Tropidurus catalanensis Gudynas & Skuk, 1983

Kunz, Tobias Saraiva & Borges-Martins, Márcio, 2013, A new microendemic species of Tropidurus (Squamata: Tropiduridae) from southern Brazil and revalidation of Tropidurus catalanensis Gudynas & Skuk, 1983, Zootaxa 3681 (4), pp. 413-439 : 427-432

Tropidurus catalanensis Gudynas & Skuk, 1983 , revalidated

( Figs. 13–17 )

Tropidurus catalanensis Gudynas & Skuk 1983: 2 . Type locality: “from a hill 1 km 300 ESE of route Nº 30 and Catalán Grande stream (airline), Departamento de Artigas, Uruguay ”. MNHN 3489.

Tropidurus torquatus — Rodrigues 1987: 190 (Partim).

Tropidurus torquatus catalanensis — Cei 1993: 315.

Tropidurus catalanensis — Cei 2003: 135.

Holotype. Museo Nacional de Historia Natural, Uruguay ( MNHN) 3489; male, from a hill near route nº 30 and Arroyo Catalán Grande (airline), Departamento de Artigas, Uruguay; collected 30 March 1983 by L. Amato, E. Gudynas and G. Skuk; by designation on the original description ( Figure 13 ).

Diagnosis. Tropidurus catalanensis is distinguished from all congeners, except those of the torquatus group, by lacking a middorsal scale row and by having imbricate and keeled dorsal scales. From those of the torquatus group, except from T. torquatus and T. imbituba sp. nov., it can be distinguished by having folds and pockets of the type “A” (sensu Rodrigues 1987). From T. imbituba sp. nov. and T. torquatus , it differs in the yellow coloration of the chest and throat, more intense in adult males. From T. imbituba sp. nov. it also differs, with little overlap, in dorsal scale counts, ranging 104–130 (mean 116.9 ± 4.8) in males and 110–140 (mean 126.7 ± 6.8) in females, while in T. imbituba it ranges 99–113 (mean 104.9 ± 4.6) in males and 102–116 (mean 110.6 ± 3.7) in females.

Variation. Head length 21–25% of SVL; tail length 58–64% of total length; largest male presented 127.9 mm SVL; Smaller male with opaque and convoluted efferent ducts presented 79.1 mm SVL; largest female presented 98.8 mm SVL and the smaller female with oviductal eggs presented 72.7 mm SVL.

Frontal scales of the head generally convex in adults; 2–4 scales between the nasals; rostral contacting nasals in 37.3% of specimens; 10–15 scales between rostral and interparietal; 2–4 scale rows of enlarged supraoculars, generally three; 6–9 enlarged supraoculars in the first row (examples of the supraocular scuttelation patterns are in Gudynas & Skuk 1983, p. 4, fig. 1; Cei 1993, p. 319, fig. 49A; and Cei 2003, p. 135, fig. 2F); 4–7 supralabials to bellow the center of eye generally 5, followed by 3–7 (generally 4–5) small elongated scales to the commissure of mouth; supralabials contacting subocular in 60% of specimens, generally with 5th or 6th (rarely with both), and less frequently with 4th or 7th; 6–10 infralabials, generally 8–9; preauricular fringe with 4–9 spines, generally 7; 9–15 scales between the subocular and the preauricular fringe, generally 11–12; mental triangular or polygonal, followed by 2–5 (generally 3–4) angulated postmentals; first postmentals contacting one another in 13.8% of specimens; 2– 4 canthals, generally 3; 46–65 gular scales (mean 56.6 ± 3.8, n=216) (47–64 in Gudynas & Skuk 1983).

Two mite pockets under the oblique neck fold, the upper pocket is well developed and the lower one is poorly developed; antehumeral fold present; 2–3 axillary pockets, generally two; inguinal granular pocket present; 24–34 subdigital lamellae on the fourth toe (mean 29 ± 1.9, n=216) (26–32 in Gudynas & Skuk 1983); 18–25 scales on the dorsum of tibia (mean 21.6 ± 1.3, n=217), usually 21–23.

In the original description, Gudynas and Skuk (1983) stated that there were no significant sexual differences, thus, presenting all meristic and morphometric variables grouped for both sexes. Our data do not corroborate this statement in relation to dorsal scales and SAB. Males present 104–130 imbricate, mucronate and keeled dorsals (mean 116.9 ± 4.8, n=103), while females present 110–140 (mean 126.7 ± 6.8, n=110). Specimens from lowlands of southwestern Rio Grande do Sul and the vicinities of the mouth of the Paraguay River (northern Argentina and southern Paraguay) present the lowest means (113.2 ± 4.6 in males; 122.4 ± 4.7 in females) while those of the valleys of the upper Uruguay Basin present the highest means (119.8 ± 4.3 in males; 130.4 ± 5.5 in females).

Gudynas and Skuk (1983) presented vertebral and paravertebral scale counts, which ranged, respectively, 107– 131 and 110–142. Since lizards of the torquatus group lack a vertebral crest or enlarged vertebral scale rows, distinguishing vertebrals and paravertebrals is difficult, but these values are similar to what we found in our dorsal counts. SAB ranged 91–116 (mean 103.4 ± 5.4, n=97) in males, and 103–131 (mean 115.9 ± 6.6, n=105) in females (89–121 in the original description, for males and females grouped). As for dorsals, specimens from the lowlands of southwestern Rio Grande do Sul, northeastern Argentina and southern Paraguay present the lowest means (99.5 ± 3.2 in males, 110.5 ± 3.7 in females), and those of the upper Uruguay Basin, the highest means (106.5 ± 4.5 in males, 119.4 ± 5.6 in females). Ventrals 72–103 (mean 86.2 ± 6.1, n=214; the original description didn’t present variation of this character).

Color in life. Dorsal color is brown, gray or greenish, with an irregular pattern of black paravertebral patches and many yellow or cream spots in the dorsum of the trunk and limbs; yellow or cream spots are more numerous in males; black antehumeral band occupying 4–10 scale rows, separated from the opposite one by 3–35 scales (mean 15.7 ± 6.3); venter white or cream; adult males with femoral and preanal patches of black pigmented glandular scales; presence of midventral patches variable but rarely lacking in specimens larger than 100 mm SVL; temporal region usually bluish; adults with black gular patches; chin yellow with dark reticulations enclosing yellow blotches; yellow pigment reaches the chest and sometimes the infra and supralabials; yellow pigment lacking in juveniles and usually less evident, or lacking, in females.

Distribution. Northwestern Uruguay, northeastern Argentina, southern Paraguay and southern Brazil, reaching southwestern São Paulo and southeastern Mato Grosso do Sul extremes. In northwestern Uruguay and southwestern Rio Grande do Sul, the species is found on isolated rocky hills of low altitude regionally known as “cerros”. These hills are sparsely distributed along wide areas of campos (grassland) of the Pampa Biome. In the remaining areas, species distribution follows the course of the main tributaries of the Paraná and Uruguay Rivers (La Plata Basin). Along the valleys and canyons of these rivers, the species occurs mainly on isolated populations in rocky outcrops among areas originally covered by seasonal forests.

Remarks. The distribution of T. catalanensis in southern Brazil shows an interesting pattern, in association with river valleys and very restricted and localized populations, sometimes a hundred kilometers apart from other populations. The lack of gene flow between these populations is evidenced by some differences in meristic characters. For example, specimens from upstream of the Iguaçu river present, with high frequency, contact of the first post-mental with the opposite one (and, in this case, there is no contact of the gular scales with the mental scale). The frequency of this condition decreases downstream toward its mouth, and is rare in all other analyzed populations. Other variable condition is the contact between the nasals and the rostral scale, which is very frequent in some populations from southwestern Rio Grande do Sul (e.g. from São Francisco de Assis) and in those from Foz do Iguaçu (state of Paraná), but not frequent in other populations.

Populations of the river valleys inhabit rocky outcrops with abundant crevices. This punctual distribution pattern, at least in the low meanders of the Southern Brazilian Plateau, seems to indicate that the current climatic condition is unfavorable for the species (see Behling et al. 2009 for evidences of the climate dynamics of southern Brazil during the Holocene). These rocky outcrops represent the only natural open habitats among these river valleys, originally covered with seasonal forests. In addition, these river valleys and canyons retain milder climatic conditions in relation to the higher portions of the plateau. Despite the intense deforestation of the seasonal forests in southern Brazil, these populations have not expanded their occupation beyond the limits of the outcrops, pending in favor of the argument that the current climatic condition is unfavorable for the species expansion, at least in the Southern Brazilian Plateau. This situation is quite contrasting with the alleged opportunism of these lizards that, according to Rodrigues (1987), being good colonizers, would be expanding its distribution favored by deforestations (at least for the torquatus populations in the state of São Paulo). In fact, there is evidence to believe that the opposite is occurring in southern Brazil. Apparently, some populations have disappeared after the formation of reservoirs for hydroelectric dams on the Iguaçu River, in the state of Paraná (R.S. Bérnils, personal communication) and in the upper Uruguay Basin in the border of the states of Santa Catarina and Rio Grande do Sul (M. Borges-Martins, personal observation). Viability of populations of these saxicolous lizards could be conditioned to the maintenance of adequate habitats. In the surroundings of the Quebra-Queixo hydroelectric dam, on the Chapecó river (a large tributary of the Uruguay river), where rocks and crevices are very abundant, the species is also still abundant. For populations from southwestern Rio Grande do Sul, expansion of Eucalyptus spp. plantations in the vicinities of the rocky outcrops could result in shading and affect the viability of some of these populations (personal observations; see Pillar et al. 2009 for a discussion on the conservation of the southern Brazilian “ campos ”).

It is worth considering that the mainly saxicolous habit of the populations from Southern Brazil, Argentina and Uruguay ( Gudynas & Skuk 1983; Cei 1993; this study) differs in what Cei (1993) observed for populations from Corrientes ( Argentina), allegedly more arboreal. Still, the Atlas of Alvarez et al. (2002) shows that these populations are also distributed exclusively along the Parana River and in the vicinities of the Paraguay River mouth, both rivers of the La Plata Basin, as are the remaining populations.

Figures

FIGURE 13. Dorsal (left) and ventral (right) views of the holotype (MNHN 3489; SVL 114.8 mm) of Tropidurus catalanensis.

FIGURE 14. Tropidurus catalanensis from Iguaçu National Park, Foz do Iguaçu, Paraná, Brazil (not collected). Note the yellow coloration of chin, including infra and supralabials.

FIGURE 15. Tropidurus catalanensis from Campos Novos, Santa Catarina, near the Uruguay riverbank (not collected).

FIGURE 16. Tropidurus catalanensis from São Francisco de Assis, Rio Grande do Sul. Adult male (not collected).

FIGURE 17. Lateral view of head of Tropidurus catalanensis (UFRGS 5324) from São Francisco de Assis, Rio Grande do Sul, Brazil. Freshly killed subadult male (head length 21.4 mm).