Parathalassius melanderi Cole. A 1912
Creators: name: Cumming, Jeffrey M.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Parathalassius
Parathalassius melanderi

description: Parathalassius melanderi Cole
(Figs 28, 42, 60–61, 86, 99–100, 125, 136, 147)
Parathalassius melanderi Cole, 1912: 154.
Type material examined. LECTOTYPE (here designated in order to fix identity of the species), ♂, from Laguna Beach [ca. 33°32′24″N 117°47′04″W], Orange County, California, USA, labelled: “Laguna Bch/ Cal. Cole [1912] ”; “8”; “ Parathalassius / melanderi / n.sp. [red label]”; “LECTOTYPE/ Parathalassius / melanderi Cole / des. Brooks & Cumming 2016 [red label]” (USNM). PARALECTOTYPE: USA: California: same data as lectotype except, S. Cal. (1♂, EMEC). Our paralectotype label has additionally been attached to this specimen.
Other material examined. MEXICO: Baja California: Ensenada [ca. 31°50′06″N 116°36′39″W], 24.vi.1950, A.L. Melander (2♂, 1♀, USNM); 10 mi. N El Rosario, El Consuelo Dunes [ca. 30°11′N 115°47′W], 24.iii.1979, J.D. Pinto, UCRC ENT 461757 (1♀, UCRC). USA: California: Orange County: Corona Del Mar [ca. 33°35′33″N 117°52′26″W], 19.xi.1946, A.L. Melander (1♀, USNM); Crystal Cove State Park, 33°34′51.9″N 117°50′55.7″W, 6.vi.2016, swept sandy seacoast & beach vegetation, S.E. Brooks (40♂, 59♀, CNC; 2♂, 2♀, CSCA); same data except, CNC574905, CNC574937 (2♂, barcoded, CNC), CNC574932, CNC574943 (2♀, barcode-associated, CNC); same data except, J.M. Cumming (8♂, 22♀, CNC); same data except, CNC580763, CNC580778 (2♂, barcoded, CNC), CNC580779 (1♀, barcode-associated, CNC); same data except, S.H. Cumming (1♀, CNC); Crystal Cove State Park, Pelican Point, moist sand in tidal zone, 6.viii.1993, H. Ulrich (2♀, ZFMK); same data except, 7.viii.1993 (1♂, 4♀, ZFMK); same data except, 8.viii.1993 (43♂, 13♀, ZFMK); same data except, 20.vii.1994 (8♂, 8♀, ZFMK); same data except, 21.vii.1994 (56♂, 10♀, ZFMK); Crystal Cove, 33°34.8'N 117°50.7'W, beach, 6.iv.2005, W.N. & D. Mathis (9♂, 1♀, USNM); same data except, CNC478112 (1♀, barcode-associated); Laguna Beach [ca. 33°32′24″N 117°47′04″W], Cole (2♀, EMEC); Doheny Park [33°27′42″N 117°40′56″W], 22.v.1944, A.L. Melander (1♂, USNM); San Clemente State Beach, 33°24′18.7″N 117°36′22.8″W, 7.vi.2016, swept sandy seacoast, S.E. Brooks (4♂, CNC); same data except, J.M. Cumming (5♀, CNC); same data except, S.H. Cumming (1♀, CNC); San Clemente, 23.v.1944, A.L. Melander (1♂, USNM); San Diego County: Carlsbad [ca. 33°09′27″N 117°21′12″W], 22.vi.1950, A.L. Melander (1♂, USNM); same data except, 24.vi.1954 (1♂, USNM); San Onofre State Beach, 33°22′29.3″N 117°34′04.7″W, 7.vi.2016, swept sandy seacoast, S.E. Brooks (1♀, CNC); Silver Strand State Beach (east shore), 32°37′49.9″N 117°08′24.9″W, 8.vi.2016, swept sandy shore & beach vegetation, S.E. Brooks (2♂, 2♀, CNC); Silver Strand State Beach, 4.viii.1993, H. Ulrich (1♀, ZFMK); Santa Barbara County: Carpinteria [ca. 34°23′35″N 119°31′29″W], 23.ix.1946, A.L. Melander (1♂, 1♀, USNM); Ventura County: San Nicolas Is., Dutch Harbor area [ca. 33°13′N 119°29′W], 6.v.1978, R. Coville (3♂, 1♀, EMEC); same data except, J. Powell (1♂, EMEC).
Diagnosis. This relatively small distinctive species is characterized by a short-subtriangular antennal postpedicel, longer lower male ommatrichia, 2 notopleural bristles, male with a wing darkened towards the apex, and female with slight infuscate shading along the wing veins near the apex of cell dm. Parathalassius melanderi is most similar to P. dilatus, but does not have male foretarsomeres 1–2 dilated.
Redescription. Male: Body length 2.3–2.9 mm, wing length 2.0– 2.2 mm. Dark brown ground colour covered mostly with dense greyish-white pruinosity. Setae of body and legs white. Head (Fig. 28): Eyes with ommatrichia of lower third distinctly longer and slightly flattened, forming dense reflective mat of whitish coloured hair. Face and clypeus concolourous with greyish-white frons and vertex. Face narrowest at middle, about 2.0–2.5X width of anterior ocellus. Gena and postgena with long white setae, forming distinct beard flanking mouthparts. Antenna (Fig. 42) including arista-like stylus, entirely dark brown; postpedicel short-subtriangular, 1.35–1.45X longer than wide; arista-like stylus of medium length, about 1.5X length of postpedicel. Palpus with dense brush of 1 0–12 setae on outer surface of apical half. Thorax: Acrostichal setulae biserial; 6 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, tarsomeres 1–2 pale yellowish-brown, tarsomeres 3–5 brown to greyish-brown. Coxa with moderately long stout pale setae, densely covering anterior surface. Femur with moderately long setae on posterior surface, posteroventral rows prominent. Tibia with short setae and setulae. Tarsus with setulae; tarsomeres 1–2 not dilated. Midleg: Dark grey, pale at knee and apex of tibia, tarsomeres 1–2 pale yellowish-brown, tarsomeres 3–5 brown to greyish-brown, darker apically. Femur with anterodorsal setae most prominent, short. Tibia with pair of apicoventral bristles. Tarsomeres 1–4 each with several dark spine-like apicoventral setae. Hindleg: Dark grey, femur dark brown posteriorly, pale at knee and apex of tibia, tarsomeres 1–2 and base of tarsomere 3 pale yellowish-brown, apex of tarsomere 3 and tarsomeres 4– 5 brown to greyish-brown, darker apically. Femur with anteroventral row of setae most prominent, short basally, longer apically. Tibia clothed with short setae. Tarsus 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 long, longer than tarsomere 4; tarsomere 4 longer than tarsomere 5. Wing (Fig. 60): Lightly infuscate apically, hyaline basally, with yellowish veins basally and dark brown veins apically. Cell dm slightly produced apically, dm-m crossvein nearly straight. Vein CuA+CuP short to medium length, straight. Abdomen: Tergites 2–4 with setae well-developed. Sternite 5 without projecting pregenitalic process, posterior edge of sternite deeply emarginate. Sternite 8 subquadrate with setae longer along posterolateral margins. Hypopygium (Figs 86, 99–100, 125): Large. Left epandrial lamella with ventral portion elongate (about 2X longer than high); ventral epandrial process broadly bifurcate, dorsal arm elongate and strongly curved ventrally, more or less evenly slender, apex slightly expanded dorsally and prominently hook-like, ventral arm thick with minute apicodorsal seta and pair of minute setae along distiventral margin, apex with expanded lamelliform concavity. Dorsal lobe of left surstylus subtriangular, with basiventral edge broadly rounded, apex pointed, with long basidorsal seta, short lateral seta and long apical seta, medial surface with knob-like projection bearing lamelliform apical process. Ventral lobe of left surstylus shallowly bilobate in lateral view, dorsal lobe short with apex rounded, ventral lobe with rounded base bearing short lateral seta and complex upturned bifurcate projection arising medioventrally. Right epandrial lamella with ventral epandrial process spur-like; 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 (lowermost seta weaker), apex narrowed with rounded tip bearing thick apically-frayed prensiseta on medial surface. Ventral lobe of right surstylus recurved at base with lateral seta near middle, with elongate finely-tipped process proximal to narrow apex. Hypandrium very large, elongate-reniform with convex anterior and posterior ends extending to or beyond margins of epandrial lamellae in lateral view, bare. Left postgonite lobe ovoid basally, constricted near middle, distal portion subrectangular and flat without claw-like apical process, base of lobe with broad curved apically-pointed medial projection. Right postgonite lobe with broad lateral protuberance pointed at apical margin and lamelliform medial projection, apex bifurcate with short digitiform process and rounded lamelliform process. Phallus short and weakly curved, basal portion broad with ventral flange, gradually tapering distally, lacking dorsal flange and left lateral protuberance at 2/3 length. Ejaculatory apodeme broadly subtriangular. Hypoproct strongly projected dorsally as pair of acutely pointed subtriangular lobes, each lobe with 3 preapical ventral setae, lower seta strong, left lobe with piliferous flange lateral to lower seta. 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 weakly deflected dorsally, truncate with pair of setae along apicolateral margin; left cercus oblong-subrectangular in dorsal view, apex even with apex of right cercus, weakly deflected dorsally, broadly pointed with pair of apical setae.
Female: Body length 2.4–3.0 mm, wing length 2.1–2.4 mm. Similar to male except as follows: Head: Eyes with ommatrichia of nearly uniform length, not distinctly longer on lower third. Face wider, at middle about 4.0– 4.5X width of anterior ocellus. Palpus less densely setose. Legs: Foreleg: Coxa with slightly shorter more slender setae on anterior surface. Wing (Fig. 61): Hyaline, with (in most specimens) slight infuscate shading along veins near apex of cell dm. 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, not narrowed apically, apical half without longitudinal ridges, apex emarginate (Fig. 136); sternite 9 reduced to narrow weakly-developed transverse sclerotized band; tergite 10 with hemitergites subtriangular and short, each with 2 acanthophorite spines; cercus short, blunt-tipped.
Distribution and seasonal occurrence. Parathalassius melanderi is currently known to occur on sandy seashores from Carpinteria in Southern California, south to El Consuelo Dunes, near El Rosario in Baja California (Fig. 147). Adults have been collected from late March to mid November.
Remarks. A large series of P. melanderi collected at Crystal Cove State Park in southern California (Fig. 21) exhibited a behavioural change depending on the time of day. Early in the day, from morning through to mid afternoon, a few adult flies (both males and females) were collected on open dry or wet sand near the ocean, but apparently nowhere else. After 6:30 pm however, flies were no longer found on this part of the beach, but numerous individuals (both males and females) were taken further away from the ocean, on vegetation bordering the beach (Fig. 22).
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 28-30, DOI: 10.11646/zootaxa.4314.1.1, http://zenodo.org/record/858378