Brasilotyphlus dubium, Correia & Sales Nunes & Gamble & Maciel & Marques-Souza & Fouquet & Rodrigues & Mott, 2018

Correia, Larissa Lima, Sales Nunes, Pedro M., Gamble, Tony, Maciel, Adriano Oliveira, Marques-Souza, Sergio, Fouquet, Antoine, Rodrigues, Miguel Trefaut & Mott, Tamí, 2018, A new species of Brasilotyphlus (Gymnophiona: Siphonopidae) and a contribution to the knowledge of the relationship between Microcaecilia and Brasilotyphlus, Zootaxa 4527 (2), pp. 186-196 : 189-193

Brasilotyphlus dubium sp. nov.

Figs. 2–4 ; Table 2

Holotype. Museu de História Natural da Universidade Federal de Alagoas ( MUFAL) 13638, field number MTR 23151, a male collected by Pedro M. Sales Nunes, Antoine Fouquet and Felipe Franco Curcio, from Serra da Maroquinha (N 2° 22' 44", W 61° 22' 37"), 400 m from sea level, Mucajaí municipality, Roraima, Brazil, May 2012.

Paratypes (n = 5). MUFAL 13639 , male, field number MTR 23216, collected in pitfall trap, with same collection data as the holotype ; MUFAL 13640 , field number SMS 873, immature , MUFAL 13641 , field number SMS 920, female, and MUFAL 13642 , field number SMS 940, female, collected by Sergio Marques de Souza, Pedro M. Sales Nunes and Antoine Fouquet, from Serra do Apiaú (N 2° 24' 30", W 61° 24' 54") at 140 m, 685 m and 835 m from sea level respectively, state of Roraima, Brazil, in November 2011; and MPEG 7779 , female, collected by Laurie J. Vitt, from 7 km east of the Ajarani river (N 1° 59' 50", W 61° 32' 4"), Iracema municipality, Roraima, Brazil, 3 July 1993 .

Identification. The new species is considered a species of Brasilotyphlus on the basis of it having eyes covered by bone and a diastema between the vomerine and palatine teeth with the following associated characters: palatine extends posteriorly to the series of premaxillary-maxillary teeth; a semicircular vomerine series of teeth.

Diagnosis. Brasilotyphlus dubium sp. nov. differs from B. braziliensis in having fewer primary and secondary annular grooves (123–129 and 9–16 vs 142–147 and 23–36, respectively), and in having premaxillary-maxillary teeth reaching the level of the posterior edge of the choanae (in B. braziliensis the maxillary teeth do not reach the level of the choanae). The new species differs from B. guarantanus in having fewer primary annuli (123–129 vs 151–170) and more secondary annular grooves (9–16 vs 0–2).

Description of the holotype. Morphometric and meristic data are in Table 2. Specimen in good condition, a 3.7 mm midventral incision and slightly broken corners of the mouth. Body subcylindrical, slightly flattened dorsoventrally throughout (BW x BH 3.9 x 2.9 mm), slightly narrower anteriorly and posteriorly (WTR 3.6 mm). In dorsal view, head intermediate between U- and V-shaped. In lateral view, top of head slightly convex; upper lip slightly concave at the anterior end and lower lips straight. Snout projects strongly beyond recessed mouth (SP 1 mm). Eyes not visible. Tentacles slightly elevated and not visible from above, closer to the corner of the mouth (TCM 1.3 mm) than to nares (TN 1.6 mm). Nares visible from above, but not from below. Teeth pointed and gently recurved. Premaxillary-maxillary teeth monocuspid, forming a series (21 teeth) with posterior maxillary teeth slightly smaller, extending to the level of the posterior edge of the choanae. Nine prevomerine and 10 palatine bicuspid teeth, with no apparent variation in size, smaller than those of the premaxillary-maxillary series and with a large diastema between them, which corresponds to a distance of approximately three tooth positions. Dentary teeth monocuspid, forming a series of 13 teeth, posterior ones slightly smaller, larger than those of premaxillarymaxillary series. Subcircular choanal apertures, separated by an approximate distance of 1.5 times the width of each choanal aperture, anterior edges approximately level with tentacles. Two collars clearly marked by three nuchal grooves (NG1, NG2, and NG3); NG1 and NG2 completely encircling the body, NG3 incomplete, curving posteriorly on the venter. In dorsal view, NG1 straight, NG2 slightly curved anteriorly, and NG3 straight; first collar smaller than second. In ventral view, NG1 curved anteriorly, NG2 straight and NG3 slightly incomplete and curved posteriorly; first and second collar similar in size. NG1 oblique laterally. A conspicuous transverse groove is present on the dorsolateral surface of the second collar. Following collars, 125 PAs, being 123 complete and two interrupted by the vent; First SG short, dorsally located on 112 th PA; SGs complete from 119 th PA. Vent with six main denticulations and some irregular subdivisions, the interdenticular creases shorter anteriorly. Dorsally, body terminus strongly convex. Distinct vertical terminal keel present. Annular scales limited to a single and incomplete row in the 92 th groove of scales wider than long (e.g., 0.1 x 0.2 mm); in a single incomplete row at 107 th groove (e.g., 0.1 x 0.3 mm) and in a complete row of ovate scales at 120 th groove (e.g., 0.4 x 0.8 mm).

Coloration: In life, body pale purple; head pinkish. Venter and lateral surfaces, areas surrounding vent, nostrils and tentacles paler than dorsum. In preservative, body brownish; paler anteriorly than posteriorly in dorsal and ventral view. Ventral and lateral surfaces slightly paler than dorsum along the entire body. Areas surrounding the vent, nostrils, tentacles and lips less pigmented, as is the ventral surface anterior to the second collar.

Variation and additional information from paratypes. Variation in some meristics and morphometrics is summarized in Table 2. The vertical terminal keel is less distinct in MUFAL 13642 . In preservative, MUFAL 13641 and 13642 have steel grey body color, but the pattern of paler regions is similar to that observed on the holotype. The first collar of MUFAL 13641 and 13642 are less robust than observed in the holotype, forming an almost straight transition line from head to body. In paratype MPEG 7779 , scales begin in the 90 th groove, limited to a single and incomplete row of small scales, wider than long (e.g., 0.1 x 0.3 mm); in a single incomplete row at 109 th groove (e.g., 0.1 x 0.4 mm) and in a complete row of ovate scales at 122 th groove (e.g., 0.5 x 0.7 mm). Except for minor details in their visibility, the nuchal grooves of all paratypes are as described for the holotype.

Etymology. The epithet dubium means “dubious”, reflecting our doubt whether or not Brasilotyphlus should be considered a synonym of Microcaecilia . For nomenclatural purposes, the species epithet is considered a noun in apposition.

Phylogenetic analyses. The concatenated dataset consisted of 1,682 base pairs (bp) (605 bp of 16srRNA and 1,077 bp of cytochrome b). After removal of 121 bp in the 16SrRNA fragment (31–43, 218-284, 311-354) due to ambiguous alignment, 1,563 bp were used in the analyses. The families Caeciliidae , Typhlonectidae , Herpelidae , Indotyphlidae and Siphonopidae were each recovered as monophyletic with high support ( Figure 5 ). Typhlonectidae and Caeciliidae were recovered as sister clades. The basal split within Siphonopidae is between a clade comprising Luetkenotyphlus brasiliensis ( Lütken 1851) and Siphonops annulatus ( Mikan 1820) (PP = 1), and a clade comprising all sampled species of Microcaecilia [ M. unicolor ( Duméril 1863) , M. dermatophaga Wilkinson, Sherratt, Starace & Gower 2013 , M. savagei Donnelly & Wake 2013, Microcaecilia sp1. and Microcaecilia sp2.], B. guarantanus and B. dubium sp. nov. (PP = 1). The latter two were recovered as monophyletic (PP = 1), but nested within a paraphyletic Microcaecilia ( M. savagei and M. sp.2 are more closely related to Brasilotyphlus than to other Microcaecilia : PP = 0.86).

The maximum likelihood tree (not shown) is similar to our Bayesian phylogeny at well-supported nodes. The families Caeciliidae , Typhlonectidae , Herpelidae and Indotyphlidae were each monophyletic with high support (bootstrap value [BS] ± 97), and although Siphonopidae was recovered with moderate support (BS = 79), the relationships among Brasilotyphlus and Microcaecilia were identical to those recovered in the Bayesian analysis. The AU test could not reject a monophyletic Microcaecilia (difference -lnL = 1.77643; AU test, P = 0.2099).

Figures

FIGURE 2. MUFAL 13638, holotype of Brasilotyphlus dubium sp. nov. from Serra da Maroquinha, Roraima, Brazil. Left column: head and anterior part of body in dorsal (above), lateral (middle) and ventral view (below). Right column: posterior part of body in dorsal (above), lateral (middle) and ventral view (below).

FIGURE 3. Palatal view of Brasilotyphlus dubium sp. nov. (holotype) showing disposition of tooth rows, diastema and choanae. Scale bars = 1 mm.

FIGURE 4. Brasilotyphlus dubium sp. nov. (A) Specimen from the type series in life in dorsal view. (B) Habitat at type locality, Serra da Maroquinha, Roraima, Brazil. (C) Habitat at Serra do Apiaú, Roraima, Brazil.

FIGURE 5. Phylogram obtained from Bayesian analysis (consensus by majority rule 50%) using 1,683 base pairs of concatenated mitochondrial genes (16SrRNA and cytochrome b). Numbers at internal branches are posterior probabilities.