Alavesia angusta, 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 : 14

Alavesia angusta , new species

Figures 1A , 2A , 12A

DIAGNOSIS: Postpedicel slender, fusiform, L/ W 4.47; wing slender, L/ W 2.8; M 1+2 and R 4 +5 parallel for entire lengths; crossvein bm-cu at midlength of cell dm; crossvein dm-m slanted; CuA straight, directed to wing base, in line with crossvein m-cu; cell dm extending well beyond apex of cell cua .

DESCRIPTION: Male. Coloration not preserved. Head: Scape small, goblet-shaped; pedicel quadrate; postpedicel narrow, almost fusiform, L/ W 4.47 (figs. 1A, 12A); stylus short, length 0.46 × the postpedicel, with 2 small basal articles. Palpus light, extended slightly beyond level of proboscis.

Thorax: Chaetotaxy: acrostichals fine, short, in biserial rows; dorsocentrals similar to acrostichals, ending in pair of long, fine prescutellars; 2 short postpronotal setae; 4 short, fine anterior notopleural setae, 2 large posterior notopleural setae; 1 postsutural supraalar seta; 1 finer postalar seta; 3 pairs scutellar setae, apical pair longest, upright, crossed for ~0.5 × their length.

Legs: Forecoxa with many short setae on anterior surface. Forefemur with ventral row ~15 short, stiff setae. Tibiae with long, apical ventral seta. Hind tibia with dense dorsal row of setae, length about half width of tibia; posterior surface with fine, brushy setae.

Wing: Length 1.4 mm (fig. 2A); C terminating slightly beyond M 1+2; Sc nearly reaching costal margin; R 4+5 parallel to M 1+2 for entire lengths; crossvein r-m slightly distal to middle of cell dm; apex of M 4 slightly closer to M 1+2 than to CuA+CuP; CuA strongly recurved, in line with bm-m; apex of cell cua truncate, cell cua shorter than cell bm; CuA+CuP slightly curved.

Abdomen: No longer than thorax; setae short, without differentiated posteromarginal setae. Segments 1–5 broad, other segments retracted into segment 5. Terminalia well preserved in holotype (not illustrated): Epandrium complete dorsally, U-shaped, with fringelike row of five long setae on ventral margin; cercus flat, broad, scalelike, meeting medially. Surstylus long, slightly curved (as in A. magna , sp. nov.); postgonites + phallus as for most other species: thicker at base, hook-shaped, bend in middle, phallus downturned.

TYPE MATERIAL: Holotype, male, USNM PAL 726867 ( USNM).

ETYMOLOGY: The specific epithet is from the Latin angustus (narrow, slender), in reference to the narrow wing and cell cua.

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 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.