Aulacigastridae

Family Aulacigastridae View in CoL View at ENA

Diagnosis. The family Aulacigastridae is distinguished from other opomyzoid families by the following combination of characters: Body predominantly dark brown to black. Fronto­orbital setae 2; postocellar and interfrontal setae absent. Pedicel lacking a dorsal cleft. Greater ampulla present. Cell dm+bm flat, lacking a longitudinal crease or fold; crossvein r­m at midlength or toward base of combined length of cell dm+bm; subcosta partially fused with vein R 1 apically. Male abdomen with 6 visible tergites; surstylus fused with epandrium; hypandrial bridge present; female with 3 spermathecae.

Description. Adult: Coloration: Body predominantly dark brown to black. Frons often with anterior 1/4–1/2 yellowish, pale brown or orange. Scutum typically uniformly microtomentose; pleura white microtomentose on ventral half in some species of Aulacigaster . Wing hyaline or infuscate, brown.

Morphology: Body robust (scutal ratio 1.10–1.35), or elongate (scutal ratio 1.50– 1.75).

Head: Head higher than long (head ratio less than 0.9), or longer than high (head ratio higher than 1.1); face completely sclerotized, often projected, easily visible in profile; gena narrow, usually less than 1/3 width of 1 st flagellomere. Ocellar seta absent or present; postocellar seta absent; medial vertical seta typically mesoclinate; seta at most 3/4 length of lateral vertical seta; fronto­orbital setae 2, in some species with posterior seta medial to and almost horizontally aligned with anterior seta; setulae between fronto­orbital setae 1­ 2, one proclinate; interfrontal setae absent; peristomal setae consisting of weak ( Aulacigaster ) to strong ( Curiosimusca ) setae posterior to pseudovibrissal seta. First flagellomere round, oval or triangular; arista unsegmented, sometimes naked and straight, but often rayed and zigzagged, if present, rays alternating dorsal and ventral on apical 2/3 of arista.

Thorax: Anepisternum bare ( Curiosimusca ) or bearing 1–2 setae along posterior margin ( Aulacigaster ); greater ampulla present; dorsocentral setae 0+1 or 0+2; scutellar setae 1 or 2, apical setae nearly parallel, curved posteriorly; prosternum (basisternum) large, approximately as wide as long, with a medial groove and precoxal bridge. Wing: Costal vein with humeral and subcostal breaks ( Curiosimusca ) or with subcostal break only ( Aulacigaster ). Cell dm+bm flat, lacking a longitudinal crease or fold; crossvein r­m at midlength or slightly basal of combined length of cell dm+bm; subcosta partially fused with vein R 1 apically; vein R 1 often with apical kink.

Male abdomen and terminalia: 6 th “tergite” large, representing fused 6 th tergite with 7 th and 8 th syntergosternites (=circumverted 7 th and 8 th segments); 6 th sternite asymmetrical and fused with 6 th tergite on left side. Abdominal sternites narrower than respective tergites, with sternites slightly increasing in width posteriorly ( Aulacigaster ), or as wide as respective tergites ( Curiosimusca ). Surstylus fused with epandrium; cerci membranous to strongly sclerotized, separate or partially fused basally; hypandrial bridge present; phallus short, partially sclerotized; phallapodeme projected ventrally on both sides, shielding base of phallus.

Female abdomen and terminalia: Postabdomen distinctly shorter than preabdomen. Spermathecae 3, often with ventral digitiform projections.

Immatures (only known for Aulacigaster ): Larva (3 rd instar): Subcylindrical, amphipneustic, bearing a long, partially retractile terminal respiratory tube; integument white, almost transparent, covered with minute spicules and sensory setae, or smooth; 3 thoracic and 8 abdominal segments present; abdominal segments with ventral creeping pads bearing minute spicules; last abdominal segment with a small perianal pad; anterior spiracle small, retracted into a deep, narrow pocket; posterior spiracles on apex of respiratory tube, joined together at their base, bifurcating posteriorly; cephalopharyngeal skeleton slender with well­developed mandible bearing 2 pairs of accessory teeth; hypopharyngeal and tentoropharyngeal sclerites separate. Puparium: light brown, oval in shape, with prothoracic spiracle completely everted.

Distribution. Worldwide, excluding Australasian and Oceanian Regions.

Discussion. Curiosimusca shares with Aulacigaster the following characters of which most are also present in some other families of Opomyzoidea and may indicate phylogenetic relationships. These character data are being tested within a more extensive and comprehensive quantitative phylogenetic analysis (Rung, Mitter & Mathis in prep.).

1. Postocellar seta absent. The postocellar seta is absent in several isolated opomyzoid

taxa, although it is present in most Acalyptrates. Hennig (1958, 1969, 1971) and J. F.

McAlpine (1989) considered the absence of the postocellar seta to be a synapomorphy for the Aulacigastridae , including Cyamops , Stenomicra and Planinasus .

2. Greater ampulla present. The greater ampulla corresponds to a basal swelling of the pleural wing process (at mediodorsal margin of the anepimeron that articulates with the wing). It is usually absent in Acalyptrates but is present in the opomyzoid families Periscelididae and Aulacigastridae . It is also present in the Acalyptrate family Psilidae (Diopsoidea) , Tephritidae (Tephritoidea) and most if not all Calyptrates. J. F. McAlpine (1989) based the monophyly of Periscelididae plus Aulacigastridae on the presence of a greater ampulla.

3. Vein R 1 with a preapical kink. Roháček (1998) mentioned this character as being unique to Anthomyzidae and Opomyzidae , but it occurs in Agromyzidae (Agromyzinae) , Aulacigaster and Curiosimusca . In some Aulacigastridae , this kink is better developed and reaches the costal vein, whereas in other (undescribed) species, it is nearly unnoticeable.

4. Crossvein bm­cu absent. This crossvein is usually present in the Opomyzoidea , being absent also in some Neurochaetidae , some Stenomicra , some Australian and Oceanic species of Cyamops ( Baptista & Mathis 2000) , Nemula longarista (Neminidae) ( Freidberg 1994: 476, Fig. 10 View FIGURES 9–11 ), Asteiidae and Xenasteiidae ( Papp 1998b: 306, Fig. 26.2).

5. Presence of a hypandrial bridge. When the hypandrium is closed posteriorly, forming a ring around the base of the phallus, it is sometimes said to have a hypandrial bridge. A closed hypandrium is present in the Clusiidae ( Soós 1987: 856, Fig. 70.8), Anthomyzidae (Roháček 1998b: 270, Fig. 22.19) and Opomyzidae ( Vockeroth 1987: 884, Fig 74.10), besides the Aulacigastridae . It also occurs in other Acalyptrate families, sometimes receiving other names. J. F. McAlpine (1989: 1456) considered the absence of a hypandrial bridge to be a synapomorphy for the Opomyzoidea and the presence of a hypandrial bridge to be a secondary acquisition.

6. Shape of the distiphallus. The distiphallus is relatively membranous, bears two internal rod­like sclerites and is minutely haired, resembling a brush apically. The phallus of Echidnocephalodes barbatus (incertae sedis) also has internal rod­like sclerites.

7. Male abdomen with six visible pregenital segments (tergites and sternites) and with the 6 th “tergite” apparently representing the fusion of the true 6 th tergite with the 7 th and 8 th syntergosternites (=circumverted 7 th and 8 th segments)( Fig. 12 View FIGURES 12–14 ). The 6 th sternite is asymmetrical and is fused with the 6 th tergite on the left side.