Sunday, July 7, 2024

[Herpetology • 2024] Thamnophis ahumadai • A New Species of Thamnophis (Serpentes: Colubridae) from Jalisco, Mexico, with A Discussion on the Phylogeny, Taxonomy, and Distribution of Snakes related to Thamnophis scalaris

Thamnophis ahumadai 
C. I. Grünwald, Mendoza-Portilla, A. J. Grünwald, Montaño-Ruvalcaba, Franz-Chávez, García-Vázquez & Reyes-Velasco, 2024
 Ahumada’s Alpine Garter Snake | Culebra Listonada de Montaña de Ahumada ||  DOI: 10.3897/herpetozoa.37.e122213

Garter snakes in the genus Thamnophis from Mexico have a long and convoluted taxonomic history. From 2015 to 2022, we conducted a comprehensive sampling of Mexican Thamnophis species, aiming to link molecular phylogenies with the recognized species related to T. scalaris in the highlands of Mexico. Here, we present an analysis of mitochondrial DNA to resolve the status of two enigmatic highland Thamnophis populations. Our research resulted in the identification and morphological characterization of a previously undescribed Thamnophis species from the state of Jalisco in western Mexico. We also clarify the identity and relationships of several previously enigmatic populations of Thamnophis. This work presents new data for Thamnophis phylogenetics from the Mexican highlands and offers a framework for future conservation efforts.

Key Words: Adelophis, conservation, errans, godmani, pine-oak woodland, Mexican Transverse Ranges, scaliger

Thamnophis ahumadai sp. nov. holotype (INIRENA 2933) from the vicinity of Cumbre de Guadalupe, in the Municipio de Cuautla, Jalisco, Mexico.

Thamnophis ahumadai sp. nov. paratypes.
 A. Male (INIRENA 2932) from same locality as holotype; B. Male (INIRENA 2936) from 2.5 km SE of Atemajac de Brizuela, Municipio de Atemajac de Brizuela, Jalisco, Mexico; C. Male (MZFZ 4595) from 4.2 km airline ESE of Cumbre de Guadalupe, Municipio de Tomatlán, Jalisco, Mexico; D. Male (INIRENA 2935) from 2.5 km SE of Atemajac de Brizuela, Municipio de Atemajac de Brizuela, Jalisco, Mexico; E. Male (MZFZ 4593) from Cumbre de Guadalupe, Municipio de Talpa de Allende, Jalisco, Mexico.

 Thamnophis ahumadai sp. nov.
Proposed standard English name: Ahumada’s Alpine Garter Snake.
Proposed standard Spanish name: Culebra Listonada de Montaña de Ahumada.

Diagnosis: A relatively small Garter Snake, with a maximum of 565 mm SVL and 705 TotL; head narrow, scarcely wider than neck, with a short muzzle (INK + PFK = 3.0 mm); tail long in length, 31–36% of SVL and 23–27% of TotLin males, 25–26% of SVL and 20–21% of TotLin females; internasals wider than long; frontal 2–2.25 times longer than wide; loreal slightly longer than wide; one preocular; 2–4 postoculars; temporals 1 + 2; 7 supralabials, third and fourth entering orbit; 9–10 infralabials, first four in contact with anterior chinshields; anterior chinshields shorter than posterior. Dorsal scales always in 19-17-17 rows, strongly keeled except for the outermost row, which is smooth; ventral scales in males 134–142, in females 139–141; subcaudals in males 61–69, in females 54–55; anal scale undivided. Dorsal pattern consists of a pale mid-vertebral stripe restricted to the mid-dorsal row and a pale lateral stripe on second scale row. One or two rows of dark brown or black dorso-lateral spots, usually in one row on the anterior third of the dorsum, then divided into two rows along the remaining posterior two thirds. Ventral coloration dark, pale anteriorly, becoming progressively darker until dark gray or black posteriorly.

Etymology: A patronym honoring Iván Trinidad Ahumada-Carrillo (1984–), who has made many contributions to diverse areas in herpetology, including extensive studies of the herpetofauna of Jalisco and Zacatecas. Iván collected the first specimen of this new species in the Sierra Cacoma (MZFZ 4593) and pointed out its distinctiveness from typical T. scalaris and T. errans.

Christoph I. Grünwald, María del Carmen G. Mendoza-Portilla, André J. Grünwald, Carlos Montaño-Ruvalcaba, Héctor Franz-Chávez, Uri O. García-Vázquez and Jacobo Reyes-Velasco. 2024. A New Species of Thamnophis (Serpentes, Colubridae) from Jalisco, Mexico, with A Discussion on the Phylogeny, Taxonomy, and Distribution of Snakes related to Thamnophis scalarisHerpetozoa. 37: 157-179. DOI: 10.3897/herpetozoa.37.e122213

Resumen: Las culebras del género Thamnophis de México tienen una historia taxonómica larga y complicada. De 2015 a 2022, realizamos un muestreo integral de las especies de Thamnophis de México, con el objetivo de conciliar la filogenética molecular con las delimitaciones de especies establecidas en el complejo relacionado con T. scalaris en las tierras altas de México. Aquí presentamos un análisis del ADN mitocondrial para resolver las trayectorias evolutivas y el estado de dos enigmáticas poblaciones de Thamnophis de las tierras altas. Nuestra investigación resultó en la identificación y caracterización morfológica de una especie de Thamnophis no descrita previamente del estado de Jalisco en el oeste de México. También aclaramos la identidad y las relaciones de varias poblaciones de Thamnophis previamente enigmáticas. Este trabajo presenta nuevos datos para nuestra comprensión de la filogenética de Thamnophis del altiplano mexicano y ofrece un marco para futuros esfuerzos de conservación.