Greenwaltarachne pamelae, 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 : 5-7

Greenwaltarachne pamelae sp. nov.

( Figure 4 )

zoobank.org/ 4103050F-F23B-457A-BF45-075B41247CAA

Etymology. The fossil species is named for the author’s (MRD) mother Pamela.

Type. Holotype adult female, part only, from Coal Creek Member of the Kishenehn Formation ; Eocene age; northwestern Montana; deposited in the Smithsonian Institution National Museum of Natural History , Paleobiology Department.

Diagnosis. As for the genus.

Description of PAL 32280. Carapace oval in outline, longer than wide (L 1.49, W 0.87); sternum heart shaped, longer than wide, attenuated posteriorly, not extending past coxae IV; Labium rebordered (thickened anteriorly), wider than long. Abdomen rounded, longer than wide (L 1.59, W 1.38), clothed in setae, projecting beyond spinner-

PALAEO- ELECTRONICA.ORG ets. Walking leg formula I>II>IV>III.; stout, but tapering legs, Leg III noticeably short; legs covered in dense fine setae, large macrosetae on most podomeres; trichobothrium on distal Leg IV mt; Legs striped with colored (darkened) bands; Leg IV fe with only distal darkening.

Podomere lengths: Pd 0.77 (visible); leg I fe 1.22, pa 0.34, ti 0.85 mt 0.74, ta 0.38; leg II fe 0.9, pa 0.31, ti 0.8, mt 0.59, ta 0.33; leg III fe 0.49, pa 0.2, ti 0.34, mt 0.35, ta 0.24; leg IV fe 0.73, pa 0.29, ti 0.64, mt 0.54, ta 0.30.

Remarks. The banded legs and podomere lengths resemble those of other araneid genera like Larinioides , Neoscona , and Zygiella ( Baba and Tanikawa, 2015; Tanikawa, 2017; Framenau, 2019). Neoscona has fewer bands on Leg IV, and specifically, only one band on metatarsus IV. Some Larinioides have two bands on metatarsus IV, but the distal half of tibia IV is a solid band, in contrast to the fossil. Zygiella also has banded legs, although lighter in color and an abdomen that does not overhang the spinnerets as much as what is observed in the fossil.

Figures

FIGURE 4. Specimen PAL 32280 Greenwaltarachne pamelae gen. et sp. nov. photograph and interpretive drawing.