Alavesia brevipennae, Sinclair & Grimaldi, 2020

Sinclair, Bradley J. & Grimaldi, David A., 2020, Cretaceous diversity of the relict genus Alavesia Waters and Arillo (Diptera: Empidoidea: Atelestidae), American Museum Novitates 2020 (3961), pp. 1-40 : 15

Alavesia brevipennae , new species

Figures 1B , 2B , 8D , 12B, C

DIAGNOSIS: Tiny species (fig. 12B, C), wing length 0.75 mm; postpedicel 2.3 × longer than aristalike stylus, slightly curved; wing shortened, rounded, and broad (L/ W 1.75); M 1+2 strongly arched, this vein and M 4 very divergent; CuA arched apically, CuA+CuP weakened, not reaching wing margin, M 4 closer to CuA+CuP than M 1+2.

DESCRIPTION: Male. Coloration not preserved. Head: Scape and pedicel quadrate, subequal in size and length. Postpedicel elongate, straplike, slightly curved, gradually tapered apically, 2.3 × longer than stylus (fig. 1B). Stylus with two basal articles, short (fig. 8D), without apical flaglike expansion; length 0.32 × that of postpedicel. Mouthparts very short; palpus short, not projecting.

Thorax: Chaetotaxy thickened, in numerous rows (not clearly visible): 2 anterior and 1 posterior postpronotal setae; 4 notopleural setae of variable lengths, 1 postsutural supraalar seta; 1 postalar seta; 2 pairs of scutellar setae.

Legs: Most setae thickened. Forecoxa with short erect anterior setae; anteroapical setae longer and stouter. Forefemur with anteroventral and posteroventral row of short setae. Mid and hind femora with anteroventral row of short setae. Mid and hind coxae with 2–3 stout lateral setae on apical half. Tibiae with biserial row of short, stout ventral setae; apex of tibiae with long, apical ventral seta; hind tibia with several dorsal setae, length about half width of tibia.

Wing (wing length 0.75 mm) (fig. 2B): shortened and rounded; costa terminating slightly beyond M 1+2; Sc nearly reaching costal margin; R 4+5 closely associated with M 1+2; M 1+2 arched, strongly divergent from R 4+5 distally; cell dm very short, crossvein r-m nearly opposite apex of cell bm; M 4 straight to wing margin; apex of M 4 closer to CuA+CuP than M 1+2; CuA arched; apex of cell cua convex, length of cell cua subequal to cell bm; CuA+CuP mostly straight, strongly curved subapically to wing margin.

Abdomen: Setae short, without distinct posteromarginal setae. Segments 1–5 broad. Terminalia and remaining segments damaged and partially obscured.

TYPE MATERIAL: Holotype, male, AMNH Bu-494 ( AMNH).

ETYMOLOGY: The specific epithet is from the Latin penna (wing, feather) and brevis (short), referring to the shortened wing that characterizes this species.

Figures

FIGURE 2. Wings of six species of Alavesia in Burmese amber. All are males, to the same scale. Specimens: A. USNM PAL 726867. B. AMNH Bu-494. C. AMNH Bu-496. D. USNM PAL 726868. E. AMNH Bu-1476. F. JZC Bu-556.

FIGURE 8. Heads and antennae of Burmese amber Alavesia. A. A. lanceolata, head and antennae, dorsolateral view, holotype, USNM 726868. B. A. pankowskiorum, head and antennae, lateral view, paratype, AMNH Bu-KL7-19. C. A. magna, left antenna, lateral view, holotype, AMNH Bu-KL2-7. D. A. magna, left antenna detail, lateral view, holotype, AMNH Bu-KL2-7. E. A. brevipennae, lateral view, AMNH Bu-494. Note the longer microtrichia on the postpedicel. F. A. longicornuta, holotype, stylus tip, lateral view, JZC Bu-556.

FIGURE 12. Alavesia spp. in Burmese amber. A. A. angusta, USNM PAL 726867. B. Drawing of A. brevipennae, AMNH Bu-494. C. Photomicrograph of A. brevipennae, AMNH Bu-494. D. A. myanmarensis, AMNH Bu-496.

FIGURE. 1. Antennae of Burmese amber Alavesia species, lateral views. All are males except N, O, P. Some antennae were reversed in direction for optimal comparison; longicornuta and longistylata are slightly reconstructed to account for curvature of the stylus. All are to the same scale. Specimen numbers: A. USNM PAL 726867. B. AMNH Bu-494. C. AMNH Bu-496. D. USNM PAL 726868. E. AMNH Bu-KL2-7. F. AMNH Bu-1476. G. JZC Bu-556 (AMNH). H. USNM PAL 726872. K. USNM PAL 726869. L. AMNH Bu-KL7-18. M. JZC Bu-282. N. Undetermined species. O. A. zigrasi. P. A. zigrasi.