Sorex chiapensis Jackson 1925

Sorex chiapensis Jackson, 1925

Chiapas Shrew

Sorex veraepacis chiapensis Jackson, 1925: 129. Type locality: “San Cristobal, altitude 9,500 feet, State of Chiapas, Mexico.” Sorex veraepacis veraepacis: Woodman et al. 2012: 217, in part.

Holotype. No. 75877, U. S. Nat. Mus., Biological Survey Collection; adult, female, skin and skull; collected October 1, 1895, by E. W. Nelson and E. A. Goldman, original number 8528.

Distribution. Known only from the highlands of Chiapas, México, and mountains of adjacent northwestern Guatemala.

Diagnosis. Sorex chiapensis is a member of the S. veraepacis species group. Size is small for the species group. U3 usually <U4 (one specimen had U3 = U4). The skull is smaller on average than in all other species in this species group in Guatemala. Color of the dorsum in S. chiapensis is gray to dark gray, the venter only slightly lighter. The dorsal pelage of the rump in some specimens has reddish tips on the hairs but this is not consistent. The tail is unicolor to slightly bicolor. Average measurements for specimens of S. chiapensis from the type locality (San Cristobal, Chiapas, México) are given in Table 1.

Description. The size of S. chiapensis is small compared to that of S. ibarrai and S. veraepacis, but only slightly smaller than in the populations from the Sierra Madre of Guatemala. Compared to the new species from the Sierra Madre of southwestern Guatemala, S. chiapensis has shorter mandibles, more flattened skull, and a wider, shorter rostrum.

Remarks. In her account of S. veraepacis chiapensis, Carraway (2007: 78) stated “ Sorex v. chiapensis can be distinguished from S. v. mutabilis by median tine located above the pigment on the I1 …”. In our examination of 7 specimens from the type locality, 5 did have the anteriomedial tine above the pigmented area on I1, one had the tine well within the pigmented area, and one had the tine at the interface of the pigmented area. Of six specimens we assign to S. chiapensis, from above Cuilco (El Retiro), Huehuetenango, Guatemala, 2 had the tine above, 2 had the tine at the interface, and 2 had the tine well into the pigmented area. Clearly, there is not consistency to this trait in our populations. Woodman et al. (2012) assigned the specimens from El Retiro to S. v. veraepacis; however, our PCA analysis (Figure 6) shows that these specimens clearly group with S. chiapensis.

Ecology. Carraway (2007) summarized ecological data for S. chiapensis in Chiapas. Woodman et al. (2012) described the habitat at El Retiro, in the Montaña Cuilco, as a mixture of conifers and hardwoods, and the area had been heavily logged. We consider the area to be cloud forest with conifers (mostly pines and cypress) and scattered hardwoods (mostly oaks). Ground cover is a mixture of mosses and leaf litter. One lactating individual was captured at El Retiro in July 2008. Small mammal associates include Peromyscus beatae, P. guatemalensis, Reithrodontomys microdon, and R. sumichrasti. In addition, Carraway (2007) listed Cryptotis goodwini, Heteromys desmarestianus goldmani, Nyctomys sumichrasti, P. aztecas oaxacensis, R. megalotis, R. mexicanus, and Sorex veraecrucis cristobalensis.

Specimens examined (15). Guatemala, Huehuetenango, 9.5 km NNE Cuilco (El Retiro), 3030 m (USNM 570378, 570397, 570398); 10 km NNE Cuilco El Retiro, 3160 m (USNM 570232, 570408, 570426); México, Chiapas, Pinabite (USNM 77685); San Cristobal de las Casas (USNM 75876–75882, 75884).