Palaeonemouridae Sinitshenkova 1987

Abstract

3.1.4. † Palaeonemouridae † Palaeonemouridae, a large Permian family, is represented in the Southern Hemisphere by a single nymph from Antarctica, † Ohionympha schopfi Carpenter. Nymphs are placed in this family based on morphometric characters such as proportions of the wing pads, legs, abdominal segments and pronotum (Sinitshenkova 1987). Sinitshenkova places this family within “Nemourina” (equivalent to Nemouroidea Billberg), based on the lack of crossveins in the distal region of the wing (Fig. 5) and long first and third tarsomeres, compared to subequal, moderately long or shortened first two tarsomeres in Antarctoperlaria and Systellognatha (Nelson 2009; Sinitshenkova 1987). Both characters are derived, as they differ from the stem-group species † G. carpenteri (Béthoux et al. 2011), and are regularly used in keys (see for example: Zwick 2004, DeWalt & Resh 2015, Fenoglio et al. 2021). A long first tarsomere is a synapomorphy of most Nemouroidea (Nelson 2009), but can be inconsistent for identification; Gripopterygidae also regularly have long first tarsomeres (McLellan & Zwick 2007; Nelson 2009; Sinitshenkova 1987), and all three are the same length in Taeniopterygidae Klapalek (Fenoglio et al. 2021). The combination of wing venation and tarsomere length provides at least circumstantial evidence that † Palaeonemouridae are stem-Euholognatha. However, the assignment of † O. schopfi to this family, or even stem Euholognatha, is unsupported as the fossilised nymph lacks wing venation and preserved tarsi, or association with an adult.