Description of a new subterranean breeding brown frog (Ranidae: Rana) from Japan

Abstract

Taxonomic relationship of two forms of Rana tagoi, a brown frog endemic to Japan, is assessed. Based on morphological and bioacoustical comparisons, as well as molecular analysis, we consider the large-form-lineage as true R. tagoi, and describe the small-form-lineage as Rana kyoto sp. nov. The new species and R. tagoi occur sympatrically in many places around the Kinki District, although the former can be distinguished from the latter by smaller body size, more developed dark marking on ventral side of legs, less developed toe webs, and advertisement call with fewer notes and lower dominant frequency. Rana kyoto sp. nov. sympatric with R. tagoi show smaller body size than the allopatric ones, whereas R. tagoi sympatric with the new species show larger body size than the allopatric ones, suggesting that the character displacement of body size occurs between the two species around the type locality of Rana kyoto sp. nov.

A New Brown Frog from the Goto Islands, Japan with Taxonomic Revision on the Subspecific Relationships of Rana tagoi (Amphibia: Anura: Ranidae)

“…In addition, toe-webbing was evaluated following Savage & Heyer (1967; 1997). We also evaluated the pigmentation of ventral side of thigh and tibia in three categories: (1) absent or very little pigmentation; (2) pigmentation forming fine dots; and (3) pigmentation forming blackish blotches or mottling, following Eto et al (2022).…”

“…Following Eto et al (2022), we categorized each call into several call types. First, we categorized each call into four groups following NN: (I) single-note call, (II) two-note call, (III) three-to-five-note call, and (IV) call with six or more notes.…”

“…nov. is distinct by its smaller body size of adult males (ca. 36–40 mm) compared to members of the R. tagoi species complex except for R. kyoto (29–44 mm), i.e., R. tagoi (38–58 mm), R. okiensis (38–46 mm), R. yakushimensis (37–48 mm), R. sakuraii (38–56 mm), and R. neba (37–48 mm) (Matsui and Maeda, 2018; Eto et al, 2022; present study). Compared to R. tagoi , males of the new species have a relatively narrower head (ratio [r] of HW mean±SD=34.1±1.0%, vs 37.1±1.5% in R. tagoi ), shorter snout (rSL 12.6±0.5%, vs 12.9±1.0%), larger eye (15.5± 0.6%, vs 14.0±1.0%), longer forelimb and hands (rLAL 47.2±2.0%, vs 44.9±1.8%), longer hindlimb and toe (rHLL 188.3±6.7%, vs. 172.4±7.2%).…”

“…The Japanese brown frog, Rana tagoi Okada, 1928, is a common species in mountain areas of this country except for Hokkaido and most of the Ryukyus (Matsui and Maeda, 2018). Although some studies recognized several cryptic species within it (Matsui and Matsui, 1990;Ryuzaki et al, 2014;Eto et al, 2022), R. tagoi is still considered as a widespread species occurring on most of the main islands of Japan, i.e., Honshu, Shikoku, and Kyushu Islands (Matsui and Maeda, 2018;Eto et al, 2022). Three subspecies are recognized in R. tagoi: R. t. tagoi from main islands (holotype: Sp.…”

“…Asterisks indicate that the note contains continuous pulse(s). Data of R. tagoi topotypes cited fromEto et al (2022).…”