Sunday, February 18, 2018

[Herpetology • 2018] Xenosaurus fractus • A New Species of Knob-scaled Lizard (Xenosauridae, Xenosaurus) from the Sierra Madre Oriental of Puebla, Mexico

Xenosaurus fractus 
de Oca, Sánchez-Vega & Durán-Fuentes, 2018

A new species of Xenosaurus in the X. tzacualtipantecus clade is described from the Sierra Madre Oriental of northern Puebla, Mexico. The new species differs from all of its congeners in possessing a unique combination of characters. The new species appears to be allopatric and fills in the geographic gap between the geographic distributions of X. tzacualtipantecus and the species in the newmanorum clade to the north and northwest and those of the species in the grandis and rackhami clades to the south and southeast. The new species occurs between approximately 880 m and 1470 m of elevation, and appears to be restricted to cloud forest, which has been replaced by coffee plantations in many areas. An updated key to the species of Xenosaurus is provided.

Keywords: Mexico, new species, Puebla, Sierra Madre Oriental, Xenosauridae, Xenosaurus, Xenosaurus tzacualtipantecus clade

Figure 3. Xenosaurus fractus in life. Specimens not collected.
from Puebla, Municipality of Xochitlán, 200 m N ex-hacienda Apulco, cloud forest, 1450 m.
Photograph by Luis Canseco Márquez.

Figure 3. Xenosaurus fractus in life. Specimens not collected.
from Municipality of Huehuetla (no further data).

Photograph by Luis Canseco Márquez.

Xenosaurus fractus sp. n.

Diagnosis: Xenosaurus fractus may be distinguished from all of the other species of Xenosaurus, except X. tzacualtipantecus, by lacking a continuous dark crossband on the nape, or collar; and having instead a funnel-shaped mark on the nape formed by the dorsal color pattern of the head extending posteriorly, gradually narrowing on the nape (while bordered by the posterior extension of a narrow, dark brown stripe on the canthus temporalis, the posterior extension of a broad, cream subocular stripe, and a broad, black stripe on each side), to the first brown crossband on the trunk (posterior extensions of the subocular stripes remaining narrowly separated medially at their posterior end), versus a mainly uninterrupted dark crossband on the nape enclosed anteriorly by the pale subocular stripes, which extend medially onto the nape producing a pale crossband (often interrupted medially) similar to those on the trunk, and a pale crossband in the scapular region separating the dark crossband on the nape from the first dark crossband on the trunk in the other species.

Xenosaurus fractus may be distinguished from X. tzacualtipantecus by having, on average, more subdigital scales on the fourth toe (26–34, x = 29.9, n = 10; versus 23–28, x = 25.6, n = 8, in X. tzacualtipantecus) and dorsal surface of the limbs barred (black-edged, cream bars on mid upper arm, forearm, thigh, and shank; versus limbs usually not barred in X. tzacualtipantecus [upper arm, forearm, thigh, and shank specked with black; specks usually not forming a distinct pattern; coalescing into narrow lines, bordering ill-defined bars and showing a tendency to anastomose, on thigh and shank in one specimen; n = 8]).

Etymology: The specific epithet is an adjective in the nominative case (masculine, singular declension) derived from the Latin verb frangō (“to break”), meaning “broken” or “fragmented.” The name is in reference to the broken dark crossband on the nape in this species. A continuous dark crossband on the nape, or collar, is present in most species of Xenosaurus, and represented in the new species only by black stripes on the sides of the nape, widely separated by posterior extensions of the dark lines on the canthi temporales and the cream subocular stripes.

 Adrián Nieto-Montes de Oca, Helder Sánchez-Vega and Itzel Durán-Fuentes. 2018. A New Species of Knob-scaled Lizard (Xenosauridae, Xenosaurus) from the Sierra Madre Oriental of Puebla, Mexico. ZooKeys. 737; 141-160.  DOI: 10.3897/zookeys.737.15095

Resumen: Se describe una nueva especie de Xenosaurus del clado X. tzacualtipantecus de la Sierra Madre Oriental del norte de Puebla, México. La nueva especie difiere de todos sus congéneres por poseer una combinación única de caracteres. La nueva especie parece ser alopátrica y llena el hueco geográfico entre las distribuciones geográficas de X. tzacualtipantecus y las especies del clado newmanorum hacia el norte y noroeste, y aquellas de las especies de los clados grandis y rackhami hacia el sur y sureste. La nueva especie se ha encontrado en elevaciones entre aproximadamente 880 m y 1470 m y parece estar restringida al bosque mesófilo de montaña, el cual ha sido reemplazado por cafetales en muchas áreas. También se ofrece una clave actualizada para las especies de Xenosaurus.

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