Range extension of Anisospira ( Trachycion ) velascorum ( Gastropoda : Urocoptidae ) in Oaxaca , southeastern Mexico

Anisospira (Trachycion) velascorum Breure was described in 1977 from a locality near the highroad between the towns of Pochutla and Puerto Escondido on the coast of Oaxaca, southern Mexico. After its discovery, the species was never reported again elsewhere. Herein we report a new record of several specimens of A. velascorum near Pochutla town, in the Chepilme Botanical Garden, 58.3 km west of the type locality. This find represents an opportunity to study several unknown aspects of this species.

The great biodiversity of Mexico is largely known.However, our knowledge of several taxa in many areas is scarce.One of the least studied groups is terrestrial Gastropoda in spite of its ecological importance.
Urocoptidae is one of the most conchologically and taxonomically diverse land snail families.It significantly contributes to the land-snail diversity in southwestern North American and circum-Caribbean regions (Uit de Weerd 2008).However, diversity of Urocoptidae in Mexico has been poorly studied.Most studies where the family is mentioned deal with total species richness of snails in the reported localities (e.g., Correa-Sandoval 1999;Correa-Sandoval 2000;Correa-Sandoval and Salazar-Rodríguez 2005;Avendaño-Gil et al. 2010).There are few articles dealing exclusively with Urocoptidae (e.g., Thompson 1968;Thompson and Correa-Sandoval 1994;Thompson and Mihalcik 2005).
Anisospira is a genus restricted to lowland regions of Colima, Michoacán, and Oaxaca, Mexico (Thompson 2011).It comprises seven species and two subspecies, according to Thompson (2011).Geographic distribution of these taxa is practically unknown; four species are recorded from only their type locality, and the rest are recorded in ambiguous geographic localities without additional data (e.g., "Cerro Las Plumas, near Puerto Angel", Pfeffer 1887).Additional information on the life history of Anisospira spp. is still lacking.
The last species of the genus formally described is Anisospira (Trachycion) velascorum Breure, 1977.Since its discovery, the species has never been reported from other areas besides the type locality.The first specimens from A. velascorum were collected at km 151 of the Pochutla-Puerto Escondido Road, in leaf litter on the forest floor of medium evergreen selva (Breure 1977).Nowadays, the type locality has been affected by the construction of a highway between Oaxaca City and Puerto Escondido and all the original vegetation has since been destroyed.
During 2014 and 2015, 35 empty shells of A. velascorum were sampled at Chepilme Botanical Garden.Given that The altitude is 150 m above sea level.Climate is subhumid and warm, with rainy season during summer, mainly between May and November.Annual precipitation is 900 mm.The predominant soil is regosol.The shells were found in leaf litter.
The 35 shells were deposited in the Colección Malacológica de Referencia from Laboratorio de Paleobiología, Universidad del Mar, campus Puerto Escondido under the acronym UMCMR 0022 to 0056.
The cylindrical shells reported here compare well with the description of A. velascorum reported in Breure (1977): a reddish-brown shell, with length up to 30.5 mm, rimate, with rather convex sides, surface slightly shining, and numerous fine riblets, which are recurved and equally spaced over the surface.As pointed by Breure (1977), the shells show some variation in shape, but all the collected specimens bear the diagnostic features of the species (Figure 3).Abraham S.H. Breure, who erected the taxon, verified species identification.
This new record of Anisospira (Trachycion) velascorum extends its former known distribution 58.3 km west of the type locality and represents the second occurrence in Oaxaca, Mexico.
Given that the known geographic range of A. velascorum at present only comprises two localities, its the shells were empty and the species is not endangered or vulnerable status in the list of threatened species, a permit was not required; this was verified with X. Isidro, Inspector General de Vida Silvestre in Federal Attorney for Environmental Protection (PROFEPA).
The garden is located at 3.5 km of San Pedro Pochutla, Oaxaca, at 15°46ʹ17.68ʺN, 096°26ʹ50.02ʺW (Figure 1), and belongs to Universidad del Mar.The garden is dedicated to scientific research, environmental education, and collection and display of a wide range of plants and comprises an area of 8.5 ha, a third of which is used to display native and non-native plants, as well as different environmental education activities.The remaining area  conservation status is uncertain.It is necessary either to verify if this species is restricted to the vicinity of the type locality and the new locality in Chepilme Botanical Garden, or if it is more widely distributed.
The natural and evolutionary histories of A. velascorum are practically unknown.Its record in UMAR Botanical Garden is essential to develop future research, such as taxonomical, ecological or morphometric studies.Longterm studies of A. velascorum are now feasible because anthropogenic activities are prohibited inside Chepilme Botanical Garden, which allows for its conservation.

Figure 1 .
Figure 1.Index map of Oaxaca in southern Mexico, showing the town of Puerto Escondido, the type locality of Anisospira (Trachycion) velascorum and the location of the Chepilme Botanical Garden.

Figure 2 .
Figure 2. A general view of where the specimens were sampled in the Chepilme Botanical Garden.