The Agromyzidae are the main subject of this CD-ROM. Both the module "Morphology" (External adult morphology) and most sections of the "Introduction" (Preface) are dedicated to some general characteristics of this family. This text is only a brief systematic overview about the group. On the other hand this comprehensive diagnostic summary cannot be found elsewhere on the CD.
Agromyzidae (mining flies) are small black, greyish or yellowish flies usually 2-5 mm long. Despite their color variation, there are several common characters that usually allow easy identification of the family.
The mining flies can be subdivided into the two monophyletic subfamilies Agromyzinae and Phytomyzinae, which are treated separately. Currently only 28 genera are accepted as valid groups, of these 18 are treated in the higher taxa cards of this CD. In this section only a brief diagnosis and some apomorphic characters are given. Since the agromyzids are the main topic of this CD-ROM a separate module (morphology) is dedicated to the general characteristics of these flies. The phylogeny of the group is reviewed in a section of the Introduction-module (Evolutionary history).
According to Hennig, 1958 (cited after Spencer, 1987) the imagines of Agromyzidae can be recognized by the following external characters:
- Vibrissae present (converging)
- One to seven frontal bristles present
- Costal break present at the apex of Sc
- Cell cup (posterior cubital) small
- Vein A1 not reaching wing margin
- Pregenital sclerites of male with a simple (fused) tergal complex (tergites 6/8) with only two spiracles between tergite 5 and the genital segment.
Apart from agromyzids, there are several members of other dipteran families with leaf-mining or in a wider sense endophagous life history (Scathophagidae, Anthomyiidae, Tephritidae, Drosophilidae). This CD-ROM deals with Agromyzidae only. The major larval characters to separate agromyzids (the true mining flies) from other leaf-mining Diptera, basically two larval characters can be employed:
Cephalopharyngeal skeleton normally slender, dorsal bridge of cephalopharyngeal skeleton small or missing.
Anterior spiracles close together on the dorsal side.
Agromyzidae can be confirmed as monophyletic group by the following evolutionary novelties (apomorphies) shared by all species:
The female postabdomen of Agromyzidae underwent numerous modifications, which enables the female puncturing and oviposition in plant tissue. Although some other phytophagous dipteran families with ovipositors exist, a homology of the corresponding structures with the agromyzid ovipositor have never been suggested (Griffiths, 1972 a, Hennig, 1958). This is because the following character is missing in all other dipteran groups equipped with an ovipositor for puncturing plants:
The first section of the seventh abdominal segment forms a syntergosternite (oviscape) that bears a dorsal and ventral appendage extending below the preceding tergite and sternite (female terminalia.pct). Oviscapes of other Diptera are generally lacking these appendages.
Sternites 6-8 of males are strongly reduced or missing, making the postabdomen nearly symmetrical. Furthermore the strongly developed aedeagal apodeme is characteristic for the family.
The larval characters, already summarized above, are apomorphies.