Parathalassius dilatus, 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 : 11-13

publication ID	https://doi.org/ 10.11646/zootaxa.4314.1.1
publication LSID	lsid:zoobank.org:pub:6758Dc40-4356-4Adc-9Bd6-456652Ea5162
DOI	https://doi.org/10.5281/zenodo.6022464
persistent identifier	https://treatment.plazi.org/id/03E9879C-8D37-FFC5-57E0-2DF5FA665F8A
treatment provided by	Plazi
scientific name	Parathalassius dilatus
status

Treatment

Key to the world species of Parathalassius View in CoL View at ENA

This key treats all 15 species of Parathalassius currently known, including the 12 species comprising the newly expanded Nearctic fauna, and the three described Palaearctic species. This key may be used to identify both sexes of each species, except P. dilatus sp. nov., for which females are unknown. Females of most species can be identified using this key, except for those of P. abela sp. nov. and P. candidatus , which are apparently indistinguishable morphologically.

1 Males, abdomen ending in moderate to large sized globular genital capsule (hypopygium) lateroflexed to right and inverted into cavity formed by pregenitalic segments ( Figs 68–71 View FIGURES 68 – 71 )......................................................2

- Females, abdomen tapered posteriorly with apical segments partially retracted into segment 5 ( Figs 127–132 View FIGURES 127 – 132 )...........16

2 Tibiae and tarsi pale yellow to yellowish-brown ( Figs 5–6 View FIGURES 5 – 10 ).....................................................3

- Tibiae dark, tarsi dark at least apically.....................................................................5

3 Head with golden-yellow setae on gena and postgena ( Figs 29–30 View FIGURES 29 – 37 ); wing with dark apical spot ( Fig. 62 View FIGURES 56 – 67 ); Nearctic................................................................................................. P. midas View in CoL sp. nov.

- Head with pale setae on gena and postgena; wing without dark apical spot, entirely hyaline; Palaearctic.................4

4 Antenna with postpedicel subtriangular, 1.45–1.5X longer than wide (cf. Figs 38–39 View FIGURES 38 – 47 ); western Palaearctic.... P. blasigii Mik View in CoL

- Antenna with postpedicel short-subtriangular, 1.1X longer than wide (cf. Fig. 45 View FIGURES 38 – 47 ); eastern Palaearctic...................................................................................................... P. maritimus Shamshev View in CoL

5 Head and thorax with dark setae; eastern Palaearctic........................................... P. ulrichi Shamshev View in CoL

- Head and thorax with pale setae; Nearctic.................................................................. 6

6 Thorax with 2 notopleural setae, smaller sized species........................................................7

- Thorax with 3 or 4 notopleural setae, medium to larger sized species............................................13

7 Wing darkened at least towards apex ( Figs 59–60 View FIGURES 56 – 67 )............................................................8

- Wing entirely hyaline ( Figs 57, 65, 67 View FIGURES 56 – 67 )....................................................................10

8 Foreleg with tarsomere 1 dilated, tarsomere 2 slightly expanded ( Figs 48–49 View FIGURES 48 – 49 )......................... P. dilatus View in CoL sp. nov.

- Foreleg with tarsomeres 1–2 narrow, not dilated.............................................................9

9 Wing broadly infuscate with base of M2 usually appearing indistinct ( Fig. 59 View FIGURES 56 – 67 )...................... P. infuscatus View in CoL sp. nov.

- Wing darkened only towards apex with base of M2 distinct ( Fig. 60 View FIGURES 56 – 67 )............................... P. melanderi Cole View in CoL

10 Eyes with ommatrichia of nearly uniform length, without dense reflective mat of long thickened hairs on lower third ( Fig. 36 View FIGURES 29 – 37 ).................................................................................... P. uniformus sp. nov.

- Eyes with ommatrichia of lower third distinctly longer and thickened, forming dense reflective mat of long whitish hairs ( Figs 25 View FIGURES 23 – 28 , 34 View FIGURES 29 – 37 )............................................................................................. 11

11 Antenna with postpedicel short-subtriangular, 1.25–1.4X longer than wide ( Fig. 45 View FIGURES 38 – 47 ); hind tarsomere 1 with long erect setae dorsally; hypopygium compact, with parts somewhat concealed.................................... P. socali View in CoL sp. nov.

- Antenna with postpedicel subtriangular, 1.5–1.6X longer than wide ( Fig. 39 View FIGURES 38 – 47 ); hind tarsomere 1 without long erect setae dor- sally; hypopygium larger, with parts more exposed (cf. Figs 70–71 View FIGURES 68 – 71 )............................................. 12

12 Hypopygium with right cercus truncate at apex, apicomedial margin short and blunt ( Fig. 121 View FIGURES 121 – 126 ); phallus with pointed dentiform process near apex ( Figs 103–104 View FIGURES 103 – 110 ); dorsal lobe of left surstylus with apex broadly rounded ( Figs 73–74 View FIGURES 72 – 75 ); central California, from Mendocino County south to San Luis Obispo County ( Fig. 143 View FIGURES 142 – 144 )............................ P. aldrichi Melander View in CoL

- Hypopygium with right cercus pointed at apex, apicomedial projection long and narrow ( Fig. 122 View FIGURES 121 – 126 ); phallus with pointed denti- form process more basal at 3/4 length ( Figs 105–106 View FIGURES 103 – 110 ); dorsal lobe of left surstylus with apex narrow and digitiform ( Fig. 72 View FIGURES 72 – 75 ); British Columbia, south through Washington and Oregon to Humboldt County in northern California ( Fig. 153 View FIGURES 152 – 153 )................................................................................................ P. wheeleri View in CoL sp. nov.

13 Head with golden-yellow pruinosity on face and clypeus, not concolourous with greyish-white frons and vertex ( Figs 1, 3 View FIGURES 1 – 4 , 23 View FIGURES 23 – 28 )........................................................................................ P. abela View in CoL sp. nov.

- Head with face and clypeus mostly concolourous with greyish-white frons and vertex ( Figs 26 View FIGURES 23 – 28 , 33, 35 View FIGURES 29 – 37 ).................14

14 Hind tibia with short anterodorsal row of erect comb-like setae ( Fig. 51 View FIGURES 50 – 55 ); hind tarsus with tarsomeres 2–4 bearing several short thick perpendicular peg-like setae dorsally ( Fig. 54 View FIGURES 50 – 55 )........................................... P. sinclairi View in CoL sp. nov.

- Hind tibia with relatively long anterodorsal setae ( Figs 50, 52 View FIGURES 50 – 55 ); hind tarsus with tarsomeres 2–4 bearing short thin or thick angled setae dorsally, setae not perpendicular and peg-like ( Fig. 53 View FIGURES 50 – 55 )............................................. 15

15 Hind tarsomere 2 distinctly longer than tarsomere 3 ( Fig. 53 View FIGURES 50 – 55 ); hind tibia with anterodorsal setae mostly longer than width of tibia, evenly curved towards apex of tibia ( Fig. 50 View FIGURES 50 – 55 ); antenna with postpedicel subtriangular ( Fig. 40 View FIGURES 38 – 47 ); wing with vein CuA+CuP ending close to wing margin, slightly curved in most specimens ( Fig. 58 View FIGURES 56 – 67 ).............. P. candidatus Melander View in CoL

- Hind tarsomeres 2 and 3 nearly subequal in length ( Fig. 55 View FIGURES 50 – 55 ); hind tibia with anterodorsal setae mostly subequal or equal to width of tibia, barely curved towards apex of tibia ( Fig. 52 View FIGURES 50 – 55 ); antenna with postpedicel elongate-conical ( Fig. 46 View FIGURES 38 – 47 ); wing with vein CuA+CuP ending far from wing margin, straight ( Fig. 66 View FIGURES 56 – 67 )................................... P. susanae View in CoL sp. nov.

16 Wing broadly infuscate with base of M2 usually appearing indistinct (cf. Fig. 59 View FIGURES 56 – 67 )................... P. infuscatus View in CoL sp. nov.

- Wing entirely hyaline, with at most slight infuscate shading along veins near apex of cell dm, base of M2 distinct ( Figs 61, 63 View FIGURES 56 – 67 )................................................................................................... 17

17 Tibiae and tarsi pale yellow to yellowish-brown ( Figs 5–6 View FIGURES 5 – 10 )....................................................18

- Tibiae dark, tarsi dark at least apically....................................................................20

18 Terminalia prominent with long pointed hemitergites (divided tergite 10) that each bear 2 acanthophorite spines ( Figs 127– 128 View FIGURES 127 – 132 ); sternite 8 with apex distinctly bifurcate ( Figs 129 View FIGURES 127 – 132 , 134 View FIGURES 133 – 141 ); Nearctic.............................. P. midas View in CoL sp. nov.

- Terminalia small with short broad hemitergites (divided tergite 10) that each bear 2 acanthophorite spines (cf. Figs 130–131 View FIGURES 127 – 132 ); sternite 8 with apex truncate or weakly emarginate (cf. Figs 133, 139 View FIGURES 133 – 141 ); Palaearctic.................................19

19 Antenna with postpedicel subtriangular, 1.45–1.5X longer than wide (cf. Figs 38–39 View FIGURES 38 – 47 ); western Palaearctic.... P. blasigii Mik View in CoL

20 Head and thorax with dark setae; eastern Palaearctic........................................... P. ulrichi Shamshev View in CoL

- Head and thorax with pale setae ( Figs 24 View FIGURES 23 – 28 , 37 View FIGURES 29 – 37 ); Nearctic......................................................21

21 Thorax with 2 notopleural setae, smaller sized species.......................................................22

- Thorax with 3 or 4 notopleural setae, medium to larger sized species............................................26

22 Wing with slight infuscate shading along veins near apex of cell dm (most specimens) ( Fig. 61 View FIGURES 56 – 67 ); hind tarsomere 2 usually pale on basal half; sternite 8 without longitudinal ridges on apical third or half ( Fig. 136 View FIGURES 133 – 141 )................... P. melanderi Cole View in CoL

- Wing entirely hyaline, without infuscate shading along veins (cf. Figs 57, 65, 67 View FIGURES 56 – 67 ); hind tarsomere 2 usually entirely darkened (rarely pale basally); sternite 8 with or without longitudinal ridges on apical third or half............................23

23 Sternite 8 with longitudinal ridges absent or barely apparent ( Fig. 139 View FIGURES 133 – 141 ), at most slightly developed laterally along apical margin and not present medially................................................................... P. socali View in CoL sp. nov.

- Sternite 8 with longitudinal ridges on apical third or half, extended across sternite including medial margin ( Figs 138, 140 View FIGURES 133 – 141 )...................................................................................................... 24

24 Sternite 8 with longitudinal ridges on apical third, with weak basal bulge, apex emarginate ( Fig. 138 View FIGURES 133 – 141 )... P. uniformus sp. nov.

- Sternite 8 with longitudinal ridges on apical half, with distinct basal bulge, apex truncate ( Fig. 140 View FIGURES 133 – 141 )...................25

25 Central California, from Mendocino County south to San Luis Obispo County ( Fig. 143 View FIGURES 142 – 144 )............. P. aldrichi Melander View in CoL

- British Columbia, south through Washington and Oregon to Humboldt County in northern California ( Fig. 153 View FIGURES 152 – 153 )................................................................................................ P. wheeleri View in CoL sp. nov.

26 Sternite 8 with apical quarter rugose ( Fig. 137 View FIGURES 133 – 141 )............................................... P. sinclairi View in CoL sp. nov.

- Sternite 8 without apical rugosity, apical half with longitudinal ridges ( Figs 133, 135, 141 View FIGURES 133 – 141 )..........................27

27 Hind tarsomeres 2 and 3 nearly subequal in length (cf. Fig. 55 View FIGURES 50 – 55 ); wing with vein CuA+CuP ending far from wing margin, straight (cf. Fig. 66 View FIGURES 56 – 67 ); sternite 8 not distinctly narrowed apically ( Fig. 141 View FIGURES 133 – 141 )........................... P. susanae View in CoL sp. nov.

- Hind tarsomere 2 distinctly longer than tarsomere 3 (cf. Fig. 53 View FIGURES 50 – 55 ); wing with vein CuA+CuP ending close to wing margin, slightly curved or straight (cf. Figs 56, 58 View FIGURES 56 – 67 ); sternite 8 widened near base, distinctly narrowed apically ( Figs 133, 135 View FIGURES 133 – 141 )......................................................................... P. abela View in CoL sp. nov. or P. candidatus Melander View in CoL