Chikila alcocki Kamei, Gower, Wilkinson & Biju, 2013
|Species Description: Kamei RG, Gower DJ, Wilkinson M, Biju SD 2013 Systematics of the caecilian family Chikilidae (Amphibia: Gymnophiona) with the description of three new species of Chikila from northeast India. Zootaxa 3666: 401-435.
Chikila alcocki is a caecilian from northeastern India, which is a global hotspot for amphibian diversity. The length of the body is between 216 - 270 mm and is about 25 times as long as its width, which ranges from 6.1 - 9.4 mm. In the anterior half, the body slightly tapers. From the dorsal view, the sides of the head are straight, quickly converging to the level of the tentacular aperture between the tentacular aperture and the eye. From the profile, the top of the head can be straight or weakly convex. The upper lip is slightly concave, its apex being somewhat closer to the eye level than the tentacular aperture. The lower and upper jaws are about the same height at the corners of the mouth. From the anterior view, the lips are much more blunt anteriorly than the snout tip. The eyes are not visible. The nares and tentacular apertures are only visible ventrally with the latter being just barely elevated. The nuchal region is not noticeably bigger than the back of the head or the adjacent body. There are two nuchal grooves that fully encircle the body and curve toward the head and vertebrae on the dorsum. The second collar has one dorsal transverse groove that lies between two transverse creases. There are between 87 - 94 primary annuli. At the middorsum, the annular grooves are complete, except for in the middle third of the body, where they are incomplete. The annular grooves are mostly incomplete along the ventral midline, especially on the anterior half, but there are a few complete ventral grooves in the posterior region. The posterior edges of most primary annuli are slightly raised, and many primary annuli have one or more transverse creases. Secondary annular grooves toward the anterior are short, being middorsally complete around the 78th primary annulus and ventrally complete from around the 85th primary annulus. The last four or five annular grooves are interrupted by the vent region, which includes an ovular vent that is wider than it is long and in a discrete disc with 10 denticulations. There are two rows of overlapping, squarish scales on the dorsum in the posterior, around the 87th primary annular groove. The skin is smooth but may have irregular creases (Kamei et al. 2013).
DIAGNOSIS: (How this species is differentiated from similar species)
Compared to other members of the Chikila genus, C. alcocki is primarily unicolored with weak bicoloration toward the anterior, while C. darlong and C. fulleri are moderately bicolored, and C. gaiduwani is strongly bicolored. Chikila alcocki also has weak annular grooves, which are moderately distinct in C. darlong and C. gaiduwani, and strongly distinct in C. fulleri (Kamei et al. 2013).
COLORATION: (In life and/or in preservative)
In life, the dorsum is dark lilac and darkens in the last quarter of the body. The head and venter are paler. The head has whitish patches around the mouth corners, the snout tip, the nares, and the lower jaw, where the white patch is in a thick V-shape that extends toward the lip margins (Kamei et al. 2013).
VARIATION: (if known)
The anterior of the body does not taper as much in thinner individuals. The collar may be larger than the adjacent body and head. The region of the body where there are dorsally incomplete annular grooves may be up to half of the body length, instead of just the middle third. The top of the head may be significantly grayer than the rest of the body, possibly having a pale central patch. The light spots around the nares and tentacular apertures may be connected (Kamei et al. 2013).
Distribution and Habitat
Life History, Abundance, Activity, and Special Behaviors
Chikila alcocki was fairly abundant at the type locality. Individuals can be found in soil at the edges of rice paddies, banana plantations, and jhum fields. The soil is slushy and silty or may be clay loam. Specimens were collected by digging between 30 - 45 cm deep into soil in marshy areas or near streams (Kamei et al. 2013).
Breeding in Chikila species likely occurs at the start of the monsoon season around the second week of May (Kamei et al. 2013).
Trends and Threats
Relation to Humans
Possible reasons for amphibian decline
General habitat alteration and loss
Chikila fulleri, which was initially thought to be more widespread, but has been divided into several distinct species including C. alcocki, was originally described as Herpele fulleri. After its initial description, C. fulleri was moved from Herpele to the Gegeneophis genus, members of which were only known from the Western Ghats of India. Maximum Likelihood analysis and Bayesian Inference of cox1 and 16S mtDNA revealed that C. fulleri included multiple species, which include C. alcocki, C. darlong, and C. gaiduwani. These species with C. fulleri form the Chikila genus and Chikilidae family. Chikila alcocki is sister to C. darlong (Kamei et al. 2013).
ETYMOLOGY (Origin or explanation of scientific name):
Chikila alcocki is named after Alfred William Alcock, who originally described Chikila fulleri as Herpele fulleri in 1904 (Kamei et al. 2013).
OTHER INTERESTING INFORMATION:
Originally submitted by: Madeline Ahn (2023-09-28)
Description by: Madeline Ahn (updated 2023-09-28)
Distribution by: Madeline Ahn (updated 2023-09-28)
Life history by: Madeline Ahn (updated 2023-09-28)
Trends and threats by: Madeline Ahn (updated 2023-09-28)
Relation to humans by: Madeline Ahn (updated 2023-09-28)
Comments by: Madeline Ahn (updated 2023-09-28)
Edited by: Ann T. Chang (2023-09-28)
Species Account Citation: AmphibiaWeb 2023 Chikila alcocki: Alcock's chikila <https://amphibiaweb.org/species/8018> University of California, Berkeley, CA, USA. Accessed Mar 3, 2024.
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Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 3 Mar 2024.
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