Alavesia longicornuta, 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 : 17-25

Alavesia longicornuta , new species

Figures 1G , 2F , 5A , 8F , 9C–D , 13D , 14A

DIAGNOSIS: Males of this species are distinctive, characterized by greatly lengthened aristalike stylus (figs. 13D, 14A) (2.9 × length of postpedicel), bearing a light, apical flaglike expansion; elongate and flattened palpi; CuA strongly recurved, in line with m-cu; CuA+CuP sharply curved subapically to wing margin. Distinguished from males of A. longistylata by slightly longer stylus with a light (vs. dark) apical “flag,” broader palpus, longer and narrower wing; cell cua significantly thicker.

DESCRIPTION: Male. Coloration, except stylus, not preserved. Head: Scape and pedicel quadrate, scape longer than pedicel. Postpedicel greatly lengthened, L/ W 4.0, tapered on apical two-thirds, longer than head height. Stylus with two small basal articles, with apical aristalike stylus 2.9 × length of postpedicel (fig. 1G); apex of stylus with light, oval, flaglike flattened expansion (fig. 8F). Palpus bladelike (fig. 9C, D), flattened, projecting, strongly tapered, with fine setae ventrally, length about subequal to eye height.

Thorax: Chaetotaxy thickened (fig. 5A): biserial row of short acrostichal setae; dorsocentral setae similar to acrostichals, ending in pair of long prescutellar dorsocentral setae; 2 anterior and 1 posterior postpronotal setae; 4 anterior notopleural setae of variable lengths, 1 posterior notopleural seta; 1 postsutural supraalar seta; 1 postalar seta; 2–3 pairs of scutellar setae.

Legs: Forecoxa with short erect anterior setae. Femora with anteroventral row of short setae. Tibiae with long, apical ventral seta. Hind tibia with dorsal row of setae, length about half width of tibia; posterior face clothed with brush of fine setae.

Wing: Length 2.2 mm (fig. 2F), costa terminating slightly beyond M 1+2; Sc nearly reaching costal margin; R 4+5 parallel to M 1+2 until near wing margin; crossvein r-m opposite near middle of cell dm; apex of M 4 at equal distance between M 1+2 and CuA+CuP; CuA straight, turned toward wing base, aligned with bm-m; apex of cell cua truncate, length of cell cua shorter than cell bm; CuA+CuP mostly straight, sharply curved subapically to wing margin.

Abdomen: Setae short, without distinct posteromarginal setae. Segments 1–5 broad, remaining segments retracted with segment 5. Terminalia obscured by bubble.

TYPE MATERIAL: Holotype, male, JZC Bu-556 ( AMNH) . Paratype: USNM PAL 726871 (1 male, USNM) .

ETYMOLOGY: The specific epithet is from the Latin cornutus (“horned, bearing horns”), in reference to the elongate aristalike stylus.

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 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 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 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 13. Alavesia spp. in Burmese amber. A. A. lanceolata, USNM PAL 726868. B. A. pankowskiorum, USNM PAL 726869. C. A. latala, holotype, AMNH Bu-1476. D. A. longicornuta, holotype, JZC Bu-556

FIGURE 14. Alavesia spp. in Burmese amber. A. A. longicornuta, paratype male, USNM PAL 726871. B, C. A. longistylata, USNM PAL 726872.

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.