Parathalassius uniformus Cumming 2017, sp. nov.
Creators: name: Cumming, Jeffrey M.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Parathalassius
Parathalassius uniformus

description: Parathalassius uniformus sp. nov.
(Figs 8–10, 36–37, 47, 67, 91, 109–110, 124, 138, 152)
Type material. HOLOTYPE ♂ labelled: “ USA: CA: Santa Barbara Co.:/ Surf Beach, Vandenberg Air / Force Base, 34.683801°N / 120.605520°W, 5.iv.2016 / A.J. Abela, ex: sandy coastal/ foredune”; “ HOLOTYPE / Parathalassius uniformus / Brooks & Cumming [red label]” (CNC). PARATYPES: USA: California: same data as holotype (37♂, 3♀, CNC); same data as holotype except, 6.iv.2016 (10♂, 6♀, CNC).
Other material examined. USA: California: same data as holotype except, 4.vi.2016, ex: Ambrosia chamissionis & coastal dunes (14♂, 34♀, CNC); same data except, CNC573801, CNC573803 (2♂, barcoded, CNC), CNC573765 (1♀, barcode-associated); same data except, S.E. Brooks (25♂, 30♀, CNC; 2♂, 2♀, CSCA); same data except, CNC573332 (1♂, barcoded, CNC), CNC573254, CNC573337 (2♀, barcode-associated, CNC); same data except, J.M. Cumming (4♂, 13♀, CNC); same data except, CNC582777 (1♂, barcoded, CNC), CNC582785 (1♀, barcode-associated, CNC); same data except, S.H. Cumming (1♂, 4♀, CNC).
Diagnosis. This relatively small species is characterized by a subtriangular antennal postpedicel, uniformly short male ommatrichia, 2 notopleural bristles, hyaline wing, relatively dark legs, male hypopygium compact, and female sternite 8 with longitudinal ridges extended across apical third.
Description. Male (Figs 8–10): Body length 1.7–2.1 mm, wing length 1.5–1.7 mm. Dark brown ground colour mostly covered with dense greyish-white pruinosity. Setae of body and legs white. Head (Fig. 36): Eyes with ommatrichia of nearly uniform length, not distinctly longer on lower third. Face and clypeus concolourous with greyish-white frons and vertex. Face narrowest at middle, about 2.5X width of anterior ocellus. Gena without setae and postgena with moderately short sparse setae, not forming beard flanking mouthparts. Antenna (Fig. 47) including arista-like stylus, entirely dark brown; postpedicel subtriangular, 1.4–1.5X longer than wide; arista-like stylus of medium length, about 1.7X length of postpedicel. Palpus with 2–3 moderately long setae and several short setulae on outer surface of apical half. Thorax: Acrostichal setulae biserial; 6–7 dorsocentral bristles, 0 presutural intra-alar bristles, 1 presutural supra-alar (posthumeral) bristle, 2–3 postsutural supra-alar bristles, 2 notopleural bristles. Scutellum with 2–3 pairs of bristles. Legs: Foreleg: Dark grey, pale at knee and apex of tibia, tarsomere1 pale yellow basally, apex of tarsomere 1 and tarsomeres 2–5 brown. Coxa with short pale setae on anterior surface. Femur with short setae on posterior surface. Tibia with short setae and setulae. Tarsus with setulae; tarsomeres 1–2 not dilated. Midleg: Dark grey, pale at knee and extreme apex of tibia, tarsomere 1 pale yellow basally, apex of tarsomere 1 and tarsomeres 2–5 brown. Femur with apical anterodorsal setae most prominent, relatively short. Tibia with 1 apicoventral bristle. Tarsomeres 1–4 each with several dark spine-like apicoventral setae. Hindleg: Dark grey, femur dark brown posteriorly, pale at knee and extreme apex of tibia, tarsomere 1 pale yellow, tarsomeres 2–5 pale brown to brown. Femur with anteroventral row of setae prominent, short basally, longer apically. Tibia with anterodorsal and anteroventral rows of setae short to moderate length, shorter or subequal to width of tibia. Tarsus slightly longer than tibia with short setae and setulae; tarsomere 1 shorter than combined length of tarsomeres 2–4; tarsomeres 1–4 lacking peg-like or thickened setae dorsally; tarsomere 2 longer than tarsomere 3; tarsomere 3 longer than tarsomere 4; tarsomere 5 subequal in length to tarsomere 3. Wing (Fig. 67): Hyaline with brown veins. Cell dm produced apically, dm-m crossvein slightly concave. Vein CuA+CuP short to medium length, nearly straight. Abdomen: Tergites 2–4 with setae relatively short and weak. Sternite 5 with short straight digitiform pregenitalic process present, base lacking anterior projection, apex blunt and covered with microtrichia, posterior edge of sternite 5 (behind process) emarginate. Sternite 8 subquadrate with setae longer along posterolateral margins. Hypopygium (Figs 91, 109–110, 124): Relatively compact. Left epandrial lamella with ventral portion elongate (about 2X longer than high); ventral epandrial process broadly bifurcate, dorsal arm with weak ventral curve, apex expanded and blunt, ventral arm thick with minute apicodorsal seta and minute distiventral seta, apex with expanded lamelliform concavity. Dorsal lobe of left surstylus with basiventral edge rounded and flap-like, apex broadly rounded, with long basidorsal seta on bump-like protuberance, short lateral seta and long apical seta, medial surface with stalk-like projection bearing lamelliform apical seta. Ventral lobe of left surstylus shallowly bilobate in lateral view, dorsal lobe short with apex subquadrate, ventral lobe with basal pointed process bearing apical seta and complex upturned bifurcate projection arising medioventrally. Right epandrial lamella with ventral epandrial process barely developed as a short angular projection; basal portion of epandrial lamella narrowed and dorsally curved, with deep dorsal emargination bordering ventral margin of right cercus. Dorsal lobe of right surstylus with 3 lateral setae (distal-most seta strongest, middle seta weakest), apex narrowed with subtriangular tip bearing thick apically-frayed prensiseta on medial surface. Ventral lobe of right surstylus with lateral seta at basal third, distal 2/3 recurved, slender with narrow apically pointed lamelliform seta proximal to rounded lamelliform apex. Hypandrium large, reniform and bare. Left postgonite lobe subquadrate basally, constricted near middle, distal portion subrectangular and flat with claw-like apicodorsal process, base of lobe with broad curved apically-pointed medial projection. Right postgonite lobe with broad lateral protuberance and lamelliform medial projection, apex bifurcate with well-developed digitiform ventral process and lamellate dorsal process. Phallus relatively short and moderately curved, flattened preapically with membranous region on right side, apex straight. Ejaculatory apodeme subtriangular with apex slightly curved ventrally. Hypoproct projected dorsally as pair of slender pointed lobes, each lobe with ventral cluster of 3–4 minute setae proximal to apex, left lobe also with piliferous region apicoventrally. Cerci with anal setae well-developed and differentiated from surrounding hairs; right cercus much larger than left cercus with basal portion distended and rounded laterally, apex slightly widened, not dorsally deflected, truncate with pair of setae at apicolateral margin; left cercus oblong in dorsal view, apex broad, even with apex of right cercus, not dorsally deflected, with stub-like apicolateral projection bearing pair of thickened setae.
Female (Fig. 10): Body length 1.9–2.8 mm, wing length 1.5–2.1 mm. Similar to male except as follows: Head (Fig. 37): Face wider, at middle about 4.0–4.25X width of anterior ocellus. Legs: Hindleg: Femur with anteroventral row of setae shorter. Tibia with anterodorsal and anteroventral rows of setae shorter. Abdomen: Tergites 2–4 with setae slightly longer. Tergite 5 broadly subtriangular to semicircular in dorsal view with posterior margin rounded (cf. Fig. 131). Terminalia distinctly narrower than base of segment 5 (cf. Figs 131–132); sternite 8 trough-like, with weak basal bulge, not narrowed apically, apical third with longitudinal ridges extended across sternite including medial margin, apex emarginate (Fig. 138); sternite 9 unsclerotized and indistinct; tergite 10 with hemitergites subtriangular and short, each with 2 acanthophorite spines; cercus short, pointed apically.
Distribution and seasonal occurrence. Parathalassius uniformus is currently known only from the coastal dunes at Surf Beach, Santa Barbara County, California (Fig. 152). Adults have been collected from early April to early June.
Etymology. The specific name refers to the uniform length of the ommatrichia on the male eyes (Fig. 36).
Remarks. Adults were frequently found on open sand between patches of beach bur (Ambrosia chamissonis) (Figs 10, 19).
description: Published as part of Cumming, Jeffrey M., 2017, Revision of the Nearctic Parathalassius Mik (Diptera: Dolichopodidae: Parathalassiinae), with a review of the world fauna, pp. 1-64 in Zootaxa 4314 (1) on pages 49-51, DOI: 10.11646/zootaxa.4314.1.1, http://zenodo.org/record/858378