Alavesia zigrasi, 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 : 34-36

Alavesia zigrasi , new species

Figures 1M , 4B–C , 7D , 9A–B , 10D , 16

DIAGNOSIS: Large species (fig. 16), wing 2.1 mm; M 1+2 and R 4+5 parallel; cell dm extending well beyond apex of cell cua; crossvein br-m at two-thirds of cell dm; CuA arched apically.

DESCRIPTION (based on holotype): Male. Coloration of holotype well preserved; body almost entirely dark brown, including pleura and halter. Coxae mostly yellowish, dark area on distal portion of anterior surface. Forefemur yellowish, basal 2/3 of mid and hind femora yellowish, apices brown. Tibiae and tarsi dark brown. Wing slightly tinted, trailing edge lighter. All tergites dark, including epandrium; cerci light.

Head: Scape barely observable; pedicel short, conelike. Postpedicel large, broad (fig. 1M), L/ W 3.22. Stylus short, L 0.36 × length of postpedicel, with two small basal articles. Palpus broad, rounded apically; labellum with at least 10 pseudotracheae (fig. 9A, B).

Thorax: Macrosetae very thickened; acrostichals robust, in biserial rows; dorsocentral setae similar to acrostichals, ending in 2 pairs long prescutellars (posterior pair longest); 1 anterior and 1 posterior postpronotal seta; notopleural setae of variable lengths (3 most posterior ones thick and long); 1 postsutural supraalar seta; 1 postalar seta; 3 pairs scutellar setae, lateral pair 0.6 × L apical pair.

Legs: Forecoxa with short, erect setae on anterior surface, 5–6 of them thick. Forefemur with anteroventral row of short, 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 dense dorsal row of setae, length about half width of tibia, plus row of ~6 larger, spinelike setae (length slight less than tibial width); posterior surface of hind tibia with fine, brushy setulae.

Wing: Length 2.1 mm (fig. 4B, C), vein C terminating slightly beyond M 1+2; Sc nearly reaching costal margin; R 4+5 parallel to M 1+2; crossvein r-m at distal third of cell dm; apex of M 4 slightly closer to M 1+2 than to CuA+CuP; CuA oblique, slightly arched, not aligned with bm-m, apex of cell cua acute, cell cua longer than cell bm; apex of CuA+CuP slightly curved at apex. Vein A well developed.

Abdomen: Slightly longer than thorax, setae short, spinulelike setae on posterior and lateral margins of sternites 2–5. Segments 1–5 broad, others retracted into segment 5. Terminalia unique (fig. 7D): Epandrium dorsally incomplete, long fringe of ~8 setae on ventral margin. Cercus small; surstylus straight (curved slightly inward), projecting backward, thicker than in other species. Phallus flexed anteroventrad, apex bifid and minutely feathered.

TYPE MATERIAL: Holotype, male JZC Bu-281. The left antenna and distal half of the right foreleg lost . Paratypes, three females ( AMNH Bu-KL9-21, JZC Bu-165a, JZC Bu-165b), JZC Bu-282 (male), genitalia not well preserved; coloration not preserved, body with some compression; differs from holotype by venation (fig. 4C): r-m at middle of cell dm, bm-m and m-cu slanted, CuA strongly arched .

ETYMOLOGY: The specific epithet is named in honour of James Zigras, from whose collection these and other fossil specimens originate.

Undetermined Specimens

Four pieces of Burmese amber in the AMNH contain specimens that are difficult to identify to species, based on inadequate preservation. All except AMNH KL7-7 were found in a large batch of unprocessed amber ( Grimaldi et al., 2002). A significant portion of Burmese amber contains arthropod inclusions that are too distorted by compression for definitive identification; since these usually contain many fine fractures, such pieces are rarely sold commercially, a source of the fossils that will skew the natural abundances of inclusions. The undetermined Alavesia species are reported here for the sake of completeness.

AMNH Bu-129: Possibly male; postpedicel long, slender; R 4+5 curved, quite divergent from M 1; CuA arched, not recurved. Amber turbid, fractured; specimen crumpled. Syninclusions: Psychodidae , female empidoid (? Neoturonius ).

AMNH Bu-769: Male, very poor preservation, identifiable as Alavesia on basis of very distinctive antennae. Left wing preserved but most venation not visible; CuA recurved. Piece with many fine fractures; fly is partial and crumpled. Syninclusions: particulate debris; undetermined larva.

AMNH Bu-957: Like A. brevipennae a tiny species, postpedicel microtrichose and lanceolate (tapered for entire length), stylus microtrichose; R slightly arched, quite divergent with M 1. Unlike in A. brevipennae CuA is recurved (vs. acute). Head is deformed, but mouthparts well preserved and visible. Syninclusions: stellate trichomes, 2 fine feather barbs with very fine, short barbules.

4+5

AMNH KL7-7 : A piece that contains 2 males and 1 female of possibly A. myanmarensis . Species of average size; male postpedicel large, lanceolate ; R 4 +5 arched, M 1 slightly arched, CuA arched (not recurved). Syninclusions indicate a ground-dwelling assemblage: Staphylinid beetle, cecidomyiid midge, 5 mites, soil particles, 3 leaflets (with parallel venation), a thrips, and a male coccoid .

The following undetermined females of Alavesia species are reported here for the sake of completeness: JZC Bu-1729 (AMNH) (figs. 1N, 3F, 10C, 11E–F, 17B); USNM PAL 726870

(USNM) (fig. 17C, E); USNM PAL 726874 (USNM) (figs. 11G, 17D); and USNM PAL 726875 (USNM) (fig. 17F).

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 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 9. Mouthparts of Burmese amber Alavesia. A. A. zigrasi head, lateral view, AMNH Bu-KL9-21. B. A. zigrasi (same specimen as A), mouthparts, showing labellum with pseudotracheae, labrum, hypopharynx. C. A. longicornuta, holotype, JZC Bu-556, showing setose palps. D. A. longicornuta, paratype, USNM PAL 726871, showing setose palps. E. A. longistylata, USNM PAL 726872, showing slender, setose palps.

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 16. Alavesia zigrasi in Burmese amber. A. Holotype, JZC Bu-281. B. Male paratype, JZC Bu-282. C. Female paratype, AMNH Bu-KL9-21. D. Female paratype, JZC-165a. E. Female paratype, JZC Bu-165b.

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.