Tricheilostoma brevissimum ( Shreve 1964 )

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 : 3-6

Tricheilostoma brevissimum ( Shreve 1964)

Figs. 1 , 2

Leptotyphlops brevissima Shreve 1964 , Breviora, 211:1.

Leptotyphlops brevissimus— Orejas-Miranda 1967, Atas do Simpósio sobre a Biota Amazônica, 5:421–442. Leptotyphlops brevissimus— Peters & Orejas-Miranda 1970, Bulletin of the United States National Museum, 297:168. Leptotyphlops brevissimus— Hahn 1980, Das Tierreich, 101:9.

Leptotyphlops brevissimus— McDiarmid, Campbell & Touré 1999, Snakes Species of the World, 1:24. Leptotyphlops brevissimus— Passos, Caramaschi & Pinto 2006, Amphibia-Reptilia, 27:349.

Tricheilostoma brevissimum— Hedges, Adalsteinsson & Branch in Adalsteisson et al. 2009, Zootaxa, 2244:11.

Holotype. MLS 1311, collected by Brother Nicéforo Maria on February 10, 1951, from municipality of Florencia (01o 37’N, 0 75o 37’W; ca. 560 m), department of Caquetá, Colombia.

Paratype. MCZ 38950, collected by Brother Nicéforo Maria in 1925, from municipality of Sonsón (05º43’N, 75º19’W; ca. 2240 m), department of Antioquia, Colombia. The paratype was taken from the stomach of Micrurus mipartitus ( MCZ 21988), so the head is partially destroyed.

Diagnosis. Tricheilostoma brevissimum is distinguished from all congeners by the following combination of characters: snout truncate in dorsal view; rounded in lateral view; supraocular present; rostral scale subtriangular in dorsal view; ocular subhexagonal with rounded shape at the eye level; supraocular longer than frontal scale; temporal distinct; fused caudals present; nostril posterior to nasal suture; three supralabials (2+1); four infralabials; 152–162 middorsal scales; 141–152 midventral scales; 12–14 subcaudals; 10 scales around the middle of tail; seven dorsal scale rows uniformly brown, and seven ventral series pale brown.

Redescription of the holotype. Juvenile male, 66 mm TL, 5 mm TAL; 1.6 mm MB; 13.2 TL/TAL; 41.3 TL/ MB; 3.1 mm HL, 1.8 mm HW; head slightly depressed; body subcylindrical, slightly enlarged on the head and slightly tapered caudally near of tail.

Head subcylindrical, almost twice as long as wide, cervical constriction indistinct; snout truncate in dorsal and ventral views, rounded in lateral view; rostral straight in frontal and ventral views, dorsal apex triangular, reaching a transverse imaginary line between anterior margins of ocular scales; rostral contacting supranasal and infranasal laterally and frontal dorsally; nasal completely divided horizontally by an oblique suture crossing nostril and descending posteriorly near to first supralabial; nostril roughly elliptic, obliquely oriented and placed posteriorly in the nasal suture; supranasal about twice as high as long, bordering rostral anteriorly, infranasal inferiorly, first and second supralabials and ocular scale posteriorly, and frontal and supraocular scales dorsally; supranasal longer than upper border of infranasal scale; infranasal about twice as high as long; infranasal and second supralabial with similar size; upper lip border formed by rostral, infranasal, two anterior supralabials, ocular, and posterior supralabial; temporal scale distinct from dorsal scales of lateral rows; three supralabials, first two anterior to ocular and one posterior (2+1); first supralabial higher than long, not reaching nostril and eye level; second supralabial twice as high as long, higher than first supralabial, crossing level of nostril and reaching eye level; third supralabial trapezoidal, longer than high, not reaching eye level, its posterior margin in broad contact with temporal; ocular enlarged, with rounded shape in the eye level, twice high as long, contacting posterior margins of supranasal and second supralabial anteriorly, parietal and third supralabial posteriorly, and supraocular dorsally, with its dorsal apex straight; eye distinct, concentrated in the central area of the expanded upper part of ocular; supraocular about twice as long as wide, subtly longer and smaller than frontal, placed between ocular and frontal, contacting supranasal anteriorly, frontal, postfrontal and ocular laterally, and parietal posteriorly; midsaggital head scales (frontal, postfrontal, interparietal and interoccipital) subequal in size, hexagonal in dorsal view, non imbricate; frontal wider than long, contacting rostral, supranasal, supraocular and postfrontal; postfrontal wider than long, contacting frontal, supraocular, parietals and interparietal; interparietal wider than long, contacting postfrontal, parietals, occipitals and interoccipital; interoccipital wider than long, contacting interparietal, occipitals and the first dorsal scale of the vertebral row; parietal and occipital subequal, irregularly hexagonal; parietal almost twice as wide as long, lower margin contacting upper border of third supralabial, posterior margin contacting respective temporal, occipital and interparietal, anterior border in broad contact with ocular, supraocular and postfrontal; occipital almost twice as wide as long, its lower limit attaining the level of the upper margin of third supralabial, separated from latter by temporal; symphysial trapezoidal, anterior and posterior borders respectively straight and slightly convex, four times wider than long; four infralabials on both sides (six according to Shreve 1964); first three infralabials similar in size, slightly higher than long; fourth infralabial distinctively longer than first three scales, almost three times longer than high, as long as third supralabial. Dorsal scales homogeneous, cycloid, smooth, weekly imbricate, and almost twice as wide as long; 152 middorsal scales; 141 midventral scales; 14 scale rows around midbody, reducing to 10 rows in the middle of the tail; cloacal shield semicircular, almost twice as wide as long; 12 subcaudals (13 according to Shreve 1964); fused caudals present; terminal spine large, conical, longer than wide.

Colour of the holotype in preservative. Its colour has considerably faded after preservation. Seven dorsal scale rows uniformly pale brown and seven ventral scale rows beige; lower margins of scales forming the upper lip border beige; cloacal shield pale brown, slightly paler than dorsal coloration; terminal spine not pigmented.

Variation. Middorsal scales 152–162 (x¯ = 158.7 ± 5.8, n = 3); midventral scales 141–152 (x¯ = 148.0 ± 6.1, n = 3); subcaudal scales 12–14 (x¯ = 13.0 ± 1.0, n = 3); TL 66–139 mm (x¯ = 102.0 ± 36.5, n = 3); TL/TAL ratio 12.6– 13.2 (x¯ = 12.9 ± 0.3, n = 3); TAL 7.6–7.9% of TL (x¯ = 7.8 ± 0.0, n = 3); TL/MB ratio 30.3–41.3 (x¯ = 34.8 ± 5.7, n = 3); TAL/MT ratio 2.8–3.3 (n = 2); relative eye diameter 1.7–2.5 (n = 2); rostral width 0.4 (n = 2).

Distribution. Florencia (01º37’N, 75º37’W) in the east versant of Cordillera Oriental and Sonsón (05°43'33''N 74°43'46''W) in the east versant of Cordillera Central of Colombia ( Fig. 3 ).

Remarks. Shreve (1964) distinguished Leptotyphlops brevissimus from L. anthracinus and L. macrolepis by the lower middorsal and subcaudal scale counts and venter light brown (vs. black in L. anthracinus or brown with distinct ventral scales white bordered in L. macrolepis ). Shreve (1964) also compared L. brevissimus with L. dugandi , which according to him have similar middorsal scale counts, but differing the first by lower number of subcaudals, dorsum uniformly dark brown and venter light brown (vs. dorsum stripped, uniformly white ventrally, and with anterior portion of head white in L. dugandi ). Shreve (1964) pointed out that L. anthracinus was close related to L. brevissimus , and suggested both species may be only subspecifically distinct. Orejas-Miranda (1967) argued that criteria used by Shreve (1964) to recognize L. brevissimus was puzzled, since there is a specimen of L. anthracinus (FMNH 34353) with 172 middorsal scales close to the known range of L. brevissimus . However, we re-examined this specimen and found that middorsal scales in fact are 187 instead of 172 as previously reported by Orejas-Miranda (1967), and besides the additional differences between these taxa (see above), the number of middorsal scales still differs between the two taxa. The paratype presented 162 middorsal scales instead of 164 according to Shreve 1964.

Figures

FIGURE 1. General view of the holotype of Tricheilostoma brevissimum (MLS 1311).

FIGURE 2. Dorsal (A), lateral (B), and ventral (C) views of head of the paratype of Tricheilostoma brevissimum (MCZ 38950).

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