Sematopoda elata Collin

Sinclair, Bradley J., 2008, Review of three little-known monotypic empidoid genera (Diptera: Empidoidea: Brachystomatidae), assigned to Trichopezinae, Zootaxa 1754, pp. 52-62 : 58-61

Sematopoda elata Collin

( Figs. 9–11 )

Sematopoda elata Collin, 1928: 52 .

Holotype male labelled: “ Type ɗ [circle label with red border]”; “Full page figure/ of ɗ TYPE / figured with/ author’s description [hand-written label]”; “ Sematopoda / elata, Collin / TYPE ɗ [hand-written label]”; “Sematop./ elata n.sp. [hand-written on orange circle label]”; “ New Zealand / Ohakune./ ii.1924 / T.R. Harris. / B.M. 1924-278 [printed label]” ( BMNH).

Recognition. This genus and species is distinguished from other New Zealand empidoids on the basis of elongate narrow wings, especially at the base; abdominal sclerities 5–8 reduced and modified, male genitalia with enlarged cercus, which arches over the apical abdominal segments.

Description. Male. Eyes rounded, well separated on frons, very narrowly so on face (nearly approximated); facets enlarged in front and bare. Gena nearly absent. Face silvery pubescent. Antenna dark with basal segments subequal in length, bearing stiff setae; postpedicel ovate, produced apically into short cylindrical projection longer than wide, clothed in long pruinescence; first article of stylus short, square, not longer than wide; second article arista-like, approximately as long as remaining antenna, bearing short apical peg. Ocellar bristle short, inserted anterior to posterior ocellus; 1–2 vertical bristles, shorter than ocellar bristle; postocular setae reduced. Labrum long and narrow, nearly subequal to height of head. Palpus yellow, with long, pale seta. Labellum well developed. No internal mouthparts could be observed clearly.

Dorsum of scutum dark brown, except lateral silvery margin in front, including upper part of postpronotal lobe, continued posteriorly and narrowing to point at base of wing. Pleura silvery-grey, with dark patches below postpronotal lobe, including anterior spiracle, posterior half of anepisternum, lower portion of katepisternum, and about posterior spiracle. Prosternum fused to proepisternum. Pair of very stout acrostichals (now broken off) anteriorly, with several short setulae near antepronotum; 6 dc, antepenultimate longest and most stout; 1 spine-like pprn; 2 npl, upper similar to pprn, but longer, lower very thin and short; 0 presut spal; 0 psut spal; 1 pal, short and fine; pair of long sctl, with outer shorter seta, more than half-length of bristle. Presence of mesepimeral pocket uncertain. Laterotergite bare; antepronotum with pair of short setulae.

Wing (length 3.8 mm) infuscate, very narrow, especially at base, anal angle not at all developed; 1 basal costal bristle, slender, shorter than scutellar bristle; stigma distinct, elongate and slender, at apex of R1. All veins lacking setae; costa circumambient, lacking erect spine-like setae; Sc evanescent; R4+5 branched, R4 slightly curved, strongly divergent from R5; cell dm very elongate, produced apically, emitting 3 veins; base of M1 and M2 broadly separated. Cell cua (= anal cell) narrow, truncate apically, slightly longer than half-length of cell bm; CuP+CuA (= anal vein, A1+CuA2) very long, 1.5X longer than cell cua, arched to wing margin. Posterior wing margin from base to apex of anal vein thickened, especially at mid-length; bearing slender hook-like setae ( Collin 1928, fig. 14). Haltere brownish.

Legs generally slender, lacking distinct bristles; coxae with silvery pruinescence, femora reddish-brown, remaining segments brown, apical tarsomeres dark. Fore coxa approximately two-thirds as long as femur or 2X as long as mid coxa, with pale inner apical setae. Fore femur somewhat swollen, posteroventrally about base with 2–3 slender, pale setae, longer than width of femur; anteroventrally with row of approximately 7 shorter, stiff setae, followed by 2 stout spur-like setae on apical third with small spine in between, followed by row of 4 minute, spine-like setae; dense white pruinescent pile beneath. Fore tibia about as long as femur, with row of erect, pale setae, approximately as long as width of tibia; small black apical spine-like seta beneath.

Mid femur somewhat swollen, similar to fore femur; with double row of pale, fine ventral setae, longer and darker at base of femur; cluster of 3 short, curved, stout claw-like setae subapically. Mid tibia sinuous (concave at middle ventrally, convex towards tip), with double row of very short, dark stout ventral setae, becoming longer towards tip, but stouter basally in position, opposite claw-like setae of femur double row when tibia is reflexed against femur. Hind femur long and narrow basally, somewhat clavate apically, with anteroventral row of short, dark setae. Hind tibia expanded apically, slightly longer than femur, with subapical dorsal seta. Fore and hind tibial combs present. All tarsi slender, except fifth tarsomere dorsoventrally flattened, lacking dorsoapical projection; empodium not pulvilliform, but with short micro-pubescence.

Abdominal sclerites 5–8 reduced ( Figs. 10, 11 ); T5 with oval anterior margin, posterior margin straight bearing setulae; T6 subtriangular; T7 with anteromedial projection, posterolateral margin produced posteriorly; T8 very narrow, heavily sclerotized, fused laterally with S8 forming ring. S5–7 with anterior margin shallowly, broadly cleft, anterior margin with U-shaped weakly sclerotized zone with apical row of setulae; S8 deeply cleft apically, posterior margin with row of setulae.

Terminalia ( Fig. 9 ): held erect, lying over apical abdominal segments. Hypandrium small, oval, onefourth size of epandrium; short gonocoxal apodemes present; pair of sickle-shaped postgonites encircle base of phallus, extending parallel to phallus, apex rounded. Phallus with expanded spherical apex; ejaculatory apodeme small, narrow attached to base of phallus. Epandrium rounded, lamellae unattached anteriorly, lacking dorsal bridge; bearing long setulae along posterior margin. Surstylus subrectangular, bearing short spines on outer and posterior margins; bacilliform sclerite bearing long setae. Cercus greatly enlarged and extended apically; posterior margin expanded, bearing peg-like spines on margin; apex attenuated subapically, expanded apically into large brush-like lobe, thickly clothed in long setae; apical lobe produced posteriorly into beak-like projection; anal opening surrounded by long setae, directed anteriorly.

Female. Unknown.

Distribution. Only known from the holotype, collected near Ohakune in central North Island, New Zealand.

Remarks. Collin (1928) based his description of Sematopoda on a single male specimen. He provided an excellent description and habitus figure, and the holotype remains in excellent condition. Collin (1928) assigned this genus to the Hemerodromiinae , due to similarities of the wing venation and lengthening of the fore coxa. However, he did note the absence of raptorial forelegs and shortness of the thorax compared to Hemerodromiinae . On the basis of the lack of raptorial forelegs, lack of row(s) of ventral spine-like setae on the fore femur, and shortness of the thorax, this species is clearly not a hemerodromiine (see Sinclair & Cumming 2006). It appears related to the African genus Rubistella Garrett Jones due to the similar condition of the abdominal sclerites [thinly sclerotized, modified in shape, transverse banding (cf. Smith 1967, figs 27,28)]. In addition, the ejaculatory apodeme appears to be fused to the base of the phallus as found in many genera of Trichopezinae . Consequently, on the basis of these characters Sematopoda was assigned to the Trichopezinae (see Sinclair & Cumming 2006). Discovery of a female specimen of Sematopoda and whether the terminalia is modified as in other Trichopezinae should help to clarify this assignment.

The male terminalia of S. elata is here described and illustrated in detail for the first time.

Figures

FIGURES 9 – 11. Sematopoda elata, male. 9. terminalia, lateral view. 10. abdominal terga 5 – 8, dorsal view. 11. abdominal sterna, 5 - 8, ventral view. Abbreviations: cerc – cercus, epand – epandrium, goncx apod – gonocoxal apodeme, hypd – hypandrium, ph – phallus, pgt – postgonite, S – sternum, sur – surstylus, T – tergum. Scale bar = 0.1 mm.