Description
Microcaecilia butantan is a caecilian with a total body length ranging from 159 - 208 mm. Its eyes are indiscernible. Dorsally, the head shape is between a U- and V-shape in appearance with the sides of the head appearing quite straight and gradually convergent as they approach the tentacular apertures and more sharply curving at the level of the nares until it reaches a moderately pointed snout tip. From the side, the top of the head is somewhat convex with the upper lip somewhat concave and slightly downturned. The ridge-bearing vomeropalatine teeth are clearly discernible at the corner of the mouth. It has a strong lower jaw that is approximately 2/3 the height of the upper jaw at the corner of mouth and tentacular aperture level. From the ventral view, the snout protrudes strongly over the mouth. The snout tip is much less blunt than the anterior regions of the upper and lower jaws. The tentacular pores are somewhat elevated on the undefined, wide, low papillae that are barely discernible both ventrally and dorsally. The pores are very near the corners of the mouth rather than the nares, and markedly above the imagined “lines” between the nares and the corners of the mouth. The small nares are dorsolateral, superficial, ovate depressions that are longer than high or wide, and each with deeper, more ovate, and wider than long apertures as you move anteriorly. Nares are closer to the level of the snout tip than to the anteromedial limit of the mouth on the upper jaw. They are approximately 1.5x farther from the bottom than the top of the snout and from the snout tip laterally. From below the nares they are not visible.

Microcaecilia butantan’s teeth are pointed and gently curved, without serrations or blades with the last couple components of the outer series decreasing in size posteriorly. Outer mandibular teeth and premaxilary-maxillary teeth are monocuspid with the latter slightly smaller. Vomeropalatine teeth are smaller and more consistent in size. Bicuspid and vomerine series are mostly rounded anteromedially, and palatines extend posteriorly a little farther than the premaxillary-maxillary series. Anteriorly, the distance is smaller between the vomeropalatine and premaxillary-maxillary series (about half as large) as the anteromedial limit of the mouth on the upper jaw-snout tip distance viewed ventrally. The upper series extends posteriorly far beyond the choanae. Transversely and longitudinally, the palate arches strongly. Choanal apertures are sub-circular with each separated from each other by approximately two times the width of an individual choana, and the anterior margins about even with the tentacular apertures. The tongue is slightly pointed at the tip and smooth excluding the medial longitudinal groove running posteriorly.

Microcaecilia butantan has a sub-cylindrical body with some slight dorsoventral flattening throughout that slightly narrows anteriorly as well as posteriorly (from right in front of the vent). The width of the vent varies between 2.4 and 2.9 mm. Its body is slightly narrower than its nuchal region, which consist of two nuchal collars distinctly marked by two encircling nuchal grooves and a third incomplete groove. Laterally, the first nuchal groove is markedly oblique. The second collar and the transverse groove on the dorsal surface of the collar are substantial and much longer than the transverse groove on the dorsal surface of the collar on the first collar. The transverse groove (located anteromedially) on the dorsal surface of the collar, the second nuchal groove and the third nuchal groove bend slightly. The ventral transverse groove on the first nuchal groove is slightly longer than that of the dorsum. Between the corners of the mouth, a modest mid-ventral crease extends to slightly past the ventral transverse groove on the dorsal surface of the collar on the first collar. 143 - 157 primary annular grooves are behind the collars and are for the most part complete or slightly incomplete dorsally. Except for the 12 posteriormost and 20 anteriormost, the primary annuli are most narrowly incomplete on the ventrum. The primary annuli are longest at the middle of the body; anteriorly, they are shorter and become progressively shorter posteriorly. On the holotype, the first second annular groove is short and dorsolateral on the 139th primary annulus. Posteriorly, more secondary annular grooves gradually extend further ventrolaterally, but none are ventrally complete. On the last two primary annuli, the secondary annular grooves are completely absent. The last primary annulus is divided by a secondary annular groove that is slightly anterior to the level of the vent. Posterior to the vent is the last primary annular groove. The last four primary annular grooves disrupt the vent region and the body ends with a short terminal cap. Viewed laterally, it is 1.5 times the length of the last primary annulus and tappers to a point. This is more evident in dorsal view, as the body becomes narrower in the last five primary annuli. Looking laterally, behind the vent, the ventral surface strongly upturns. The vent is noticeably transverse with approximately four major denticulations posterior and five anterior. There are some irregular subdivisions with the interdenticular creases shortening anteriorly. The vent is not an obvious “disk” but is modestly elevated without any noticeable papillae. On the dorsal surface of the terminal cap, there is a definite terminal keel. The shallow pockets of the posteriormost annular grooves (<0.5 mm deep) contain scales in single major row with additional supernumerary scales surrounding it. There are no indications of scales In the sub-dermal connective tissue (Wilkinson et al. 2015).

Microcaecilia butantan has a combination of more than 135 primary annuli and long premaxillary-maxillary tooth series running posteriorly from the choanae, which distinguishes it from previously discovered Microcaecilia (Wilkinson et al. 2015).

Microcaecilia butantan body color ranges from pink to purple in life. In preservative, the majority of the body becomes a light tan color with a somewhat darker 3 mm wide band at the mid-dorsal region. There is not much regional distinction in color, but there is a strong transition to noticeably paler lateral flanks and a slower transition to a somewhat darker venter. The darker coloration of the dorsal region slightly extends ventrally on the posteriormost annuli, especially where secondary annular grooves are present. The ventral surface of the nuchal and the head are pale and almost without pigment. On the ventral surface of the terminal cap, they are paler (whitish) directly around and anterior to the vent and on the ventral surface of the terminal cap. Annular grooves have a whitish edge and a somewhat more defined adjacent streak of relatively darkened pigment macroscopically appears darker than the intervening skin. Many visible whitish glands are scattered throughout the skin with numerous larger glands aligned along the annular grooves (Wilkinson et al. 2015).

All of the paratypes have smaller heads and narrower bodies at the vent, which may indicate slight sexual dimorphism. The number of terminal primary annuli missing secondary annular grooves may also vary (Wilkinson et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

View distribution map in BerkeleyMapper.

Microcaecilia butantan is found in the State of Pará, Brazil, specifically in forests within the limits of Área de Proteção Amiental, Aramana, municipality of Belterra. Within protected areas, they were found in both native forests and cupuaçu plantation (Wilkinson et al. 2015).

Life History, Abundance, Activity, and Special Behaviors
Microcaecilia butantan specimens were found during the rainy season (Wilkinson et al. 2015).

Trends and Threats
The species authority reported that Microcaecilia butantan is not under any immediate conservation threat because specimens were found in a relatively short amount of time, which suggests that the species is locally abundant. Twenty-one specimens were found in three expeditions (Wilkinson et al. 2015).

Relation to Humans
Microcaecilia butantan can be found in cupuaçu (a tropical fruit) plantations (Wilkinson et al. 2015).

Comments
The species authority is: Wilkinson M, Antoniazzi MM, Jared C 2015 A new species of Microcaecilia Taylor, 1968 (Amphibia: Gymnophiona: Siphonopidae) from Amazonian Brazil. Zootaxa 3905: 425-431

Because the Instituto Butantan facilitated the discovery of the species through the Butantan na Amazonia (Butantan in Amazon project), the epithet honors their contributions. The species epithet is regarded as a noun to promote stability and in apposition for nomenclatural purposes. Butantan microcaecilia is the suggested English name (Wilkinson et al. 2015).

Although 21 specimens were found, only four were preserved, the female holotype and three male paratypes. The rest of the specimens are in captivity for histology studies (Wilkinson et al. 2015).

Microcaecilia is the third-most speciose genus globally with the exception of Caecilia and Ichthyophis (Wilkinson et al. 2015).

References

Wilkinson, M., Antoniazzi, M.M., Jared, C. (2015). ''A new species of Microcaecilia Taylor, 1968 (Amphibia: Gymnophiona: Siphonopidae) from Amazonian Brazil.'' Zootaxa, 3905, 425-432.

Species Account Citation: AmphibiaWeb 2015 Microcaecilia butantan: Butantan Microcaecilia <https://amphibiaweb.org/species/8300> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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