Nyctibatrachus robinmoorei

Nyctibatrachus robinmoorei was described in 2017 by the herpetologist Sonali Garg and her colleagues based on an adult male specimen collected from the Kalakkad Mundanthurai Tiger Reserve in the state of Tamil Nadu. The species is named after the conservationist and wildlife photographer Robin Moore to honour his contribution to the conservation of amphibians.[1]

The species is one of 34 species in the night frog genus Nyctibatrachus, in the robust frog family Nyctibatrachidae.[4] It is sister (most closely related) to N. manalari, and both of these species are further sister to a clade (group formed by all of a common ancestor's descendants) formed by N. anamallaiensis, N. pulivijayani, and N. sabarimalai. The clade formed by these five species is sister to N. beddomii.[1][5] The following cladogram shows relationships among these species, according to the 2017 study that described the species.[1]

Figure illustrating various aspects of N. robinmoorei's appearance in life and after preservation

N. robinmoorei is a diminutive frog, with a snout–vent length of 12.2–13.4 mm (0.48–0.53 in) for adult males. The head is almost as wide as it is long, and the snout is rounded and longer than the diameter of the eye. Males can be distinguished from females by the presence of the nuptial pads and femoral glands (bulbous glands near the inner thigh).[1]

In adult males, the upperside is reddish-brown, with a pair of light orangish-brown bands running from behind the eyelids to the middle of the back. The snout has a triangular light orangish-brown patch, demarcated by a light orangish-brown stripe between the eyes. The side of the head is dark greyish-brown, with scattered minute black speckles and prominent white spots, and the upper eyelids are dark greyish-brown. The underside is light grey with prominent minute black spots, and the sides of the abdomen are light brown with scattered white spots. The limbs are light brown with faint dark grey horizontal bands, with the hands and feet being slightly darker.[1]

When preserved in 70% ethanol, the upperside turns brown, while the light patch on the snout, stripe between the eyes, and stripe over the back become light brown. The underside turns light greyish-white with dark grey spots, the limbs turn light greyish-brown, and the sides of the abdomen become light greyish-brown.[1]

N. robinmoorei can be distinguished from its congeners by a combination of its small snout–vent length; the head being almost as wide as it is long; the absence of webbed feet; weakly developed glandular folds on the upper sides, separated by scattered granular projections; the presence of the dorso-terminal groove (groove on the upper side of the tip of the digit) on the third finger and fourth toe; the discs on third finger and fourth toe being slightly sider than the finger and toe, respectively; a single tubercle on the palm; the thigh being longer than both the lower leg and foot; and the forearm being longer than the hand.[1]

N. robinmoorei is endemic to the Western Ghats of India, where it is known only from its type locality in Tirunelveli district, south of the Palakkad Gap in Tamil Nadu. All known specimens of the frog have been collected from a marshy area with thick ground vegetation, near a stream inside primary forest at an elevation of 1,290 m (4,230 ft). Male are known to vocalise during the afternoon, from 12 PM to 2 PM, and late in the evening, around 6 PM. A female collected in late August had 15 small, pigmented eggs, with an average egg diameter of 1.7 mm (0.067 in).[1] The species has not yet been assessed by the IUCN.[6]