Description

DESCRIPTION:

At the time of its description, Chikila darlong is the first and only caecilian species endemic to Arunachal Pradesh, India. Its body length ranges from 131 - 198 mm, tapering distinctly in the anterior half. The body length is about 32 times longer than it is wide. In the dorsal view, the sides of the head are straight and converge strongly to the level of the tentacular apertures, and more gradually between the tentacular aperture and the snout tip. In lateral view, the top of the head is slightly convex while the upper lip is concave, its apex being closer to the eye level than the tentacular aperture. At the corner of the mouth, the lower and upper jaw are about the same height. The anterior of the lips is more blunt than the snout tip in ventral view. The eyes are visible and larger than the tentacular apertures and the nares. They are located about halfway between the lip and the top of the head in lateral view. From the dorsal view, they are only slightly inset from the sides of the head. The tentacular apertures and nares are only visible ventrally and laterally. The tentacular apertures are closer to the imaginary line between the nares and the eyes than they are to the lip. The nuchal collar is larger than the adjacent body and back of the head. The first nuchal groove strongly encircles the body completely, while the second nuchal groove, while also encircling the body, is more weakly marked on the ventral side. There are about 87 - 92 primary annuli. Except for the anterior sixth and posterior eighth of the body, most annular grooves are barely incomplete middorsally. Ventrally, most annular grooves are incomplete along the midline, the gap being more narrow in the anterior than in the midbody, and are complete on the posterior sixth of the body length. Most posterior edges of the primary annuli are flat and somewhat elevated posteriorly. The vent region is wider than it is long, interrupting the last five annular grooves. The vent is located in a distinct disc with 10 vent denticulations. There is one row of overlapping, squarish scales (0.6 mm) present in the posterior of the dorsum at about the 84th primary annulus (Kamei et al. 2013).

DIAGNOSIS:

Chikila darlong is distinct from others in the Chikila genus because of its head shape, smaller size, and visible eyes. Chikila darlong has a more pointed head shape in the dorsal view, which is moderately broad in C. alcocki, moderately pointed in C. fulleri, and broad in C. gaiduwani. The maximum size of C. darlong is below 200 mm in length, while all other members of the genus may exceed 225 mm in length. The eyes of C. darlong are dark and distinct in life and preservative, while C. alcocki, C. fulleri, and C. gaiduwani do not have visible eyes (Kamei et al. 2013).

COLORATION: (In life and/or in preservative)

In life, C. darlong is bicolored, having a lavender-brown dorsum that darkens in the posterior tenth of the body length and is a darker shade on the venter. About halfway down the flank, the dark posterior of the dorsum blends with the ventral color. The head is paler than the rest of the body with whitish patches around the nares, lips, and mouth corners. The eyes are dark. The eyes and tentacular apertures are located in flesh-colored spots, which are connected by a thin stripe. The snout tip is whitish and the lower jaw has a thick, whitish V-shaped marking that is separate from the whitish lip margins (Kamei et al. 2013).

In preservative, C. darlong is bicolored, having a gray dorsum and a light brown venter. The venter has a dark midventral line that darkens on the posterior tenth of the body. The gray of the dorsum transitions abruptly to brown slightly above the halfway mark down the flank, and the transition is more gradual in the posterior of the body. The top of the head has pale central patches and the anterior midline of the lower jaw is the same shade of brown as the venter. Two V-shaped markings are lateral to this, the first being gray and the next being thick and whitish. The nares, tentacular aperture, and eyes have whitish spots around them, with the tentacular aperture and eyes are connected by a thin whitish stripe. The whitish spots around the nares meet anteriorly at the snout tip, which is pale (Kamei et al. 2013).

VARIATION: (if known)

The anterior of the body may only taper weakly. The eye may be only slightly visible on either side. The median throat line is generally a pale groove that extends onto the back of the first collar, but may only be barely visible on the first collar. The white patch on the throat may not be complete in the anterior region, and it may be very thin. Pale areas on the lower jaw can be continuous with pale spots at the mouth corner (Kamei et al. 2013).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Chikila darlong is known from Darlong and Pakke Tiger Reserve in the East Kameng district of Arunachal Pradesh, India. Individuals are found in slushy mud near streams and paddy fields. The soil is clay loam. The Pakke Tiger Reserve consists of secondary forest habitat with slushy areas and small streams. The species is known to occupy altitudes of 120 - 350 m (Kamei et al. 2013).

Life History, Abundance, Activity, and Special Behaviors
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
Unlike others in the genus, which are Least Concern, C. darlong may qualify for the Vulnerable status in the IUCN Red List if it continues to only be known from one small area. However, Chikila populations have also been found outside of protected areas in degraded agricultural habitats. Additionally, with breeding aligning with the monsoon season in mid-May to mid-August, eggs and hatchlings have been killed by increased agricultural activity during this time. In general, the large-scale the destruction of tropical rainforests in northeast India occurs at a large scale, even within protected areas, and may be a threat (Kamei et al. 2013).

Relation to Humans
Agriculture is well-established in northeast India, and Chikila species are common in some agricultural localities. Farmers are generally familiar with Chikila species (Kamei et al. 2013).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing

Comments

PHYLOGENETIC RELATIONSHIPS:

OTHER INTERESTING INFORMATION:

References
Kamei R.G., Gower D.J., Wilkinson M., and Biju S.D. (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. [link]

Species Account Citation: AmphibiaWeb 2024 Chikila darlong: Darlong chikila <https://amphibiaweb.org/species/8019> University of California, Berkeley, CA, USA. Accessed May 8, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 8 May 2025.

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