Haplusia Karsch 1877

Genus Haplusia Karsch, 1877

Haplusia — Karsch 1877: 16. Type species, plumipes Karsch, by original designation.— Gagné 1978: 518 (new concept, new synonymy, discussion); Spungis 1985: 39 (discussion); Jaschhof & Jaschhof 2013: 59 (discussion).

Chastomera — Skuse 1888: 112; Mamaev 1964: 902 (discussion); Panelius 1965: 24 (discussion); Gagné 1978: 518 (as synonym of Haplusia, discussion).

Species of Haplusia:

afrotropica Jaschhof sp. nov., described below. Afrotropical. bella (Skuse, 1888) [Chastomera]. Australasian.

braziliensis (Felt, 1915) [Johnsonomyia]. Neotropical. cincta (Felt, 1912) [Johnsonomyia]. Neotropical.

obscuripes (Mamaev, 1968) [Johnsonomyia]. Palearctic. pallida (Mamaev, 1966) [Johnsonomyia]. Palearctic.

plumipes Karsch, 1877. Neotropical.

Nine unnamed species from the Nearctic, Neotropical, and Oriental regions.

The original descriptions of Haplusia from Brazil (Karsch 1877), Chastomera from Australia (Skuse 1888) and Johnsonomyia from North America (Felt 1908) are so imprecise that subsequent authors read them in different ways. Gagné (1978) outlined the varying uses of these names in the past (see Rübsaamen 1892; Mamaev 1964, 1966) and, with reference to the wing venation that he deemed characteristic, subsumed the three genera under Haplusia. At the same time he suggested the possibility that a broad study of world Diallactiini might consider separating his broadly defined Haplusia in two or more genera. The present review arrived at the very same standpoint. Accordingly, Johnsonomyia is here released from the synonymy with Haplusia and restored as a distinct genus (see below), and several of the species that were previously classified with either Haplusia or Chastomera are newly combined in Gynapteromyia (see above).

Haplusia, as conceived here, are showy, eye-catching midges as Marshall’s (2012: 180, fig. 3) color photograph, possibly of a H. cincta, attests. Karsch’s (1877) description of the type species, H. plumipes, makes mention of several of the characters regarded by me as diagnostic of the genus Haplusia (see Diagnosis). The holotype female of H. plumipes, last studied and redescribed by Rübsaamen (1892), was upon request not found in the collections of the Museum für Naturkunde Berlin, Germany (Joachim Ziegler, in litt.), so is presumably lost. It should be possible, however, to collect fresh specimens of H. plumipes in Brazil to appropriately describe this species, including the male. Except for H. bella, the other species classified here in Haplusia were described as Johnsonomyia, but one should bear in mind that Felt (1912, 1915), on the one hand, and Mamaev (1966, 1968), on the other hand, used different definitions of Johnsonomyia.

Haplusia is here confirmed as a senior synonym of Chastomera, following the view of Rübsaamen (1892) and Gagné (1978). That Chastomera does not differ from Haplusia is apparent from Skuse’s (1888) original description of the type species, Ch. bella, as well as from photographs of male and female Ch. bella (including the female holotype) made available to me through the kindness of Peter Kolešik, who is preparing a redescription of this species for publication (Kolešik, in litt.).

I have seen specimens of unnamed Haplusia from eastern United States (Maryland and Virginia, 2 species), Dominica (1 species), Costa Rica (5 species), and Brunei (1 species), which renders the genus cosmopolitan in distribution. The species from Maryland was illustrated by Plakidas (1999: figs 50–53; 2007: figs 16–18) under the name of Johnsonomyia rubra Felt, a species treated below. All the species from Costa Rica were collected at a single site. Most of the named species assigned here to Haplusia were described on the basis of only one sex. With respect to preimaginal stages, Plakidas (1999) described larvae of an unnamed Haplusia (as Johnsonomyia rubra).

Diagnosis. The focus here is on delimitating Haplusia from particularly Johnsonomyia and Gynapteromyia. Haplusia displays striking coloration, typically a combination of chalky white and bright yellow. One to three of the following characters may be found in a species: white antennae with long white hairs; milky white wings with dark spots around Rs and CuA; and bicolored, banded legs (with the coloration attributable to pigmentation of the the leg segment itself, or its vestiture, or both). Light-colored specimens studied by transmitted-light microscope appear extremely pale and low in contrast, with their white setae and white wing membranes being close to invisible. Male body lengths exceed, often considerably, 2.5 mm (corresponding females are even slightly longer); the eye bridge, which is (6–)7–12 ommatidia long dorsally, usually occupies the entire vertex; on male flagellomeres, the subbasal setae are arranged in a irregular single to double whorl intermingled with hair-shaped translucent sensilla; the 4-segmented palpus is longer than the head height; the clypeus is unsetose; the wing base is broad, with the anal lobe moderately convex; the wing membrane is fully covered with setae; Rs and the membrane around it are darkened, which produces a marked spot (a similar spot may be present on CuA); and empodia are untraceable. Male genitalic characters typical of Haplusia are as follows. Tegmina occur in two different types, either poorly sclerotized, subtrapezoid to subtriangular, often serrate apicolaterally, or strongly sclerotized, with apicolateral processes and concave posterior edge. Of the gonocoxae, the medial bridges are usually densely covered with ordinary to bristle-like setae, and the dorsal portions are strongly sclerotized at the medial edges. Gonostylar teeth are slender and pointed, and the individual spines making them are barely apparent.

Other characters. Male body length 2.5–5.2 mm. Head. Postfrons unsetose. Genal setae 10–15, more or less clearly clustered. Scape and pedicel concolorous with, or lighter than flagellum, scape slightly larger than pedicel. Scape usually with setae, pedicel unsetose. Male flagellomeres 14; fourth flagellomere with neck usually longer than node, rarely shorter; node subcylindrical to barrel-shaped, a crenulate whorl of long sensory hairs with hooded alveoli medially, further such sensory hairs distally, either in short line(s) or scattered, numerous hair-shaped translucent sensilla distally, microtrichia only basally. Female flagellomeres 14; neck of fourth flagellomere as long as node or shorter, none or a few sensory hairs with hooded alveoli medially/distally, hooded alveoli shorter than in male, translucent sensilla same as in male but more numerous. Labella slender. Palpus: translucent sensilla typically on first to third segments, occasionally on all segments, simply hair-shaped, variable in size. Thorax. Antepronotum and pleural sclerites unsetose. Scutum with sparse lateral and dorsocentral setae. Scutellum sparsely setose. Wing. Membrane either milky white (meaning completely transparent in slide-mounted specimens) or brownish. Length / width 2.5–2.7. Costal break usually distinct. Vein btv always setose. CuA extending to wing margin. Legs with both setae and narrow scales of various lengths. Basitarsi without spine. Vestiture on distitarsi same as on proximal tarsomeres. Claws small, very slightly bent, untoothed. Abdomen. Tergites and sternites entire, with scattered setae. Sternum 1 and pleura unsetose. Male genitalia. Ninth tergite subtrapezoid. Gonocoxae: ventral emargination with more or less deeply U-shaped outline, membranous and thus vaguely contoured basally; ventral bridge in some species with faint transverse suture; dorsal apodemes long, anterior processes usually about as long as distance separating them, rarely shorter. Gonostylus of normal size and shape. Parameral apodemes small, protruding ventrally. Ejaculatory apodeme present as long, strong, sclerotized rod, occasionally slightly modified apically and / or basally. Ovipositor similar to that described above for Gynapteromyia. No sclerotized spermathecae.