Boiruna maculata ( Boulenger 1896 )

Scott Jr., Norman J., Giraudo, Alejandro R., Scrocchi, Gustavo, Aquino, Aida Luz, Cacciali, Pier & Motte, Martha, 2006, THE GENERA BOIRUNA AND CLELIA (SERPENTES: PSEUDOBOINI) IN PARAGUAY AND ARGENTINA, Papéis Avulsos de Zoologia (São Paulo) 46 (9), pp. 77-105 : 80-86

Boiruna maculata ( Boulenger 1896)

Oxyrhopus maculatus Boulenger, 1896: Original description, type locality: Uruguay

Oxyrhopus occipitoluteus ; Boulenger, 1896: Asunción, Paraguay

Oxyrhopus occipitoluteus ; Koslowski, 1898: Argentina

Oxyrhopus Cloelia (part.); Serié, 1915: Departamento Central, Paraguay

Pseudoboa occipitolutea ; Serié, 1921: Chaco, Argentina

Pseudoboa maculata ; Amaral, 1925: Mendoza, Argentina

Pseudoboa cloelia ; Saporiti, 1946: Salta, Argentina

Pseudoboa cloelia ; Abalos et al., 1964: Santiago del Estero, Argentina

Pseudoboa maculata ; Abalos et al., 1964: Santiago del Estero, Argentina

Clelia clelia clelia ; Freiberg, 1968: Argentina

Clelia occipitolutea ; Bailey, 1970: Argentina and Paraguay

Clelia clelia clelia ; Abalos & Mischis, 1975: Argentina

Clelia occipitolutea ; Abalos & Mischis, 1975: Argentina

Clelia occipitolutea ; Scott & Lovett, 1975: Paraguayan Chaco

Clelia occipitolutea ; Gallardo, 1979: Argentina

Clelia clelia clelia ; Laurent & Terán, 1981: Tucumán, Argentina

Clelia occipitolutea ; Laurent & Terán, 1981: Tucumán, Argentina

Clelia clelia clelia ; Di Fonzo de Abalos & Bucher, 1981: Córdoba, Argentina

Clelia occipitolutea ; Di Fonzo de Abalos & Bucher, 1981: Córdoba, Argentina

Clelia clelia ; Di Fonzo de Abalos & Bucher, 1983: Córdoba, Argentina

Clelia occipitolutea ; Di Fonzo de Abalos & Bucher, 1983: Córdoba, Argentina

Clelia clelia clelia ; Cei, 1986: Western, central and southern Argentina

Clelia occipitolutea (part.); Cei, 1986: Western, central and southern Argentina

Clelia clelia ; Böckeler, 1988: Paraguayan Chaco

Clelia occipitolutea ; Böckeler, 1988: Paraguayan Chaco

Clelia clelia ; Yanosky, 1989a,b: Formosa, Argentina

Clelia occipitolutea ; Yanosky, 1989b: Formosa, Argentina

Clelia clelia ; Bergna & Álvarez, 1990: Northeastern Argentina

Clelia rustica ; Bergna & Álvarez, 1990: Northeastern Argentina

Clelia clelia clelia (part.); Scrocchi & Viñas, 1990: Argentina

Clelia clelia ; Cruz et al., 1992: Salta, Argentina

Clelia clelia clelia (part.); Cei, 1993: Eastern Argentina

Clelia clelia ; Yanosky et al., 1993: Formosa, Argentina

Clelia spp. ; Norman, 1994: Paraguayan Chaco

Clelia clelia clelia ; Vuoto, 1995: Entre Ríos, Argentina

Clelia clelia clelia ; Lavilla et al., 1995: Salta, Argentina

Clelia clelia ; Álvarez et al., 1995: Departamento Itapúa, Paraguay

Clelia clelia (part.); Álvarez et al., 1996: Corrientes, Chaco, and Formosa, Argentina

Clelia rustica ; Álvarez et al., 1996: Corrientes, Chaco, and Formosa, Argentina

Clelia clelia (part.); Aquino et al., 1996: Paraguay

Clelia rustica ; Aquino et al., 1996: Paraguay

Boiruna maculata ; Zaher, 1996: Argentina

Clelia clelia ; Yanosky et al., 1996: Formosa, Argentina

Boiruna maculata ; Giraudo & Arzamendia, 1997b: Santa Fe, Argentina

Boiruna maculata ; Leynaud & Bucher, 1999: Gran Chaco

Boiruna maculata ; Cabrera, 2001: Interior Argentina

Boiruna maculata (part.); Giraudo & Scrocchi, 2002: Argentina

Boiruna maculata (part.); Giraudo, 2002: Northeastern Argentina

Boiruna maculata (part.); Álvarez et al., 2002: Chaco, Formosa, and Corrientes, Argentina

Boiruna maculata (part.); Arzamendia & Giraudo, 2002: Santa Fe, Argentina

Clelia clelia ; Ziegler et al., 2002: Paraguayan Chaco

Boiruna maculata ; Scrocchi & Giraudo, 2005: Formosa, Argentina

Taxonomic History – Oxyrhopus maculatus was described from Uruguay by Boulenger (1896). However, based on the high number of ventral scales, Boulenger’s O. occipitoluteus from Asunción, Paraguay almost certainly belongs to the same taxon, as do some of his Brazilian specimens listed under O. cloelia . Until recently, these three names have continued to be applied to the large species, usually with dark posterior ventrals, that is distributed from the Atlantic Ocean in southern Brazil, south through Argentina, Paraguay, and Uruguay as far La Pampa Province, Argentina, and east to the Andean foothills in Argentina.

Zaher (1996) cleared up most of the confusion when he reviewed Clelia throughout its range. He determined that the original description of Brachyrruton occipitoluteum of Duméril, Bibron, and Duméril 1854 is a synonym of Pseudoboa coronata Schneider 1801 , and that Oxyrhopus maculatus Boulenger 1896 was the proper original description for this species. Zaher (1996) then used the taxon as the type species of a new genus Boiruna . Since then, the name Boiruna maculata has been widely applied in Paraguay and Argentina, although C. clelia has also been included under that designation in recent literature (e.g., Giraudo & Scrocchi 2002, Álvarez et al. 2002).

Diagnosis – Boiruna maculata in Paraguay and Argentina can generally be distinguished from all species of Clelia except C. plumbea by its larger number of ventrals (212-247; Appendix 4, Fig. 4 ). There is some overlap in the number of ventrals in female C. clelia (maximum 218) and female B. maculata (minimum 214), and male C. clelia (maximum 213) and male B. maculata (minimum 212).

A lack of spines between the arms of the divided sulcus spermaticus (intrasulcal spines) was one of the diagnostic characters that Zaher (1996) used to distinguish the genus Boiruna from Clelia , and these spines were lacking in all of the B. maculata that we examined. However, two of our 7 males of C. clelia are missing one or both of the usual pair of intrasulcal spines (Appendix 2).

Large juvenile and adult B. maculata have dark pigmentation on the entire scale in the posterior ventrals and subcaudals ( Zaher, 1996; Giraudo, 2002). Clelia rustica may rarely have the posterior ventrals almost entirely black, but there is almost always a clear central portion. Other species of Clelia have mostly clear, ivory-colored ventrals; the dark dorsal coloration invades only the lateral tips and part of the free edges of the ventrals, never covering the entire scale.

Among the larger species, the average B. maculata is slightly longer than C. rustica and shorter than C. clelia and C. plumbea ( Fig. 3 ). The tail of B. maculata is relatively shorter than all others except female C. rustica ( Fig. 5). Like C. clelia , C. plumbea , and C. rustica , B. maculata usually has 7 supralabials on each side (Appendix 1).

The dark dorsal stripe distinguishes hatchling B. maculata from other hatchlings in our area except C. bicolor and C. quimi . The smaller size of hatchling C. bicolor (~ 180 mm total length) and C. quimi (~ 205 mm) should serve to separate them from B. maculata (~ 350 mm), as do the numbers of supralabials and ventrals.

Description – Detailed descriptions, drawings, and photographs of B. maculata in the Southern Cone are found in Boulenger (1896; as O. maculatus and O. occipitoluteus ), Abalos et al. (1964; as P. cloelia and P. maculata ), Achaval (1973; as C. occipitolutea ), Cei (1986; as C. clelia ; his C. occipitolutea seems to be a composite of B. maculata and C. rustica ), Böckeler (1988; as C. clelia and C. occipitolutea ), Scrocchi & Viñas (1990; as C. clelia clelia ; their paradigm included two specimens of true C. clelia ), Lavilla et al. (1995 as C. c. clelia ), Achaval & Olmos (1997 as C. occipitolutea ; 2003), Giraudo (2002; one of his specimens is a C. clelia ), Achaval & Olmos (2003), Scrocchi & Giraudo (2005), Carreira et al. (2005) and Figure 6 . Zaher’s (1996) description of B. maculata covers a wider geographic area, and the details are not always pertinent to our area.

The total lengths of the smallest and largest of 47 B. maculata were 351 mm and 1800 mm, respectively. There seems to be no significant difference in size between the sexes (t-test; P>0.75).

Boiruna maculata in Paraguay and Argentina has 212-247 ventrals, 52-84 subcaudals, and 7 supralabials (rarely 8; Appendix 1 and 4). The single loreal scale is generally slightly smaller than that of C. clelia , contacting only the second supralabial in almost half of 21 specimens (Appendix 3, Fig. 2B ) .

Zaher (1996) gave a detailed description and photograph of the hemipenis of B. maculata . The sample that Zaher (1996) observed had longitudinal rows of 13-17 spines, or a total of 26-34, on both sides of the sulcus spermaticus. The 13 specimens in our sample lacked intrasulcal spines and had 13-39 spines in the extrasulcal position (Appendix 2).

Hatchling B. maculata have the top of the head black or dark brown, fading to dusky on the supralabials. There is a pale nape band that can be white, yellow, or orange. Hatchlings from a clutch of 6 eggs from FML 13376 had either white or orange nape bands. Hatchlings have a black medial dorsal stripe 13 scale rows wide. The lateral three scale rows on each side are red or orange with black tips. The ventrals are opalescent white. The subcaudals are white with black margins where the scale pairs meet, forming a zigzag line down the underside of the tail. Lavilla et al. (1995), Giraudo (2002), and Achaval & Olmos (1997, 2003) have photographs of juveniles. The coloration of hatchling B. maculata is similar to that of some hatchling C. bicolor (e.g., Giraudo 2002), although the former is about twice as long ( Fig. 3 ).

As the juvenile grows, the black color on the tips of the lateral scales and the scales of the nape band expands, gradually obscuring the paler colors. The lateral scales are gray or black in most adults, although some retain a reticulated pattern of pale brown to red dark-tipped lateral body scales, especially anteriorly. A faint indication of the pale nape band can be seen in many small adults. Posterior ventrals and subcaudals gradually become uniformly black or dark gray.

Most adult B. maculata are a solid dark gray or black dorsally ( Fig. 6 ). The underside of the head and anterior ventrals are clear ivory, with dark dorsal color on the tips of the anterior ventrals; this color invades the entire ventral scale on the posterior body and tail ( Zaher, 1996; Giraudo, 2002). Some specimens show extensive reticulated areas on the lateral, anterior portion of the body, where the dorsal scales are pale with dark edges (e.g., Cei, 1993: Plate 83-3). Specimens with this coloration are responsible for erroneous reports of C. rustica in Paraguay (e.g., Aquino et al., 1996) and probably Argentina (e.g., Bergna & Álvarez, 1990).

Boiruna maculata shares, with C. clelia , C. plumbea , and species of Pseudoboa , the peculiarity that some specimens are irregularly spotted with varying amounts of white (e.g., Boulenger 1896, Cei 1993; Giraudo 2002). In the most extreme cases, the snake is almost completely white with a few small pigmented patches (e.g., CENAI 2738, UNNEC 4846).

Distribution – Boulenger (1896) described Oxyrhopus maculatus from Uruguay and recorded O. occipitoluteus from Asunción, Departmento Central, Paraguay. This was the first report of Boiruna maculata from the study area.

Range wide, B. maculata is found from southeastern Bolivia and Brazil south of the Amazonian wet forest and east of the Andes , south through Paraguay, Uruguay , and Argentina ( Zaher 1996; Achaval Elena 2001, as C. occipitolutea ). In the study area, the species ranges from the northern borders of Argentina and Paraguay , south as far as 36°S latitude in Argentina ( Fig. 7 ) . It occurs in an enormous range of habitats from Monte desert and dry Chaco to the wet Atlantic forests of Misiones Province and coastal Brazil .

Figures

FIGURE 2. Diagrams of the lateral head squamation in Boiruna and Clelia. A) C. clelia (MNHNP 3840); B) C. plumbea (MNHNP 3059); C) Boiruna maculata (MNHNP 7674); D) C. bicolor (MNHNP 2616); E) C. rustica (FML 2766).

FIGURE 3. Total lengths of Boiruna and Clelia from Argentina and Paraguay.

FIGURE 4. Distribution of ventral counts in female and male Boiruna and Clelia from Paraguay and Argentina.

FIGURE 6. Boiruna maculata. FML 2494, Finca “Los Colorados”, Salta Province, Argentina. A large juvenile retaining some reddish coloration on the sides. Photo by G. Scrocchi.

FIGURE 7. Geographic distribution of Boiruna maculata in Paraguay and Argentina.