Tropidurus chromatops Harvey & Gutberlet, 1998 (Squamata, Tropiduridae): first records from and range extension to the Beni Department, Bolivia

. We present the first records of Tropidurus chromatops Harvey & Gutberlet, 1998 from the Beni Department (Bolivia) and extend this species’ distribution to western Bolivia by approximately 256 km in a straight line to the Beni Floodplains ecoregion. Likewise, we contribute information on some aspects of the natural history, altitude of occurrence, and the geographic distribution of T. chromatops in the Department of Beni.


Introduction
At the end of the last century, Harvey and Gutberlet (1998) described three new species of endemic lizards of the genus Tropidurus-Tropidurus callathelys Harvey & Gutberlet, 1998;Tropidurus chromatops Harvey & Gutberlet, 1998;and Tropidurus xanthochylus Harvey & Gutberlet, 1998-discovered from near the Bolivian Precambrian formations, currently Serranía de Huanchaca in the Parque Nacional Noel Kempff Mercado (Noel Kempff Mercado National Park) in the Department of Santa Cruz, Bolivia.
In 2014, T. chromatops and T. callathelys were confirmed in Parque Estadual Serra Ricardo Franco, Mato Grosso, Brazil and the distributions of these species were extended 176 and 89 km east across the Brazilian border, respectively (Morais et al. 2014). The habitat, topography, and biogeography are contiguous in this area, enabling these species to occur in both countries (Litherland and Power 1989;Harvey and Gutberlet 1998;Navarro and Maldonado 2011;Morais et al. 2014).
Tropidurus chromatops is a saxicolous and heliophilous species that occurs in the Serranía de Huanchaca, the Serra Ricardo Franco, and areas surrounding each of these mountain ranges (Harvey and Gutberlet 1998;Morais et al. 2014). Furthermore, this species is sympatric with T. callathelys (Harvey and Gutberlet 1998;Carvalho 2013;Morais et al. 2014). Tropidurus chromatops differs from T. callathelys by a lack of a vertebral crest and tufts of neck spines (present in T. callathelys), seven preauricular spines (2-5 in T. callathelys), and facial coloration pattern complex in males (dark olive-brown with white spots in T. callathelys) (Harvey and Gutberlet 1998;Morais et al. 2014). However, Harvey and Gutberlet (1998) and Morais et al. (2014) indicated that T. callathelys occurs exclusively in dense rock outcropings, prefers more direct sunlight and vertical surfaces, and is less active than T. chromatops.
Information on population dynamics, distribution, and natural history of T. chromatops is scarce in the literature (Harvey and Gutberlet 1998;Dirksen and De la Riva 1999;Cortez 2009;Carvalho 2013;Morais et al. 2014;Carvalho et al. 2018;Azurduy and Maillard 2022). In this article, we present new occurrence records of T. chromatops from the Department of Beni, Bolivia. This information contributes to our understanding the geographic distribution, natural history, and ecology of T. chromatops in Bolivia and will be helpful in the creation of conservation measures.

Methods
In June 2007 and February-March 2023, we surveyed the herpetology of the Cerro Oricore (Fig. 1), a rock outcrop on the banks of the San Martin River in the Parque Departamental y Area Natural de Manejo Integrado Iténez (PDyANMI Iténez) in the Department of Beni, Bolivia. This departmental protected area is represented by Amazonian Forest, floodplains of Beni, and influenced by Cerrado in the Precambrian Shield (Navarro and Maldonado 2011).
During daytime and nighttime surveys, we collected five specimens of Tropidurus chromatops. All specimens were captured by hand in exposed rock outcrops. Snout-vent lengths (SVL) and tail lengths (TL) were measured for all captured individuals, and weights in grams were obtained using an Ohaus model HH 320 electronic balance after euthanasia of the specimens. For morphometric data (i.e. number of head and body scales, lamellae on fourth toe, mite pockets, femoral pores, and others structures) we used an Olympus SZX10 DF PL 0.5X stereomicroscope. We also determined sex and photographed each individual following the methodology outlined by Eversole et al. (2019).
All collected specimens were deposited in the herpetological collections of the Museo de Historia Natural Alcide d'Orbigny (MHNCR), Cochabamba and the Centro de Investigación de Recursos Acuáticos (CIRAH), Beni, Bolivia. Specimens were identified as T. chromatops by comparison with the original description of the species (Harvey and Gutberlet 1998) and additional sources of information (Harvey and Gutberlet 2000;Frost et al. 2001;Morais et al. 2014). We follow the scutellation and terminology by Frost (1992) and Harvey and Gutberlet (1998).
Geographic coordinates of collected specimens were obtained in decimal degrees (WGS84 datum) using a Garmin etrex GPS receiver. A map was prepared using ArcGIS software (ArcMap 10.1) and including our new records of T. chromatops and those reported by Harvey and Gutberlet (1998), Morais et al. (2014), and Azurduy and Maillard (2022). Identification. The coloration, pattern, morphometric, and meristic data of the specimens (Table 1) are congruent with the descriptions by Gutberlet (1998, 2000) as well as others (Frost et al. 2001;Morais et al. 2014;Carvalho et al. 2018). All specimens of T. chromatops studied had the following combination of morphological characters: a) vertebral crest and tufts of neck spines absent (vs. vertebral crest and tufts of neck spines present in T. callathelys); b) preauricular fringe complete, consisting of a row of seven spines, and ear canal deep in adults (vs. preauricular fringe with granular scales and a lower cluster of 2-5 spines in T. callathelys); c) tail longer than combined length of head and body, cylindrical, and not armed with heavy mucrons (vs. tail longer than the head + body in T. callathelys); d) two deep, subequal mite pockets medial to oblique neck fold (vs. pair of deep, ventrolateral mite pockets medial to antegular fold in T. callathelys); e) 0-1 patches of granular scales behind axilla, not forming a pocket (vs. axillary granular pocket absent in T. callathelys); f) 25-29 subdigital lamellae under the fourth toe (vs. 27-32 subdigital lamellae in T. callathelys); g) complex facial color pattern in males, back without large yellow spots (vs. dark olive-brown with white spots in T. callathelys); h) midventral patch of black granular scales in males (vs. absent in T. callathelys). Additionally, the first postmental contacts the first infralabial, supralabials, and enlarged infralabials Gutberlet 1998, 2000). The SVL of the male (MHNCR 230) measures 98.6 mm, and the four females (MHNCR 231, CIRAH-1009-1011) measure 78-90 mm (Table 1); these SVL values are slightly greater than the range given by Harvey and Gutberlet (1998) in their description of T. chromatops.

Tropidurus chromatops
The color pattern in life is similar to that described by Harvey and Gutberlet (1998); however, individuals from Cerro Oricore exhibit mostly marked shades of blue in the lateral regions of the head and body, on the extremities, and on the tail, especially in males (Fig. 3A).

Discussion
Tropidurus chromatops is known to be elusive and often seeks out rock crevices, thorny bushes, and adjacent trees (Harvey and Gutberlet 1998). Additionally, this species is known to occur in areas with frequent exposure to sunlight, and it is active during most of the daylight hours (Harvey and Gutberlet 1998). The diet of T. chromatops consists of a variety of insects but primarily is comprised of ants (Harvey and Gutberlet 1998). The specimens observed in Cerro Oricore exhibited similar behavior to what Harvey and Gutberlet (1998) and Morais et al. (2014) described; however, we observed that their feeding activity, on mainly flying insects,  Tropidurus chromatops inhabits a complex mosaic of Cerrado vegetation and savannas with patches of isolated forests and scattered streams in the Serranía de Huanchaca and Serra Ricardo Franco in the Bolivian and Brazilian Cerrado, respectively. It also inhabits Chiquitano forest in both Bolivia and Brazil, but there it is closely associated with rocky outcrops (Harvey and Gutberlet 1998;Carvalho 2013;Morais et al. 2014;Azurduy and Maillard 2022) (Fig. 2). Although T. chromatops is known to occur along an altitudinal gradient of 300-500 m in the Serrania de Huanchaca, Bolivia and between 630-660 m in the Serra Ricardo Franco, Brazil (Harvey and Gutberlet 1998;Morais et al. 2014), we found this species at lower altitudes between 160 and 245 m in Cerro Oricore, Bolivia (Fig. 1). It is possible that these lower altitudinal records are at lower limit of the altitudinal gradient of the rock outcrops where T. chromatops is known to occur.
Brazilian populations of T. chromatops are more fragmented than Bolivian populations, possibly as a result of agricultural practices and timber extraction (Morais et al. 2014;IUCN 2023), and Bolivian populations may more stable because of their location Parque Nacional Noel Kempff Mercado, a large protected area (Harvey and Gutberlet 1998). It is possible that T. chromatops may have a broader distribution than currently known, but its populations are likely to be naturally isolated in the complex and heterogeneous landscape of the Cerrado (Morais et al. 2014;IUCN 2023), and the presence of T. chromatops in the Cerro Oricore (PDyANMI Iténez) in the Beni Floodplains biogeographic region supports this.
Our new records of T. chromatops constitute the first from the Department of Beni and extend the geographic distribution of this species into the Beni Floodplains.
The new records are approximately 256 km in a straight line from the nearest previously known record in Bajo Paragua Forest Reserve, Santa Cruz, Bolivia (Harvey and Gutberlet 1998; Fig. 2). Ten et al. (2001) and Quintana and Padial (2003) also reported Tropidurus from the Reserva Inmovilizada Iténez in the Department of Beni; however, the species was not reported, but it is probable that this was T. chromatops, as suggested by Langstroth (2005).