Empididae Giebel 1856

Empididae

Empides Latreille, 1809: 189, 191. Type genus Empis Linnaeus, 1758.

Empididae Giebel, 1856: 206.

The definition of the Empididae in this study is more restrictive than in previous classifications. The family is recognized on the basis of the following suite of characters (see also below—Key to Families and unplaced Genus Groups of Empidoidea): Vein R 4+5 normally branched, prosternum enlarged forming precoxal bridge, laterotergite usually with setae, male terminalia often with clasping­like cerci or hypandrium laterally flattened or keel­like, female terminalia usually telescopic with simple cerci. No distinct apomorphy is known to define this diverse lineage and further studies on the relationships of all genera in this family are urgently required. This family includes the following generic groupings, tribes and subfamilies:

Incertae sedis within Empididae

Ragas group (includes: Dipsomyia Bezzi, Hormopeza Zetterstedt, Hydropeza Sinclair, Ragas Walker, and Zanclotus Wilder)—This genus group of predaceous empidoids was clearly defined by Sinclair (1999) and is mainly characterized by the recurved labrum and apical epipharyngeal comb. The single tree obtained by a posteriori character weighting using successive approximations, placed this lineage and Brochella in the Empididae as the sister group to the Clinocerinae (Tree 4) primarily on the basis of the presence of a dorsal mesepimeral pocket (character 31.1), reduction of antennomere 10 (character 8.1), and a slender male tergite 8 (character 71.1). However, because of the degree of homoplasy associated with the last two characters in particular, and until the relationships and definition of the entire Empididae are better resolved, the phylogenetic assignment of the Ragas group will continue to remain uncertain.

The postpedicel of Hormopeza possesses a pair of sensory pits (Fig. 8; Tuomikoski 1960, fig. 1e), which are also very similar in form to those observed in the platypezid genus Microsania (Fig. 47). Both genera are commonly known as smoke flies and it is assumed that these pits and inner glands are used in the detection of smoke. Large swarms of both taxa have been observed in smoke from wood fires (see Sinclair 1995b and Bickel 1996b for references). Swarms of Hormopeza usually consist of equal numbers of both sexes, whereas swarms of Microsania consist almost entirely of males.

It has always been assumed that these flies use smoke as an aggregating queue to concentrate both sexes in an area that has been burned over by fires. It is also assumed that certain fungi, which grow only on fire­scarred wood function as hosts for Microsania larvae (Kessel 1989: 180). But the immature stages of both taxa remain unknown. It is possible that the smoke from fires does function as an aggregating queue, but mostly to attract the flies to fresh oviposition sites as has been observed for long­horned beetles (Cerambycidae), where great numbers swarm about forest fighting crews battling fires in Ontario (Carney 1999). It is possible that Hormopeza and Microsania also oviposit into the freshly damaged trees. This is a breeding habitat that should be more fully explored.

Brochella Melander —This monotypic genus is an odd unique taxon that occurs in the Cascade Mountains of the western Nearctic Region. Brochella is possibly a flower visitor on the basis of its mouthpart morphology. The single tree obtained by a posteriori character weighting using successive approximations, placed this genus with the Ragas group in the Empididae, as the sister group to the Clinocerinae (Tree 4). However, the phylogenetic assignment of Brochella will remain uncertain, until the relationships of the Empididae are better resolved.

Philetus Melander —This genus includes two species confined to western North America. Very little is known of this genus and most specimens have been sporadically collected. Recently, one species was collected in large numbers during a canopy study of wet temperate rainforests on Vancouver Island (BC, Canada; specimens in CNC).

Hesperempis group (includes: Dryodromia Rondani, Hesperempis Melander, and Toreus Melander)—This genus group represents another flower­feeding lineage and possibly also includes an undescribed Australian genus. The thoracic chaetotaxy is reduced in all genera, and the bristles are pale white to yellowish.

Empidinae

Schiner (1862: lii) was apparently the first author to recognise the subfamily Empidinae, and also the first to arrange the empidids into five subfamilies (from Chvála 1983: 54). This subfamily is defined by the following suite of characters: palpi normally strongly upcurved, broad wings (anal lobe usually developed), forelegs not raptorial, empodium usually bristleform. Cumming (1994) hypothesized that presentation of nuptial gifts to females by males, correlated with loss of hunting ability in females, might represent two additional synapomorphies of the Empidinae (or at least a portion of the subfamily), although mating behaviors of the more plesiomorphic genera, such as Edenophorus, Empidadelpha and Sphicosa, are presently unknown. The Empidinae includes the following tribes:

Empidini

Collin (1961: 326) was perhaps the first worker to separate the Empididae into two tribes. This tribe is presently undefined and undoubtedly paraphyletic and presently simply a dumping group for all genera not assigned to the Hilarini. This lineage is distinguished from Hilarini on the basis of a setose laterotergite, cercus enlarged and functioning as a clasping organ, costa usually ending at or just beyond R 4+5, vein R 1 of constant thickness and male tarsomere 1 of foreleg rarely enlarged (Bickel 1996a). The Empidini includes the following genera: Clinorhampha Collin, Empidadelpha Collin, Empis Linnaeus, Hystrichonotus Collin, Lamprempis Wheeler and Melander, Macrostomus Wiedemann, Opeatocerata Melander, Porphyrochroa Melander, Rhamphella Malloch, Rhamphomyia Meigen, and Sphicosa Philippi (Smith 1980; Chvála & Wagner 1989; Rafael & Cumming 2004).

Edenophorus Smith was originally assigned to the Microphorinae when male specimens were not known. It was later transferred to the Ocydromiinae (Chvála, 1981), but males still remained unknown. Ulrich (1994) believed it showed affinities to the Empididae sensu Chvála (1983). Male specimens were identified by Sinclair (2002), confirming its assignment to the Empidinae. However, on the basis of the absence of strongly arched palpi, Edenophorus is excluded from the clade comprising Empidadelpha, Empidini and Hilarini (Sinclair 2002). It is tentatively assigned herein to the Empidini until a better definition or diagnosis of this tribe is made available.

Hilarini

Hilarini Collin, 1961: 326. Type genus Hilara Meigen, 1822.

The tribe is well defined on basis of laterotergite usually bare, cercus usually small and desclerotised, hypandrium usually forming a keel­like hood over the phallus along the posterior margin, costa usually circumambient, R 1 thickened before it joins the costa and male tarsomere 1 of foreleg enlarged (Bickel 1996a). The following genera are included in the Hilarini: Afroempis Smith, Allochrotus Collin, Amictoides Bezzi, Aplomera Macquart, Atrichopleura Bezzi, Bandella Bickel, Cunomyia Bickel, Deuteragonista Philippi, Gynatoma Collin, Hilara Meigen, Hilarempis Bezzi, Hilarigona Collin, Hybomyia Plant, Pasitrichotus Collin, Thinempis Bickel, and Trichohilara Collin (Smith 1980; Cumming 1994; Bickel 1996a, 1998, 2002).

Bickel (1998) considered Cunomyia primitive with respect to other Hilarini on the basis of the form of its male cercus and postabdominal structure. The male eyes are separated on the frons in this genus and the upper facets are not enlarged. It is possibly closely related to Bandella (Bickel 2002). Members of the Hilara flavipes Meigen complex have holoptic males with the upper ommatidia enlarged and Chvála (1999) has considered this the ground plan state based on outgroup comparison with the Empidini. This head morphology is co–related to primitive unmodified small synorchesic swarms.

Hemerodromiinae

Hemerodrominae Schiner, 1862: li, lii. Type genus Hemerodromia Meigen, 1822.

Hemerodromiinae Wheeler & Melander, 1901: 376.

This is one of the most distinctive empidoid subfamilies, characterized by raptorial

forelegs well separated from the midlegs and the fore femur bearing at least a single

ventral row of stout setae. Some genera possess aquatic larvae, with adults of many genera

found on emergent rocks and riparian vegetation of streams and rivers. The larva of

Chelipoda is terrestrial (Trehen 1969). The Hemerodromiinae is divided into two tribes.

Chelipodini

Chelipodini Hendel, 1936: 1929.

This tribe can be separated from Hemerodromiini on the basis of the long arista more than twice the length of the postpedicel, scutum with well­developed setae, laterotergite with setae and male terminalia reflexed over abdomen (MacDonald 1988). The following genera are included in the Chelipodini: Afrodromia Smith, Chelipoda Macquart, Chelipodozus Collin, Drymodromia Becker, Monodromia Collin, Phyllodromia Zetterstedt, and Ptilophyllodromia Bezzi (Smith 1967, 1975, 1980, 1989).

The genus Cephalodromia Becker is not an empidoid and is assigned to the Mythicomyiidae (Platypyginae) (see Greathead & Evenhuis 2001). However, the generic assignment of the Taiwan species, C. pictipennis Bezzi, requires examination, but it should probably be tentatively assigned to Chelipoda until the Chelipodini can be defined on a world basis.

Hemerodromiini

This tribe can be separated from Chelipodini on the basis of the short antennal style less than twice the length of the postpedicel, scutum lacking well developed setae, laterotergite bare and male terminalia erect or projecting posteriorly (MacDonald 1988). The following genera are included in the Hemerodromiini: Chelifera Macquart, Cladodromia Bezzi, Colabris Melander, Doliodromia Collin, Hemerodromia Meigen, Metachela Coquillett and Neoplasta Coquillett (Smith 1967, 1975, 1980, 1989).

Clinocerinae

Clinocerinae Collin, 1928: 2, 3, 59. Type genus Clinocera Meigen, 1803.

Clinoceratinae Melander, 1928: 10.

The Clinocerinae is a very well defined lineage and one of the few lineages where the phylogenetic relationships of the genera have been evaluated with modern techniques (Sinclair 1995a). Anumber of genera remain to be described from the Australasian region. The larval habitat of the majority of taxa is considered aquatic, normally streams and rivers with rocky substrates. The most primitive genera dominate the Southern Hemisphere. The subfamily can be identified by the stout, erect costal setae, sucker­like labellum, pulvilliform empodium, anal lobe of wing not developed and CuA 2 recurved at apex of cell cu p (Sinclair 1995a). The following genera are included in the Clinocerinae: Aclinocera Yang & Yang, Afroclinocera Sinclair, Asymphyloptera Collin, Bergenstammia Mik, Clinocera Meigen, Clinocerella Engel, Dolichocephala Macquart, Hypenella Collin, Kowarzia Mik, Oreothalia Melander, Phaeobalia Mik, Proagomyia Collin, Proclinopyga Melander, Rhyacodromia Saigusa, Roederiodes Coquillett, Trichoclinocera Collin, and Wiedemannia Zetterstedt (Sinclair 1995a).