Zalea D. McAlpine

McAlpine, D. K., 2007, The Surge Flies (Diptera: Canacidae: Zaleinae) of Australasia and Notes on Tethinid-Canacid Morphology and Relationships, Records of the Australian Museum 59 (1), pp. 27-64 : 45

Genus Zalea D. McAlpine

Zale D. McAlpine, 1982: 108–110 . (Preocc. Hübner 1818.) Type species (original designation) Z. minor D. McAlpine.

Zalea D. McAlpine, 1985: 82 . Replacement name for Zale D. McAlpine.

Diagnostic description. Small to very small flies; wing c. 1.4–3.0 mm long. Arista three-segmented; antennal segment 4 distinct but small.

Head. Postvertical bristles proclinate, divergent to convergent; postfrons with several setulae on central part in front of ocelli, often tending to form a double series, like rudimentary interfrontal bristles, also with few smaller setulae on frontal orbits and between ocelli.

Thorax. Prothoracic precoxal bridge present or absent; acrostichal setulae biseriate, extending posteriorly to the distinct prescutellar acrostichal bristle; scutellum with two major bristle pairs and, in most species no other bristles or setulae. Mid femur with distal posteroventral comb of short suberect bristles in male (sometimes blunt and incrassate, always absent in female). Distal section of subcosta almost uniformly sclerotized from humeral crossvein to termination in subcostal break; anterior crossvein meeting vein 4 near or distad of mid-length of discal cell, except in wisei group; basal section of vein 4 separating first and second basal cells slender but well sclerotized; alula scarcely narrowed distally, with largely transverse distal margin, with marginal setulae much shorter than maximum width of alula.

Abdomen of male. Dorsal protandrial sclerite c. twice as long as tergite 5 or slightly less; two pairs of basally articulated surstyli present; hypandrium on each side with two combs of three closely placed setulae each, one comb much larger than the other ( Fig. 53, setulae of smaller group not yet observed in some species though possibly present); distiphallus subcylindrical, elongate, but not very long, largely membranous, encircled by three prominent papillae (one posterior and two anterior).

Abdomen of female. Tergite 7 with median anterior posteriorly forked apodeme, which is incorporated in floor of pouch below margin of tergite 6 (not investigated for some New Zealand spp.)

Distribution. Australia: temperate coasts, but not yet recorded for Queensland and South Australia. New Zealand: North Island; South Island; Snares Islands.

Notes

The following two apparent autapomorphies, not present, so far as known, in Suffomyia , support the monophyletic status of Zalea : in male, base of distiphallus encircled by three membranous papillae; in female, tergite 7 with median, anterior, posteriorly forked apodeme. The aedeagal details have not been fully checked for the wisei group, but, in the only microscopic preparation of Z. wisei , there appear to be structures in the nature of membranous papillae. Although the presence of the internal apodeme is not yet confirmed for females of some New Zealand species, the doubtful species are closely related to better known ones, or others in which the external features of sternite 7 are consistent with the presence of an apodeme (as in the wisei group). The complex hypandrium in such diverse species as Z. johnsi , Z. clava , and Z. minor is so uniform and distinct from that of Suffomyia scutellaris as figured by Freidberg (1995), that it may provide further cladistic data when a better range of material is available.

The known species of Zalea are divisible into three morphologically well defined groups. It is uncertain if these are monophyletic, because of doubt as to the state of certain characters in the groundplan of the genus, e.g., orientation of postvertical bristles, prosternal structure, and presence/ absence of certain bristles.

1 Horningi group: Zalea johnsi , Z. mathisi , Z. uda , Z. ohauorae , Z. lithax , Z. horningi , Z. earlyi ( New Zealand).

2 Wisei group: Zalea sp. 1 , Z. wisei ( New Zealand).

3 Minor group: Zalea clava , Z. minor , Z. major , Z. dayi ( Australia) ,? Zalea sp. 2 ( New Zealand).

These groups are characterized below in the key to species. It is added that the horningi group is the only one with bridged prosternum.