Consteniusi leonae, Downen & Selden, 2020

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 : 5

Consteniusi leonae sp. nov.

( Figure 3 )

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Etymology. The fossil, nicknamed Leona’s Spider, is named for the mother of Kurt Constenius, Leona, who graciously donated the specimen for study.

Type. Holotype adult female, only known specimen, part only, specimen CM 56099 from Coal Creek Member of the Kishenehn Formation ; Eocene age; northwestern Montana; deposited in the Carnegie Museum of Natural History , Pittsburg, PA.

Diagnosis. As for the genus.

Description of CM 56099. Sternum triangular, longer than wide, with setae that lengthen anteriorly. Labium triangular, wider than long. Maxillae short and stout, widest anteriorly. Chelicerae robust and stout. Palps with abundant setae and macrosetae. Abdomen subtriangular, wider than long (L 0.0.87, W 0.95), distinctly sclerotized portion round and half the length of abdomen. Colulus present. Walking leg formula I>II>IV>III. Legs covered in abundant spine-like macrosetae. Single trichbothrium on proximal tibia of legs III and IV just after pa-ti joint. Length of mt + ta> ti + pa.

Podomere lengths: Pd 0.42 (visible); leg I fe 1.01, pa 0.26, ti 0.99 mt 1.18, ta 0.47; leg II fe 0.94, pa 0.21, ti 0.71, mt 0.83, ta 0.0.36; leg III fe 0.56, pa 0.16, ti 0.41, mt 0.4, ta 0.25; leg IV fe 0.82, pa 0.2, ti 0.52, mt 0.62, ta 0.24.

Remarks. The fossil is similar to Metepeira in that the combined length of metatarsus I and tarsus I is greater than the combined length of tibia I and patella I ( Piel, 1998). The subtriangular abdomen is similar to Neoscona in ventral view, although the abdomen is slightly more rounded in Neoscona ( Berman and Levi, 1971) . The fossil also has a distinct patch of color on the anterior ventral portion of the abdomen. Many species in the subfamily Araneinae are distinguished by ventral patches of color, but any patterns useful for classification are not visible here.

Figures

FIGURE 3. Specimen CM 56099 Consteniusi leonae gen. et sp. nov. A) photograph and interpretive drawing. B) Prosoma region and palps with cluster of long macrosetae (arrow) in UV light. C) Opisthosomal region in UV light showing subtriangular abdomen in UV light. D) Tarsus of Leg IV showing claws and setae in UV light. E) Leg III pa-ti joint with macrosetae and trichobothrium (arrow).