Trifionyximus Lepeco & Melo, 2022

Lepeco, Anderson, Barbosa, Diego N. & Melo, Gabriel A. R., 2022, A remarkable new family of stinging wasps from the Cretaceous of Myanmar and China (Hymenoptera, Aculeata), Journal of Hymenoptera Research 94, pp. 163-190 : 163

† Trifionyximus Lepeco & Melo gen. nov.

Type species.

† Trifionyximus cracens Lepeco & Melo, sp. nov.

Diagnosis.

The new genus is distinguished from the other genera described from Burmese amber by the presence of enclosed cells in the forewing (Fig. 6E ); and head comparatively small. From † Mirabythus , it differs in having the clypeus relatively short with a smooth apex, without denticles; and submarginal cell relatively long, about twice as long as wide, distally closed by vein 2rs-m (in † Mirabythus the cell is closed distally by vein 2Rs, judging by its confluence with m-cu), which is distanced from vein m-cu by about its length. An additional difference between both genera is the smaller size of † Trifionyximus gen. nov., not surpassing 5 mm.

Description.

Head. Not enlarged, slightly wider than mesosoma; obliquely hypognathous. Apical margin of clypeus entire, without denticles; disc of clypeus smaller than compound eye, strongly convex. Frons gently convex. Frontal line inconspicuous. Compound eye relatively large, occupying most of lateral surface of head, glabrous. Vertex arcuate, short, extending behind lateral ocelli for less than length of ocellar triangle. Lower margin of lateral ocelli below upper eye tangent. Antenna. F1-F8 about 1.5 times as long as maximum width; F1 about as long as F2. Mesosoma. Pronotal collar longer than mesoscutum; anterior surface somewhat narrowed medially in dorsal view, with transverse sulcus at mid-height; surface near posterior edge depressed transversally. Surface of mesoscutum between notauli convex, bulging in relation to lateral surfaces. Mesepisternum without transverse sulcus above mesepisternal pit. Metanotum without carinae on sublateral surfaces. Propodeum without box-like aspect, posterior slope convex; dorsal surface not depressed between spiracles. Legs. Arolia enlarged. Forewing. Veins C and Sc+R partially fused. Vein C nebulous, costal cell very narrowed and obscured at its mid-length. Pterostigma well developed, small. Marginal cell open, distal portion of vein Rs ending as nebulous vein near distal margin of wing. Submarginal cell posteriorly closed by 2rs-m. Medial cell posteriorly closed by nebulous veins. Vein M+Cu tubular. Vein cu-a tubular. Distal portion of vein Cu ending as a nebulous vein near distal margin of wing. Vein A tubular. Hindwing. Vein C present, tubular for at least basal third of wing, becoming nebulous distally. Vein A present, short. Metasoma. Long, but shorter than lengths of head and mesosoma combined; segments not distinctly telescopic within each other.

Etymology.

The name is derived from the type genus of the family with the addition of the Latin suffix - imus, meaning "pertaining to" or "related to". The name is masculine.

Figures

Figure 6. † Trifionyximus cracens sp. nov. A, B holotype female (DZUP Bur- 828) A habitus, dorsolateral view B dorsolateral view of head and mesosoma C-F paratype male (DZUP Bur- 1386) C habitus, lateral view D head, lateral view E forewing. Scale bar: 1 mm (A, C); 0.5 mm (B); 0.2 mm (D); 0.4 mm (E).