Gnaphosidae, Pocock, 1898

Downen, Matthew R. & Selden, Paul A., 2020, Fossil spiders (Araneae) from the Eocene Kishenehn Formation of Montana, USA, Palaeontologia Electronica (a 56) 23 (3), pp. 1-10 : 7-8

Gnaphosidae incertae sedis

( Figure 5 ).

Description of PAL 20480. Carapace outline suboval, longer than wide (L 0.77, W 0.46). Chelicerae relatively large, projecting forward. Abdomen longer than wide (L 1.24, W 0.73). Labium triangular,

DOWNEN & SELDEN: KISHENEHN FOSSIL SPIDERS as long as wide, and notched distally. Maxillae slightly narrowed at center. Sternum ovoid. Body and legs clothed in dense short setae. Relatively few macrosetae on legs. Claw tufts present.

Podomere lengths: Leg I fe 0.60, pa 0.27, ti 0.56, mt 0.57, ta 0.29; Leg II fe 0.59, pa 0.29, ti 0.46, mt 0.43, ta 0.26; Leg III fe 1.21 pa 0.23, ti 0.29, mt 0.35, ta 0.25; Leg IV fe 0.65 pa 0.30, ti 0.67, mt 0.48, ta 0.30.

Remarks. The small size of the specimen suggests it is a juvenile. There are also no clear reproductive structures visible and the palps are not inflated. The fossil also resembles spiders from Clubionidae and Corinnidae . Both corinnids and clubionids usually have well-developed spines on the legs. Corinnids have shorter spinnerets that are closer together. Clubionids can have elongated cylindrical spinnerets like gnaphosids, but the anterior lateral spinnerets are not as widely separated in clubionids.

Figures

FIGURE 5. Specimen PAL 20480 Gnaphosidae incertae sedis photograph and interpretive drawing.