FAMILY DESCRIPTIONS CAT = Although they do not contain keys, the identification references include recent cata- logues as valuable source on genera, species, distribution and references. CMPD = Contributions to a Manual of Palaearctic Diptera. Lindner = Chapter in Lindner, E., Die Fliegen der Paläarktischen Region. ( ) Family names between brackets refer to names as found in the literature, not recognised here as a separate family but, as indicated, considered part of another family. et al. References with more than two authors are given as First author et al. As far as not yet outdated, the number of genera and species in Europe is largely based on the Catalogue of Palaearctic Diptera, the CMPD and Fauna Europaea, the latter available online at: www.faunaeur.org (consulted was version 1.2, updated 7 March 2005). As to size, the following categories are distinguished: minute: smaller than 2 mm; small: 2- 5 mm; medium sized: 5-10 mm; large: 10-20 mm; very large: over 20 mm. Acartophthalmidae (key couplet 113; fig. 243) Systematics: Acalyptrate Brachycera; superfamily Opomyzoidea; in Europe 1 genus, Acartophthalmus, with 3 species. Characters: Minute to small (1-2.5 mm), brownish grey flies. Arista pubescent, ocelli present; Oc-bristles present; P-bris- tles strong, far apart, diverging; 3 pairs of F-bristles, curving obliquely out-backward, increasing in size, the upper pair the largest; scattered interfrontal setulae present; vibrissae absent but with a series of strong bristles near the vibrissal angle. Wing unmarked or tinged along costa; costa with a humeral break only; vein Sc complete; crossvein BM-Cu present; cell cup closed. Tibiae without dorsal preapical bristle. Biology: The larvae of this small family are presumed to feed on rotting organic matter. The adults appear to inhabit woodland and are found on rotting bracket fungi and mushrooms, decay- ing wood, droppings and carrion; deposition of eggs on a dead 452 Acartophthalmus nigrinus snail and carrion has been observed. (Zetterstedt), female; Papp 1978 Identification references: Ozerov 1986 (review); Stackelberg 1989al (former USSR); CMPD: Papp & Ozerov 1998; CAT: Papp 1984e. 110 Acroceridae (key couplet 45; fig. 98-99) Systematics: Lower muscomorph Brachycera; superfamily Nemestrinoidea; in Europe 8 genera and about 35 species. Characters: Despite variability in size (2.5-20 mm), colour and wing venation, these flies are easily recognised by their small head situated almost below the hunchbacked thorax, the large ear- shaped lower calypter and large abdomen. Body colour dull or lus- trous, usually black with white, yellow, or orange markings on thorax and abdomen. The small head largely occupied by the rela- tively large eyes, holoptic in both sexes. Wing clear or tinged; venation varying from complete to strongly reduced. Legs simple, femora sometimes swollen; empodium pulvilliform. Biology: The larvae are endoparasitoids of spiders, usually one larva per spider, rarely two or more. The spider continues functioning 453 Astomella hispaniae Lamarck, normally until just prior to completion of the fourth instar. At the male; Sack 1936 end of this stage the spider is largely eaten and the larva pupates outside the spider in the web the spider has woven at the very last. There are apparently no fixed host-parasitoid relationships at the species level. Adults may more or less abound locally but apart from species visiting flowers and feeding on nectar, they are rarely observed. They are mainly active on warm sunny days. Males may sometimes gather in large numbers at higher points in the landscape (hilltopping). Mating takes place in flight. Identification references: Chvála 1980 (Central Europe); Van der Goot 1963, De Jong et al. F 2000 (Netherlands), Nartshuk 1989f (former USSR); Oldroyd 1969; Stubbs & Drake 2001 (British Isles); Weinberg & Bächli 1997 (Switzerland); CMPD: Nartshuk 1997; CAT: Nartshuk 1988. (Aenigmatiidae): part of the Phoridae. Agromyzidae (key couplet 110, 123; fig. 241-242, 263-266) Systematics: Acalyptrate Brachycera; superfamily Opomyzoidea; in Europe some 23 genera and about 910 species. Characters: Minute to medium sized (1-6 mm) flies, varying in colour from all yellow to black to metallic green. Arista bare to pubescent; ocelli present; Oc-bristles present; P-bristles diverg- ing; 2-8 pairs of F-bristles, the lower 1–3 pairs curving inward, the other pairs backward; interfrontal bristles absent; interfrontal setulae sometimes present; vibrissae present but in some cases weak. Wing unmarked; costa with subcostal break; vein Sc com- plete or incomplete, apically ending in vein R1 (Agromyzinae) or separate from vein R1 but reduced to a fold that may or may not reach the costa (Phytomyzinae); crossvein BM-Cu present; cell cup closed. Tibiae without dorsal preapical bristle. Female with oviscape, non retractable basal segment of the ovipositor. Biology: The larvae are mining, generally in the stalks or leaves of 454 Mines of the larva of Aulagromyza herbs, sometimes in roots, seeds or under bark. In the few species populi (Kaltenbach) on Populus; Hering living on woody plants this may lead to gall formation. Most 1957 species are more or less host specific and several species cause damage to economically important plants. The shape of the mine is often characteristic of the species and therefore useful for identification. Adults occur in a variety of habitats, depending on the larval host plants. Identification references: Dempewolf 2004 (World); Hering 1957 (mines); E.B. Rohdendorf 1989 (former USSR); Spencer 1972 (British Isles), 1976 (Northwestern Europe), 1987 (North America); CMPD: Darvas & Papp 2000 (genera); CAT: Papp 1984d (see also Spencer & Martinez 1987). 111.