Microhyla nilphamariensis Howlader, Nair, Gopalan & Merilä 2015

Microhyla niphamariensis is a small species of frog with a snout-vent length of 17.36 mm in the lone male specimen and 17.84 mm in a female paratopotype specimen. No information on the snout-vent length of other specimens is available. Its snout appears round when viewed from the side, and it has a large, triangular wide that is broader than it is long. The canthus rostralis is faint, and the region between the eye and nostril is rounded inwards and granular. There are some tubercles present on the upper eyelids. The nostrils are round, small, and located closer to the snout tip than the eyes. The tympanum is not visible. The underside of the body is smooth. The back is smooth and slightly granular. The sides of the body are also slightly granular. The arms are fairly long and glandular on the backside, and the fingers are small and lack webbing. The fingertips are flat. The relative finger lengths are: I < II < IV < III. The inner metacarpal tubercle is ovoid, and the outer metacarpal tubercle is small and round. There is a noticeable subarticular tubercle under each digit. The legs are fairly long and smooth on the underside. Both the thigh and the base of the foot are glandular. The toes are long, slender, and have rounded tips. There is rudimentary webbing on the toes. The relative toe lengths are: I < II < V < III < IV. The inner metatarsal tubercle is small, round, and located at the base of the first toe. The outer metatarsal tubercle is ovoid, small, and faint. The subarticular tubercles are prominent, and mildly ovoid. The cloaca is slightly granular (Howlader et al. 2015).Microhyla nilphamariensis is distinct on a morphological basis from other closely related species such as M. ornatus and M. rubra. The inner metacarpal tubercle is small and ovoid-shaped in M. nilphamariensis, while in M. ornata it is large and goblet shaped and in M. rubra it is elongated. The outer metacarpal tubercle is very small and rounded in M. nilphamariensis while in M. ornata and M. rubra it is very large, prominent and heart shaped. The inner metatarsal tubercle is small and round in M. nilphamariensis, while in M. ornata it is elongated, large and very prominent. In M. rubra the inner metatarsal tubercle is shovel shaped. The outer metatarsal tubercle is ovoid-shaped, minute, and indistinct in M. nilphamariensis while in M. ornata it is compressed and large. The outer metatarsal tubercle is large and shovel-shaped in M. rubra. The head length is 77% of the head width in M. nilphamariensis while in both M. ornata and M. rubra the head length is roughly equal to the head length. The distance from front of the eyes to the nostril is six times greater than the nostril to snout length in M. nilphamariensis. This distance is over one and a half times greater than the nostril to snout length in M. ornata and over single time greater than the nostril to snout length in M. rubra. The internarial distance is five times greater than the nostril to snout length in M. nilphamariensis while in M. ornata it is nearly two times greater. In M. rubra the internarial distance is less than two times greater than nostril to snout length. The interorbital distance is two times greater than the internarial distance in M. nilphamariensis while in M. ornata and M. rubra it is more than three times greater than the internarial distance. The distance from the back of the mandible to the back of the eye is fifteen percent of the head length while in both M. ornata and M. rubis it is more than thirty-six percent of the head length. Microhyla nilphamariensis is morphologically different from all known Southeast Asian species in that it has reduced webbing, absent discs and irregular dorsal surface markings (Howlader et al. 2015).Pairwise genetic divergence and number of substitutions per site were also used to diagnose M. nilphamariensis as a new species. Analysis of the whole genomic DNA showed a 5.7% - 13.2% divergence in the 16S rRNA gene from sympatric Microhyla species, compared to a 0.5% divergence within the species itself. This data was backed up with high maximum likelihood bootstrap and posterior probability support (Howlader et al. 2015).In life, it has a light brown back. There is a dark brown diamond over the back, which extends from between the eyes to the eyelids, then contracts to behind the head and broadens to the shoulders, then contracts once more before spreading out and leading to a stripe that goes to the groin and thigh. There is a dark band running from the sides behind the eye and to the shoulder. The underside is white, and the gular region and chest are brown. There are dark cross bars on the limbs (Howlader et al. 2015).There is no known variation in males as only one has been found. Female variation, except for morphological measurements, was not reported (Howlader et al. 2015).The species authority is: Howlader, M. S. A., Nair, A., Gopalan, S. V., Merilä, J. (2015). "A New Species of Microhyla (Anura: Microhylidae) from Nilphamari, Bangladesh." PLoS ONE, 10(3), e0119825.It is a sister taxa to M. ornata. Research suggests that it is part of an Indian Microhyla species group that comprises M. nilphamariensis, M. ornata, and M. rubra (Howlader et al. 2015).The name of the species is derived from the location the specimens were collected, in Nilphamari District, Bangladesh (Howlader et al. 2015).

Microhyla nilphamariensis was encountered in Saidpur City, Nilphamari District, Bangladesh. However, it is worth noting that individuals found carrying similar haplotypes to those found in Saidpur were encountered in the town of Dinajpur, Dinajpur District, Bangladesh. This suggests that the range of M. nilphamariensis may extend beyond Saidpur. No information on elevational range was reported. This species was observed only on a rainy night at Saidpur. The specimens were found in a grass field near temporary pools (Howlader et al. 2015).

Currently unknown.

Currently unknown, however, M. ornata is morphologically similar and considered one of the most common Microhyla in Bangladesh (Howlader et al. 2015).

Microphyla nilphamariensis is a species of narrow-mouthed frog. It is found in Bangladesh, India, Nepal, and northern Pakistan.