A new rare species of the Rhadinaea decorata group from the Sierra Madre del Sur of Guerrero, Mexico (Squamata, Colubridae)

Abstract

A new species of the Rhadinaeadecorata group is described based on two specimens from the Sierra Madre del Sur, Guerrero, Mexico. The new species differs from all other members of the genus Rhadinaea by having: eight supralabials; 149–151 (male) ventrals; 63–77 (male) subcaudals; two large pale nuchal blotches, forming an incomplete collar that occupies two scales laterally and is bissected along the dorsal midline; a postocular pale marking consisting of a well-defined, narrow line beginning behind the upper posterior margin of the eye and extending posteriorly nearly horizontally until connecting with the nuchal blotches; and the dark ground color of the flanks extending to the lateral portion of the ventrals. The large nuchal blotches distinguish the new species from the other members of the R.decorata group, except for R.cuneata and some individuals of R.hesperia (pale nuchal marking one-scale wide in R.marcellae, absent in the other species). The condition of the postocular pale marking distinguishes it from R.cuneata and R.hesperia (postocular pale marking wedge-shaped in R.cuneata, not connected with the pale post-cephalic markings in R.hesperia). Furthermore, the number of subcaudals and the coloration of the lateral portion of the ventrals distinguish it from R.omiltemana and R.taeniata, the remaining congeners found in Guerrero (85–90 in males of R.omiltemana and 91–121 in R.taeniata; dark color of the flanks not reaching ventrals in the former species, occasionally and faintly in R.taeniata). Additionally, a new combination for R.stadelmani is proposed. The new species is the first described in the genus Rhadinaea in more than 40 years.

A new species of forest snake of the genus Rhadinaea from Tropical Montane Rainforest in the Sierra Madre del Sur of Oaxaca, Mexico (Squamata, Dipsadidae)

“…Apart from R.laureata mentioned in the previous paragraph, there are 15 other species distributed in Mexico (Heimes 2016; García-Vázquez et al 2018), which are arranged in two species groups recognized by Myers (1974). These two groups are the taeniata group, with three species, and the decorata group, with 13 species.…”

“…Myers (2011) resurrected the genus Rhadinella to contain the species he had placed earlier in the Rhadinaeagodmani group. The eleven species he included in this group in 1974 had been augmented to 15 by his 2011 paper and now comprises a total of 19 species, including 18 listed at the Reptile Database (http://reptile-database.reptarium.cz/; accessed 15 June 2018) and one other species, Rhadinellastadelmani , which was resurrected by Mendelson and Kizirian (1995), but not placed in the genus Rhadinella by Myers (2011), as noted by García-Vázquez et al (2018). Savage and Crother (1989) placed the Rhadinaealateristriga group of Myers (1974), with seven species, along with the species of Pliocercus in the genus Urotheca .…”

“…Finally, Myers and Cadle (1994) placed the Rhadinaeabrevirostris group of Myers (1974), with six species, in the resurrected genus Taeniophallus . As a result of the changes engendered in this systematic work over the last 44 years, Rhadinaea has been restructured to include only 21 species, arranged in five species groups (the flavilata group, containing R.flavilata and R.laureata ; the decorata group, with R.bogertorum , R.cuneata , R.decorata , R.forbesi , R.gaigeae , R.hesperia , R.macdougalli , R.marcellae , R.montana , R.myersi , R.nuchalis [described by García-Vázquez et al 2018], R.omiltemana , and R.quinquelineata ; the taeniata group, with R.fulvivittis and R.taeniata ; the calligaster group, with only R.calligaster ; and the vermiculaticeps group, with R.pulveriventris , R.sargenti , and R.vermiculaticeps .…”

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

“…The distribution of the genus Rhadinaea Cope, 1863 extends from Florida, USA, south to Ecuador, between sea level and around 3200 m elevation, and its members mainly inhabit humid forested regions (Myers 1974). The genus contains 22 species distributed within 6 species groups: the calligaster group, decorata group, eduardoi group, flavilata group, taeniata group, and vermiculaticeps group (Myers 1974, 2011, García-Vázquez et al 2018, Mata-Silva et al 2019. The 12 species included in the decorata group are found in Mexico and 11 are endemic to the country including Rhadinaea marcellae Taylor, 1949.…”

“…The geographical distribution of R. marcellae is poorly understood and contains many apparent gaps. Only 12 specimens are currently known from an altitudinal range between 600 m and 1600 m: the holotype from Xilitla region, San Luis Potosí (Taylor 1949); 1 from eastern Tlanchinol, Hidalgo (Hernández-García and Mendoza-Quijano 1994); 7 hatchlings from northeast of Tlanchinol; 1 from near Tepango de Rodríguez, Puebla (Nieto Montes de Oca and Mendelson 1997); 1 from Xalpanat, near Cuetzalan, Puebla (Canseco-Márquez et al 2000); and 1 from Xilitla, San Luis Potosí (García-Vázquez et al 2018). These records do not necessarily reflect the distribution of R. marcellae accurately.…”