Notonemouridae Ricker 1950

Abstract

3.1.7. Notonemouridae The first fossil of a putative Notonemouridae in the Southern Hemisphere is † Talbragaria australis Sroka & Prokop. This family lacks accepted apomorphies, and until recently, its monophyly was considered uncertain (Cui et al. 2019; McLellan 1972, 1991; Sroka & Prokop 2023; Zwick 2000, 2006). Cui et al. (2019) erected the Northern Hemisphere family †Paranotonemouridae Cui & Béthoux as a stem sister to Notonemouridae based on wing venation. The characteristic “Nemourid X” wing vein pattern, which is present in some Notonemouridae and in its putative sister, Nemouridae, is also shared with this family. This is plesiomorphic; it is the remains of an ancient crossvein condition (Zwick 2000), and is present in other Euholognatha. Cui et al. (2019) separated the Notonemouridae lineage from Nemouridae by the shape of the CuP vein, which approaches the wing margin, diverges, and rejoins distally in Notonemouridae. While this shape does differ between the families, a similar pattern is present in at least some Leuctridae (e.g., Fig. 5, A. Kirkaldy pers. obs., Fig. 7 in Béthoux 2005). As the sister relationship of Notonemouridae and Nemouridae is uncertain (García-Girón et al. 2024; Letsch et al. 2021; McCulloch et al. 2016), this vein pattern may be the remnants of a plesiomorphic condition, an independently derived homoplasy, or a synapomorphy of these two families. Therefore, the assignment of †Paranotonemouridae to stem-Notonemouridae must remain uncertain. Sroka & Prokop (2023) used the same characters to assign † T. australis to Notonemouridae. In this case, the above characters are synapomorphies of members within Euholognatha. As Notonemouridae is the only Euholognathan family in the Southern Hemisphere, it is most likely that this fossil represents at least a stem relative of the Notonemouridae.