Angoulême Microcaecilia

Microcaecilia dermatophaga has a body length of 175 – 181 mm in live male specimens, 148 – 164 mm in preserved male specimens, 183 mm in the lone female specimen in life, and 156 mm in the lone female specimen in preservative. The body is cylindrical in shape and dorsoventrally compressed, though it narrows towards the end by the cloaca. The head appears U-shaped when viewed from above. When viewed from underneath, the snout protrudes a bit past the sunken mouth, and the mouth is duller than the snout tip. The tentacular apertures are moderately aised, and they're visible when viewed from both the back and underside. The eyes are not apparent. The nostrils are small, circular, slightly depressed, and project towards the sides of the back. They are not visible when viewed from the underside. Narial plugs are present on the nostrils. The neck is wider than the adjacent areas of the body. The two collars are marked by three nuchal grooves, with the first two completely encircling the body and the third being incomplete on the underside. There is a prominent transverse groove on the back of the second collar, which is visible from the sides. There are 108 primary annular grooves behind the collars, and most are incomplete on the back and underside. Secondary annular grooves appear on the body from the 100th primary annular groove, and go all the way towards the end of the body with the exception of the 101st primary annular groove. Some annular grooves may be slightly raised. The end of the body is terminated by a cap that is level with the cloaca. Scales are shallowly deposited on the annular grooves nearest to the end. The cloaca interrupts the last two primary annular grooves. There are ten notches around the cloaca (Wilkinson et al. 2013).This species can be distinguished from M. taylori in lacking a transverse groove on the first collar. The species is also different from all other Microcaecilia in having fewer than twenty primary annuli that are divided by secondary annular grooves, and unlike other Microcaecilia, it may have narial plugs (Wilkinson et al. 2013).In preservative, it is lilac to grey in color, with a dark band halfway down its back. From here, there is an abrupt change to very pale lateral stripes before slowly transitioning into a slightly darker underside. The back of the head is not much lighter than the adjacent area of the body, though the underside of the upper jaw as well as the margin of the lower jaw is a bit paler. The underside is paler between the mandibles and the first collar, as are the nostrils, the cloaca, and the lower half of the terminal cap. The annular grooves are somewhat white in color. There are several whitish glands distributed throughout the skin. In life, it has a similar coloration, though the stripe on the back is much more evident. The back of the head is pinker in color, and the underside of the upper jaws as well as the margin of the lower jaw is white (Wilkinson et al. 2013).Though the morphology is generally the same, there exists some noticeable variation. Generally, the curvature of the upper lip and top of the head differs among specimens. The tentacular aperture is found just below the imaginary line running from the nostrils to the corner of the mouth in one of the paratypes. Two other paratypes have a noticeably less robust lower jaw, and the third nuchal groove of another paratype is more complete on the underside than the described holotype. One of the paratypes has keel-like terminal cap, which is absent in the other specimens. There may be anywhere from 9 - 12 notches on the cloaca (Wilkinson et al. 2013).The species authority is: Wilkinson, M., Sherratt, E., Starace, F., Gower, D. J. (2013). "A New Species of Skin-Feeding Caecilian and the First Report of Reproductive Mode in Microcaecilia (Amphibia: Gymnophiona: Siphonopidae)." PLoS ONE, 8(3), 1-11.The specific epithet, dermatophaga, is derived from the Greek words derma, meaning skin, and phago, meaning to eat. This is in reference to the form of parental care provided by the mother to its offspring (Wilkinson et al. 2013).As this skin-feeding behavior has been observed in two other distantly related caecilian species, it is hypothesized that this is an ancestral form of parental care, and thus is very widespread in many caecilian species. As very little is known about caecilians, more studies need to be conducted to verify this (Wilkinson et al. 2013).

This species is currently known to occur in Angoulême in French Guiana. It has also been found in two other localities, one in the settlement of Saint Jean, and the other in Cascades Voltaires. In all three localities the species has been recorded only in forested environment with relatively dense canopy and abundant litter on the soil. Most of the specimens were found under decaying logs (Wilkinson et al. 2013).

Microcaecilia dermatophaga consumes a wide variety of prey, including but not limited to termites, earthworms, crickets, and ants. It is a fossorial burrower, and is known to occur in orange-brown sandy loam with some organic matter, or dark brown, less sandy loam with lots of organic matter. It is an oviparous caecilian species that probably breeds in March or April (Wilkinson et al. 2013). The species seems to fare well in captivity and first direct observation of its breeding behavior comes from captive specimens. The young are known to feed on the skin of the mother, and they do so by tearing bits of the skin with specialized teeth and ingesting it. During this time, the mass of the mother decreases, which is correlated with a mass increase in the young. Eventually, the young become free-living, and switch to feeding on live prey as well as begin to burrow in the soil. The young continue to grow once they leave the mother, and the mother’s mass eventually increases back to its initial state. The young reach maturity at around one year of age (Wilkinson et al. 2013).

There is currently no information available on trends or threats in this species.

This new species is the first new caecilian to be described from French Guiana for more than 150 years. It differs from all other Microcaecilia in having fewer secondary annular grooves and/or in lacking a transverse groove on the dorsum of the first collar. Observations of oviparity and of extended parental care in M. dermatophaga are the first reproductive mode data for any species of the genus. Microcaecilia dermatophaga is the third species, and represents the third genus, for which there has been direct observation of young animals feeding on the skin of their attending mother. The species is named for this maternal dermatophagy, which is hypothesised to be characteristic of the Siphonopidae.

Body somewhat dorsoventrally flattened throughout (width and depth at midbody 5.0×4.1 mm), relatively uniform, narrowing substantially only posteriorly, from just in front of the vent; L/W c. 34. In dorsal view, head much more U- than V-shaped, sides of head curve and converge gently from to back of head to level of TAs, more strongly to level of nares, ST moderately bluntly rounded. In lateral view, top of head somewhat convex; margins of upper jaw (lip) concave, somewhat downturned anterior to halfway between nares and TAs; ridge bearing vomeropalatine teeth just visible close to CM; lower jaw robust, two-thirds to four-fifths height of upper jaw at levels of CM and TA. In ventral view, snout projects moderately beyond recessed mouth, margins of lower jaw and upper lips slightly more blunt than ST. Eyes not visible. TAs slightly elevated, their papillae visible dorsally and ventrally, distinctly closer to CMs than to nares, minimally above imaginary lines between nares and CMs. Nares small, dorsolateral, circular depressions superficially, each with deeper, more ovate aperture anteriorly, slightly closer to level of AM than to ST, almost twice as far from bottom than from top of snout and from ST in lateral view, not visible from below.

Teeth pointed, gently recurved, lacking serrations or blade-like flanges, elements of outer series much smaller posteriorly: dentaries largest, monocuspid; premaxillary-maxillary teeth large, monocuspid; vomeropalatines much smaller, more uniform in size, bicuspid, vomerine series forming a slight angle anteromedially, palatines extending posteriorly slightly further than premaxillary-maxillary series; distance between vomeropalatine and premaxillary-maxillary series anteriorly approximately the same as AM-ST in ventral view; upper series extending posteriorly distinctly beyond choanae. Palate gently arched transversely and longitudinally. Choanal apertures subcircular, separated from each other by little more than one and a half times their individual widths, lying mostly posterior to the level of the TAs. Tongue rounded, attached anteriorly, paired swellings of the tongue opposite the choanae.

Nuchal region a little more massive than adjacent body. Two collars clearly marked by three nuchal grooves, first two completely encircling body, NG1 somewhat oblique on the sides, NG2 bending slightly anteromedially on dorsum, NG3 widely incomplete ventrally; substantial TG on dorsum of C2, visible laterally. Behind collars, 108 definitive PAGs, mostly narrowly incomplete dorsally and ventrally, except for approximately first (anteriormost) and last (posteriormost) twenty complete dorsally and about first and last six complete ventrally, the last PAG slightly in front of the level of the vent. Body ends in a terminal cap posterior to approximately level with vent, a little less than two times longer than adjacent PA, unsegmented except for single transverse groove on the dorsum. First SAG present middorsally on 100th PA, none on 101st, on right only on 102nd, complete across middorsum from 103rd; more posterior SAGs gradually extending further ventrolaterally, none complete ventrally. AGs slightly raised in places, particularly on the inside of body curves. Vent region interrupts last two PAGs. Scales in shallow pockets in posteriormost AGs, three rows dorsally. No indications of scales in subdermal connective tissue. Body terminus slightly acuminate, narrowing only at approximately the 107th PA without obvious vertical terminal keel. In lateral view, ventral surface strongly upturned behind vent. Vent rather transverse, with five denticulations anterior and five posterior, the interdenticular creases shorter anteriorly, not in an obvious ‘disc’ and without obvious papillae.

In preservative, lilac to steel grey, with dark middorsal band (2.5–3 mm wide), abrupt transition to much paler lateral stripes and more gradual transition to slightly darker venter. Differentiation less pronounced anteriorly and posteriorly, with darker ventral colouration fading out a little anterior to the vent on the 105th PA. Dorsum of head not noticeably paler than adjacent body; ventral surface of upper jaw and periphery of lower jaw a little paler, much paler midventrally between mandibles and on C1; paler (whitish) around nares, vent, and on posterior half of terminal cap. AGs with both whitish edge and more posterior darker aglandular border, generally appear paler than the intervening skin. Numerous whitish glands visible scattered in the skin. In life (Fig. 3), colour similar, dorsal stripe a little more obvious, dorsum of head more pinkish, paler areas of upper and lower jaws almost white.

French Guiana

Observations of reproduction in captivity reveal that this is a third caecilian species known from direct observation to practice maternal dermatophagy.

On the afternoon of 26th July 2010 one of us (MW) observed the approximately last 30 seconds of an episode of active skin feeding, in which the normally quiescent hatchlings were moving rapidly over and around mainly the middle region of the body of their motionless mother, removing and ingesting pieces of her skin. Immediately following this the mother and young were observed for a further approximately 30 seconds during which the mother remained motionless and the young moved very slowly upon soil adjacent to the mother. This was our only direct observation of any post-hatching parental care. By 28th July the mass of the presumed mother had decreased from 3.7 to 3.09 g while the combined mass of the two hatchlings increased from 0.5 to 0.89 g. After a further six days the mass of the presumed mother had fallen further to 2.85 g and the combined mass of the two young had increased to 0.93 g. At this time the young measured 73 and 75 mm in total length and were able to burrow in loose soil. This is approximately the size of the smallest free-living specimen collected in the wild.