Pipunculidae

McAlpine, David, 2011, Observations on Antennal Morphology in Diptera, with Particular Reference to the Articular Surfaces between Segments 2 and 3 in the Cyclorrhapha, Records of the Australian Museum 63 (2), pp. 113-166 : 130-131

The Pipunculidae

I have taken for study antennae of the genera Chalarus and Tomosvaryella .

In Chalarus segment 2 ( Figs 37, 38 ) is bilaterally compressed and otherwise resembles that of the less modified taxa of Syrphidae . The distal articular surface is moderately concave with moderately developed rim, receding ventrally. The conus is broad, little raised, and approximated to the medial side of the segment. The annular ridge and distal foramen are tilted dorsolaterally and the button lies in the relatively slight concavity between the conus and the midlateral part of the rim.

Segment 3 in Chalarus ( Fig. 39 ) is broadly rounded and bilaterally compressed. The basal hollow is present, but too small to contain the prominence bearing the basal articular foramen and there is no sub-basal caecum. The single sacculus is located on the ventral side of the segment and opens on the lateral surface. Much of the surface is covered with relatively large, saucer-like pits. The arista is inserted dorsally not far from the base of the segment; it is threesegmented with segment 4 forming a complete annulus.

The notable differences in antennal structure of Tomosvaryella from the above are probable apomorphies (see Figs 40, 41 ). The conus is absent and the smooth annular ridge, together with the distal foramen, is sunk into a deep, narrow cavity on the distal articular surface of segment 3. The annular ridge and foramen are located centrally on this surface and are almost symmetrical, not tilted. The button (not visible in the preparation) is apparently concealed in the narrow cavity between the annular ridge and the lateral part of the rim.

Segment 3 is much prolonged ventrally and has no basal hollow. The basal segment of the arista (segment 4) is sclerotized only on the dorsal side.

The antenna of the Pipunculidae shows the basic structure of the Eumuscomorpha, but does not appear to provide evidence as to whether this family is the sister group of the Syrphidae or the Schizophora. Neither J. McAlpine (1989) nor Zatwarnicki (1996) gave very convincing synapomorphies for the Syrphoidea ( Syrphidae + Pipunculidae ) as a monophyletic group. The work of Collins & Wiegmann (2002b) suggested that the Pipunculidae alone represent the sister group to Schizophora, and that the Syrphoidea (sensu J. McAlpine, 1989) are paraphyletic. These conclusions are supported by Wiegmann et al. (2011).

Figures

Figures 37–41. Antennae of Pipunculidae. (37) Chalarus sp., segs. 1 and 2, after removal of seg. 3. (38) The same, part of distal articular surface of seg. 2. (39) The same, right seg. 3, with base of arista. (40) Tomosvaryella sp., right segs. 1 and 2, lateral view after removal of seg. 3. (41) The same, right seg. 3, with base of arista. bf, basal foramen of segment 3; bh, basal hollow; bu, pedicellar button; f, distal foramen of segment 2; sc, sacculus.