Atractus paraguayensis Werner, 1924

Passos, Paulo, Fernandes, Ronaldo, Bérnils, Renato S. & De Moura-Leite, Julio C., 2010, Taxonomic revision of the Brazilian Atlantic Forest Atractus (Reptilia: Serpentes: Dipsadidae) 2364, Zootaxa 2364 (1), pp. 1-63 : 24-30

publication ID	https://doi.org/ 10.11646/zootaxa.2364.1.1
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scientific name	Atractus paraguayensis Werner, 1924
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Figs. 8B View FIGURE 8 , 10 View FIGURE 10

Atractus paraguayensis Werner, 1924 ; Sitz. Akad. Wiss. Wien 133:40.

Atractus reticulatus paraguayensis – Amaral, 1930; Mem. Inst. Butantan 4:27.

Atractus taeniatus – Williams & Gudynas, 1991; Cont. Biol. 15:2.

Atractus paraguayensis – Fernandes, 1996; Comun. Mus. Ciênc. Tecnol. PUCRS, Sér. Zool. 8:39.

Atractus taeniatus – Lema, 1994:106; Fernandes, 1996:51; Moura-Leite, Morato & Bérnils, 1996:216; Giraudo & Scrocchi, 2000:83; Giraudo, 2001:28; Giraudo & Scrocchi, 2002:11; Passos, Fernandes & Zanella, 2005:211; Zaher, Souza, Gower, Hingst-Zaher & Jorge da Silva, 2005:29; Bérnils, Giraudo, Carreira & Cechin, 2007:19.

Atractus reticulatus – Vanzolini, 2000; Pap. Avul. Zool. 41:140.

Atractus paraguayensis – Giraudo & Scrocchi, 2002; Smithsonian Herp. Inform. Serv.132:10.

Atractus trihedrurus – Lema, 2005; Comun. Mus. Ciênc. Tecnol. PUCRS, Sér. Zool. 18:53.

Atractus paraguayensis – Passos, Fernandes & Borges-Nojosa, 2005:795; Prudente & Passos, 2008:731.

Holotype: Adult female, NMW 23443 (formerly NMW 130 View Materials ), collected by G. Wieninger, Paraguay (specimen examined).

Diagnosis: Atractus paraguayensis is distinguished from all congeners by the combination of the following characters: (1) 15/15/15 smooth dorsal scale rows; (2) usually two postoculars; (3) moderate loreal; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) usually seven infralabials, first four contacting chinshields; (7) eight or nine maxillary teeth; (8) usually three gular scale rows; (10) 147–167 ventrals in females, 136–162 in males; (11) 19–29 subcaudals in females, 21–33 in males; (12) dorsum beige with black paravertebral blotches, a single vertebral line, or both; (13) venter immaculate creamish white; (14) moderate body size, females reaching 490 mm SVL, males 375 mm SVL; (15) tail moderate in females (9.3– 14.8% SVL), moderate to long (12.7–18.1 % SVL) in males; (16) slightly bilobed, semicapitate, and semicalyculate hemipenis.

Comparisons: Among all congeners, A. paraguayensis shares 15 dorsal scale rows, seven upper and lower labials, first four infralabials contacting chinshields, creamish white occipital band, black collar on the neck, venter immaculate creamish white, and semicapitate and semicalyculate hemipenis only with A. reticulatus . Atractus paraguayensis differs from A. reticulatus by having a conspicuous vertebral line occasionally broken into paravertebral blotches, transverse blotches covering flanks, eight or nine maxillary teeth, and hemipenis slightly bilobed (vs. dorsum dark brown reticulate with pale colour on centre of scales, lacking transverse bands on the flanks, six or seven maxillary teeth, and moderately bilobed hemipenis).

Description: Head twice as long as wide, arched in lateral view, round in dorsal view; snout truncate in lateral view, round in dorsal view; cervical constriction indistinct; rostral sub-triangular, about twice as broad as high, poorly visible in dorsal view; internasal moderate; internasal suture sinistral with respect to prefrontal suture; prefrontal as long as wide; supraocular sub-trapezoidal slightly longer than wide; frontal sub-triangular, broader than long; parietal twice as long as wide; nasal divided; nostril restricted to prenasal; prenasal and postnasal twice as high as long; loreal moderate, contacting second and third supralabials; pupil round or subelliptical; one or two postoculars; upper postocular usually slightly higher and longer than lower postocular; temporals 1+2; anterior temporal twice as long as high; upper posterior temporal elongate, twice as long as wide; usually seven supralabials, third and fourth contacting orbit; first two supralabials of similar size and slightly smaller than third; sixth supralabial higher and seventh longer than remaining supralabials; symphisial triangular, twice as broad as long; generally seven infralabials, first four contacting chinshields; first pair of infralabials in contact behind symphisial, preventing symphisial/chinshields contact; chinshields three times longer than wide; generally three gular scale rows; usually three preventrals; 15/15/15 smooth dorsal scale rows; dorsals lacking apical pits, supra-anal tubercles, and keels; caudal spine, long, robust, and rhomboid.

Maxillary arch: Flattened in dorsal view, with five or six prediastemal and two or three postdiastemal teeth; prediastemal teeth large, moderately spaced, similar in size, curved posteriorly, angular in cross section, robust at base, and narrower on the apices; maxillary diastema short; postdiastemal teeth slightly smaller than last prediastemal tooth; lateral process well developed, lacking posterior projection.

Colour in preservative: Dorsum of head with black cap extending from rostral to anterior margin of parietals; occipital band (posterior region of parietal, temporals, and supralabials) creamish white or beige covering region between black cap and black collar; black collar disposed above first dorsal scale rows (two or three scales long), occasionally connected to vertebral body line; head black laterally, extending to middle of supralabials; first six supralabials creamish white with black dorsal edges; seventh supralabial generally uniform creamish white; gular region creamish white, occasionally with brown blotches covering first infralabials; venter and tail immaculate creamish white; dorsal ground colour variable, occasionally adults with vertebral line lacking transverse blotches on the paravertebral region; frequently adults with reddish brown ground colour and irregular vertebral line, sometimes broken into paravertebral blotches; generally paravertebral blotches connected to irregular vertebral line and/or barely defined paravertebral lines, constituting a variegated general pattern; adults occasionally with vertebral line entirely fragmented into transverse black blotches or irregular bands (two or three scales long and three or four scales wide), covering paravertebral region and flanks; sometimes individuals have a combination of latter two colour patterns; frequently first three scale rows are pale (pale brown) and small black dots (one or two scales wide) connected dorsally to transverse blotches ( Fig. 8B View FIGURE 8 ).

Juvenile colouration in preservative: Juveniles and sub-adults usually with beige ground colour and regular black vertebral line (one or two scales wide); juveniles rarely with vertebral line fragmented into paravertebral spots or transverse bands; sometimes youngs with irregular vertebral and paravertebral blotches.

Colour in life: Dorsum and lateral region of head (cephalic cap) grayish brown to black, generally with pale (beige) pigmentation concentrated on loreal region; occipital band white to pale brown (in melanic specimens); cephalic cap generally continuous with black collar through mid parietal suture; mental region white with disperse black blotches covering anterior infralabials mainly; venter and tail creamish white to creamish yellow; dorsal ground colour of body red, red orange, or reddish brown; dorsum covered with regular black vertebral line, frequently fragmented on black paravertebral blotches or conspicouous bands; line, blotches, or bands poorly distinct from ground colour on melanic individulas ( Fig. 10 View FIGURE 10 ).

Hemipenis morphology (everted organs n = 4): Retracted organ bifurcates and extends to the level of seventh subcaudal. Hemipenis slightly bilobed, semicapitate, and semicalyculate; lobes poorly defined and restricted to distal portion of capitulum; apices of lobes separated from each other by median calycular crest on distal portion of capitulum, with medial projections directed upward; lobes barely clavate with round tip, having spinules oriented dorsally; lobes and capitulum uniformly covered with spinulate calyces; calyces distributed irregularly on the intrasulcar and asulcate side of capitulum; lateral portion of capitulum on the sulcate side with calyces disposed transversally, forming well defined calyculate flounces; capitulum located just above sulcus spermaticus bifurcation; capitular groove distinct on both sides of hemipenis; capitulum of similar size to hemipenial body; sulcus spermaticus divides at middle of organ, in the distal portion of hemipenial body; branches of sulcus spermaticus with centrifugal orientation, running to tips of lobe projections; sulcus spermaticus margins narrow and stout, bordered with spinules from the base of the organ to tip of lobes; hemipenial body subcilyndrical, uniformly covered with moderate hooked spines; large spines located on lateral portion of sulcate side and medial region adjacent to capitulum on the asulcate side; basal naked pocket extending to distal portion of hemipenial body; basal portion of hemipenial body with longitudinal plicae and disperse spinules ( Fig. 6F View FIGURE 6 ).

Variation: Largest male 375 mm SVL, 54 mm CL, largest female 490 mm SVL, 65 mm CL; tail 8.8– 18.1% (x¯ = 14.9; SD = 1.4; n = 95) SVL in males, 6.3–14.8% (x¯ = 11; SD = 1.3; n = 112) SVL in females; 136– 162 (x¯ = 145; SD = 3.4; n = 96) ventrals in males, 147–167 (x¯ = 159.4; SD = 3.2; n = 123) in females; 21–33 (x¯ = 26.7; SD = 2; n = 96) subcaudals in males, 19–29 (x¯ = 23; SD = 2; n = 116) in females; 1 (n = 2 sides), or 2 (n = 182 sides) postoculars; 6 (n = 1 side), 7 (n = 410 sides), or 8 (n = 1 side) supralabials; 6 (n = 11 sides), 7 (n = 392 sides), or 8 (n = 4 sides) infralabials; 3 (n = 7 sides), 4 (n = 396 sides) or 5 (n = 3 sides) infralabials contacting chinshields; 2 (n = 5), 3 (n = 31) or 4 (n = 8) preventrals; 6–10 (x¯ = 7.8; SD = 0.8; n = 88 sides) dorsal scale rows on the level of second subcaudal; 8 (n = 25 sides) or 9 (n = 41 sides) maxillary teeth; 9 (n = 2) dentary teeth; retracted organ extends from fifth to ninth subcaudal (n = 20).

Distribution: Forests associated with the Paraná river basin, from Cascavel (24º56’S, 53º27’W) in the state of Paraná, Brazil, southward to Villa Urquiza (31º39’S, 60º22’W) in the province of Entre Rios, Argentina. Atractus paraguayensis inhabits riparian to Lower Montane Semi-deciduous Forest between 30–1000 m elevations ( Fig. 11 View FIGURE 11 ).

Remarks: Werner (1924) described A. paraguayensis on the basis of a single specimen from Paraguay, collected by George Wienienger but without more detailed data, although Vanzolini (2000) suggested that Wieninger's localities were all near Asunción. Werner (1924) compared A. paraguayensis with A. emmeli (another Atractus species having 15 dorsal scale rows) diagnosing the former by its single postocular (vs. two postoculars in A. emmeli ). Amaral (1930) considered A. paraguayensis to be a subspecies of A. reticulatus . Peters and Orejas-Miranda (1970) followed the arrangement proposed by Amaral (1930). Williams and Gudynas (1991) associated specimens of Atractus having 15 dorsal scale rows from northwestern Argentina with A. taeniatus (species previously synonymyzed with A. emmeli by McCoy 1971). Fernandes (1996) revised the A. reticulatus complex (see below) and considered A. paraguayensis a valid species, but did not include the Argentinean specimens reported by Williams and Gudynas (1991). Despite Fernandes’ (1996) argumentation, Vanzolini (2000) proposed that A. paraguayensis is a synonym of A. reticulatus , although without inspection of the holotype and examination of additional specimens, or any further justification. Giraudo and Scrocchi (2000) reported new specimens of A. paraguayensis from southeastern Paraguay and northeastern Argentina, but they identified specimens from northwestern Argentina as A. taeniatus , according with the proposition of Williams and Gudynas (1991). Specimens identified as A. taeniatus (sensu Williams & Gudynas 1991) were cited again from northeastern Argentina by Giraudo (2001) and also from southern Brazil by Lema (1994), Moura-Leite et al. (1996), Passos et al. (2005), and Bérnils et al. (2007).

Our examination of the holotype of A. paraguayensis , as well as photos and data from the holotype of A. taeniatus , revealed that Argentinean (e.g., Williams & Gudynas 1991; Giraudo & Scrocchi 2000; Giraudo 2001) and Brazilian (e.g., Lema 1994; Moura-Leite et al. 1996; Passos et al. 2005) populations previously referred to A. taeniatus are in fact A. paraguayensis . The results of our quantitative analyses were congruent in placing together populations from Argentina, Brazil, and Paraguay previously associated with A. taeniatus and/or A. paraguayensis . The principal orthogonal axes from DFA were unable to discriminate the holotype of A. paraguayensis from A. taeniatus groups based on any of the colour patterns and/or geographical populations for females as well males ( Fig. 12 View FIGURE 12 ).

The qualitative analyses of colouration, dentition, and hemipenial characters corroborate the morphometric results. Furthermore, the distribution of A. paraguayensis , as herein defined, provided additional insights for considering these populations within a single evolutionary unit associated with semideciduous forests in the Paraná River basin. Therefore, all populations referred to A. taeniatus in Brazil and Argentina are herein considered to be A. paraguayensis . The type of A. taeniatus would more usefully be considered in a study of A. emmeli and other similar Amazonian species of Atractus (P. Passos unpubl. data).

Finally, an old specimen of A. paraguayensis housed at the Instituto Butantan (IBSP 4784, dated from 03 December 1927) is labeled from the municipality of São Carlos, state of São Paulo, about 700 km from the northernmost record for the species (Cascavel, state of Paraná). Due to the improbability of this provenance, as well as that the fact the specimen was obtained at the beginning of the Butantan collection, we believe this may be labeled in error. Therefore, we decide to not include this record in the distribution of A. paraguayensis .