Atractus zebrinus ( Jan, 1862 )
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publication ID |
https://doi.org/ 10.11646/zootaxa.2364.1.1 |
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DOI |
https://doi.org/10.5281/zenodo.5323934 |
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persistent identifier |
https://treatment.plazi.org/id/0390751B-3D5D-FFF8-FF61-FF3AFF0BBCF0 |
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treatment provided by |
Felipe |
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scientific name |
Atractus zebrinus ( Jan, 1862 ) |
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Atractus zebrinus ( Jan, 1862)
Figs. 18B View FIGURE 18 , 19 View FIGURE 19 , 20 View FIGURE 20
Rabdosoma zebrinum Jan, 1862 ; Arch. Zool. Anat. Fis. 2:15.
Rhabdosoma maculatus – Günther, 1858; Catalogue of the Colubrine Snakes in the British Museum:421. (part.). Atractus maculatus – Boulenger, 1894; Catalogue of the Snakes in the British Museum 2:306. (part.).
Atractus guentheri – Amaral, 1978; Serpentes do Brasil: Iconografia Colorida:114.
Atractus cf. guentheri – Lema, 1994; Comun. Mus. Ciênc. Tecnol. PUCRS, Sér. Zool. 7:105. (part.).
Atractus maculatus – Moura-Leite, Morato & Bérnils, 1996; Herp. Rev. 27:216.
Atractus zebrinus – Fernandes, Freire & Puorto, 2000; Bol. Mus. Nac. Nov. Sér. Zool. 419:4.
Holotype: Specimen without defined locality, originally housed at Museo Civico di Storia Naturale di Milano ( Jan 1862), believed to have been destroyed during the Second World War (S. Scali pers. comm.).
Diagnosis: Atractus zebrinus is distinguished from all congeners by the following combination of characters: (1) 17/17/17 smooth dorsal scale rows; (2) two postoculars; (3) loreal moderate; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) generally seven infralabials, first four contacting chinshields; (7) eight to ten maxillary teeth; (8) generally three gular scale rows; (9) generally three preventrals; (10) 149–170 ventrals in females, 136–153 in males; (11) 15–27 subcaudals in females, 20–32 in males; (12) dorsum creamish red with irregular transverse black blotches with white borders in adults; (13) venter immaculate creamish white; (14) moderate body size, with females reaching 600 mm SVL and males 457 mm SVL; (15) tail short in females (6.8–11.7% SVL), moderate to long (10.0–16.5% SVL) in males; (16) hemipenis slightly or moderate bilobed, semicapitate, and semicalyculate.
Comparisons: Among all congeners, A. zebrinus shares 17 dorsal scale rows, seven upper and lower labials, first four infralabiais contacting chinshields, usually three gular scale rows, seven to ten maxillary teeth, preserved specimens having pale dorsum with irregular transverse black blotches, venter creamish white only with A. maculatus . Atractus zebrinus differs from A. maculatus by having blotches with white borders in adults, ground colour creamish red, and capitulum shorter than hemipenial body (vs. blotches lacking white border, dorsal ground colour creamish yellow, and capitulum longer than hemipenial body).
Description: Head twice longer than wide, flattened in lateral view, sub-triangular in dorsal view; snout truncate in lateral view, round in dorsal view; canthus rostralis well marked in lateral view; cervical constriction barely distinct; rostral broader than high, sub-triangular in frontal, clearly visible in dorsal view; internasal as long as wide; internasal suture sinistral with respect to prefrontal suture; prefrontal as long as wide; supraocular sub-trapezoidal, twice longer than wide; frontal sub-triangular, as long as wide; parietal twice as long as wide; nasal divided; nostril restricted to prenasal; prenasal and postnasal about twice as high as long; loreal moderate, contacting second and third supralabials; pupil round; two postoculars of similar size; occasionally upper postocular longer than lower postocular; temporals 1+2; anterior temporal twice as long as high; upper posterior temporal generally elongate, about four times longer than wide; seven supralabials, third and fourth contacting orbit; second supralabial higher than first and smaller than third; sixth higher and seventh longer than remaining supralabials; symphisial sub-triangular, twice broader than long; seven infralabials, first four contacting chinshields; first pair of supralabials in contact behind symphisial, preventing symphisial/chinshields contact; chinshields twice longer than wide; three or four gular scale rows; generally three preventrals; 17/17/17 smooth dorsal scale rows; dorsals lacking apical pits, supra-anal tubercles, and keels; caudal spine moderate, robust, and rhomboid.
Maxillary arch: Slightly arched in dorsal view, with six to eight prediastemal and one or two postdiastemal teeth; prediastemal teeth large, generally of similar size, moderately spaced, curved posteriorly, angular in cross section, robust at base, narrower on the apices; maxillary diastema short; postdiastemal teeth half size of last prediastemal tooth; lacking lateral process.
Colour in preservative: Dorsum of head pale to dark brown with black blotches above frontal and parietals; background of head pale brown to dorsal margins of supralabials; supralabials, except for dorsal edges, uniformly creamish white; mental region, preventrals, venter, and tail immaculate creamish white; dorsal ground colour creamish red with 29–47 transverse black irregular blotches or bands (one to three scales long); blotches or bands alternated on the flanks, bands frequently connected to opposite one along vertebral region; blotches or bands white bordered, extending to third dorsal scale rows; tail dorsally similar to body pattern, with 4–9 transverse blotches or tiny crossbands. Adults from low latitudes tend to be melanic dorsally, with blotches little distinct from ground colour.
Juvenile colouration in preservative: Juveniles and sub-adults with dorsal ground colour beige to creamish red with narrow transverse blotches or tiny bands (one or two scales long), lacking white pigment on the blotch margins.
Colour in life: Adult dorsum beige to reddish brown to dark brown, covered with black blotches creamish red bordered; juveniles dorsum creamish red to red, covered with black blotches without contrasting border; ventral margins of supralabials and mental region creamish yellow; venter and tail immaculate creamish white ( Figs. 18 View FIGURE 18 , 20 View FIGURE 20 ).
Hemipenis morphology (everted organs n = 5): Retracted organ bifurcates at and extends to the level of eighth subcaudal. Hemipenis slightly moderately bilobed, semicapitate, and semicalyculate; lobes restricted to distal portion and generally weakly distinct from capitulum; lobes clavate and similar in size to remaining capitulum; lobes and capitulum covered with concentrated spinulate calyces; capitular groove evident on both sides of hemipenis; capitulum located at the level of sulcus spermaticus bifurcation; capitulum of similar size to hemipenial body; sulcus spermaticus bifurcates at the middle of organ; sulcus spermaticus oriented centrifugally, running to the tip of lobes; margins of sulcus spermaticus stout and narrow, bordered with spinules from the base of organ to lobes apices; hemipenial body sub-cylindrical uniformly covered with moderate hooked spines; basal naked pocket restricted to basal portion of hemipenial body; basal region of hemipenis with longitudinal plicae and disperse spinules ( Fig. 14F View FIGURE 14 ).
Variation: Largest male 457 mm SVL, 51 mm CL, largest female 600 mm SVL, 49 mm CL; tail 10.0– 16.5% SVL in males, 6.8–11.7% SVL in females; 136–153 (x¯ = 145.4; SD = 3.7; n = 52) ventrals in males, 158–174 (x¯ = 155.7; SD = 4.1; n = 61) in females; 20–32 (x¯ = 25.1; SD = 2.7; n = 52) subcaudals in males, 15– 27 (x¯ = 155.7; SD = 4.1; n = 61) in females; 6 (n = 2 sides) or 7 (n = 172 sides) infralabials; 3 (n = 4 sides) or 4 (n = 170 sides) infralabials contacting chinshield; 2 (n = 2 sides), 3 (n = 153 sides), or 4 (n = 17 sides) gular scale rows; 2 (n = 4), 3 (n = 66), or 4 (n = 7) preventrals; 7–11 (x¯ = 8.9; SD = 0.8; n = 87 sides) dorsal scale rows on the level of second subcaudal; 7 (n = 2 sides), 8 (n = 9 sides), 9 (n = 9 sides), or 10 (n = 3 sides) maxillary teeth; 3.0– 13.0 mm body diameter; retracted hemipenis bifurcates at and extends to seventh to 10 th subcaudal (n = 17).
Distribution: High mountain chains of southern and southeastern Brazil (Espinhaço, Mantiqueira, Serra dos Órgãos, Serra do Mar, and Paranapiacaba), from Santa Teresa (19º55’S, 40º36’W) in the state of Espírito Santo southward to Peritiba (27º22’S, 51º54’W) in the state of Santa Catarina, and also reaching the state of Minas Gerais up to Itabira (19º37’S, 43º13’W). Atractus zebrinus inhabits Submontane to Upper Montane Rainforest and Semi-decidous forests and Cerrado/Semi-decidous Forest transition zones between 500–1700 m ( Fig. 9 View FIGURE 9 ). Records of this species for localities below 500 meters are based on specimens labeled only with municipality's headquarters, without other data sources; all these municipalities are located at foothills of high mountains.
Remarks: Jan (1862) described Rabdosoma zebrinum on the basis of a specimen from an unknown source. Boulenger (1894) synonymized R. zebrinum with A. maculatus , and all subsequent authors followed this proposition, except for Amaral (1978) and Lema (1994) who identified specimens of A. zebrinus as A. guentheri . Fernandes et al. (2000) redescribed the holotype and reported additional individuals of A. maculatus , restricting the species concept to populations from the Brazilian state of Alagoas. Fernandes et al. (2000) resurrected A. zebrinus associating it with populations occurring from Bahia southward to Santa Catarina.
We examined nearly 100 specimens of A. zebrinus and agree with Fernandes et al. (2000) about the distinctness of A. zebrinus from A. maculatus (see also the remarks section for A. maculatus above). However, we could not confirm the identity of the specimen from Porto Seguro, Bahia (IBSP 57202), previously identified as A. zebrinus ( Fernandes et al., 2000) , because this individual is poorly preserved. Although Fernandes et al. ’s (2000) determination is most probably correct, we choose not to include this record in describing the species’ distribution, and prefer to wait for new material to confirm occurrence North of Itabira and Santa Teresa.
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