Archebittacus Riek, 1955

Lambkin, Kevin J., 2017, Archebittacus exilis Riek — the oldest hangingfly (Insecta: Mecoptera: Bittacidae), Zootaxa 4290 (2), pp. 385-389 : 386

Archebittacus Riek, 1955

Archebittacus Riek, 1955: 666 .

Type species. Archebittacus exilis Riek, 1955 , by original designation.

Diagnostic characters. Forewing sub-petiolate, base narrowed but not as much as in extant and most fossil genera; costal space without crossveins (humeral vein apparently not preserved); Sc simple, terminating just before level of R4+5 fork; one sc–r1 at level of primary fork of Rs; R1 with two short terminal branches, R1b evenly curved; pterostigma quite long, defined posteriorly by a fine, evenly curved groove; one pterostigmal crossvein, running to R2+3 not R2 (preserved only between pterostigmal groove and R2+3); one backwardly oblique r1–r2+3; primary fork of R distal to level of separation of M and CuA; R2+3 with two branches; stem of Rs much shorter than its branches; primary fork of M slightly proximal to that of Rs; M with five branches, M3+4 fork distinctly proximal to that of M1+2, M4 deeply forked; m–cu variable, running from M3+4 ( Fig.4 ) or M4 ( Fig.2 ); 1r–m, m1+2–m3, and m–cua not aligned, quite discordantly oblique; apical fields of Rs and M with limited crossveins (although slight kinking detected in some longitudinal veins suggesting the presence of more than are preserved); stem of CuA oblique, fused with M for a very short distance; one, or possibly two, cua–cup; 1A long, extending to level of primary fork of M; 1A and 2A more widely spaced than in extant and most fossil genera; 2A extending beyond level of the separation of M and CuA.

Hindwing shape and costal space as in forewing; Sc simple, shorter than in forewing, terminating proximal to primary fork of Rs; one apical sc–r1; relative positions of forks of main veins and terminations of 1A and 2A as in forewing; apex of R1 and pterostigmal area indistinctly preserved; Rs as in forewing; M with four branches, M3+4 fork distinctly proximal to that of M1+2; r–m, im, and m–cua not aligned, the latter two less oblique than in forewing; apical fields of Rs and M indistinctly preserved, crossveins not detectable; one cua–cup; one cup–1a; CuP and anal veins of usual bittacid form (CuP and 1A fused basally, 1A after separation from CuP forming a Y-vein with 1a–2a), except 2A and 3A longer and more widely spaced; one 2a–3a.

Notes. As noted by Riek (1955), Archebittacus is most similar to the Jurassic Protobittacus Tillyard, 1933 ( Tillyard 1933, Fig. 18), but the forewing differs in the more proximal position of sc–r1, the presence of r1–r2+3 (absent in Protobittacus ), the crossvein between M and CuA originating from M3+4 or stem of M4 (from posterior branch of M 4 in Protobittacus ), and in the presence of cua–cup (absent in Protobittacus ).

Figures

FIGURES 4 – 5. Archebittacus exilis Riek: 4, forewing; 5, hindwing; Pcv, pterostigmal crossvein, Pg, pterostigmal groove.

FIGURES 1 – 3. Archebittacus exilis Riek, forewing: 1, holotype, UQG C 2139 (mirrored); 2, paratype, UQG C 1495 (mirrored); 3, paratype, UQG C 1545.