Nanosialidae, Shcherbakov, Dmitry E., 2013

Shcherbakov, Dmitry E., 2013, Permian ancestors of Hymenoptera and Raphidioptera, ZooKeys 358, pp. 45-67 : 49-50

Family Nanosialidae fam. n.

Type genus.

Nanosialis gen. n.

Diagnosis.

Minute insects (wings 2.5-4.5 mm long). Sc joining base of large pterostigma. RP origin distal; ir1 crossvein at base of pterostigma. RP and MA simple (sometimes MA with small fork); rp-ma crossvein absent; MP1 with 3-4, MP2 with 2 branches; CuA apparently simple or with terminal fork. MP fork level to, or just before R fork. M and CuA forming X-junction or very short anastomosis much before R fork (M stem arched towards CuA distad of junction). In forewing, RA sometimes with break at base of pterostigma. Free base of MA developed as crossvein originating from base of MP1 (in hind wing sometimes absent). Hind wing similar to forewing, with narrow anal area. Nygmata absent. Veins beset with strong setae; wing membrane bare. Body short. Pterothorax heteronomous: metanotum smaller and much shorter than mesonotum, without scutoscutellar sutures. Abdomen with short segments; 1st tergite with posteromedian notch.

Composition.

Two subfamilies.

Remarks.

The body structure is known for the type genus only; the degree of pterothoracic heteronomy and first abdominal tergite division may vary among genera, like with modern genera of some neuropteran families.

In the structure of the proximal wing part (especially in the course of M, oblique direction and position of MA, shape of cells) Nanosialidae are similar to Mesoraphidiidae , but in the latter the pterothorax is always homonomous, anal area is much shorter, pterostigma is displaced distally, and RP+MA is usually more branched.

Among isolated wings of Nanosialidae , those having a shorter anal area, narrower costal area, and more delicate membrane are interpreted as the hind wings.