Palerasnitsyninae, Wichard, 2023

Wichard, Wilfried, 2023, Fossil Trichoptera embedded in mid-Cretaceous Burmese amber, Contributions to Entomology 73 (2), pp. 167-179 : 167

Subfamily † Palerasnitsyninae stat. nov.

Type genus.

Palerasnitsynus Wichard, Ross & Ross, 2011.

Subfamily diagnosis.

The species of the extinct subfamily Palerasnitsyninae are characterised by the combination of the fore and hind wings’ characters: in forewings by the presence of forks II, IV, V and by the absence of forks I and III and in hind wings by the presence of forks II and V and by the absence of the forks I, III, IV (Fig. 3B ). Furthermore, the adults possess latero-apical dark sporns at the 3rd maxillary palp segments (Fig. 3A ).

Systematic position.

The extinct genus Palerasnitsynus , with currently 10 species, was found in the Oriental mid-Cretaceous Burmese amber and initially placed in the family Psychomyiidae ( Wichard et al. 2011). The wing venation is remarkably reduced, with only apical forks II, IV, V in forewings and apical forks II and V in hind wings. The reduction of forewing venations with the absence of forks I and III and of hind wing venations with the absence of forks I, III and IV is observed in some Xiphocentronids, but not in the family Psychomyiidae . This combination of reduced forewings and hindwings is significantly true for the family Xiphocentronidae . Based on these characters, it is proposed to transfer the genus Palerasnitsynus to family Xiphocentronidae and to establish an extinct subfamily Palerasnitsyninae stat. nov. Its species are the oldest Xiphocentronids with a geological age of about 100 million years.

In Burmese amber, the species of the subfamily Palerasnitsyninae are certainly among the smallest caddisflies, reaching forewing lengths of only 1.8-2.6 mm ( Wichard et al. 2011, 2018b). With an abundance of almost 40% of caddisflies, Palerasnitsynus species dominate the picture of caddisflies in the Burmese amber. They obviously have a tendency to swarm, as up to 100 embedded individuals have been counted in some ambers (Fig. 3C ).

Figures

Figure 3. Genus Palerasnitsynus in mid-Cretaceous Burmese amber. A. Typical dark sporns at the 3 rd maxillary palp segment; B. Typical presence of forks II, IV, V in forewings and of forks II and V in hind wings; C. Palerasnitsynus swarming activities.