Acumyia Harris

Harris, Keith M., 2008, The Acer seed midge, Acumyia acericola, an unusual new species and genus of Lasiopteridi (Diptera: Cecidomyiidae) with aciculate ovipositor and larval puparium, Zootaxa 1910, pp. 21-26 : 22

Acumyia Harris (new genus)

Figures 1–10 .

Diagnosis. This new genus is distinguished from all other known genera of Cecidomyiidae by the following combination of characters: larval sternal spatula with single triangular (not bilobed) anterior blade (fig. 8); plus final instar encased in a distinctive brown, shiny puparium (fig. 7); plus female ovipositor needle-shaped (aciculate) and fully retractable into the abdomen (fig. 4) and pupa with exceptionally long cephalic setae and prothoracic spiracles (figs 9,10). The presence of parameres in the male genitalia indicates that the genus belongs in the supertribe Lasiopteridi and other characters (especially the male flagellomeres with long, narrow necks; wing with R5 joining C before the wing apex and longitudinally divided female abdominal tergite 8) suggest that it is morphologically close to Dasineura Rondani and associated genera. But it is difficult to place it with any certainty, especially as the higher classification of the Dasineurini is not well defined ( Sylvén and Tastás-Duque 1993; Gagné 2004). Various types of piercing ovipositor occur in a few genera of Lasiopteridi ( Gagné 1975) but aciculate ovipositors rarely occur in the supertribe, one known exception being in the genus Actilasioptera Gagné. A similar aciculate ovipositor is also characteristic of the widespread and speciose genus Asphondylia Loew , which belongs in the supertribe Cecidomyiidi, and is therefore not closely related to Acumyia . The occurrence of a larval puparium is similarly unusual. The only other genus of Lasiopteridi in which puparial development is known to occur is Mayetiola Kieffer , with the so-called 'flax-seed' puparia of the Hessian fly, M. destructor (Say) , the best-known example. But the aciculate ovipositor of Acumyia is quite unlike the soft, telescopic ovipositor of Mayetiola and the male genitalia and female abdominal tergites of Acumyia suggest closer affinity with the Dasineurini . DNA sequencing may help clarify this tentative assessment. The genus Acumyia currently contains only the type species, Acumyia acericola Harris.

Etymology. The name is derived from Latin acus (needle), and Greek myia (fly), and relates to the needlelike aciculate ovipositor.

Figures

FIGURES 1 – 4. Acumyia acerivora gen. nov., sp. nov. 1. Acer campestre fruit with ovular cavity exposed to show two puparia lying near the developing ovule. [Scale line = 5 mm.] 2. male and 3. female [Scale lines = 0.5 mm.]. 4. Micrograph of the aciculate ovipositor partly everted from the abdomen, showing the divided tergite 8 above the bulbous base of the ovipositor. [Scale line = 0.05 mm.]

FIGURES 5 – 10. Acumyia acerivora gen. nov., sp. nov. 5. Micrograph of male genitalia, dorsal view. [Scale line = 0.05 mm.] 6. Micrograph of the male genitalia, lateral view, focused on the brown parameres that enclose the aedeagus and also showing one of the dorsobasal lobes and the hypoproct. [Scale line = 0.05 mm.] 7. Puparium with sternal spatula and head capsule of the enclosed final instar larva visible at left. [Scale line = 1 mm.] 8. Sternal spatula of final instar larva. [Scale line = 0.1 mm.] 9. Pupal exuvium of head showing long cephalic setae. [Scale line = 0.1 mm.] 10. Pupal prothoracic spiracle. [Scale line = 0.05 mm.]