Baltileuctra Chen, 2018

Chen, Zhi-Teng, 2018, Baltileuctra gen. nov., a new genus of Leuctridae (Insecta: Plecoptera) in Baltic amber, Zootaxa 4407 (2), pp. 281-287 : 282

Genus Baltileuctra Chen , gen. nov.

Type species. Baltileuctra foraminis gen. et sp. nov., by monotypy.

Diagnosis. The new genus exhibits typical characters of the family Leuctridae , such as the apical segment of labial palpus similar to other segments, gills absent, forewing without an X-pattern of crossveins at cord, AA2 of forewing forked, second tarsal segment shortest, cerci one-segmented. It can be distinguished from other genera of Leuctridae by having the combination of the following characters: 1) wings with banded patterns; 2) prothoracic furcasternum and postfurcasternum bilobed and isolated; mesothoracic presternum reduced and fused with basisternum, furcasternum fused with basisternum, the furcasternal arms and the furcasternal pit reduced; metathoracic presternum kidney-shaped and isolated; 3) tergum and sternum of segment 2–8 completely separated; 4) ventral vesicle of sternum 9 present; 5) posterior margin of sternum 9 distinctly extended backwards, showing a U-shaped pattern from ventral aspect; 6) subanal probe upcurved, lateral surfaces sclerotized, dorsomedian line seems pale, gradually widened from base to apex in lateral view, dorsoapically with a circular hole; 7) cercus unmodified except for the small apical lobe.

Etymology. The genus name, Baltileuctra is a combination of the holotype collection locality, Baltic, and the extant genus Leuctra Stephens, 1836 , which is the type genus of Leuctridae .

Remarks. The new genus can be assigned to the family Leuctridae by its general habitus and visible terminalia. However, its thoracic ventral sclerites and abdominal structures differ from all known genera of Leuctridae . Due to the coverage of unknown substance, the dorsal aspect of the holotype is not visible and the tergal structure and epiproct of the new genus remain unknown. Therefore, an accurate relationship between the new genus and other known genera is not possible to reconstruct, unless better preserved material become available. Based on the terminalia structure, the new genus may have a close relationship to Megaleuctra . The evolutionary trend of these extinct tiny leuctrids may include evolving to large size for stronger flight capability for successful longer dispersal.