Risa Becker, 1907

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2023, Phylogeny and Taxonomy of the Risa Genus-group (Diptera: Ephydridae), with Description of a New Genus from Australia, Records of the Australian Museum (Rec. Aust. Mus.) 75 (1), pp. 1-23 : 12-13

Key to species of Risa Becker

1 Palpus yellow ............................................................................................................................ 2

—— Palpus black ............................................................................................................................... 3

2 Forecoxa black. Ocellar triangle short, slightly protruding beyond middle of frons. Postocellar setae present .................................... R. flavipalpis Ozerov

—— Forecoxa yellow. Ocellar triangle long, reaching lunule. Postocellar setae absent .............................................................. R. flavicoxa Krivosheina & Ozerov

3 Fronto-orbital setae 3 (rarely 2 or 4), proclinate, small, hair-like, equal or subequal in size ( Figs 22 , 38, 39 , 49, 50 , 57–60 ) ........................................................ 4

—— Anterior fronto-orbital seta about 2–3 times longer than middle fronto-orbital seta, inclinate; posterior fronto-orbital seta usually reclinate, occasionally proclinate, usually as long as anterior fronto-orbital setae, occasionally as long as middle fronto-orbital seta ( Figs 21 , 26, 27 ) ........................................................................................... 9

4 Labellum about twice length of ventral margin of head in lateral view ( Figs 24 , 46 ) ...................................................................................................................... 5

—— Labellum about 1–1.5 times length of ventral margin of head ( Figs 23, 25 , 40, 41 , 58 ) ............................................................................................................ 8 5 Prescutellar acrostichal setae well developed; scutellar disk bearing scattered, sparse setulae; setulae along costal margin numerous; large species (length about 2 mm) ............................................... R. asiatica Ozerov

—— Prescutellar acrostichal setae greatly reduced or lacking ( Fig. 37 , 59–60 ); scutellum lacking setulae; setulae along costal margin sparse; smaller species (length about 1–1.5 mm) ...................................................................... 6

6 Scutum distinctly microtomentose; setulae along costal margin more numerous and denser (24–34 on distalmost section). Halter knob with large dark spot .......................................................... R. brevicornis Papp comb. nov.

—— Scutum indistinctly microtomentose; setulae along costal margin fewer and sparser (11–16 on distalmost section). Halter knob entirely yellow or with large dark spot ............................................................................. 7

7 Antenna and arista predominantly brownish ( Fig. 37 ). Halter knob yellow ...................................................... R. salsolae (Mathis & Zatwarnicki) comb. nov.

—— Antenna predominantly or entirely yellow, scape and pedicel and basal flagellomere anteroapically occasionally darker, arista yellow to brown ( Figs 49, 50 ). Halter knob with large dark spot ........................................................................................................... R. nettae sp. nov.

8 Face nearly flat, without prominent shallow/low carina ( Fig. 58 ); antenna elongate, basal flagellomere ratio 1.75; scutum distinctly microtomentose ( Figs 59, 60 ); lower portion of frons, parafacial and lateral margin of face conspicuously and finely whitish to silvery microtomentose ( Figs 57, 60 ) ............................................................ R. kotrbae sp. nov.

—— Face with distinct carina ( Figs 38, 39 ); antenna short, basal flagellomere ratio 1; scutum practically without microtomentum; lower position of frons, parafacial and lateral margins of face almost bare of microtomentum, shiny ( Figs 38, 39 ) ............................................................................................ R. brevirostris sp. nov.

9 Proboscis short, labellum about 1.25 times length of ventral margin of head ( Fig. 25 ); antenna elongate, basal flagellomere ratio 2.5–3 ( Fig. 25 ) ................................................................................... R. longicornuta Papp

—— Proboscis long, labellum about 1.5 times length of ventral margin of head ( Figs 23 , 40, 41 ); antenna shorter, basal flagellomere ratio 2 ( Figs 23 , 26, 27 ) ............................................................................ R. longirostris Becker

Figures

Figures 20–25. Line drawing of frons and associated setae, dorsal view. (20) Notorisa mcalpinei sp. nov. (21) Risa longirostris Becker. (22) R. asiatica Ozerov. (23–25) Line drawing of head, lateral view. (23) R. longirostris Becker. (24) R. brevicornis Papp. (25) R. longicornuta Papp.

Figures 38–41. Photographs of Risa brevirostris sp. nov. (38–39) and R. longirostris Becker (40–41). (38) Head, anterior view. (39) Same, dorso-oblique view. (40) Habitus, lateral view. (41) Head, antero-oblique view. Scale bars = 0.1 mm (38–39), = 0.2 mm (40–41).

Figures 46–50. Line drawing and photographs of Risa nettae sp. nov. (46) Head, lateral view. (47) Ventral receptacle, lateral view (microscopic photograph). (48) Ventral receptacle, posterior view (microscopic photograph). (49) Head, anterior view.(50) Same, laterooblique view. Scale bars = 0.05 mm (47–48), = 0.2 mm (49–50).

Figures 57–60. Photographs of Risa kotrbae sp. nov. (57) Head, anterior view. (58) Head and thorax, lateral view. (59) Same, dorsal view. (60) Same, dorsolatero-oblique view. Scale bars = 0.2 mm (57), = 0.5 mm (58–60).

Figures 26–33. Photographs of Risa longirostris Becker (26–27, 29–31, 33) and Risa brevirostris sp. nov. (28, 32). (26) Head, anterooblique view. (27) Same, anterior view. (28) Proboscis, lateral view. (29) Rostrum, anterior view (microscopic photograph). (30) Same, lateral view. (31) Labellum, posterior view. (32) Labellum, anterior view. (33) Terminal female abdominal segments, anterior view. Scale bars = 0.2 mm (26–27), = 0.1 mm (28–30, 33), = 0.05 mm (31–32).

Figures 34–37. Line drawing and photographs of Risa. (34) Terminal female abdominal segments of R. brevirostris sp. nov., anterior view. (35) Habitus of R. brevicornis (Papp), antero-oblique view. (36) Head of R. brevirostris sp. nov., lateral view. (37) Habitus of R. salsolae (Mathis & Zatwarnicki), antero-oblique view. Scale bars = 0.1 mm (34), = 0.2 mm (35, 37).