Omyxa scuta Mathis & Zatwarnicki 2002

Omyxa scuta

DIAGNOSIS.—As the only know species, the generic diagnosis will serve to distinguish this species. Should additional species be discovered, the structures of the male terminalia will undoubtedly be diagnostic.

DESCRIPTION.—As in generic description but with details as follows: medium-sized to large shore flies, body length 3.80–5.10 mm; body mostly microtomentose except posterior portion of frons and mesonotum.

Head (Figures 54, 55): Generally densely microtomentose except for posterior portion of frons. Frons more or less square, shield-like, bearing numerous setulae and with distinctive color pattern, anterior portion whitish yellow to whitish tan, abruptly differentiated from black to blackish brown posterior portion of frons, demarcation line zigzagged from lateral margin to medial, oriented posteromedially then anteromedially, medial thinly but deeply incised to anterior ocellus; inner vertical seta short, thin, about size of outer vertical seta (these with apex apparently broken). Antenna essentially concolorous with anterior margin of frons, 1st flagellomere slightly darker; 1st flagellomere short, length subequal to combined length of scape and pedicel; arista extended beyond apex of 1st flagellomere, bearing 7–10 dorsal hairs, these more curved toward apex. Face concolorous with anterior portion of frons but duller and uniformly colored, dorsal portion of face between antennal bases vertical, not projected, thereafter ventrally flared anteriorly to oral margin, generally lacking setae or setulae except bearing row of short, thin, pale-colored setulae in vertical groove parallel to parafacial. Parafacial moderately wide, slightly less than width of pedicel at apex, concolorous with face; gena high, becoming wider posteriorly from parafacial, also becoming more silvery white, lacking a prominent genal seta; gena-to-eye ratio 0.38. Clypeus band-like, black with gray microtomentum; palpus short, mostly black but with some gray microtomentum.

Thorax (Figure 56): Mesonotum generally concolorous with posterior portion of frons, with only very sparse microtomentum, mostly blackish brown to black with thin gray stripes medially and laterally, these more evident anteriorly, basolateral margin of scutellum gray, microtomentose; pleuron ventrad of postpronotum and notopleuron, including femora and tibiae, uniformly silvery gray. Wing hyaline with mostly brown veins; costal-vein ratio 0.41; M-vein ratio 1.0. Legs mostly black with dense, whitish gray microtomentum; tarsi with some yellowish orange coloration; foretarsus with tarsomeres 2–5 blackish brown, distinctly flattened, forebasitarsomere much paler than apical tarsomeres.

Abdomen: Tergites 2–4 (and perhaps tergite 5, dissected before observation on it) with blackish brown bank along anterior margin, otherwise grayish, microtomentose. Male terminalia (Figures 57–60): generally robust externally, thickly sclerotized; epandrium U-shaped in posterior view (Figure 57), arms extended ventrally, becoming slightly wider ventrally; cercus narrowly ovoid, almost 4 times longer than wide, widest just above midheight, dorsal margin rounded, ventral margin narrowed; presurstylus in posterior view (Figure 57) irregularly triangular, medial margin with dorsal moderately deeply concave, dorsomedial portion produced into narrow, short process, with similar process meeting it from other side, ventral portion pointed, lateral margin shallowly arched and in lateral view sharply angulate, higher than wide, basal squarish, projected posteriorly to just below midheight, forming 90° angle, posterodorsal surface invaginated, ventral mostly oriented ventrad, parallel sided, ventral margin sharply truncate; postsurstylus in lateral view (Figure 58) relatively short, length about twice width, bilobed on ventral ; aedeagus in lateral view (Figure 60) narrow basally at attachment with aedeagal apodeme, dorsal margin irregular, projected laterally as a flap, apicodorsal portion with an upcurved, short projection, immediately ventrad with a more truncate process, and ventral margin large, broadly curved, in dorsal view base of aedeagus much wider than apex, becoming slightly wider to about midlength, thereafter tightly recurved, forming a short, lateral process, then angled medially to wider, capitate apex; aedeagal apodeme in lateral view (Figure 60) with only apices curved posteriorly toward attachments with aedeagus and hypandrium, anterior crest long, irregularly arched; hypandrium in lateral view (Figure 60) angulate, anterior wide, anterior margin truncate, in ventral view (Figure 59) deeply incised subbasally, with narrowly angulate lateral processes.

TYPE MATERIAL.—The holotype male is labeled “S. Iran 40 km SE Minab 21. 5 1973 [21 May 1973]/Loc. no. 205 Exp. Mus. Nat Praha/Cat. No. 33751 [pink label with black submargins; handwritten].” The holotype is double mounted (minuten in a small block of cork), is in good condition (some setae missing), and is deposited in NMSAC. The allotype female and six paratypes (4, 2; NMSAC, USNM) bear the same locality data as the holotype but with different catalog numbers (NMSAC 33747–33754). Other paratypes are as follows: Oriental. INDIA. Tamil Nadu: Coimbatore, Jul 1956, P.S. Nathan (1, 1; BMNH); Karaikal (10°55′N, 79°45′E), Jul 1956, P.S. Nathan (8, 12; BMNH, USNM); Kurumbagaram, Karaikal, Jul–Dec 1952, P.S. Nathan (2, 3; BMNH); Walayar Forests (10°51′N, 76°51′E), South Malabar, 5 Aug 1956, P.S. Nathan (10, 7; BMNH, USNM). Palearctic. OMAN. A1 Gharbi (650 m), 10 Apr 1985, P. Ardö (1; ZIL).

DISTRIBUTION (Figure 12).—Oriental: India (Tamil Nadu). Palearctic: Iran, Oman.

ETYMOLOGY.—The specific epithet, scuta, refers to the shield-like frons of this species.

Oedenopiforma Cogan, 1968:319 [as a subgenus of Paralimna;; type species: Paralimna madecassa Giordani Soika, 1956a, original designation].—Cogan, 1980:663 [Afrotropical catalog, as a subgenus of Paralimna].—Mathis and Zatwarnicki, 1995:117 [world catalog, accorded generic status].

DIAGNOSIS.—This genus is distinguished from other genera of Dryxini by the following combination of characters: arista bearing 8 or more dorsal hairs; proclinate fronto-orbital setae greatly reduced and subequal, setula-like; facial setae 2 or 3, if 2, these well spaced, dorsal seta at about midheight, ventral seta closer to oral margin than dorsal seta; dorsocentral setae 4 (1+3), anterior seta well developed; presutural supra-alar seta present; notopleuron bearing 2 large setae (anterior notopleural seta well developed); anepisternal and katepisternal setae well developed; forefemur bearing anteroventral row of very short, stout, spine-like setae (difficult to see) along apical ; and mid- and hindfemora normally developed, much shorter than length of abdomen.

DESCRIPTION.—Small to moderately small shore flies, body length 1.65–2.85 mm; densely microtomentose, gray to brown dorsally, usually becoming darker ventrally.

Head: Frons shallowly arched anteroventrally, not projected forward, sparsely setulose; ocelli in isosceles triangle, distance between posterior pair longer than between anterior ocellus and either posterior ocellus; ocellar seta, inner vertical seta, and reclinate fronto-orbital seta well developed; proclinate fronto-orbital setae greatly reduced, subequal in length, anterior seta not conspicuously larger than posterior seta; paravertical seta well developed, subequal to length of posterior notopleural seta. First flagellomere broadly rounded; arista bearing 6–8 long hairs along dorsal surface. Face with 2 or 3 long (subequal to length of large, reclinate seta), inclinate (but not cruciate) facial setae on ventral of face and 3 or 4 smaller setulae interspersed along same vertical alignment as larger setae, facial setae and setulae vertically aligned, parallel with parafacial. Parafacial at anterior margin of eye narrow, width much less than length of 1st flagellomere. Gena high, height subequal to combined length of 1st flagellomere and pedicel.

Thorax: Dorsocentral setae 4 (1+3), well developed, posterior pair displaced laterally; acrostichal setulae well developed, conspicuous, in about 8 irregular rows; presutural supraalar seta well developed, subequal in length to anterior, dorsocentral seta; postpronotal seta well developed; notopleural setae 2, posterior seta shorter; anepisternum variable, bearing 1 large seta along posterior margin and with dorsal seta reduced, or (usually) bearing 2 setae with apical seta – length of larger, ventral seta; katepisternal seta well developed. Posterior margin of scutellum truncate, nearly flat. R stem vein bearing 1–3 (usually 2) setulae, these oriented posteriorly; crossvein dm-cu regularly developed, nearly straight, longer than apical section of vein CuA1, and at distinct angle with posterior margin of wing. Forefemur bearing comb-like row of short, stout, spine-like setulae along apical of anteroventral surface; foretibia of male bearing several long, slender setae at apex on ventral surface; forebasitarsus with row of long, slender, pale setulae inserted along anterior surface; midtibia with 3 dorsal extensor setae (subapically, subbasally, and near middle); mid- and hindfemora normally developed, much shorter than length of abdomen.

Abdomen: Lacking pattern of facia. Male terminalia: epandrium in posterior view a broad to moderately narrow inverted U, bearing setulae toward posterior margin; cercus ovoid, dorsum in posterior view slightly narrower than venter, bearing numerous setulae, especially on medial portion; presurstylus in posterior view wider than high, bearing few to many short to long setulae; postsurstylus slightly curved anteriorly in lateral view, base wider than apex, especially in lateral view, with preapical notch, bearing setulae in patches along inner curvature; aedeagus simple, usually broad basally, apex pointed to truncate; aedeagal apodeme with conspicuous, moderately deep to deep keel; hypandrium wider than long (best seen in posterior view), shallowly and sometimes irregularly curved in lateral view.

HISTORICAL REVIEW.—Oedenopiforma was first described by Cogan (1968) as a subgenus of Paralimna and initially included only two species, O. madecassa (Giordani Soika, 1956a), the type species, and O. argentea, which Cogan described in the same paper. Other than Cogan's (1980) Afrotropical catalog and our world catalog (Mathis and Zatwarnicki, 1995), there are no further references to the genus and species. Consistent with our catalog, herein we accord generic status to this taxon, but we also expand the generic concept to include two additional species, Paralimna uniseta Malloch and P. ligabuei Canzoneri. The latter species is Afrotropical in distribution, like the two originally included species