Araneidae, Clerck, 1757

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 : 4-5

Araneidae incertae sedis

( Figure 2 )

Description of PAL 20412.1. Male. Carapace longer than wide (L 1.3, W 0.91). Posterior half of sternum pointed, with sparse fine setae. Abdomen rounded, about as long as wide (L 1.2, W 1.37); dark patch running through the abdomen midline. Walking leg formula I>II>IV>III.; legs long and slen- der, clothed in dense fine setae; Leg III distinctly short (2.5x shorter than Leg 1); Metatarsi of Legs I and II noticeably curved; relatively few erect spine-like macrosetae on all legs: one on proximal mt of Legs I, II, III, none on Leg IV mt; two on proximal ti of Leg III; one proximal and one distal on Leg IV ti.

Podomere lengths: Leg I fe 1.57, pa 0.24, ti 1.59, mt 1.91, ta 0.56, Leg II fe 1.31, pa 0.28, ti 1.10, mt 1.36, ta 0.49, Leg III fe 0.68, pa 0.18, ti 0.55, mt 0.59, ta 0.44, Leg IV fe 1.04, pa 0.15, ti 0.75, mt 0.93, ta 0.36.

Remarks. The position of the legs of this spider is similar to fossil uloborids from Montsech, Spain (Cretaceous) and the Daohugou Beds of China (Jurassic), however no plumose or feathery setae, which are present in uloborids, were observed. The seta of this spider appears smooth. The spider also lacks a cribellum and calamistrum, but these features are lost in adult male uloborids.

Figures

FIGURE 2. Specimen PAL 20412.1 Araneidae incertae sedis photograph and interpretive drawing.