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

description: Parathalassius midas sp. nov.
(Figs 29–32, 43, 62–63, 76–77, 88, 113–114, 120, 127–129, 134, 148)
Type material. HOLOTYPE ♂ labelled: “USA: WA: Pacific Co., Cape/ Disappointment, nr. Ilwaco,/ Benson Beach, N46°16′20.4″/ W124°04′25.4″, 1.vii.2014, swp [swept]/ dunes & beach grass (Ammophila)/ S.E. Brooks”; CNC/ 588234; “HOLOTYPE/ Parathalassius midas / Brooks & Cumming [red label]”; “Legs removed/ for DNA/ analysis [green label]” (CNC). PARATYPES: MEXICO: Baja California: 3.2 mi. S Colonia Guerrero [ca. 30°41′N 116°01′W], 27.iv.1963, P.H. Arnaud Jr. (2♂, USNM). USA: California: Orange County: Corona Del Mar [ca. 33°35′33″N 117°52′26″W], 19.xi.1946, A.L. Melander (1♂, USNM); Laguna Beach [ca. 33°32′24″N 117°47′04″W], Baker (1♀, EMEC); same data except, 20.x.1951, A.L. Melander (1♀, USNM); San Diego County: Cardiff State Beach, 33°00′53.4″N 117°16′51.0″W, 8.vi.2016, swept sandy seacoast, S.E. Brooks (2♀, CNC); same data except, CNC574847 (1♀, barcode-associated, CNC); same data except, J.M. Cumming, CNC576883 (1♀, barcode-associated, CNC); same data except, S.H. Cumming (2♀, CNC); Carlsbad [ca. 33°09′27″N 117°21′12″W], 22.vi.1950, A.L. Melander (3♂, USNM); Santa Barbara County: Carpinteria [ca. 34°23′35″N 119°31′29″W], 12.vi.1953, A.L. Melander (6♀, USNM); same data except, 17.vi.1953 (4♀, USNM); U.C., Goleta [ca. 34°25′02″N 119°49′33″W], 27.vi.1965, D. Bragg (1♀, UCDC). Oregon: Lane County: Florence, 44°01′N 124°08.2′W, beach, 1.viii.2005, D. & W.N. Mathis (2♂, USNM).
Other material examined. USA: WA: Pacific County: Ilwaco, Cape Disappointment, Waikiki Beach, on wet sand, 23.vii.1993, H. Ulrich (1♀, ZFMK).
Diagnosis. This relatively large distinctive species is characterized by 2 notopleural bristles, pale legs, males with golden pruinosity and golden-yellow setae on the lower part of the head, uniformly short male ommatrichia, male wing with dark anteroapical spot, left ventral epandrial process of the male hypopygium bifurcate with broad hook-shaped dorsal arm and sclerotized flattened serratulate apex on ventral arm, and prominent unique female terminalia.
Description. Male: Body length 2.6–3.3 mm, wing length 2.7–3.0 mm. Dark brown ground colour covered mostly with dense greyish-white to brownish-grey pruinosity. Setae of body and legs pale yellow to golden-yellow. Head (Figs 29–30): Eyes with ommatrichia of nearly uniform length, not distinctly longer on lower third. Face, clypeus and lower frons covered with golden pruinosity, not concolourous with greyish-white to brownish-grey upper frons and vertex. Face narrowest at middle, about 1.75X width of anterior ocellus. Gena and postgena with moderately long golden-yellow setae, forming beard flanking mouthparts. Antenna (cf. Fig. 43) including aristalike stylus, entirely dark brown; postpedicel subquadrate, with expanded anteroventral margin, 1.4–1.5X longer than wide; arista-like stylus long, about 2.0X length of postpedicel. Palpus with 7–8 golden-yellow setae on outer surface of apical half. Thorax: Acrostichal setulae primarily biserial; 6–8 dorsocentral bristles, 0–1 presutural intra-alar bristles, 1 presutural supra-alar (posthumeral) bristle, 3–4 postsutural supra-alar bristles, 2 notopleural bristles. Scutellum with 3 pairs of bristles. Legs: Foreleg: Dark grey basally, pale yellow from knee to apex of tibia, tarsus pale yellow, tarsomeres 2–5 or 3–5 pale brown to dark brown in some specimens. Coxa with moderately long pale yellow to golden-yellow setae on anterior surface. Femur with numerous long pale yellow to golden-yellow setae on posterior surface, posterodorsal and posteroventral rows prominent. Tibia with short pale yellow setae and setulae. Tarsus with pale yellow setulae; tarsomeres 1–2 not dilated. Midleg: Dark grey basally, pale yellow from knee to apex of tibia, tarsus pale yellow, tarsomeres 2–5 or 3–5 pale brown to dark brown in some specimens. Femur with pale yellow to golden-yellow setae on anterior surface, anteroventral rows long and prominent. Tibia with 1 apicoventral bristle. Tarsomeres 1–4 each with several dark spine-like apicoventral setae. Hindleg: Dark grey basally, pale yellow from knee to apex of tibia, femur brown posteriorly, tarsus pale yellow, tarsomeres 2–5 or 3–5 pale brown to dark brown in some specimens. Femur with pale yellow to golden-yellow setae on anterior surface, anteroventral row long and prominent. Tibia clothed with short pale yellow setae. Tarsus slightly shorter than tibia with mostly short pale yellow 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. 62): Hyaline with dark brown veins and infuscate anteroapical spot. Cell dm produced apically, dm-m crossvein concave. Vein CuA+CuP short to medium length, slightly curved to straight. Abdomen: Tergites 2–4 with setae well-developed and relatively long. Sternite 5 with slender anteriorly curved hook-like pregenitalic process present, base with short blunt anterior projection, apex pointed and lacking distinct microtrichia, posterior edge of sternite 5 (behind process) deeply emarginate. Sternite 8 subrectangular with setae relatively sparse, elongate on posterolateral margins. Hypopygium (Figs 76–77, 88, 113–114, 120): Large. Left epandrial lamella with ventral portion short, about as long as high; ventral epandrial process with short stem-like base proximal to broad bifurcation, dorsal arm elongate hook-shaped and strongly curved ventrally, ventral arm thick in basal part with minute preapical dorsal seta and pair of minute setae along distiventral margin, sclerotized apex flattened and slightly narrowed, ventral edge and medial surface serratulate. Dorsal lobe of left surstylus with basiventral edge produced as a subquadrate flap-like lobe, apex with broad bifurcate asymmetrical process arising from short tubular base, dorsal margin with 2 long setae (distal-most seta shorter), medial surface lacking knob- or stalk-like projection. Ventral lobe of left surstylus broadly subtriangular with narrow base, with complex upturned projection arising medioventrally. Right epandrial lamella bluntly pointed below articulation with ventral lobe of surstylus, ventral epandrial process not developed; basal portion of epandrial lamella narrowed and straight, with shallow dorsal emargination bordering ventral margin of right cercus. Dorsal lobe of right surstylus very broad with 2 long lateral setae (lower seta thickened), apex narrowed with blunt bilobate tip without apically-frayed prensiseta on medial surface. Ventral lobe of right surstylus broad, basally articulated, with preapical ventral ridge bearing short seta, apex flap-like and ventrally curved. Hypandrium small, reniform, bare, interior surface with weak longitudinal carina extending from base of posterior notch. Left postgonite lobe large with anteriorly curved dorsal projection and shorter ventral projection basally, markedly broadened preapically, apex deflected medially and tapered to acute tip, middle of lobe with broad lamelliform medial projection. Right postgonite lobe trifurcate, with slender upturned ventral projection, basally broad medial projection with elongate digitiform apex, and narrowly pointed dorsal projection. Phallus elongate and broadly curved, dorsoventrally flattened in basal half with serratulate process on right side near mid-length, apical half narrower with bifurcate tip. Ejaculatory apodeme subrectangular and relatively small. Hypoproct projected dorsally as pair of apically tapering, asymmetrical lobes, left lobe digitiform in distal part with blunt tip, right lobe broader with dentiform ventral process proximal to acute tip. Cerci with anal setae welldeveloped and differentiated from surrounding hairs; right cercus slightly larger than left cercus, subrectangular, apex not deflected dorsally, truncate and shallowly excavated with long thick submarginal seta; left cercus suboval in dorsal view, apex not deflected dorsally, acute with pair of long thick marginal setae.
Female: Body length 3.0– 4.3 mm, wing length 2.9–3.6 mm. Similar to male except as follows: Body covered with greyish-white pruinosity. Setae of body and legs lighter, white to pale yellow. Head (Figs 31–32, 43): Face, clypeus and lower frons without golden pruinosity, concolourous with greyish-white frons and vertex. Face wider, at middle about 3.0–3.5X width of anterior ocellus. Legs: Foreleg: Coxa with paler slightly shorter more slender setae on anterior surface. Wing (Fig. 63): Entirely hyaline with yellowish veins basally, brown veins apically. Abdomen: Tergite 5 subrectangular in dorsal view with posterior margin truncate (Fig. 128). Terminalia large, nearly as broad as base of segment 5 (Figs 128–129); sternite 7 with a few setae along posterior margin; sternite 8, plate-like, lacking basal bulge, widened beyond base and narrowed apically, apical half without longitudinal ridges, apex bifurcate (Figs 129, 134); sternite 9 with trough-like transverse sclerite posteriorly and concave oval sclerite anteriorly; tergite 10 with hemitergites subtriangular and long, each with elongate apical projection bearing 2 acanthophorite spines at tip (Figs 127–128); cercus relatively long, blunt-tipped, with well-differentiated ventral lobe.
Distribution and seasonal occurrence. Parathalassius midas is currently known to occur on sandy seashores from Cape Disappointment, Washington, south to Colonia Guerrero, Baja California, including localities in Oregon and California (Fig. 148). Adults have been collected from late April to mid November.
Etymology. The specific name is derived from Midas, the Greek mythical king with a golden touch, in reference to the gold face and setae of males of this new species.
Remarks. The COI barcoded Washington male holotype shows a significant degree of genetic divergence (at minimally 4.1%) from the two female southern California COI barcoded specimens (Fig. 154), possibly indicating the presence of an additional cryptic species within the current concept of P. midas. Despite this degree of genetic divergence, the northern populations of P. midas from Washington and Oregon, appear morphologically identical to the southern populations from California and Baja California.
This species is rarely collected and does not appear to be abundant on the beaches it has colonized.
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 30-32, DOI: 10.11646/zootaxa.4314.1.1, http://zenodo.org/record/858378