Parathalassius susanae, Cumming, 2017

Cumming, Jeffrey M., 2017, Revision of the Nearctic Parathalassius Mik (Diptera: Dolichopodidae: Parathalassiinae), with a review of the world fauna, Zootaxa 4314 (1), pp. 1-64 : 42-48

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.

Figures

FIGURE 154. Neighbour-joining tree of 147 Parathalassius specimens and one outgroup specimen with COI sequences> 300 base pairs (bp), including unique voucher number, sequence length, geographic locality, and GenBank number.

FIGURES 29 – 37. Heads of Nearctic Parathalassius. 29 – 30. Parathalassius midas sp. nov., male, anterior and lateral views. 31 – 32. Parathalassius midas sp. nov., female, anterior and lateral views. 33. Parathalassius sinclairi sp. nov., male, anterior view. 34. Parathalassius socali sp. nov., male, anterior view. 35. Parathalassius susanae sp. nov., male, anterior view. 36. Parathalassius uniformus sp. nov., male, anterior view. 37. Parathalassius uniformus sp. nov., female, anterior view.

FIGURES 38 – 47. Antennae of Nearctic Parathalassius (male left antenna in medial view, unless otherwise noted). 38. Parathalassius abela sp. nov. 39. Parathalassius wheeleri sp. nov. 40. Parathalassius candidatus Melander. 41. Parathalassius infuscatus sp. nov. 42. Parathalassius melanderi Cole, right antenna in lateral view. 43. Parathalassius midas sp. nov., female. 44. Parathalassius sinclairi sp. nov. 45. Parathalassius socali sp. nov., right antenna in lateral view. 46. Parathalassius susanae sp. nov. 47. Parathalassius uniformus sp. nov. Abbreviations: ar styl—arista-like stylus; ppedpostpedicel.

FIGURES 50 – 55. Male left hindlegs of Nearctic Parathalassius. 50. Parathalassius candidatus Melander, hindleg, lateral view. 51. Parathalassius sinclairi sp. nov., hindleg, lateral view. 52. Parathalassius susanae sp. nov., hindleg, lateral view. 53. Parathalassius candidatus Melander, apex of tibia and tarsus, dorsolateral view. 54. Parathalassius sinclairi sp. nov., apex of tibia and tarsus, dorsolateral view. 55. Parathalassius susanae sp. nov., apex of tibia and tarsus, dorsal view.

FIGURES 56 – 67. Wings of Nearctic Parathalassius. 56. Parathalassius abela sp. nov., male. 57. Parathalassius wheeleri sp. nov., male. 58. Parathalassius candidatus Melander, male. 59. Parathalassius infuscatus sp. nov., male. 60. Parathalassius melanderi Cole, male. 61. Parathalassius melanderi Cole, female. 62. Parathalassius midas sp. nov., male. 63. Parathalassius midas sp. nov., female. 64. Parathalassius sinclairi sp. nov., male. 65. Parathalassius socali sp. nov., male. 66. Parathalassius susanae sp. nov., male. 67. Parathalassius uniformus sp. nov., male. Abbreviations: bm-m—basal medial crossvein; cuaanterior cubital (= anal) cell; CuA—anterior branch of cubital vein; CuP—posterior branch of cubital vein; dm—discal medial cell; dm-m—discal medial crossvein; h—humeral crossvein; M 1, M 2, M 4 — medial veins; R 1, R 2 + 3, R 4 + 5 — radial veins.

FIGURES 80 – 94. Left ventral epandrial processes of Nearctic Parathalassius, lateral view (unless otherwise noted). 80. Parathalassius abela sp. nov. 81. Parathalassius candidatus Melander. 82. Parathalassius sinclairi sp. nov. 83. Parathalassius susanae sp. nov. 84. Parathalassius susanae sp. nov. 85. Parathalassius dilatus sp. nov. 86. Parathalassius melanderi Cole. 87. Parathalassius infuscatus sp. nov. 88. Parathalassius midas sp. nov. 89. Parathalassius socali sp. nov. 90. Parathalassius socali sp. nov., ventrolateral view. 91. Parathalassius uniformus sp. nov. 92. Parathalassius aldrichi Melander. 93. Parathalassius wheeleri sp. nov. 94. Parathalassius wheeleri sp. nov. Scale bars = 0.1 mm.

FIGURES 115 – 120. Male cerci of Nearctic Parathalassius, dorsal view. 115. Parathalassius abela sp. nov. 116. Parathalassius candidatus Melander. 117. Parathalassius susanae sp. nov. 118. Parathalassius sinclairi sp. nov. 119. Parathalassius infuscatus sp. nov. 120. Parathalassius midas sp. nov. Abbreviation: hyprct—hypoproct. Scale bars = 0.1 mm.

FIGURES 133 – 141. Female sternite 8 of Nearctic Parathalassius, ventral view. 133. Parathalassius abela sp. nov. 134. Parathalassius midas sp. nov. 135. Parathalassius candidatus Melander. 136. Parathalassius melanderi Cole. 137. Parathalassius sinclairi sp. nov. 138. Parathalassius uniformus sp. nov. 139. Parathalassius socali sp. nov. 140. Parathalassius aldrichi Melander. 141. Parathalassius susanae sp. nov. Scale bar = 0.1 mm.

FIGURES 1 – 4. Parathalassius habitus photographs. 1 – 3. Males of Parathalassius abela sp. nov., resting on Ambrosia chamissonis (Less.) Greene (beach bur), at Surf Beach, California. 4. Female Parathalassius abela sp. nov., resting on sand at Oso Flaco Dunes, California. Photographs by Alice Abela.

FIGURES 5 – 10. Parathalassius habitus photographs. 5. Male of Parathalassius blasigii Mik resting on sand at Parque Natural do Litoral Norte, Portugal. 6. Female of Parathalassius blasigii Mik resting on sand at Parque Natural do Litoral Norte, Portugal. 7. Male of Parathalassius infuscatus sp. nov., resting on sand at Oso Flaco Dunes, California. 8 – 9. Male of Parathalassius uniformus sp. nov., resting on Ambrosia chamissonis (Less.) Greene (beach bur) at Surf Beach, California. 10. Male and female mating pair of Parathalassius uniformus sp. nov., on sand at Surf Beach, California. Photographs by Rui Andrade (Figs 5 – 6), and Alice Abela (Figs 7 – 10).

FIGURES 11 – 16. Collection localities and habitats of Nearctic Parathalassius. 11. Island View Beach, British Columbia. 12. Sidney Spit, British Columbia. 13 – 14. Cape Disappointment, Washington. 15. Bandon, Oregon. 16. Samoa Dunes Recreation Area, California.

FIGURES 17 – 22. Collection localities and habitats of Nearctic Parathalassius. 17 – 18. Morro Bay, California. 19. Surf Beach, California. 20. Surf Beach, California, with biologist and photographer Alice Abela collecting Parathalassius from a patch of beach bur, Ambrosia chamissonis (Less.) Greene. 21. Crystal Cove State Park, California. 22. Crystal Cove State Park, California, vegetation at back of beach.

FIGURES 95 – 102. Phallus of Nearctic Parathalassius species. 95. Parathalassius abela sp. nov., entire phallus, left lateral view. 96. Parathalassius abela sp. nov., distal portion, posterior view. 97. Parathalassius sinclairi sp. nov., distal portion, left lateral view. 98. Parathalassius sinclairi sp. nov., distal portion, posterior view. 99. Parathalassius melanderi Cole, distal portion, left lateral view. 100. Parathalassius melanderi Cole, distal portion, posterior view. 101. Parathalassius dilatus sp. nov., distal portion, left lateral view. 102. Parathalassius dilatus sp. nov., distal portion, posterior view. Abbreviations: ej apod—ejaculatory apodeme; v spur—ventral spur-like projection. Scale bars = 0.1 mm.

FIGURES 127 – 132. Female terminalia of Nearctic Parathalassius. 127. Parathalassius midas sp. nov., lateral view. 128. Same, dorsal view. 129. Same, ventral view. 130. Parathalassius sinclairi sp. nov., lateral view. 131. Same, dorsal view. 132. Same, ventral view. Abbreviations: st—sternite; tg—tergite.