Chikila fulleri (Alcock 1904)

Alcock (1904) described the Chikila fulleri holotype (type specimen ZSI 14759) as 220mm in total length, with a diameter of approximately 9 mm near the end of the body narrowing to approximately 3 mm behind the snout. The snout comes to a sharp point and overhangs the subterminal mouth considerable. The nostrils are posterior and dorsal to the snout, and tentacles being posterior and dorsal to the nostrils. The eyes, covered by skull bone, are not visible. The mouth is yellow and the rest of the body is brown, becoming darker until nearly black dorsoposteriorly. Additionally, Taylor (1968) state the species has 92 primary annuli and 13 secondary annuli, with dermal scales. The squamosals and parietals are in contact. The tongue has two narial plugs (well-defined) which are surrounded by narrow but deep grooves. The tentacle is midway between the nostril and eye. The vent is transverse (Taylor 1968).A total of 1177 person hours were dedicated in the discovery of the caecilian Chikila fulleri, the first described species in the new family Chikilidae. Originally thought to be a member of the family Indotyphlidae, these caecilians are morphologically distinct by having perforate stapes and separate premaxillae and nasals. They are the sister group to Herpelidae (Boulengerula and Herpele) and share common features, such as perforate stapes and no septomaxillae. However, Chikilidae are distinguishable from Herpele and Boulengerula in that members of Chikila have an undivided antotic foramen on either side of the skull, the frontals do not contribute to the roof of the braincase beyond the sphenethmoid, and the carotid formina mark the anterior limit of the insertion of the ventral trunk muscles on the os basale. Chikilidae are also oviparous and having lower jaw teeth in two rows, no prefrontals and frontals not posterior to the sphenethmoid. Moreover, they are different from Herpele by having non-separate pterygoids and and from Boulengerula by possessing unfused premaxillae and nasals, secondary annuli and scales. Chikilids are teresomotans and therefore, lack a true tail (Taylor 1968; Kamei et al. 2012).Chikila fulleri has a dark brown (chocolate-brown) body that fades posteriorly to almost black on the dorsal surface. The head is lighter brown with yellowish tinting around the snout and mouth (Alcock 1904). The preserved specimen is a uniform brown with lips and snout paler (Pillai and Ravichandran 1999).The range of morphological variation has not been assessed yet and it has been noted that until recently only one specimen had been known (e.g., Ravichandran and Pillai 1996, Dutta 2002, Gower and Wilkinson 2005). This is an area that will hopefully be investigated soon, as several more specimens have recently been collected by Kamei and colleagues (2012).The species authorities for Chikila fulleri are Alcock 1904 (Herpele fulleri), Kamei et al. 2012 (Chikila fulleri ). The etymology of Chikila is the name of an Indian tribe in the northeast state, Meghalaya. The species epithet is after the Honorable Mr. J. B. Fuller, the chief commissioner of Assam (the type locality of C. fulleri; Kamei et al. 2012).A paper that is currently in press as of 2012 will describe three more species of Chikila from northeast India. Chikila fulleri has been shuffled around, originally being placed in a very widespread conceptualization of the genus Herpele by Alcock (1904). Subsequent revision resulted in that genus being limited to Africa (Cameroon principally) and this species being included in the genus Gegeneophis (Taylor 1968). In this position C. fulleri was aligned with other endemic Indian caecilians. A 2012 analysis collected 43 new specimens from 38 localities in northeastern India and recovered a new clade of caecilians endemic to this region. This led to the placement of this species into the newly named genus of Chikila (Kamei et al. 2012).Herpelidae, the sister taxon of Chikilidae, is confined to the East and West coasts of Africa. The divergence of Chikilidae and Herpelidae, occurring ca 140 Ma (Kamei et al. 2012), coincided with the splitting of India from Africa 165-121 Ma (Sanmartin & Ronquist 2004). For “Godwananan groups,” the establishment of localized and distinct families most likely preceded major tectonic events (Hedges et al. 1993). Thus, it is likely that this land separation reinforced spatial fragmentation, instead of caused it (Kamei et al. 2012). Although chikilids were once present in Greater India, extant chikilids radiated after India joined Asia 65-42 Ma (Briggs 2003). The Deccan Traps that divided India into two ca 65 Ma (Bossuyt and Milinkovitch 2001) likely confined chikilids to the northeast region, where they underwent in situ radiation (Kamei et al. 2012). Northeast India appears to have offered refugia for organisms during the Cenozoic era, similar to the Western Ghats-Sri Lanka region, which is a notable biodiversity hotspot (Bossuyt et al. 2004). Much evidence suggests that Northeast India is a species rich area that provides habitat to many more undiscovered organisms (Kamei et al. 2012). Chikila fulleri is the only named species within the newly erected family Chikilidae. A phylogenetic analysis using a complete mitochondrial genome and two nuclear genes (rag1 and slc8a1) recovered this new family as sister to Herpelidae. This finding reaffirms the original hypotheses of relationship by Alcock (1904), who recognized this species' close relationship with Herpelidae (Abraham 2012). An additional analysis based on the mitochondrial genes cox1 and 16S (two non-overlapping fragments) sequence suggests that there are 6 other species within Chikilidae in addition to Chikila fulleri (Kamei et al. 2012).

Chikila fulleri is known from the southern portion (Cachar district) of state of Assam in northeastern India from lowland areas (0-500m) (Kamei et al 2012). This species is also known from Arunachal Pradesh, Meghalaya, Nagaland, and Tripura and possibly adjacent Myanmar and Bangladesh (Frost 2013). This species is one of several amphibians endemic to this region of India (Ravichandran 2004). This region is a tropical monsoon climate with lowland rainforest, but much of this has been converted to grasslands (Ohler et al. 2004). Chikila fulleri is part of a monophyletic species-assemblage that radiated across northeast India. Unidentified Chikila spp. were also collected from a more widespread distribution in the northeast Indian states of Arunachal Pradesh, Assam, Meghalaya, Nagaland and Tripura at various elevations, ranging from 0 to 4000 m along the junction of the Himalayas and Indo-Burma (Kamei et al. 2012).

Chikila fulleri is thought to be a fully fossorial taxon that feeds on subterranean insects like other caecilians. This species are oviparous with direct developing young, where the mother is hypothesized to remain with the eggs throughout development and not feed until after the young hatch. The family appears to be rather abundant given that Kamei et al. (2012) encountered over 500 teresomatan caecilians, which turned out to be chikilids, at 58 out of 238 sites. (Kamei et al 2012, Ohler et al. 2004).

Little is known about Chikila fulleri in terms of population size change, range changes, or threats. However, Northeast India has a rapidly growing human population and much of the region is being deforested (Puyravaud et al. 2010). Habitat destruction and close proximity to human influence seriously threatens the future of Chikila spp. and other undiscovered organisms inhabiting this potentially diverse area.

Very little is known about Chikila fulleri, only a single specimen was known until the recent work by Kamei and colleagues (2012). However local Indian tribes did encounter this species enough to have given it a name, “Chikila,” although no information is available about their uses by local people as food or for other purposes (Kamei et al. 2012).

Chikila fulleri, also known as the Kuttal caecilian, Fuller's caecilian, and Fuller's chikila, is a species of caecilian from South Asia. In 2012 it was reassigned to a newly erected family, Chikilidae.