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

description: Parathalassius susanae sp. nov.
(Figs 35, 46, 52, 55, 66, 83–84, 117, 141, 151)
Type material. HOLOTYPE ♂ labelled: “USA: OR: Lane Co., Suislaw / North Jetty, nr. Florence,/ 44°01′07.0″N 124°08′12.6″W / 8.vii.2014, swp [swept] dunes &/ beach grass (Ammophila)/ S.E. Brooks ”; “ HOLOTYPE / Parathalassius susanae / Brooks & Cumming [red label]” (CNC). PARATYPES: USA: Oregon: same data as holotype (1♂, CNC); same data as holotype except, J.M. Cumming (3♂, CNC); same data except, CNC487190 (1♂, barcoded, CNC), CNC487191 (1♀, barcode-associated, CNC); same data except, 7.vii.2014 (2♂, CNC).
Other material examined. CANADA: British Columbia: Haida Gwaii, Graham Island: Tlell, Naikoon Prov. Park [ca. 53°33′37″N 131°55′39″W], intertidal, 14.vii.1988, S.A. Marshall (3♂, 11♀, CNC); 3 km N Tlell [ca. 53°33′37″N 131°55′39″W], 13.vii.1988, meadow behind dunes, T.A. Wheeler (1♂, 2♀, CNC); Queen Charlotte City [ca. 53°15′14.68″N 132° 05′14.01″W], 14.viii.1957, E.E. MacDougall (1♀, CNC). USA: California: Humboldt County: Clam Beach [ca. 40°59′40″N 124°06′58″W], 21.vi.1935, A.L. Melander (1♂, 1♀, USNM); Clam Beach Co. Park N of Eureka [ca. 40°59′40″N 124°06′58″W], 15.v.1978, D.D. Wilder (7♀, CAS); same data except, 16.v.1978 (1♀, CAS); Samoa Peninsula, Samoa Dunes Recreation Area, 40°45′41″N 124°13′37″W, 21.v.2009, S.E. Brooks (2♂, 2♀, CNC); same data except, CNC487193 (1♂, barcoded, CNC). Georgia: McIntosh County: Sapelo Island [ca. 31°27′21″N 81°13′16″W], 20.vi.1987, open sand dunes, BRC HYM TEAM (1♂, CNC); same data except, CNC DIPTERA #103903 (1♀, barcode-associated, CNC). Oregon: Coos County: Bandon, Bullards Beach, 43°08′44″N 124°24′56″W, 29.v.2009, swept beach-grass, S.E. Brooks (4♂, 3♀, CNC); same data except, CNC DIPTERA #103911 (1♂, barcoded, CNC); same data except, J.M. Cumming (3♂, CNC); same data except, CNC487189 (1♀, barcode-associated, CNC); Curry County: Gold Beach [ca. 42°24′N 124°25′W], dunes, 28.vii.1993, H. Ulrich (1♂, 1♀, ZFMK); 3mi. SE Pistol River [ca. 42°13′59″N 124°23′27″W], 28.vi.1972, G. Steyskal (2♂, 1♀, USNM); Lincoln County: South Beach State Park, 44°36′05.6″N 124°03′54.0″W, 3.vii.2014, swept dunes & beach grass (Ammophila), S.E. Brooks (2♂, 2♀, CNC); same data except, J.M. Cumming (1♀, CNC); Tillamook County: Manzanita, 45°42′54.9″N 123°56′25.4″W, 3.vii.2014, swept dunes & beach grass (Ammophila), J.M. Cumming (2♂, 1♀, CNC); same data except, CNC4 87188 (1♂, barcoded, CNC); same data except, S.E. Brooks, CNC487187 (1♀, barcode-associated, CNC). Washington: Jefferson County: Olympic National Park, along Kalaloch Beach [ca. 47°36′19″N 124°22′29″W], 22.vii.1978, D.D. Wilder (16♂, 11♀, CAS); Pacific County: Cape Disappointment State Park nr. Ilwaco, Benson Beach, 46°16′20.4″N 124°04′25.4″W, 1.vii.2014, swept dunes & beach grass (Ammophila), S.E. Brooks (13♂, 6♀, CNC; 2♂, 2♀, CSCA); same data except, CNC487180, CNC487181 (2♂, barcoded, CNC), CNC487185 (1♀, barcode-associated, CNC); same data except, 2.vii.2014 (1♂, 4♀, CNC); same data except, 1.vii.2014, J.M. Cumming (2♂, 2♀, CNC); same data except, 2.vii.2014 (2♂, 3♀, CNC); same data except, 1.vii.2014, swept dunes & beach vegetation, S.H. Cumming (3♂, 3♀, CNC); Ilwaco, Cape Disappointment, 23.vii.1993, H. Ulrich (8♂, 6♀, ZFMK); same data except, 24.vii.1993 (19♂, 9♀, ZFMK); same data except, 25.vii.1993 (2♀, ZFMK); same data except, Benson Beach, dunes, 24.vii.1993 (2♂, ZFMK); same data except, 25.vii.1993 (5♀, ZFMK); same data except, 5.viii.1994 (1♂, 2♀, ZFMK); same data except, 9.viii.1994 (4♂, 2♀, ZFMK); same data except, on wet sand, 27.vii.1993 (11♂, 11♀, ZFMK); same data except, sandy beach, 3.viii.1994 (11♂, 9♀, ZFMK); same data except, 5.viii.1994 (1♂, 2♀, ZFMK); same data except, 8.viii.1994 (13♂, 14♀, ZFMK); same data except, 9.viii.1994 (15♂, 7♀, ZFMK); same data except, 10.viii.1994 (44♂, 26♀, ZFMK); same data except, Waikiki Beach, on sand, 15.vii.1988 (51♂, 30♀, ZFMK); same data except, on rock, 16.vii.1988 (2♂, 4♀, ZFMK); same data except, 17.vii.1988 (2♂, ZFMK); same data except, dunes, 22.vii.1993 (1♂, 2♀, ZFMK); same data except, on wet sand, 25.vii.1993 (7♂, 8♀, ZFMK); same data except, 26.vii.1993 (17♂, 23♀, ZFMK); same data except, sandy beach, 22.vii.1993 (4♂, 2♀, ZFMK); same data except, 9.viii.1994 (10♂, 4♀, ZFMK); Ft. Canby State Park [= Cape Disappointment State Park], 29.vi.1988, W.N. & D. Mathis (3♂, 1♀, USNM); Ilwaco [ca. 46°16′20″N 124°04′25″W], vii.1917, A.L. Melander (32♂, 35♀, USNM); same data (3♂, 1♀, CUCI); same data except, 27.viii.1917 (5♂, 3♀, USNM); same data except, 12.vii.1922 (1♀, USNM); same data except, 28.vi.1925 (3♀, USNM); same data except, Beach, vii.1917 (2♂, EMEC); Seaview [ca. 46°20′05″N 124°4′02″W], 1.ix.1920, O.E. Miner (1♂, USNM).
Diagnosis. This medium sized to relatively large species is characterized by an elongate-conical antennal postpedicel, 3–4 notopleural bristles, relatively dark legs, hind tarsomeres 2 and 3 nearly subequal in length, males with greyish-white pruinosity on the face and clypeus, and longer lower male ommatrichia. Parathalassius susanae is similar to P. candidatus and P. sinclairi, but males and females are most easily distinguished from the latter two species by hind tarsomere 2 being nearly subequal in length to tarsomere 3. Males of P. susanae are further distinguished from those of P. sinclairi by the longer anterodorsal setae on the hind tibia and by the hind tarsus, which lacks dorsal peg-like setae on tarsomeres 2–4.
Description. Male: Body length 2.7–3.4 mm, wing length 2.8–3.0 mm. Dark brown ground colour covered mostly with dense greyish-white pruinosity. Setae of body and legs white. Head (Fig. 35): 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 2.0X width of anterior ocellus. Gena and postgena with moderately long white setae, forming short beard flanking mouthparts. Antenna (Fig. 46) including arista-like stylus, entirely dark brown; postpedicel elongate-conical, 1.6 5–1.75X longer than wide; arista-like stylus of medium length, about 1.6X length of postpedicel. Palpus with 7–8 setae on outer surface of apical half. Thorax: Mesoscutum with some brownish-grey pruinosity on dorsum. Acrostichal setulae quadriserial; 7–8 dorsocentral bristles, 0 presutural intra-alar bristles, 1–2 presutural supra-alar (posthumeral) bristles, 3–4 postsutural supra-alar bristles, 3 notopleural bristles. Scutellum with 3 pairs of bristles. Legs: Foreleg: Dark grey, pale at knee and apex of tibia, tarsomeres 1–2 pale yellowish-brown to brown, tarsomeres 3–5 brown to greyish-brown. Coxa with moderately long pale setae on anterior surface. Femur with numerous long setae on posterior surface, posterodorsal and posteroventral rows prominent. Tibia and tarsus with mostly short setae and setulae, tarsus with some longer setae dorsally; tarsomeres 1–2 not dilated. Midleg: Dark grey, pale at knee and extreme apex of tibia, tarsomere 1 pale yellowish-brown, tarsomeres 2–5 brown to greyishbrown. Femur with anteroventral and ventral rows of setae prominent. Tibia with pair of apicoventral bristles. Tarsus with some longer setae dorsally; tarsomeres 1–4 each with pair of dark spine-like apicoventral setae. Hindleg (Figs 52, 55): Dark grey, femur dark brown posteriorly, slightly paler at knee and extreme apex of tibia, tarsomere 1 pale yellowish-brown basally, apex of tarsomere 1 and tarsomeres 2–5 brown to greyish-brown. Femur with anteroventral and posteroventral rows of setae prominent. Tibia with anterodorsal and anteroventral rows of setae of moderate length, subequal or slightly longer than width of tibia. Tarsus slightly shorter than tibia with mostly short setae and setulae, longer setae dorsally; tarsomere 1 shorter than combined length of tarsomeres 2–4; tarsomeres 1–4 lacking peg-like or distinctively thickened setae dorsally; tarsomeres 3–5 widened apically and slightly flattened; tarsomeres 2, 3 and 5 nearly subequal in length, tarsomere 4 slightly shorter. Wing (Fig. 66): Hyaline with brown to dark brown veins. Cell dm produced apically, dm-m crossvein concave. Vein CuA+CuP of medium length, straight. Abdomen: Tergites 2–4 with setae well-developed and relatively long. Sternite 5 with slender anteriorly curved digitiform pregenitalic process present, base lacking anterior projection, apex blunt and covered with microtrichia, posterior edge of sternite 5 (behind process) deeply emarginate. Sternite 8 subquadrate with prominent elongate setae on posterolateral edges. Hypopygium (Figs 83– 84, 1 17): Large. Left epandrial lamella with ventral portion elongate (about 2X longer than high); ventral epandrial process broadly bifurcate, dorsal arm curved ventrally, narrowed in middle section, apex expanded, blunt or hook-like, ventral arm thick with minute apicodorsal seta and 1–2 minute setae along distiventral margin, apex with expanded lamelliform concavity. Dorsal lobe of left surstylus with basiventral edge weakly rounded, apex thumb-like, 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 or bluntly pointed, ventral lobe with rounded base bearing short lateral seta and complex upturned multilobate projection arising medioventrally. Right epandrial lamella with ventral epandrial process not developed; 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 squared-off tip bearing thick apically-frayed prensiseta on medial surface. Ventral lobe of right surstylus with 1–2 lateral setae near middle, distal half weakly recurved with broad lateral edge, tapered with tubercle bearing strong seta proximal to rounded 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 broadly lamelliform with claw-like apical process, base of lobe with narrow slender projection. Right postgonite lobe with broad lateral protuberance and indistinct medial projection, apex bifurcate with short digitiform process and broad rounded lamelliform process. Phallus (cf. Figs 97–98) short and weakly curved, broad in basal 2/3 with apical 1/3 narrower (in lateral view), left lateral dentiform projection present at 2/3 length, dorsal flange not developed. Ejaculatory apodeme broadly subtriangular. Hypoproct strongly projected dorsally as pair of slender lobes. 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 strongly deflected, elongate, narrow and pointed, with 2 short preapical setae present along lateral margin; left cercus oblong-subrectangular in dorsal view, apex strongly deflected dorsally, short and subrectangular, with medial and lateral corners weakly pointed, with 2 long setae on posterior margin.
Female: Body length 2.9–3.3 mm, wing length 2.9–3.5 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 3.75– 4.5X width of anterior ocellus. Legs: Foreleg: Coxa with shorter more slender pale setae on anterior surface. Femur with posteroventral row of setae only prominent apically. Tarsus with slightly shorter setae dorsally. Midleg: Tarsus with slightly shorter setae dorsally. Hindleg: Tibia with anterodorsal and anteroventral rows slightly shorter. Tarsus with slightly shorter setae dorsally. 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 distinctly narrowed apically, apical half with longitudinal ridges, apex truncate (Fig. 141); sternite 9 a narrow transverse sclerotized band; tergite 10 with hemitergites subtriangular and short, each with 2 acanthophorite spines; cercus short, pointed apically.
Distribution and seasonal occurrence. Parathalassius susanae is currently known to occur on sandy seashores from Haida Gwaii, British Columbia, south along the coast of Washington, Oregon and northern California. There is also a reliable record of this species from a sandy seashore location on Sapelo Island, Georgia along the Atlantic coast, which is presumably the result of a recent introduction (see Remarks) (Fig. 151). Adults have been collected from mid May to early September.
Etymology. This species is named in recognition of the second author’s wife, Susan Cumming, who has extensively supported his various research endeavours, including collecting many specimens of Parathalassius used in this study.
Remarks. The COI barcode sequence data obtained from specimens of P. susanae (Fig. 154) from Washington, Oregon, northern California, and even Georgia (see below), show very little genetic divergence (<1.1%), suggesting that there has been considerable gene exchange and possible movement between populations of this widely distributed species.
A male and female specimen of P. susanae were collected in 1987 from the sandy shoreline of Sapelo Island in Georgia (Fig. 151). The species identity was also confirmed through comparison of a DNA barcode (COI) sequence taken from the female specimen (Fig. 154, CNC DIPTERA #103903). This is the only record of the genus from the Atlantic coast of North America and is presumably the result of a recent introduction. This may have occurred through human-assisted movement of plants such as beach grass (Ammophila) from the Pacific coast. These plants are routinely used to counter coastal erosion and stabilize dune habitats, although currently there is no evidence that this procedure was employed on Sapelo Island.
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 42-48, DOI: 10.11646/zootaxa.4314.1.1, http://zenodo.org/record/858378