from its congeners by the combination of the following morphological characters: parotoid elongate, narrow, and sharply raised; warts on flanks less elevated than those of dorsum; cranial crests not thickened behind eyes; lores vertical; tympanum distinct, its diameter slightly exceeding two-thirds of eye length; tibia short; first finger longer than second; tip of third toe not reaching median subarticular tubercle of fourth toe; subarticular tubercles not enlarged; tarsal spine bases small; nuptial pads present; venter with low warts; ground color of flanks and dorsum light brown; dark brown stripes along the midline of the back; cranial ridges well-developed, bright orange.

Phylogenetic analysis of the mtDNA fragment, including the 12 S rRNA, 16 S rRNA, and ND 1 gene sequences (up to 4,479 bp), confirms the placement of the new species as a sister of Ingerophrynus parvus s. str. (p - distance 5.37 %). The genetic distinctiveness of Ingerophrynus сhrysolophus sp. nov. and I. parvus s. str. is further confirmed by not sharing haplotypes of three nuclear genes (POMC, BDNF, and RAG 1).

Bioacoustic analysis revealed stable differences between the male advertisement calls of the two species. Furthermore, ecological modeling shows that the new species is allopatric with respect to I. parvus s. str.; their ranges are likely separated by a biogeographical boundary of the Kangar-Pattani Line. The new species is currently known from low- to mid-elevations (ca. 65–1,000 m a. s. l.) in tropical forests of southern and western Thailand, southern Myanmar, and southwest Cambodia.

We suggest the new species be considered Least Concern (LC) according to the IUCN Red List criteria. Our study further underscores the urgent need for intensified integrative taxonomic research of the genus Ingerophrynus to clarify the taxonomy of wide-ranging species complexes and to elaborate effective conservation measures.