Trilepida pastusa, Salazar-Valenzuela & Martins & Amador-Oyola & Abstract.-We & Hedges & Andes, 2015
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publication ID |
https://doi.org/ 10.5281/zenodo.13711839 |
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publication LSID |
lsid:zoobank.org:pub:3FC7DC45-E3D4-49B6-AEDD-3925A347665E |
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persistent identifier |
https://treatment.plazi.org/id/1876EC56-FFE5-FFFA-8F7A-D43FF34AD87E |
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treatment provided by |
Felipe |
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scientific name |
Trilepida pastusa |
| status |
sp. nov. |
Trilepida pastusa View in CoL sp. nov.
urn:lsid:zoobank.org:act:E7C8FF1C-07E8-4985-B673-80A52DACA8D1
Figs. 1–3 View Fig View Fig View Fig .
Holotype. — Adult female, QCAZ 8690 View Materials , collected on 23 February 2009 by O. Torres-Carvajal, S. Aldás-Alarcón, E. Tapia, A. Pozo and local people, surroundings of Chilmá Bajo on the way to Tres Marías waterfall (0°51’53.82” N, 78°2’59.23” W; 2071 m), Tulcán County, Carchi province, Ecuador. GoogleMaps
Paratypes. — Two specimens with same locality data as holotype : one juvenile female ( QCAZ 5778 View Materials ) collected on 21 February 2013 by D. Salazar-Valenzuela, H. Pozo, A. Chalapud, and D. Males, and one juvenile of undetermined sex ( QCAZ 5846 View Materials ) collected on 20 March 2013 by D. Salazar-Valenzuela and A. Loaiza-Lange .
Diagnosis.— Trilepida pastusa is distinguished from all congeners by the following combination of characters: Snout truncate in dorsal and ventral view, rounded in lateral view; supraocular present; ocular subhexagonal with superior border straight and anterior border barely rounded at eye level; rostral subtriangular in dorsal view, reaching anterior border of ocular scales; frontal as long as supraocular and other middorsal cephalic shields, except for postfrontal which is smaller; temporal distinct; supralabials three (2+1); infralabials four or five; body width relatively thick (TL/MB = 28.6–34.6); middorsal scales 203–214; midventral scales 182–193; subcaudal scales 18–19; fused caudals present; terminal spine conical, slightly longer than wide; scales around middle of tail 12; dorsum uniform gray; venter gray with interspaces between scales cream.
Comparisons ( Table 1).—Among all congeners, Trilepida pastusa is more similar to T. guayaquilensis and T. joshuai in sharing 12 scales around midtail, three supralabials, and a uniform dark dorsum and pale venter ( Pinto and Fernandes 2012). The new species differs from both by having an ocular with an anterior border barely rounded at eye level, a thick body (TL/MB = 28.6–34.6), and a coloration pattern consisting of a uniform gray dorsum and a venter with gray on the center and cream on the outside of each scale ( Figs. 3 View Fig , 4A View Fig ) (vs ocular with rounded anterior border, thin body [TL/MB = 48.6], and uniform brown color dorsally and pale brown ventrally in T. guayaquilensis ; ocular with rounded anterior border, moderate to thin body width [TL/MB = 34.0–55.2], and uniform dark brown dorsally and cream ventral scales in T. joshuai ) ( Orejas-Miranda and Peters 1970; Pinto and Fernandes 2012; Pinto et al. 2010; Rojas-Morales and González-Durán 2011). Moreover, T. pastusa differs from T. guayaquilensis in having a lower number of middorsal (203–214 vs 253, respectively) and midventral (182–193 vs 233, respectively) scales ( Orejas-Miranda and Peters 1970; Pinto and Fernandes 2012). The new species also differs from T. joshuai by having a higher number of middorsal (203–214 vs 174–199, respectively) and midventral (182–193 vs 165–187, respectively) scales, and a higher number of subcaudals (18–19 vs 13– 18, respectively) ( Pinto and Fernandes 2012; Pinto et al. 2010; Rojas-Morales and González-Durán 2011). Some specimens of T. macrolepis can have 12 scales around midtail (see Discussion), but T. pastusa differs from this species by having an ocular with barely rounded anterior border, thick body (TL/MB = 28.6–34.6), uniform gray dorsum and venter with gray on the center and cream on the outside of each scale, 203–214 middorsal scales, 182–193 midventral scales, 18–19 subcaudals, non-enlarged eyes, and rostral reaching ocular level in dorsal view (vs ocular with rounded anterior border, moderate to thin body width [TL/MB = 32.2–68.3], reticulate dark brown dorsally and reticulate pale brown ventrally, 211– 255 middorsal scales, 201–237 midventral scales, 16–24 subcaudals, enlarged eyes, and rostral not reaching ocular level in T. macrolepis ) ( Fig. 4 View Fig ) ( Pinto and Fernandes 2012; Pinto et al. 2010).
Description of the holotype ( Figs. 1 View Fig , 2 View Fig ). —Adult female, TL 315 mm, TAL 29 mm; MB 10.2 mm; MT 7.6 mm; TL/TAL 10.9; TL/MB 30.9; TAL/MT 3.8; HL 6.2 mm, HW 6.0 mm; relative eye diameter 3.1; relative rostral width 0.4. Body subcylindrical, robust, head slightly compressed compared to body and slightly tapered caudally near tail. Head subcylindrical, as long as wide and slightly distinguishable from neck. Snout slightly round- ed in dorsal and ventral views, rounded in lateral view; rostral straight in frontal and ventral views, subtriangular in dorsal view but with rounded apex, reaching imaginary transverse line between anterior border of oculars; rostral contacting supranasal and infranasal laterally, and frontal dorsally; nasal completely divided horizontally by oblique suture crossing nostril and descending posteriorly to contact first supralabial; nostril roughly ellip- tical, obliquely oriented and located in middle of nasal suture; supranasal higher than wider, bordering rostral anteriorly, infranasal inferiorly, first and second supralabials, and ocular posteriorly, and frontal and supraocular dorsally; supranasal ventral margin half the length of upper border of infranasal scale; infranasal about twice as high as wide, longer than any of the supralabials; upper lip border formed by rostral, infranasal, two anterior supralabials, ocular, and posterior supralabial; temporal distinct in size from dorsal scales of lateral rows; three supralabials, first two anterior to ocular and one posterior (2+1); first supralabial almost twice as high as wide, not reaching nostril and eye levels, second supralabial almost twice as high as wide, higher than first supralabial, reaching nostril level; third supralabial trapezoidal, as high as wide, reaching nostril level, its posterior margin in broad contact with temporal; ocular enlarged, subhexagonal, anterior border barely rounded at eye level, higher than wide, contacting posterior margins of supranasal and second supralabial anteriorly, parietal and third supralabial posteriorly, and supraocular dorsally; eye distinct (diameter = 0.7 mm), located in central area of upper part of ocular, displaced above nostril level; supraocular longer than wide, as long as frontal, between ocular and frontal, contacting supranasal anteriorly, frontal and ocular laterally, and parietal and postfrontal posteriorly; frontal, interparietal, and interoccipital subequal in size, hexagonal and imbricate, postfrontal smaller; frontal longer than wide, contacting rostral, supranasal, supraocular, and postfrontal; postfrontal as long as wide, contacting frontal, supraocular, parietals, and interparietal; interparietal as long as wide, contacting postfrontal, parietals, occipitals, and interoccipital; interoccipital wider than long, contacting interparietal, occipitals, and first dorsal scale of vertebral row; parietal and occipital subequal, irregularly heptagonal; parietal longer than occipital, twice as high as wide, lower margin contacting upper border of third supralabial, posterior margin contacting temporal, occipital, and interparietal, anterior border in contact with ocular, supraocular, and postfrontal; occipital twice as high as wide, its lower limit attaining upper margin of third supralabial, separated from the latter by temporal; symphysial trapezoidal, anterior border slightly concave and posterior border convex except in the middle, five times wider than high; four infralabials; first infralabial twice as high as wide; second infralabial as high as wide; third infralabial twice as wide as high and not pigment- ed; fourth infralabial as high as wide. Cephalic shields with uniformly scattered sensory pits. Middorsal scales 203; midventral scales 182; scales rows around middle of body 14, reducing to 12 rows in middle of tail; cloacal shield triangular, as wide as long; subcaudals 19; fused caudals present; terminal spine conical, slightly longer than wide; elongated cloacal sacs present. Dorsal scales
A new species of threadsnake from northern Ecuador homogeneous, cycloid, smooth, imbricate, and wider than long.
Coloration in preservative of the holotype ( Fig. 2 View Fig ). — Middorsal scales (i.e., seven longitudinal rows) bluish gray. The remaining seven scale rows forming the ventral and lateral sides of the body are occupied on the center by the same bluish gray color, but the margins of each scale are cream white; the latter pattern is less apparent on the anterior fourth of the body. Border of mouth, mental scale, nostrils and eyes are cream. Cloacal shield bluish gray except on its posterior margin, which is cream with bluish-gray dots.
Color variation. —Dorsal ground color of body similar to that of the holotype in one of the juveniles (QCAZ 5846), the other juvenile (QCAZ 5778) is dark gray; ventral coloration is similar in all specimens.
Color in life. —Dorsum uniform Dark Blue Gray (Color 194) ( Figs. 3A, 3C View Fig , 4A View Fig ), with upper part of head Brick Red (Color 36) on both juveniles ( Figs. 3C View Fig , 4A View Fig ). Venter of body and tail Dark Blue Gray, with interspaces between scales Cream White (Color 52) ( Figs. 3B, 3D View Fig , 4A View Fig ). Anal plate entirely Dark Blue Gray. After a few minutes of handling, the borders of each scale became apparent and they turned Pale Neutral Gray (Color 296) ( Fig. 3D View Fig ). Tongue Smoky White (Color 261).
Quantitative variation. —Scale counts in Trilepida pastusa vary as follows: middorsal scales 203–214 (x = 206.67 ± 6.35, n = 3); midventral scales 182–193 (x = 186 ± 6.08, n = 3); subcaudals 18–19 (x = 18.67 ± 0.58, n = 3); TL 315 mm (n = 1) in adult and 123–136 mm (x = 129.5 mm ± 9.19, n = 2) in juveniles; TAL 29 mm (n = 1) in adult and 9–12 mm (x = 10.5 mm ± 2.12, n = 2) in juveniles; TL/MB ratio 30.94 (n = 1) in adult and 28.63–34.55 (x = 31.59 ± 4.19, n = 2) in juveniles; TAL/ MT ratio 3.81 (n = 1) in adult and 2.67–3.41 (x = 3.04 ± 0.52, n = 2) in juveniles; infralabials 4 (n = 1) in adult and 5 (n = 2) in juveniles; relative eye diameter 3.07 (n = 1) in adult and 1.70–1.73 (x = 1.71 ± 0.02, n = 2) in juveniles; relative rostral width 0.37 (n = 1) in adult and 0.31–0.38 (x = 0.35 ± 0.05, n = 2) in juveniles.
Skull ( Fig. 5 View Fig ).—Premaxilla roughly rectangular in frontal and ventral views, edentulous, pierced by six foramina; transverse process of premaxilla absent and vomerian process double; nasals paired, approximately quadrangular dorsally, and pierced by a pair of foramina in lateral border of contact with prefrontals; nasal septum descending as medial vertical flanges; prefrontals paired, subtriangular in dorsal view; septomaxillae paired, complex in shape, expanding dorsally into the naris; conchal invagination absent; ascending process of premaxilla pierced by single large foramen; vomers paired, located midventral to vomeronasal cupola, bearing transversal arms, and with short posterior arms; frontals paired, nearly rectangular dorsally, without anterolateral projections to attach to prefrontals; frontal pillars absent; optic nerve restricted to lateral descending surface of frontals; maxilla edentulous, irregular in shape, pierced by three large juxtaposed foramina; posterior orbital element absent; parietal single, wide, representing largest bone of braincase; parabasisphenoid arrow-like, with tapered anterior tip lying bellow palatine, and fitting in medial line of vomeronasal cupola; parabasisphenoid with shallow pituitary fossa; basioccipital single and pentagonal; supraoccipitals fused into single unit, subpentagonal; prootics paired and triangular; large statolythic mass present in cavum vestibuli; crista tubelaris not enclosing juxtastapedial recess; stapedial footplate apparently not co-ossified with prootic; otoccipitals paired and rectangular; palatines paired and triradiate; anterior margin of maxillar process slightly flexing ventrally; pterygoids slender and rod-like, not contacting quadrate posteriorly, and not extending beyond the anterior margin of basioccipital; ectopterygoid indistinct; quadrate long and slen- der, about 50% of skull length; dentary supports a series of five teeth ankylosed to the inner surface of the anterolateral margin of dental concha; mental foramen nearly under the 3 rd –4 th teeth; splenial conical, representing smallest bone in lower jaw; anterior mylohyoid foramen absent on splenial; posterior milohyoid foramen on the ventral surface of angular; angular conical; compound bone pierced by two foramina in the surangular lamina, posterior surangular foramen large and anterior to the articular portion of compound bone, anterior surangular foramen located below the coronoid; coronoid rests on the compound bone.
Postcranial data. —Precloacal vertebrae 176–184 (x = 179 ± 4.16, n = 3); cervical vertebrae 6 + trunk vertebrae 170 (n = 1); caudal vertebrae 23–24 (x = 23.3 ± 0.6, n = 3), the last vertebrae representing the fusion of three vertebrae (n = 2). Correlation (n = 3) between middorsal scales and precloacal + subcaudal vertebrae (1:0.99), between midventral scales and precloacal vertebrae (1:1.02), and between subcaudal scales and caudal vertebrae (0.8:1). Pelvic girdle located at the level of the 171 st and 176 th precloacal vertebrae (QCAZ 5778), or 176 th precloacal and 2 nd subcaudal (QCAZ 8690). Pelvic girdle represented by four non-fused bones: ilium, ischium, femur, and pubis. Ilium, ischium, and femur rod-like; ilium represents the longest bone of pelvic girdle; femur stout.
Etymology.—The specific epithet is used as a noun in apposition. As explained in Coloma et al. (2010), pastuso or pastusa is a Spanish word used to refer to the inhabitants of the Pasto region in northern Ecuador and southern Colombia. Here, we also use it to recognize the presence of Los Pastos pre-hispanic culture (500–1500 CE) ( Delgado-Troya 2004), whose vestiges remain in the type locality and allowed the discovery of Trilepida pastusa and specimens of another cryptozoic snake species: Atractus savagei ( Salazar-Valenzuela et al. 2014) .
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