Sororsenexa, Plant, 2011

Plant, Adrian, 2011, Sororsenexa-New Genus (Diptera: Empididae: Hemerodromiinae) from Australia, Records of the Australian Museum 63 (3), pp. 267-272 : 268-269

Sororsenexa n.gen.

Figs 1–7 .

Type species: Sororsenexa macalpinei n.sp., here designated.

Etymology. The generic name is a contraction of the Latin soror (sister) and senex (old person) in reference to the putative basal sister group relationship between Sororsenexa and the remaining Chelipodini . The genus is feminine.

Diagnosis. A characteristic genus of the Empididae subfamily Hemerodromiinae ( Fig. 1 ) with raptorial forelegs widely separated from the midlegs. Sororsenexa can be distinguished from other Hemerodromiinae by the combination of characters (a) costa not circumambient, continued a short way only beyond apex of wing, (b) vein R 4+5 forked, (c) front femur with a single ventral row of short specialized setae (denticles) and more or less lacking posteroventral or anteroventral rows of stronger “normal” setae on either side, (d) uniserial acrostichal setae well developed if small along entire length between anterior of scutum and front of prescutellar depression, (e) setulae present (if small) on laterotergite.

Description. (Description based on holotype and paratypes owing to shrinkage and distortion affecting all specimens). Head large, in dorsal view ( Fig. 2 ) at least as wide as thorax and half its length; somewhat dorsoventrally compressed (at least in female, male specimens are distorted). Eyes with anterior ommatidia enlarged in both sexes; crena (eye notch) absent. Face short, hardly as long as three basal antennal segments, narrow, no wider than scape is long, narrower in male, parallel sided. Mouth cavity apparently deeply recessed, abruptly receding from frons ventrally (possibly a distortion artefact due to shrinkage on drying but present in all type specimens). Frons very broad triangular, margins almost linear; 2 pairs of weak marginal setae behind antenna and much stronger pair near margin just behind level of posterior ocellus. Ocellar tubercle hardly developed with one strong and one weak pair of setae. Vertex with 2 or more strong setae more or less contiguous with line of smaller stout postocular occiputal setae which become finer on lower occiput; some distinct setae on posterior occiput and behind mouth and some longer setae lateral to mouth opening. Antenna with scape almost bare; pedicel hardly longer than wide with subapical circlet of setae; postpedicel globose, covered with minute setulae and a few longer hairs subapically; stylus somewhat longer than basal antennal segments combined, tapering, micropilose, slightly swollen basal article and bristle-like apical mechanoreceptor present. Proboscis rather stout, apically pointed, as long as head is deep, directed vertically downwards. Palpus very small, almost globular, micropilose with 2–3 long fine setae.

Thorax short, hardly longer than deep, narrowed anteriorly in profile. Scutum rather strongly arched anteriorly in lateral view ( Fig. 1 ), prescutellar area more or less flat; quadrate rectangular in dorsal view with pospronotal lobe well defined and slightly protuberant. Fused anepisternum + katepisternum rather narrowly triangular, in lateral view with longer anteroventral margin more or less linear. Scutellum with posterior margin rounded. Acrostichal setae small but distinct, uniserial extending posteriorly to anterior margin of prescutellar depression; 6–7 dorsocentral setae well developed, becoming longer posteriorly, anterior 1 or 2 setae displaced laterally such that line of dorsocentrals rather curving anteriorly; postpronotal setae long, incurved, strong, with much smaller seta below; 1 long strong seta extending laterally behind postpronotal lobe; 3–4 notopleural setae, lower pair very strong; 1 small supra-alar and stronger postalar setae; 1 strong outwardly directed seta on thoracic “collar”. Laterotergite with 3–4 fine setulae.

Legs rather stout and conspicuously setose. Front coxa rather short and broad, only 4× as long as wide and 0.6–0.7× length of thorax, 1 row of long fine erect setae anteriorly ( Fig. 3 ); mid and posterior coxae with similarly long setae anteroapically and on outer face. Front femur ( Fig. 3 ) stout, evenly inflated 4–5× as long as wide, rather longer than front coxa; line of short stout denticle-like setae ventrally at the base of which are two larger but still stout setae (in females these basal setae often more or less of equal size while in males usually unequally developed); posteroventral row of fine distinct setae widely spaced from line of denticles; anteroventral row of small setulae very weakly developed and inconspicuous; dorsal ciliation of fine setae conspicuous; posterior face with distinct setae, anterior face almost bare. Posterior femur somewhat inflated but only about 0.5 as wide as front femur and slightly longer, distinctly hairy with dorsal and anteroventral series of setae about as long as depth of limb; mid femur more slender with less conspicuous but still strong setae throughout and rather stronger posteroventral series of setae.

Front tibia about 0.8× length of front femur, geniculate basally; small sharply pointed curving apical spine ( Fig. 3 ) arising from slight ventral swelling juxtaposing with basal setae of femur when limb is reflexed; ventral row of numerous short rather spine-like adpressed setae. Mid and posterior tibiae about as long as their corresponding femora, conspicuously setose but setae not as long as depth of limb except dorsally on posterior tibia. All tarsi with segments 1–4 progressively shorter, second segment of front leg not shorter than third.

Abdomen with scattered fine hair like setae longest on posterior margins of sternites and tergites. Male terminalia ( Figs 4–5 ) reflexed to more or less vertical position; hypandrium and epandrium separate; hypandrium large, rather oblong quadrate appearing somewhat keel-shaped in posterior ( Fig. 5 ) or ventrolateral aspects, left and right lobes narrowly separated by weakly sclerotized area posteriorly (usually visible only after maceration) and bearing some long marginal setae; epandrium smaller than hypandrium, flattened ovate with numerous long setae from apex of which rather pointed leaf like subepandrial process emerges dorsally. Cercus projected vertically along anterodorsal margin of epandrium, narrow and rather strap-like in profile but viewed from in front ( Fig. 6 ) inwardly curved with numerous small stout setae apically on inner face. Distal section of phallus strongly reflexed anteriorly when not withdrawn into sinusoidal phallic sheath; sheath strongly reflexed posteriorly on distal part.

Female abdomen bluntly tapered apically, cercus about 2× as long as wide with long apical setae of equal length and a few shorter marginal setae.

Wing ( Fig. 7 ) rather short and broad, 2.5× as long as widest, apically rounded, anterior and posterior margins almost subparallel, anal lobe very weakly developed. Vein C strong to wing tip, fading thereafter and completely absent along posterior margin. Vein Sc present, free, reaching almost to C but very weak beyond level of branching of Rs; crossvein h present. Rs short, originating at about 0.25 from base of wing, diverging narrowly from R 1. R 2+3 long, ending in distal 0.3 of wing. R 4+5 forked and diverging at angle of 60–65° with R 5 ending near wing tip. Median vein linear, fork M 1+2 absent. CuA 1 linear, fading near wing margin. Cell br rather narrow, truncately pointed apically, longer than cells bm or cup. Cell cup closed, apically rectangular, A 1 strong continued for short distance beyond end of cup. Costal bristle strong.

Figures

Figure 1. Sororsenexa macalpinei n.sp., male habitus.

Figures 2–3. Sororsenexa macalpinei n.sp. (2) female head, dorsal; (3) male anterior leg, anterior aspect.

Figures 4–6. Sororsenexa macalpinei n.sp. male genitalia: (4) lateral view; (5) posterior view; (6) cerci in dorsal view.Abbreviations: cer, cercus; epan, epandrium; hyp, hypandrium; ph, phallus; ps, phallic sheath; subep, subepandrial process.

Figure 7. Sororsenexa macalpinei n.sp. male wing showing nomenclature of major veins and cells.