Description
Brasilotyphlus dubium is a Brazilian caecilian described in 2018. The total length of adults ranges from 13.7 – 18.2 mm with two male specimens measuring 16.8 and 18.1 mm and three females ranging between 13.7 – 18.2 mm. One juvenile measured 11.2 mm in total length. The head is longer than wide, and wider than high. In the dorsal view, the head is between U- and V-shaped and narrower than the body. It slightly widens after the corners of the mouth. From the dorsal view, the nares are visible, but from the ventral view they are not. In the lateral view, the dorsal surface of the head is slightly concave and the snout projects beyond the lower lip. Also in the lateral view, the anterior portion of the upper lip is somewhat concave and the lower lip is straight. The tentacles cannot be seen from the dorsal view, but are elevated, and are located closer to the corners of the mouth than to the nares. The eyes are not visible as they are covered by bone. The teeth are pointed and softly recurved. There are 19 – 23 monocuspid premaxillary-maxillary teeth. The posterior maxillary teeth are slightly smaller. There are 7 - 9 prevomerine and 10 - 12 bicuspid palatine teeth that are all the same size but smaller than the premaxillary-maxillary teeth. The prevomerine and palatine series have a space of about three teeth between them. The body is sub-cylindrical and somewhat flattened dorsoventrally all the way through and tapered at the ends. At the mid-body the width is greater than the height. There are two nuchal collars of approximately the same size that are marked by three nuchal grooves. Both the first and second nuchal grooves are complete with the first being straight and the second curving anteriorly slightly in the dorsal view while in the ventral view the first is curved anteriorly and the second appears straight. In the lateral view, the first nuchal groove is at an oblique angle. The third nuchal groove is incomplete and curves posteriorly on the ventral surface but appears straight in the dorsal view. There is an apparent transverse groove on the dorsolateral side of the second collar. After the collars there are 121 -126 complete primary annuli and 2 - 3 primary annuli that are interrupted by the vent. From the 112th to 119th primary annuli, 32 – 6 short, complete secondary grooves can be found. There are also 6 – 13 incomplete secondary grooves. Dorsally, the posterior end of the body is clearly convex. There is a singular row of annular scales that are incomplete around the 90th - 92nd groove. The scales are 0.1 mm long and 0.2 mm wide. Around the 107th – 109th groove there are incomplete rows of scales, composed of scales that are slightly wider than the annular scales. Around the 120th – 122nd groove there is a complete row of ovate scales, which are 0.4 mm long and 0.8 mm wide. The vent has six main denticulations with some irregular subdivisions. The anterior interdenticular creases are short. The terminal keel is vertical (Correia et al. 2018).

At the time of the species description, the Brasilotyphlus genus had three species. Brasilotyphlus dubium differed from B. braziliensis by the former having fewer primary and secondary annular grooves. Brasilotyphlus dubium has 123 - 129 primary annular grooves and 9 - 16 secondary annular grooves while B. braziliensis has 142 - 147 primary annular grooves and 23 - 36 secondary annular grooves. An additional difference between the species is that premaxillary-maxillary teeth reach the posterior edge of the choanae while B. braziliensis teeth does not. Brasilotyphlus dubium differs from B. guarantanus by the number of annular grooves. Brasilotyphlus guarantanus has more primary annuli (151 - 170) and fewer secondary annular grooves (0 - 2) (Correia et al. 2018).

In life, B. braziliensis is pale purple with a slightly pink head. The venter, lateral surfaces, and areas that surround the vent, nostrils, and tentacles are a paler color than the rest of the body. In preservative, the body is brown and is paler on the anterior dorsal portion of the bodies, the ventrum, and lateral surfaces. Additionally, sections that surround the vent, nostrils, lips, tentacles, and the ventral surface anterior to the second collar are less pigmented than the rest of the body (Correia et al. 2018).

There is variation in the robustness of the first nuchal collar making it difficult to tell where the head begins in some individuals. The visibility of the nuchal grooves vary but they are otherwise similar. The terminal keel also varies in distinctiveness between individuals. There are only slight variations in color between the holotype and the paratypes, which is that some of the other specimens that are preserved are a steel grey color but the patterning is similar throughout the specimens (Correia et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

View distribution map in BerkeleyMapper.

Brasilotyphlus dubium is known to only exist in Brazil, specifically in the state of Roraima in the north of Brazil near the municipalities of Mucajaí and Iracema. More specifically, individuals were collected from Serra da Maroquinha (N 2° 22' 44", W 61° 22' 37") at 400 m asl, Serra do Apiaú (N 2° 24' 30", W 61° 24' 54") at 140 m, 685 m and 835 m asl respectively, and 7 km east of the Ajarani river (N 1° 59' 50", W 61° 32' 4"). These are all areas that are solely rainforest and it is hypothesized that Brasilotyphlus is restricted to rainforest habitats (Correia et al. 2018).

Life History, Abundance, Activity, and Special Behaviors
There is very little known about this species and more sampling and research is needed to have a better understanding of these animals (Correia et al. 2018).

Comments

Maximum Likelihood Analysis and Bayesian Inference of 16S rRNA and cytB show that B. dubium is sister to B. guarantanus. The analysis did not include B. braziliensis. This analysis supported the monophyly of Brasilotyphlus but found that the clade was nested within a paraphyletic Microcaecilia, bringing into question whether Brasilotyphlus is synonomus with Microcaecilia or if Microcaecilia should be split (Correia et al. 2018).

Brasilotyphlus dubium was found 620 km northwest of the B. braziliensis type locality and 1,500 km northwest of the B. guarantanus type locality (Correia et al. 2018).

References

Correia, L.L., Nunes, P.M.S., Gamble, T., Maciel, A.O., Marques-Souza, S., Fouquet, A., Rodrigues, M.T., Mott, T. (2018). ''A new species of Brasilotyphlus (Gymnophiona: Siphonopidae) and a contribution to the knowledge of the relationship between Microcaecilia and Brasilotyphlus.'' Zootaxa, 4527(2), 186-196. [link]

Species Account Citation: AmphibiaWeb 2024 Brasilotyphlus dubium <https://amphibiaweb.org/species/8934> University of California, Berkeley, CA, USA. Accessed Dec 26, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Dec 2024.

AmphibiaWeb's policy on data use.