Alavesia magna, 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 : 26-28

Alavesia magna , new species

Figures 1E , 3B , 5B , 6D–E , 8C–D , 10A , 11B–C , 15A–B

DIAGNOSIS: One of two largest species of genus (fig. 15A, B), wing length 3.0 mm; wing linear, long and slender, L/ W 2.97; R 4+5 and M 1+2 entirely parallel; apex of CuA not recurved; postpedicel slender, L/ W 3.45. Male genitalia: surstylus very slender, digitiform, with small dorsal lobe bearing stiff, short seta; postgonites+phallus long, phallus downcurved, minutely feathered at tip.

DESCRIPTION: Coloration: Yellowish portions of body: palpus, labellum, much of coxae (also with light brown portions), stem of halter, proximal halves of femora, tergites 6–8; remaining areas light to dark brown (fig. 15A, B). Female paratype slightly darker (preservational artifact?). Wing lightly tinted yellowish on costal half. Male. Head: Scape short, caplike; pedicel short, caplike, with distal ring of setulae. Postpedicel large, lanceolate (fig. 1E), tapered in distal half, L/ W 3.45; stylus of moderate length, 0.45 × L postpedicel, with 2 minute basal articles (fig. 8C, D). Palpus very small; labellum bulbous, with ~7–8 pseudotracheae.

Thorax: Macrosetae thickened (fig. 5B); acrostichals very fine, small, in irregular biserial rows; dorsocentral setae slightly larger than acrostichals, gradually longer posteriad, ending in pair of long prescutellar setae (longest setae on thorax). Two postpronotal setae (slightly larger than setulae); 8 notopleural setae of variable lengths, 3 posterior ones longest; 1 postsutural supraalar seta; 1 postalar seta; 2–3 pairs of scutellar setae, apical pair largest, crossed at midlength.

Legs (fig. 11B, C): Forecoxa with short, erect setae on anterior surface, longer ones apically. Forefemur with anteroventral row of ~40 small, spinulelike setae; short row of such setae near apices of mid and hind femora. Tibiae with long, apical ventral setae: 1–2–2. Hind tibia with 2 dorsolateral rows of thicker setae, lengths ~0.7 × width of tibia; posterior surface with slight brush of finer setae.

Wing: Length 3.0 mm (figs. 3B, 10A). Vein C terminating slightly beyond M 1+2; Sc nearly touching costal margin; R 4+5 entirely parallel to M 1+2, both very straight, crossvein r-m at apical 1/3 of cell dm; apex of M 4 about equidistant between M 1+2 and CuA+CuP; CuA arched; apex of cell cua acute, cell cua longer than cell bm; CuA+CuP virtually straight.

Abdomen: Longer than thorax; setae short, no differentiation of posteromarginal setae on tergites or sternites. Segments 1–4 very broad (2 very large), remaining segments much smaller, partially retracted. Terminalia (fig. 6D, E): observable dorsally and laterally. Epandrium complete dorsally, with setulae and marginal fringe of ~8–10 long, fine setae on ventral margin. Surstylus long, slender, digitate, with small dorsal lobe bearing small spinelike seta, apically with minute toothlike apical seta that points inward; mesal surface of surstylus with microtrichia. Postgonites highly integrated, projecting posteriad; phallus abruptly bent ventrad, apex bifid and finely feathered. Female terminalia telescoping; cerci exposed and deflexed downward.

TYPE MATERIAL: Holotype male AMNH Bu-KL2-7. Paratype, female USNM PAL 726873 .

ETYMOLOGY: In reference to the body size, being one of the largest of all the Burmese amber species, along with A. longicornuta .

Figures

FIGURE 3. Wings of three species of Alavesia in Burmese amber. All are to the same scale. Specimens: A. USNM PAL 726872. B. USNM PAL 726873. C–E. A. pankowskiorum, see figure for specimen numbers. F. Undetermined species.

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 6. Male terminalia of three species of Alavesia in Burmese amber, shown in various views, to the same scale except for B. A. A. lanceolata, USNM PAL 726868, dorsolateral view. B, C. A. longistylata, USNM PAL 726872. B. Lateral view of abdominal apex. C. Epandrium and genitalia, posterolateral view. D, E. A. magna, AMNH Bu-KL2-7. D. Ventrolateral view. E. Dorsal view. Abbreviations: cer, cercus; ep, epandrium; pg, postgonite; pg+ph, postgonite + phallus (integrated); ph, phallus; st8, sternite 8; sur, sustylus; t8, tergite 8.

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 10. Features of Alavesia spp. A. A. magna, holotype, AMNH Bu-KL2-7, wing base. B. A. pankowskiorum male terminalia, right ventrolateral view, USNM PAL 726869. C. Female terminalia, Alavesia sp., lateral view, JZC Bu-1729. D. A. zigrasi female terminalia, lateral view, AMNH Bu–KL9–21.

FIGURE 11. Legs of Alavesia sp., showing the longitudinal furrows on the femora and tibiae (arrows). A. A. longistylata, fore and mid femora. B. A. magna, holotype, fore and mid femora, posterior surface. C. A. magna, holotype, hind tibiae. D. A. pankowskiorum, hind femur posterior/lateral surface, USNM PAL 726869. E. Alavesia sp., mid and hind femora, female, JZC Bu-1729. F. Alavesia sp., fore femur, posterior/lateral surface, same specimen as in E. G. Alavesia sp., right fore femur lateral surface, female, USNM PAL 726874.

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.