Description
Astrobatrachus kurichiyana is a small-bodied, lean frog with an adult male snout-vent length of 20 – 27 mm and adult female snout-vent length of 24 – 29 mm. The head length and width are approximately equal. The snout is relatively pointed and short, appearing more angular from the dorsal view. The nostrils are oval in shape, positioned laterally and closer to the rostrum than to the eyes. The canthus rostralis is distinct and angular. The internarial distance is equal to the distance between the upper eyelids, with the loreal region being concave. The upper eyelids are smooth with no warts. The space between the eyes is wide, more than twice the upper eyelid width, and flat. The pupil is elliptical. The tympanum is round, less than half the width of the eye, and clearly distinguishable beneath a supratympanic fold. There is a weak symphysial knob, and there are no rictal or ocular glands. The skin on the dorsum is soft and finely glandular while the skin on the ventrum is “smooth glandular” (Vijayakumar et al. 2019).

The forelimbs are slender. The fingers are short, thin, and end in blunt, triangular tips. Additionally, the fingers have minimal webbing, no dermal fringing, and no circummarginal grooves. The relative length of the fingers is: IV < I < II < III and the phalangeal formula of hand is 2 – 2 – 3 – 3. The subarticular tubercles are oblong in shape and have indistinct margins along each digit. The pollex tubercle and supernumerary tubercles are both absent. Nuptial pads are absent on males. The hindlimbs are short with the femur and tibiofibular being relatively equal in length. When adpressed at right angles to the body, the hindlimbs just touch. When the hindlimbs are adpressed along the body, the tibo-tarsal articulation reaches the posterior edge of the eye. There are no femoral glands. The outer metatarsal tubercle and supernumerary tubercles are absent. The inner metatarsal tubercle is small and is not clearly distinguishable from the subarticular tubercle of the first toe. The relative length of the toes is: I < II < V < III < IV and the phalangeal formula of the foot is 2 -2 - 3 – 4 - 3. The toes have indistinct, oblong subarticular tubercles that may be merged together on some toes, and minimal webbing that does not reach the proximal subarticular tubercle (Vijayakumar et al. 2019).

Astrobatrachus kurichiyana is in the family Nyctibatrachidae and is the only known member of its genera thus making its closest relatives members of the genera Lankanectes and Nyctibatrachus. The three genera can be differentiated by geography, morphology, and ecology. Lankanectinae can be distinguished based on distribution as it is endemic to Sri Lanka while Astrobatrachinae and Nyctibatrachinae are both found in the Western Ghats of India (Vijayakumar et al. 2019).

Morphologically, A. kurichiyana can be differentiated from Lankanectes by the former lacking dorsal skin ridges, odontoid fangs, a forked omosternum, a lateral line system as an adult, a prominent dorsal crest on the ilium, tarsal folds, and foot webbing. Additionally, A. kurichiyana have, widely spaced nostrils, a long ridge of vomerine teeth, a distinct tympanum and canthus rostralis, and separate anterior and posterior portions of the vomer with the latter fused to the neopalatine that are not found in Lakanectes. From Nyctibatrachus, which has some members that occur in sympatry with A. kurichiyana, the focal species can be differentiated by lacking rugose or wrinkled skin, a subocular gland, a forked omosternum, femoral glands, a prominent dorsal crest on the ilium, tarsal folds, and foot webbing. Astrobatrachus kurichiyana can be further distinguished from Nyctibatrachinae by the focal species having an elliptical pupil, widely spaced nostrils, a distinct tympanum and canthus rostralis, and a long ridge of vomerine teeth with separated anterior and posterior portions, the latter of which is fused to the neopalatine (Vijayakumar et al. 2019).

Unlike other members of the family Nyctibatrachidae, which tend to live in and around water, A. kurichiyana is a terrestrial forest dweller. Nyctibatrachus minimus has been seen in leaf litter in the same habitat as A. kurichiyana but the former are smaller in size (snout-vent length 10 – 13.5 mm) and have weakly developed toes discs. Furthermore, N. minimus is more tan than brown in coloration and has smaller, less concentrated white spotting along its sides. Other members of Nyctibatrachus occur in syntropy and potentially sympatry with A. kurichiyana including N. grandis, N. vrijueni, N. kempholeynsis, and N. indranli. These species can all be distinguished based on morphology from A. kurichiyana by wrinkled skin, no webbing on hands, non-triangular toe discs, and lack of spotting along sides and throat. All of the Nyctibatrachus species apart from N. kempholeynsis and N. minimus are also significantly larger in size (Vijayakumar et al. 2019).

Astrobatrachus kurichiyana has osteological differences from members of the genera Micrixalus, Indirana, and Sallywalkerana, which can also be found in the Western Ghats. From all three genera, A. kurichiyana differs by having a posterior portion of vomer that is fused to the neopalatine and lacking T- and/or Y- shaped terminal phalanges. More specific differences from Indirana and Sallywalkerana include A. kurichiyana having wide spaced nasals. Astrobatrachus kurichiyana can also be distinguished from Sallywalkerana by the former having clavicles and a well-define sternum (Vijayakumar et al. 2019).

In life, A. kurichiyana is dorsally a rufous brown coloration that is darker in the anterior regions of the body. There are small pale bluish-white spots present over the whole body but are more concentrated and relatively larger on the throat, lateral edges of the jaw, eyelids, and belly. The ventral side has an orange coloration predominantly on the fore- and hindlimbs and abdomen. Both the throat and the anterior ventrum are a darker grey color with prominent pale spots and melanocytes that become more separated posteriorly. The hands and feet are dark gray ventrally with a lighter gray coloration at the tips of the digits and on the subarticular tubercles. The iris is brown in color with gold and orange sparks distributed throughout. In preservative, the bluish-white spots and orange coloration become cream (Vijayakumar et al. 2019).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Astrobatrachus kurichiyana is only known from the Kurichiyarmala massif on the Wayanad Plateau of the Western Ghats in India. It has only been found at high elevations of 1,300 – 1,400 m but has not been assessed on the adjoining mountain clusters of Vellarimala (Camel’s Hump), and Banasuramala. It is commonly associated with montane forest habitats near water (Vijayakumar et al. 2019).

Life History, Abundance, Activity, and Special Behaviors
Astrobatrachus kurichiyana can be found in montane forest habitats in the vicinity of water. They are nocturnal and secretive, dwelling under leaf litter and do not become visible during rainy or non-rainy periods of the year. One individual was also located in grassland next to a forested area (Vijayakumar et al. 2019).

When exposed to artificial light, individuals made quick hopping movements to hide (Vijayakumar et al. 2019).

At the time of their description, no information was available on their reproductive modes, male advertisement calls, or larval biology (Vijayakumar et al. 2019).

Astrobatrachus kurichiyana overlaps in range with Nyctibatrachus grandis, N. minimus, N. vrijeuni, and N. kempholeyensis but can be differentiated from them by being a forest floor leaf-dweller while the Nyctibatrachus species are torrential frogs that live in or near perennial streams (Vijayakumar et al. 2019).

Trends and Threats
At the time of the species description, the authors proposed a “Data Deficient” threat status for A. kurichiyana because of a lack of information on abundance and geographical range. The authors also did not find any imminent threats to the species at their type localities but noted that those localities were not in any protected areas. The species is an old lineage (Vijayakumar et al. 2019), which may be of evolutionary importance in terms of conservation.

Comments
The species authority is: Vijayakumar, SP, Pyron, RA, Dinesh, KP, Torsekar, VR Srikanthan, AN, Swamy, P, Stanley, EL, Blackburn, DC, Shanker, K (2019). “A new ancient lineage of frog (Anura: Nyctibatrachidae: Astrobatrachinae subfam. nov.) endemic to the Western Ghats of peninsular India.” PeerJ 7: e6457.

Astrobatrachus kurichiyana belongs to the family Nyctibatrachidae in the newly erected sub-family Astrobatrachinae. Maximum Likelihood analysis of 15 concatenated genes sequences (5 mitochondrial and 10 nuclear), including 16s, CYTB, CXCR4, RAG1,and RHOD, placed this new lineage in a clade with Nyctibatrachus and Lankanectes. With the discovery of this new genus the relationship between these three subfamilies (Astrobatrachinae, Nyctibatrachinae, and Lankanectinae) is now unclear (Vijayakumar et al. 2019).

Astrobatrachus kurichiyana (subfamily Astrobatrachinae) is a monotypic ancient lineage that shares common ancestry with Lankanectes (subfamily Lankanectinae) and Nyctibatrachus (subfamily Nyctibatrachinae) in the family Nyctibatrachidae (Vijayakumar et al. 2019).

The generic name, “Astrobatrachus” is derived from the Greek words, “astro” meaning “star” in reference to the spots on the body, and “batrachus” meaning “frog” (Vijayakumar et al. 2019).

The species epithet, “kurichiyana”, was given in honor of the local Kurichiyana tribal community that live near the currently identified geographic range for this species (Vijayakumar et al. 2019).

References

Vijayakumar, SP, Pyron, RA, Dinesh, KP, Torsekar, VR Srikanthan, AN, Swamy, P, Stanley, EL, Blackburn, DC, Shanker, K (2019). ''A new ancient lineage of frog (Anura: Nyctibatrachidae: Astrobatrachinae subfam. nov.) endemic to the Western Ghats of peninsular India.'' PeerJ, [link]

Species Account Citation: AmphibiaWeb 2020 Astrobatrachus kurichiyana: Starry Dwarf Frog <https://amphibiaweb.org/species/8985> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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