Alavesia spinosa, 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 : 30-34

Alavesia spinosa , new species

Figures 1L , 4A , 5C , 7C , 17A

DIAGNOSIS: Wing moderately slender (fig. 17A), L/ W 2.88, with distinctly narrowed apex; R 4 +5 and M 1+2 slightly curved; bm-cu and CuA nearly symmetrical; cell dm long and slender. Postpedicel very large, L/ W 4.88, lanceolate. Male genitalia with pair of thick, spinelike setae just anterior to bases of surstyli .

DESCRIPTION: Male. Coloration partially visible, much of cuticle with layer of air. Mesoscutum and scutellum dark tan/light brown; postpedicel brown; pleura brown at least in center, perhaps more; halter knob light brown; tarsi entirely dark brown, tibiae and femora lighter; tergites 1–4 dark brown, others yellowish; wing completely hyaline. Head: Scape slender, longer than pedicel; pedicel small, quadrate, setose; postpedicel long, lanceolate (fig. 1L), L/ W 4.88; stylus relatively short, 0.39 × length of postpedicel, with 2 minute basal articles.

Thorax: Macrosetae thickened (fig. 5C); acrostichals small and fine, in biserial rows; dorsocentrals similar to acrostichals, ending in pair of long prescutellar setae plus 3 smaller macrosetae per side. Postpronotal setae only slightly larger than acrostichals; 5 notopleural setae of variable lengths; 1 postsutural supraalar seta; 1 postalar seta; 3 pairs scutellar setae, apical pair upright, crossed at tips, only slightly larger than lateralmost scutellars.

Legs: Forecoxa setose on anterior surface, longer at apex; forefemur with anteroventral row of ~30 short, spinulelike setae along length of femur; mid and hind femora with such setae only near apex. Tibia with long, apical ventral seta(e): 1-2-2. Hind tibia with short dorsal row of 3–4 thick setae, lengths ~0.7 × width of tibia, posterior surface with brush of fine setulae.

Wing: Length 1.7 mm (fig. 4A), vein C terminating slightly beyond M 1+2; Sc nearly reaching costal margin; R 4+5 parallel to M 1+2 but diverging at apices, both veins slightly curved (not straight); crossvein r-m at distal third of cell dm, cell long and slender; apex of M 4 slightly closer to M 1+2 than to CuA+CuP; CuA not aligned with bm-m; apex of cell cua acute, cell cua almost symmetrical with cell bm; CuA+CuP bent slightly in middle.

Abdomen: Slightly longer than thorax. Setae short, with little differentiation; sternites 2–4 with slightly thicker, short setulae on posterior and lateral margins. Terminalia (fig. 7C): Epandrium short, broad, dorsally complete, with some setulae and fringe of 5–6 long, fine setae on ventral margins. Cercus small. Surstylus long, slender, digitate, with medial row of 5 fine setulae, apical setula clavate. Phallus short, bifid. Genitalia uniquely with pair of stout, large, spinelike setae near bases of surstyli.

TYPE MATERIAL: Holotype, male: AMNH KL7-18 . The fly is in excellent condition, preserved in clear yellow amber with many microscopic details visible.

ETYMOLOGY: The specific epithet is from the Latin spinosus (thorny), in reference to the pair of thick, spinelike setae on the male terminalia.

Figures

FIGURE 4. Wings of Alavesia spp. in Burmese amber. A. A. spinosa, AMNH Bu-KL7-18. B–D. A. zigrasi, showing some differences in venation among three specimens: B. male; C. male; D. female.

FIGURE 5. Thoraces of three species of Alavesia in Burmese amber, showing some of the differences in notal chaetotaxy. A. A. longicornuta (JZC Bu-556). B. A. magna (AMNH Bu-KL2-7). C. A. spinosa (AMNH Bu-KL7-18). All are to the same scale. Setal abbreviations: acr, acrostichals; dcs, dorsocentrals; ntpl, notopleurals; palr, postalar; pscdc, prescutellar dorsocentrals; salr, supraalar, sct, scutellars.

FIGURE 7. Male terminalia of three species of Alavesia in Burmese amber, shown in various views, to the same scale. A. A. pankowskiorum, AMNH Bu-KL7-19, lateral view. B. A. pankowskiorum, USNM PAL 726869, anterolateral view. C. A. spinosa, AMNH KL7-18, ventrolateral view, with detail of surstylus tip showing clavate setula. D. A. zigrasi, JZC Bu-281. For abbreviations see figure 6.

FIGURE 17. Alavesia spp. in Burmese amber. B–F are all females unidentified to species. A. A. spinosa holotype, AMNH Bu-KL7-18. B. JZC Bu-1729. C. USNM PAL 726870. D. USNM PAL 726874. E. USNM PAL 726870. F. USNM PAL 726875.

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.