Description of the hemipenial morphology of Tupinambis quadrilineatus Manzani and Abe, 1997 (Squamata, Teiidae) and new records from Piauí, Brazil

Abstract Few data are available on the morphology of the hemipenis of teiid lizards, especially those of the recently-defined genus Tupinambis, a widely-distributed group of large-bodied lizards. This study provides an illustrated description of the hemipenis of Tupinambis quadrilineatus, which is similar to that of other representatives of the Tupinambinae subfamily. New records of the species from the state of Piauí, in northeastern Brazil, are also presented.


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The genus Tupinambis Daudin (Teiidae) comprises a group of large (maximum SVL of 400 mm) Neotropical lizards, which are distinguished from all other teiids by the combination of smooth dorsal scales, a single loreal, a gap in the granular scales separating the femoral from the abdominal pores, and a cylindrical tail with complete annuli alternating with annuli divided on the dorsal and lateral sides (Harvey et al. 2012). In a recent review of the Teiidae, Harvey et al. (2012) resurrected the genus Salvator Duméril and Bibron to refer to the species of the "southern clade" (sensu Fitzgerald et al. 1999) previously included in Tupinambis. These species are now known as Salvator merianae (Duméril & Bibron, 1839), S. rufescens (Günther, 1871) and S. duseni (Lönnberg, 1896). According to this scheme, the genus Tupinambis currently includes only the four species of the northern or "Amazonian" clade (sensu Fitzgerald et al. 1999) -Tupinambis longilineus Avila-Pires, 1995, Tupinambis palustris Manzani & Abe, 2002, Tupinambis quadrilineatus Abe, 1997, andTupinambis teguixin (Linnaeus, 1758). The genus Tupinambis is found in Colombia, Venezuela, Trinidad and Tobago, the Guyanas, the Amazon basin, and the savannas of Bolivia and Brazil (Harvey et al. 2012). Despite the conspicuous size of these lizards, zoogeographic data are sketchy, and new localities have been recorded recently for some species, such as T. longilineus Pimenta 2008, Costa et al. 2008) and T. quadrilineatus (Ferreira et al. 2009, Silveira 2009).
Tupinambis quadrilineatus is endemic to the Cerrado savannas of central Brazil. The species was described in 1997, based on four specimens from Goiás, Mato Grosso, and Tocantins Abe 1997, Silveira 2009). Almost simultaneously, Colli et al. (1998) described the same form under the junior-synonym Tupinambis cerradensis. A number of other specimens were collected subsequently in the Brazilian states of Goiás, Minas Gerais, Mato Grosso, Maranhão, Tocantins, Piauí, Pará and the Distrito Federal (Barreto et al. 2007, Ferreira et al. 2009, Silveira 2009, Dal Vechio et al. 2013. The geographic range of the species is extended further in the present study. The hemipenis of T. quadrilineatus is also described here for the first time. The hemipenial morphology of teiid lizards is poorly known (Harvey et al. 2012). Cope (1896) analyzed the hemipenis of the genera Dracaena, Tupinambis, Ameiva, and Cnemidophorus and concluded that the morphology of these typical teiid species consist of numerous delicate, imbricate, transverse laminae, which are closely attached to one another. Dowling and Duellman (1978, figure 83.2) published an illustration of the sulcate surface of the hemipenis of a species referred to as Tupinambis nigropunctatus Spix, 1825, however they did not provide a museum number, nor did they describe the organ. Presently, T. nigropunctatus is considered as a synonym of Tupinambis teguixin (Linnaeus, 1758), and its drawing exihibited a slightly bilobed and relatively long hemipenis, with distal laminae. In addition, the hemipenial morphology of 13 teiid species was described by Böhme (1988), but the author did not examine nor describe the hemipenis of Tupinambis.
Besides, Harvey et al. (2012) reviewed the taxonomy and phylogeny of the teiids and included descriptions of the hemipenes of a number of species of the subfamily Tupinambinae, including Crocodilurus amazonicus Spix, 1825 and Salvator merianae. This study shows that the hemipenis in the Tupinambinae can be characterized as an organ with transverse laminae, a pair of apical awns, and catchment folds. Awns are usually prominent subcylindrical structures, rounded at their distal ends, located at the apex of the lobes. The most elaborate sulcate catchment fold can be observed in Crocodilurus and Salvator, in which the portion of the fold closest to the sulcus projects outward as a prominent triangular flap. A summary of the hemipenial characters for the Teiidae subfamilies presented by Harvey et al. (2012) is shown in Table 1. The hemipenial morphology of Tupinambis nevertheless remains unknown, and the present paper provides a first detailed description of the organ in this genus.

Methods
Specimens were collected from a locality in the Cerrado savanna of the state of Maranhão and different phytophysiognomies in Piauí. The material examined is deposited in the herpetological collections of the Coleção de História Natural of the Universidade Federal do Piauí, Floriano, Piauí (CHNUFPI, curator: L. S. Carvalho) and the Museu Paraense Emílio Goeldi, Belém, Pará (MPEG, curator: A. L. C. Prudente). Museum abbreviations follow Levington et al. (1980). Scale counts, body measurements, and color pattern are based on the schemes of Manzani and Abe (1997) and Colli et al. (1998). The sex of the specimens was determined by the presence or absence of a hemipenis verified through an incision at the base of the tail. Hemipenis terminology follows Savage (1997), Myers et al. (1993) and Harvey et al. (2012), and the specimens were prepared as in Pesantes (1994), Manzani and Abe (1988) and Zaher and Prudente (2003).  Colli et al. 1998, Manzani and Abe 2002, Harvey et al. 2012). Hemipenial morphology. The hemipenis of three specimens of T. quadrilineatus (CHNUFPI 0036, CHNUFPI 0038 and MPEG 30139) were prepared for analysis. The organ is relatively long, robust and slightly bilobed, with a total length of 5.0 cm and a width of 2.0 cm in the distal portion of the body (Figure 1). When inverted, the organ extends as far as the fifteenth subcaudal scale. Sulcus spermaticus bifurcated, deep and centripetal. Edge of the sulcus spermaticus pronounced along its entire length. The point of bifurcation of the lobes extends inwardly towards the central region of the styloid process. A pair of short and prominent lobes (about 16% of the total size of the organ) in the form of styloid process are present on either side of the sulcate and asulcate surface, with a pair of catchment folds (extensions of the lips of the sulcus, in the form of prominent sulcal flaps, with rounded edges) coating the styloid process. The region between the lobes is smooth on both the sulcate and asulcate surfaces. Naked sulcate and asulcate expansion pleat. Between 35 and 38 distal laminae (mean = 36 ± 1, n = 3), arranged in a transverse row on each side, extending from just below the apical folds to the base of the lobes. A lateral sulcus separates the distal laminae from the sulcate and asulcate surfaces. Fifteen to 17 proximal laminae (mean = 16 ±1, n = 3). Basal region smooth on the sulcate surface, and wrinkled on the asulcate surface. Discontinuous laminae and basal papillae absent. Table 2. Scale counts of the specimens of Tupinambis quadrilineatus analyzed in the present study and the known range of values for the species, according to Manzani and Abe (1997) and Colli et al. (1998). The hemipenial morphology of T. quadrilineatus is similar to that of other Tupinambinae in the ornamentation of the body, which are bilobed and have lamelae (Cope 1896, Dowling and Duellman 1978, Harvey et al. 2012. As in Salvator merianae, Tupinambis teguixin and Crocodilurus amazonicus (Dowling andDuellman 1978, Harvey et al. 2012), the hemipenis of T. quadrilineatus lacks the discontinuous distal laminae seen in Ameiva ameiva and Ameivula ocellifera. However, S. merianae, formerly considered to be a member of the genus Tupinambis, has a relatively long hemipenis, which lacks the lateral and medial expansion pleats and has more laminae (distal laminae: 56-71 and proximal laminae: 33-40) than other teiids (Harvey et al. 2012). See Table 1 for the differences in the hemipenial morphology of three subfamilies of Teiidae (Harvey et al. 2012). The morphology and ornamentation of the hemipenis play an important role in the diagnosis of species, and have proven to be an excellent indicator of the phylogenetic relationships among taxa (Cope 1896, Böhme 1988, Harvey et al. 2012. Harvey et al. (2012) concluded that the relationships among the genera of Tupinambinae, especially Tupinambis and Salvator, require further study, and that a more detailed analysis of hemipenial morphology, as well as muscles and osteology, may contribute to a more definitive understanding of the systematics of the group.
Geographic distribution. The Tupinambis specimens available in Brazilian collections were examined together with the eight T. quadrilineatus specimens collected during the present study, in Maranhão and Piauí (Figure 2). The localities reported here represent the northernmost known records of T. quadrilineatus, and extend the known distribution of the species at least 500 km from the nearest locality, in Balsas, Maranhão (Barreto et al. 2007). This is the northernmost record of the occurrence of the species.
Five T. quadrilineatus specimens were examined in the collection of the Goeldi Museum. In 1993, specimen MPEG 16817 was collected in Balsas, Maranhão (reported by Barreto et al. 2007), and specimen MPEG 16845 was captured in the municipality of Lagoa Alegre, Piauí. In 2009, three specimens were collected during the Parnaiba Project in Ribeiro Gonçalves (MPEG 30139), and Uruçuí (MPEG 30141), in the state of Piauí, and São Raimundo das Mangabeiras (MPEG 30140), in Maranhão.  (26). The localities recorded in the present study are represented by red squares. The type-locality of T. quadrilineatus is shown as an asterisk, the type-locality of its junior-synonym (Tupinambis cerradensis) is shown as a star and remaining records from the literature are shown as blue circles (Manzani and Abe 1997;Colli et al. 1998;Guimarães et al. 2007;Silva Jr. et al. 2005;Vitt et al. 2005;Mesquita et al. 2006;Recoder and Nogueira 2007;Ferreira et al. 2009;Silveira 2009;Recoder et al. 2011;Dal Vechio et al. 2013). The Cerrado savanna biome is highlighted in gray.
The herpetological collection of the Universidade Federal do Piauí provided specimens or records of T. quadrilineatus from a number of sites in Piauí. Specimen CHNUFPI 0036 ( Figure 3A) was collected in 2010 in the Palmares National Forest (05°02'55"S, 42°35'59"W, SAD69), in the municipality of Altos. The vegetation of this area is semi-deciduous tropical forest typical of the Cerrado, an ecotonal region between Cerrado and Amazonia biomes, similar to that found in Lagoa Alegre. Tupinambis quadrilineatus occurs in syntopy with S. merianae in this area, as recorded at a number of other sites (Colli et al. 1998, Silveira 2009). Also in 2010, a roadkilled specimen of T. quadrilineatus (CHNUFPI 0037) was collected in the municipality of Monsenhor Gil (05°39'56"S, 42°35'28"W, SAD69). In May 2011, the third and final T. quadrilineatus specimen held in the collection (CHNUFPI 0038; Figure 3B-D) was collected in a pitfall trap installed in the vicinity of a small stream within an area dominated by Cerrado savanna (sensu strictu) in the municipality of Guadalupe (05°2'55"S, 42°35'59"W, SAD69). Two other specimens were observed in the municipality of Amarante (06°14'43"S, 42°46'46"W and 06°2'1"S, 43°3'40"W, SAD69) in 2009 and 2011, but specimens were not collected. In this area, the vegetation was dominated by secondary semi-deciduous tropical forest, mixed with patches of Cerrado sensu strictu. These findings expand the geographic distribution of T. quadrilineatus is northwards, and encompass the the region between the states of Piauí and Maranhão, which is dominated by Cerrado sensu strictu and/or forested patches of the Cerrado-Amazon ecotone. In this region, T. quadrilineatus also occurs in syntopy with Salvator merianae, which was previously classified as a member of the genus Tupinambis.