Tricheilostoma nicefori ( Dunn 1946 )

Pinto, Roberta Richard, Passos, Paulo, Portilla, José Rances Caicedo, Arredondo, Juan Camilo & Fernandes, Ronaldo, 2010, Taxonomy of the Threadsnakes of the tribe Epictini (Squamata: Serpentes: Leptotyphlopidae) in Colombia, Zootaxa 2724, pp. 1-28 : 10-13

Tricheilostoma nicefori ( Dunn 1946) — new combination

Figs. 6 , 7

Leptotyphlops nicefori Dunn 1946 , Caldasia, 4:121.

Leptotyphlops nicefori— Orejas-Miranda 1967, Atas do Simpósio sobre a Biota Amazonica, 5:421–442. Leptotyphlops nicefori— Peters & Orejas-Miranda 1970, Bulletin of the United States National Museum, 297:171. Leptotyphlops nicefori— Hahn 1980, Das Tierreich, 101:22.

Leptotyphlops nicefori— McDiarmid, Campbell & Touré 1999, Snakes Species of the World, 1:39. Rena nicefori — Hedges, Adalsteinsson & Branch in Adalsteisson et al. 2009, Zootaxa, 2244:11.

Holotype. MLS 17, from municipality of Mogotes (06o 29'N, 0 72o 58'W; ca. 1824 m), department of Santander, Colombia.

Diagnosis. Tricheilostoma nicefori is distinguished from all congeners by the combination of the following characters: snout rounded in dorsal and lateral views; supraocular present; ocular subhexagonal, dorsal apex straight and anterior border rounded in the eye level; first supralabial not reaching nostril level; two supralabials (1+1); three infralabials; fused caudals; temporal scale indistinct; rostral triangular in dorsal view; 167–168 middorsal scales; 153 midventral scales; 13–16 subcaudal scales; 10 scales around the middle of tail; dorsum with seven dorsal scale rows uniformly brown, contrasting to the beige covering the seven scale rows of the belly.

Redescription of the holotype. Juvenile male, 90 mm TL, 7 mm TAL; 2.1 mm MB; 12.9 TL/TAL; 42.9 TL/ MB; 3.9 mm HL, 2.4 mm HW; head slightly depressed; body subcylindrical, not enlarged on the head and slightly tapered caudally near the tail.

Head subcylindrical, almost twice as long as wide, slightly depressed, cervical constriction indistinct; snout rounded in dorsal and lateral views; rostral straight in frontal and ventral views, dorsal apex triangular, crossing the transverse imaginary line between anterior margins of ocular scales; rostral contacting supranasal and infranasal laterally and frontal dorsally; nasal completely divided horizontally by oblique suture crossing nostril; nostril roughly elliptic, obliquely oriented and placed in the middle of the nasal suture; supranasal about twice as high as long, bordering rostral anteriorly, infranasal inferiorly, first supralabial and ocular posteriorly, and frontal and supraocular dorsally; infranasal twice as high as long; upper lip border formed by rostral, infranasal, anterior supralabial, ocular, and posterior supralabial scales; temporal scale indistinct from the dorsal scales of lateral rows; two supralabials, entirely separated by ocular (1+1); first supralabial slightly higher than long, not reaching the level of nostril and eye; second supralabial slightly longer than high, its posterior margin in broad contact with temporal, not reaching eye level; ocular enlarged, subhexagonal, rounded in the eye level, twice as high as long, contacting the posterior margins of supranasal and first supralabial anteriorly, parietal and second supralabial posteriorly, and supraocular dorsally, its dorsal apex straight; eye distinct, situated in the middle area of the expanded upper part of ocular, displaced above the level of nostril; supraocular twice as long as wide, subtly longer than frontal scale, contacting supranasal anteriorly, frontal, postfrontal and ocular laterally, and parietal posteriorly; midsaggital head scales (frontal, postfrontal, interparietal and interoccipital) similar in size, hexagonal in dorsal view, weakly imbricate; frontal barely wider than long, contacting rostral, supranasals, supraoculars and postfrontal; postfrontal slightly wider than long, contacting frontal, supraoculars, parietals and interparietal; interparietal wider than long, contacting postfrontal, parietals, occipitals, and interoccipital; interoccipital slightly wider than long, contacting interparietal, occipitals, and the first dorsal scale of the vertebral row; parietal and occipital similar in shape, irregularly pentagonal; parietal almost twice as wide as long, lower margin contacting the upper border of second supralabial, posterior margin contacting respective temporal, occipital and interparietal, postfrontal laterally, anterior border in broad contact with ocular and supraocular; occipital twice as wide as long, its lower limit not attaining the level of the upper margin of second supralabial; symphysial trapezoidal, four times wider than long, anterior and posterior borders straight and slightly convex, respectively; three infralabials behind symphysial on both sides; third infralabial twice as long as high, longer than others, as wide as second supralabial; dorsal scales homogeneous, cycloid, smooth, weekly imbricate, slightly wider than long; 167 (170 according to Dunn 1946) middorsal scales; 153 midventral scales; 14 scale rows around midbody, reducing to 10 scale rows in the middle of tail; cloacal shield rounded, twice as wide as long; 16 subcaudals (14 according to Dunn,1946); fused caudals; terminal spine conical, with stout base, longer than wide.

Colour of the holotype in preservative. Seven dorsal scale rows uniformly brown and seven remaining scale rows beige; lower margins of scales forming the upper lip border and infralabials cream; cloacal shield beige, darker than venter coloration; terminal spine follows the dorsal pattern.

Hemipenis: Left organ partially everted with chalice shape and strait base; protected area has no evident ornamentation.

Variation. Middorsal scales 167–168 (n = 2); subcaudal scales 13–16 (n = 2); TL 90–147 mm (n = 3); TL/TAL ratio 12.9–14.7 (n = 2); TAL 6.8–7.8% of TL (n = 2).

Distribution. East versant of Cordillera Oriental from Mogotes (06o 29'N, 0 72o 58'W; ca. 1824 m) and Cañaverales (06º06’N, 73º13’W; ca. 1750 m), department of Santander, Colombia ( Fig. 3 ).

Remarks. Dunn (1946), based on morphological features (e.g., low middorsal scales) and distribution range suggested that Leptotyphlops nicefori was closely related to some species of the Leptotyphlopids occurring in Colombia ( L. dugandi , L. joshuai and L. macrolepis ) and Ecuador ( L. anthracinus ). Nonetheless, Dunn (1946) pointed out that L. nicefori differs from all of them by having just one supralabial before the ocular scale. He also affirmed that this supralabial pattern could have significant systematic importance, placing L. nicefori as an allied of the species having a higher middorsal scale counts. Orejas-Miranda (1967) suggested L. nicefori was possibly related to L dulcis , L. dimidiatus , and L. affinis on the basis of the number of supralabials. Moreover, Orejas- Miranda (1967) commented that the taxon was known only from the brief original description, which lacks illustrations of the holotype. For that reason, Orejas-Miranda (1967) pointed out L. nicefori could be close related to species lacking supraocular scale, such as L. humilis , L. septemstriatus , L. borrichianus , L. cupinensis and L. brasiliensis . Orejas-Miranda (1967) also considered the holotype of L. nicefori as missing. Peters and Orejas- Miranda (1970) allocated L. nicefori in the “ Leptotyphlops albifrons ” species group. However, the characters used by Peters and Orejas-Miranda (1970) to diagnose “ Leptotyphlops dulcis ” from the “ Leptotyphlops albifrons ” group are variable, not distinguishing any group unambiguously (Pinto & Curcio in press). Passos et al. (2006) and Pinto and Curcio (in press) proposed some additional characters of external and internal morphology that can support the “ Leptotyphlops dulcis ” group, such as: midsaggital cephalic scales with moderate size, rostral scale subtriangular in dorsal view, presence of fused caudals, subhexagonal ocular scale with rounded shape at the eye level, enlarged terminal spine, longer than wide, and narrow basal and robust terminal portions of the hemipenial body.

Adalsteinsson et al. (2009) allocated the “ Leptotyphlops dulcis ” group in two genera ( Rena and Tricheilostoma ), and the “ Leptotyphlops albifrons ” group into Epictia and Rena . According to Adalsteinsson et al. (2009), Rena nicefori was close to R. affinis , R. dimidiata , R. unguirostris and North and Central America species, based on small size of supraocular scales, white venter, two supralabials and higher number of middorsal scales. However, the diagnostic characters used by the authors for the genus Rena are ambiguous, since the white venter does not occur in R. nicefori and R. affinis (R.R. Pinto pers. obs.). Furthermore, the higher number (on average) of middorsal scales diagnosing them from Tricheilostoma (according to the authors) was not cited on their Table 2, suggesting to us that this is not a relevant character in the generic level recognition. Therefore, herein we transfer R. nicefori to the genus Tricheilostoma based on the characters proposed above and detailed in Pinto and Curcio (in press), and we emphasize the needs of corroboration of these genera also through morphological synapomorphies.

Figures

FIGURE 3. Geographic distribution of species of the tribe Epictini in Colombia. Type localities correspond to white symbols.

FIGURE 6. General view of Tricheilostoma nicefori (MLS 17).

FIGURE 7. Dorsal (A), lateral (B), and ventral (C) views of head of the Tricheilostoma nicefori (ICN 5727).