New records and morphological variation of Rhadinaea marcellae Taylor, 1949 (Squamata, Colubridae) from Sierra Madre Oriental, México

Abstract

Rhadinaea marcellae Taylor, 1949 is known from only 12 specimens. Based on recent fieldwork and research in scientific collections and databases, we report 14 new records of R. marcellae, bringing the total number of verified occurrences up to 26, updating our understanding of this secretive species’ distribution in the tropical and cloud forests of the Sierra Madre Oriental in Mexico. The new records come from the Mexican states of Hidalgo, Puebla, San Luis Potosí and Veracruz. All the newly reported specimens are morphologically concordant with R. marcellae, but exhibit noteworthy variation.

Historical biogeography of the genusRhadinaea(Squamata: Dipsadinae)

“…Our analyses place Rhadinaea calligaster as the sister group of Rhadinella (Figures 3 and 4 ). This relationship is not surprising due to the complex morphology within Rhadinaea members (Myers, 1974 ), which makes it difficult to accurately diagnose the members of this genus given the lack of exclusive diagnostic characters and the existence of variable morphological traits, such as the form of the neck collar, pigmentation, and longitudinal patterns of the dorsal scales (Myers, 1974 ; Sánchez‐García et al., 2019 ). This situation has resulted in the further modification of the scientific understanding of the composition of the genus (Myers, 2011 ; Palacios‐Aguilar & García‐Vázquez, 2020 ).…”

“…The genus is present in North and Central America from southeastern United States to Panama, with discontinuities across the Chihuahuan Desert, southern Guatemala, El Salvador, Honduras, and central Nicaragua (Table 1 ) (Myers, 1974 , 2011 ). The most speciose and widely distributed of these groups is the decorata group, represented by 12 species mainly distributed over the Mexican Sierras (García‐Vázquez, 2012 ; García‐Vázquez et al., 2009 ; García‐Vázquez, Pavón‐Vázquez, et al., 2018 ; Luría‐Manzano et al., 2014 ; Pérez‐Higareda et al., 2002 ; Sánchez‐García et al., 2019 ; Torres‐Carvajal et al., 2019 ); the taeniata group is endemic to Mexico and is composed of three species distributed in central Mexico (Canseco‐Márquez & Gutiérrez‐Mayén, 2010 ; García‐Sotelo et al., 2018 ; García‐Vázquez, Pavón‐Vázquez, et al., 2018 ; Myers, 1974 ); the flavilata group is comprised of two species with allopatric distributions in North America (Auth et al., 1999 ; Lares et al., 2013 ; Walley, 1999 ); and the calligaster and vermiculaticeps groups are restricted to Central America (Myers, 1974 ). In addition to these 21 species, the existence of two undescribed species has been suggested based on their morphology and previous analyses (pers.…”