(Sauria: Helodermatidae) on the coast of Oaxaca and increases to its distribution in Mexico

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Journal of Threatened
The beaded lizard is known coloquially as 'escorpión' and is well known to local inhabitants, yet its natural history is surrounded by mystery, notoriety and misconception (Reiserer et al. 2013;Domínguez-Vega et al. 2018), principally because these animals can pass up to 95% of their lives hidden in shelters underground, which makes it difficult to detect them. Moreover, they maintain a low population ( Herein, we provide three new records and a significant extension on the distribution of H. alvarezi about different encounters between humans while performing their activities and the species during its movement along the central coast of Oaxaca, Mexico, particularly in three different municipalities ( Figure 1).
The first observation ocurred on 04 July 2017, when a lizard was held in captivity in the town of Santa Rosa de Lima, municipality of Villa de Tututepec de Melchor Ocampo. This animal was used as an exhibition specimen to decrease the fear of this species in the town. We were prohibited from measuring it, weighing it or determining its sex; however, to the naked eye this individual presented good body condition (Image 1a). According to the people in charge of the lizard, it came from the upper zone, close to the municipality.
The second observation ocurred on 10 October 2019 at 17.15 h. An adult female H. alvarezi was found and captured by people who were cleaning a field in a locality known as 'El Porvernir' in the Municipality of Santa María Colotepec, Oaxaca. Due to their fear of the creature, people caught the lizard in order to slaughter it, but then they reflected on the situation and reported it to the Universidad del Mar in the city of Puerto Escondido. The individual was measured (total length: 670mm), photographed (Image 1b) and then traslocated and released into the Natural Protected Area El Gavilán in San Francisco Cozoaltepec, municipality of Santa María Tonameca, Oaxaca, to ensure that the individual would not be harmed.
Most recently, the third observation ocurred on 03 November 2019 at 18.20h, between the boundaries of the Universidad del Mar campus Huatulco and Huatulco National Park, in the Municipality of Santa María Huatulco. A single juvenile was found walking near a road and was later photographed on a tree (Image 2c). It was not manipulated in order to avoid causing it unnecessary stress.
The identification of these lizards was possible because this taxon is unique among the beaded lizards in that it undergoes an ontogenetic increase in melanism (Bogert & del Campo 1956;Beck 2005). Also distinctive is that yellow banding on the tail, a characteristic typical of the other species of beaded lizards, is esentially absent in adults of H. alvarezi (Bogert & del Campo 1956;Beck 2005). Although Bogert & del Campo (1956) and Beck (2005) explain that black individuals are uncommon, there is recent photographic evidence of black individuals on the coast of Oaxaca. Neonates and J TT juveniles often are distinctly marked with yellow spots and bands on the tail, but the color pattern of adults gradually transforms to an almost uniform dark brown or gray coloration.
Heloderma alvarezi was described as inhabiting dry tropical forest in the Central Depression (Río Grijalva Depression) of central Chiapas and the Río Lagartero Depression in extreme western Guatemala (Campbell & Lamar 2004;Beck 2005;Köhler 2008;Johnson et al. 2010;Wilson et al. 2010). Nontheless, Álvarez del Toro (1983in Campbell & Vannini 1988 indicated the probabiliy of sympatry areas between H. horridum and H. alvarezi in the region between the Isthmus of Tehuatepec (Oaxaca) and Cintalapa (Chiapas); however, up to this point, the literature on integration between these two species is inconclusive (Reiserer et al. 2013), and therefore, the most recent herpetofauna list in Oaxaca does not include H. alvarezi's presence in the State. Sánchez de la These three photographic records represent the most northeastern (NE) geographic records of H. alvarezi, and it increases the distribution of the species approximately 359km for the record 3, 405km for record 2, and 470km for record 1 to the northeast from the previously closest reported localities of Cintalapa and Ocozocoautla, Chiapas. It is neccesary to gather more records on the