Distribution of Chikilidae fam. nov. in northeast India. (a) Map of South Asia and Indochina showing three global biodiversity hotspots. (b) Map of northeast India showing geographical sampling effort and locations where Chikila gen. nov. were found.
Timetree of caecilian amphibians. Age estimates and confidence intervals (horizontal bars) of the divergences among Chikila gen. nov. and other extant caecilians. The timetree depicted is the unique supertree that displays both of the entirely compatible trees found in two analyses: (i) analysis of 12 413 bp of complete mt genome and two nuclear genes (rag1 and slc8a1) for one Chikila fulleri plus 22 other caecilians, and (ii) analysis of 1982 bp of mt cox1 + 16S for 10 Chikila plus the 22 other caecilians. Blue and orange bars are confidence intervals from analyses (i) and (ii), respectively. Green triangles indicate calibrations (upper and lower bounds) for analysis (i). Filled squares next to nodes indicate maximal support for Bayesian inference (BI) and maximum likelihood (ML); open squares indicate maximal support for BI and high (>90%) for ML. Colour codes of leaves correspond to geographical region. See Estimation of Divergence Times in the electronic supplementary material for details.
Morphology of Chikilidae fam. nov. (a) Chikila fulleri in life, brooding egg clutch (in captivity). Scale bar, 10 mm. (b–e) Volume reconstruction of high-resolution X-ray computed tomography data showing cranium and mandibles of C. fulleri. (b) Cranium in dorsal view. (c) Cranium in palatal view. (d) Cranium and mandible in right lateral view. (e) Mandibles in dorsal view. Scale bar (b,c), 1 mm. n, nasal; pm, premaxilla; sf, stapedial foramen; im, inner mandibular (i.e. ‘splenial’) tooth row; de, dentary tooth row. See the electronic supplementary material, figure S2 for more detailed labelling.
Volume reconstruction of high-resolution X-ray computed tomography data showing sagittal section through braincase of Chikila fulleri (SDB 1304). The left internal wall of the braincase is seen from the midline, showing the single antotic foramen, and exclusion of the frontal from the roof of the braincase posterior to the sphenethmoid (formed by the parietal). af, antotic foramen; ob, os basale; p, parietal; sp, sphenethmoid. Scale bar, 1 mm.
Genetic diversity of Chikila gen. nov. and collection localities of Chikila in northeast India. (a) Northeast India showing collection localities, relief and major drainage. (b) DNA phylogeny of Chikila based on the analysis of 696 bp of mt cox1 plus two (non-overlapping) fragments of mt 16S (463 and 823 bp). The tree is rooted according to the relationships depicted in figure 2, even though that part of the tree was not well supported. Coloured dots relate to collection localities indicated in the map. Numbers next to nodes represent support for internal branches from ML (above branch) and BI (below branch).