Tricheilostoma dugandi Dunn 1944

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 : 13-15

Tricheilostoma dugandi Dunn 1944

Figs. 8 , 9

Leptotyphlops dugandi Dunn 1944 , Caldasia, 3:52–53.

Leptotyphlops dugandi— Bailey 1946, Occasional Papers of the Museum of Zoology in the University of Michigan, 492:4. Leptotyphlops dugandi— Dunn 1946, Caldasia, 4:122.

Leptotyphlops dugandi— Shreve 1964, Breviora, 211:4.

Leptotyphlops dugandi— Peters & Orejas-Miranda 1970, Bulletin of the United States National Museum, 297:169. Leptotyphlops dugandi— Hahn 1980, Das Tierreich, 101:12.

Leptotyphlops dugandi— McDiarmid, Campbell & Touré 1999, Snake Species of the World, 1:28. Leptotyphlops dugandi— Passos, Caramaschi & Pinto 2006, Amphibia-Reptilia, 27:349. Tricheilostoma dugandi — Hedges, Adalsteinsson & Branch in Adalsteisson et al. 2009, Zootaxa, 2244:11.

Holotype. A non catalogued male specimen originally housed in the Colegio Biffi, from municipality of Juanmina (= Juan Mina; 10º57’N, 74º53’W; ca. 30 m), department of Atlántico, Colombia. Specimen not localized, probably lost (see remarks).

Paratype. A non catalogued female specimen originally housed in the Colegio Biffi, from municipality of Barranquilla (10°57'N, 074°47'W; ca. 30 m), department of Atlántico, Colombia.

Diagnosis. Tricheilostoma dugandi is distinguished from all congeners by the following combination of characters: snout truncated in dorsal and ventral views, and rounded in lateral view; supraocular present; ocular subhexagonal, dorsal apex straight and anterior border slightly rounded in the eye level; three supralabials (2+1); four infralabials; fused caudals present; temporal scale indistinct; rostral semicircular in dorsal view; 171–184 middorsal scales; 158–172 midventral scales; subcaudal scales 10–13; 10 scales around the middle of tail; dorsum brown with dark brown copper in the centre and median portion of dorsal scales, forming seven longitudinal lines from occipital scales to terminal spine; seven remaining ventrolateral scale rows whitish cream.

Redescription of the topotype [MCZ 58785]. Juvenile female, 143 mm TL, 7 mm TAL; 4.1 mm MB; 3.0 mm MT; 20.4 TL/TAL; 35.2 TL/MB; 5.7 mm HL, 3.1 mm HW; 1.5 mm relative eye diameter; 0.4 mm relative rostral width; head slightly depressed; body subcylindrical, slightly enlarged on the head and slightly tapered caudally near of tail.

Head subcylindrical, distinguishable from neck, almost twice as long as wide; snout truncated in dorsal and ventral views, and rounded in lateral view; rostral straight in frontal and ventral views, dorsal apex semicircular, not 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 oblique suture crossing nostril; nostril roughly elliptic, obliquely oriented and placed in the middle of the nasal suture; supranasal almost twice as high as long, bordering rostral anteriorly, infranasal inferiorly, two anterior supralabials, and ocular posteriorly, and frontal dorsally; supranasal as long as upper border of infranasal scale; infranasal as high as long; upper lip border formed by rostral, infranasal, first two supralabials, ocular, and posterior supralabial; temporal scale indistinct from dorsal scale of lateral rows; three supralabials (2+1); first supralabial twice as higher than long, not reaching nostril and eye levels; second supralabial about three times higher than long, crossing nostril level and lower portion of eye; third supralabial trapezoidal lower than second, slightly longer than high, reaching eye level, its posterior margin in broad contact with temporal; ocular enlarged, subhexagonal, slightly rounded in eye level, almost twice as high as long, contacting posterior margins of supranasal and first supralabial anteriorly, parietal and third supralabial posteriorly, and supraocular dorsally, its dorsal apex straight; eye distinct (0.6 mm), situated at upper part of ocular, displaced above nostril; supraocular longer than wide, subtly longer than frontal scale, contacting supranasal anteriorly, frontal, postfrontal, ocular laterally, and parietal posteriorly; midsaggital head scales (frontal, postfrontal, interparietal, and interoccipital) similar in size, subcircular in dorsal view, weakly imbricate; frontal short, almost twice as wide as long, contacting rostral, supranasals, supraocular, 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 vertebral row; parietal and occipital similar in shape, irregularly pentagonal; parietal almost twice as wide as long, lower margin contacting the upper border of third supralabial, posterior margin contacting temporal, occipital, and interparietal; anterior border in broad contact with ocular, supraocular, and postfrontal; occipital almost twice as wide as long, its lower edge attaining level of upper margin of third supralabial; symphysial trapezoidal, almost three times wider than long, anterior and posterior borders straight and slightly convex, respectively; four infralabials behind symphysial; first three infralabials subequal, somewhat higher than long; fourth infralabial longer than others, twice as long as high; dorsal scales homogeneous, cycloid, smooth, weekly imbricate, and wider than long; 182 middorsal scales; 172 midventral scales; 14 scale rows around midbody, reducing to 10 rows at middle of tail; cloacal shield short and semicircular, almost twice as wide as long; 10 subcaudals; caudals fused; terminal spine short, conical, with stout base, slightly wider than long.

Colour of the topotype in preservative. Seven dorsal scale rows brown with dark copper in the centre and median portion of each scales, forming seven longitudinal lines from occipitals to terminal spine; seven ventral scale rows whitish cream; head uniformly brown; frontal margin of snout near postfrontal dorsally and ocular laterally whitish cream; cloacal shield whitish cream; terminal spine dark brown.

Sexual dimorphism. Females have higher middorsal scales than males (U = 0.0; P <0.05), although males have more subcaudal scales than females (U = 0.0; P <0.05).

Variation: Middorsal scales 181–184 (x¯ = 182 ± 1.3, n = 5) in females, 171–174 (x¯ = 172.3 ± 1.5, n = 3) in males; midventral scales 158–160 (n = 2) in females, 172 in males; subcaudal scales 9–10 (x¯ = 10 ± 0.4, n = 5) in females, 12–13 (x¯ = 12.3 ± 0.6, n = 3) in males; TL 143–257 mm (x¯ = 182 ± 45.4, n = 5) in females, 84–174 mm (x¯ = 137.7 ± 47.4, n = 3) in males; TL/TAL ratio 18.4–30.0 (x¯ = 22.2 ± 3.7, n = 5) in females, 15.5–19.3 (x¯ = 17.2 ± 2.0, n = 3) in males; TAL 3.3–5.5% of TL (x¯ = 4.5% ± 0.0, n = 5) in females, 5.2–6.5% of TL (x¯ = 5.9 ± 0.0, n = 3) in males; TL/MB ratio 27.0–37.5 (x¯ = 33.5 ± 3.8, n = 5) in females, 33.7–52.5 (x¯ = 40.4 ± 10.6, n = 3) in males; TAL/MT ratio 2.4 (n = 1) in females; relative eye diameter 1.5 (n = 1) in females; relative rostral width 0.4 (n = 1) in females.

Distribution. Caribbean coast of Colombia near sea level, from Juan Mina to Barranquilla ( Fig. 3 ).

Remarks. Dunn (1944) proposed Leptotyphlops dugandi through brief description based on two specimens from the Caribbean coast of Colombia. Both were housed at Colegio Biffi in the city of Barranquilla, a small collection made by the efforts of fathers from La Salle order. Although many researchers unsuccessful tried to exam this collection in the past at least part of it was apparently lost during transportation to a new building (J. Lynch pers. comm.). Given the apparent loss of the types, conservative nature of the general colour pattern, and large overlap of meristic and morphometric characters in the genus (the only data provided by Dunn 1944), the designation of a neotype may be desirable.

According to ICZN (1999) the designation of a neotype is allowed when a name-bearing type is necessary to define the nominal taxon objectively (art. 75.1, ICZN 1999). On the basis of voucher species the only leptotyphlopid that occur sympatrically with T. dugandi in the Atlantic coast of Colombia is E. goudotii . However, both species differ greatly in the number of middorsal scale rows (171–184 in T. dugandi vs. 227–260 in E. goudotii ) precluding the neotype designation at this time. However, we redescribed specimens of T. dugandi from Barranquilla, which we consider as topotypes. These data can provide additional support to the diagnosis of the species and characterization, facilitating future comparisons and/or identifications.

Figures

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

FIGURE 8. Dorsal (A) and ventral (B) views of the topotype of Tricheilostoma dugandi (MCZ 58785).

FIGURE 9. Dorsal (A), lateral (B) and ventral (C) views of head of the Tricheilostoma dugandi (MCZ 58785).