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

description: Parathalassius infuscatus sp. nov.
(Figs 7, 27, 41, 59, 87, 111–112, 119, 146)
Type material. HOLOTYPE ♂ labelled: “ USA: CA: Santa Barbara Co.:/ Surf Beach, Vandenberg Air/ Force Base, 34.683801°N / 120.605520°W, 21.iii.2016 / A.J. Abela, ex: sandy coastal/ foredune”; “ HOLOTYPE / Parathalassius infuscatus / Brooks & Cumming [red label]” (CNC). PARATYPES: USA: California: same data as holotype (2♂, CNC); same data except, CNC588232, CNC588233 (2♂, barcoded, CNC); same data as holotype except, 21.iii.2016 (1♀, CNC); same data as holotype except, 11.ii.2017 (1♀, CNC).
Other material examined. USA: California: San Luis Obispo County: Dune Lakes, 3 mi. S Oceano [ca. 35°04′25″N 120°36′57″W], 27.iv.1973, J. Powell (1♂, 1♀, EMEC); Morro Bay, dunes [ca. 35°22′16.4″N 120°51′52.0″W], 12.iv.1981 (3♂, 1♀, EMEC); Oso Flaco Dunes, 35.032931°N 120.629882°W, 8.iii.2015, A. Abela (1♂, photograph, see Fig. 2 C); same data except, 11.ii.2017 (20♂, 3♀, CNC).
Diagnosis. This small distinctive species is characterized by broadly infuscate wings in both the male and female with the base of M2 usually appearing indistinct, uniformly short male ommatrichia, 2 notopleural bristles, and male hypopygium with an unbranched left ventral epandrial process.
Description. Male (Fig. 7): Body length 1.5–2.0 mm, wing length 1.4–1.5 mm. Dark brown ground colour covered mostly with dense brownish-grey pruinosity. Setae of body and legs yellowish-white. Head (Fig. 27): Eyes with ommatrichia of nearly uniform length, not distinctly longer on lower third. Face and clypeus covered with greyish-white pruinosity, not concolourous with brownish-grey frons and vertex. Face narrowest at middle, about 2.5X width of anterior ocellus. Gena without setae and postgena with moderately short sparse pale setae, not forming beard flanking mouthparts. Antenna (Fig. 41) including arista-like stylus, entirely dark brown; postpedicel subtriangular, 1.5–1.6X longer than wide; arista-like stylus of medium length, about 1.6X length of postpedicel. Palpus with 2–3 moderately long setae and several short setulae on outer surface of apical half. Thorax: Acrostichal setulae weakly developed, biserial; 5–6 dorsocentral bristles, 0 presutural intra-alar bristles, 1 presutural supra-alar (posthumeral) bristle, 2 postsutural supra-alar bristles, 2 notopleural bristles. Scutellum with 2–3 pairs of bristles. Legs: Foreleg: Dark brownish-grey, paler at knee and extreme apex of tibia, tarsus pale brown to 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 brownish-grey, paler at knee, tarsus pale brown to brown. Femur with short setae on anterior surface. Tibia with pair of dark apicoventral bristles. Tarsomeres 1–4 each with a few dark spine-like apicoventral setae. Hindleg: Dark brownish-grey, femur dark brown posteriorly, tarsus pale brown to brown. Femur with anteroventral row of setae most prominent, short basally, slightly longer apically. Tibia clothed with very short setae. Tarsus slightly longer than tibia with short setae and setulae; tarsomere 1 long, but shorter than combined length of tarsomeres 2–4; tarsomeres 1–4 lacking peg-like or thickened setae dorsally; tarsomere 2 long, longer than tarsomere 3; tarsomere 3 longer than either tarsomere 4 or 5; tarsomeres 4 and 5 subequal in length. Wing (Fig. 59): Infuscate with dark brown veins, membrane lighter and more yellow basally. Vein M2 usually appearing indistinct basally. Cell dm produced apically, dm-m crossvein slightly concave to nearly straight. Vein CuA+CuP very short, straight. Abdomen: Tergites 2–4 with setae relatively weak and sparse. Sternite 5 with short digitiform pregenitalic process present, base with short acute anterior projection, apex blunt and covered with short microtrichia, posterior edge of sternite (behind process) not emarginate. Sternite 8 subquadrate with setae relatively sparse, longer laterally. Hypopygium (Figs 87, 111–112, 119): Large. Left epandrial lamella with ventral portion elongate (about 2X longer than high); ventral epandrial process unbranched (dorsal lobe absent), basal 3/4 broadly subrectangular in lateral view with stout apically frayed apicodorsal seta and pair of minute setae along distiventral margin, apex upturned with expanded, lamelliform concavity. Dorsal lobe of left surstylus subpyriform, with basiventral edge rounded and flap-like, apex broadly rounded, with short basidorsal seta, short lateral seta and long thick apical seta, medial surface with knob-like projection bearing thick, hook-like apical seta. Ventral lobe of left surstylus broad with curved seta on distiventral margin and complex upturned projection arising medioventrally. Right epandrial lamella with ventral epandrial process short broad and rounded apically; 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 2 similar sized setae on dorsal margin, apex narrowed with squared-off tip bearing long seta on lower apical margin and thick apically frayed prensiseta on medial surface. Ventral lobe of right surstylus subtriangular with acute apex, with seta near middle of ventral margin. Hypandrium large, reniform, mainly bare except for two setae posteriorly on right side below ventral edge of right epandrial lamella. Left postgonite lobe ovoid basally, constricted medially, distal portion broadly lamelliform with claw-like apical process, base of lobe with slender medial projection. Right postgonite lobe broad basally with lateral protuberance, bifurcate, ventral arm tapered to acute tip, dorsal arm with rounded lamelliform apex. Phallus bifurcate with narrow curved ventral branch about half length of dorsal branch. Ejaculatory apodeme subrectangular. Hypoproct projected dorsally as pair of slender digitiform lobes. Cerci with anal setae relatively long, well-developed and differentiated from surrounding hairs; right cercus much larger than left cercus with basal portion distended and rounded laterally, apex weakly deflected dorsally, with broad flap-like medial expansion and stub-like tip, bearing 2 setae; left cercus Yshaped in dorsal view, basal portion narrow, strap-like, distal portion with flap-like medial and apical lobes, apical lobe weakly deflected dorsally, bearing 2 setae.
Female: Body length 1.9–2.0 mm, wing length 1.8–2.0 mm. Wing infuscate as in male (cf. Fig. 59), but usually slightly lighter. Similar to male except as follows: Head: Face and clypeus covered with brownish-grey pruinosity, concolourous with frons and vertex. Face wider, at middle about 3.5X width of anterior ocellus. Abdomen: 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, lacking basal bulge, apical portion with longitudinal ridges, apex broadly rounded; tergite 10 with hemitergites subtriangular and short, each with 2 or 3 acanthophorite spines; cercus short, pointed apically.
Distribution and seasonal occurrence. Parathalassius infuscatus is currently known only from coastal dunes in San Luis Obispo County and Santa Barbara County in southern California (Fig. 146). Adults have only been collected or photographed from February to late April. We were unable to locate specimens at the type locality (Figs 19–20), later in the season in early June, 2016.
Etymology. The specific name refers to the dark infuscated wing in both males and females.
Remarks. Adults of P. infuscatus were found on open sand between patches of beach bur (Ambrosia chamissonis) during the day (Fig. 19) and on the vegetation by late afternoon (Fig. 20).
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 24-28, DOI: 10.11646/zootaxa.4314.1.1, http://zenodo.org/record/858378