Risa (Achaetorisa) nettae, Mathis & Zatwarnicki SMNH, 2023

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 : 17-19

Risa (Achaetorisa) nettae sp. nov.

urn:lsid:zoobank.org:act:BB0DE9C8-C1AB-46F7-B475-A56099141F19

Figs 46–56

Diagnosis. This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.14–1.50 mm.

Head: Structure: Face low, with rather prominent carina ( Fig. 46 ); antennal ratio 0.4–11/31, 15/34, 13/31, 13/34; basal flagellomere ratio 1.33–2.00; aristal branches very short; labellar ratio 2.0–2.5. Coloration: Antenna predominantly or entirely yellow, scape and pedicel and basal flagellomere anteroapically occasionally darker, arista yellow to brown ( Figs 49, 50 ); palpus black to brownish; head otherwise black, without microtomentum. Chaetotaxy: Medial-to-lateral vertical setal ratio 1.3–2.0; fronto-orbital setae 3 (rarely 2 or 4), proclinate, small, hair-like, equal or subequal in size.

Thorax: Scutum without distinct microtomentum, appearing fatty, contrasted with strongly microtomentose scutellum. Prescutellar acrostichal setae lacking; 1 anepisternal seta present, inserted slightly ventral to midheight of posterior suture; scutellar disc lacking setulae. Wing: Costal setulae moderately numerous and dense. Wing length: 0.90–1.12 mm. Halter knob with large dark spot or at least not strongly contrasted with black coloration of body. Femora and tibiae almost entirely black or blackish; tibiae distally and sometimes narrowly basally yellowish.

Abdomen: Entirely black or blackish. Male: Male terminalia ( Figs 51–56 ): Epandrium in posterior view ( Figs 51, 55 ) as an inverted U, dorsal arch thin, lateral arms becoming gradually wider ventrally, in lateral view ( Fig. 52 ) with posterior margin nearly straight, anterior scalloped with a pointed projection between scallops at midheight; cercus in posterior view ( Figs 51, 55 ) narrowly rectangular with corners rounded except for right angle mediodorsal corner, uniformly setulose, in lateral view ( Fig. 52 ) elongate, very slender, wider dorsally; gonostylus in posterior view ( Figs 51, 55 ) irregularly rectangle, somewhat fused basally with ventral epandrial margin, thereafter ventrally extended more or less straight to broadly ventral apex, apex shallowly concave, bearing numerous setulae toward apex, in lateral view ( Fig. 52 ) triangular, broad basally, tapered to rounded point; aedeagus in ventral view ( Fig. 53 ) elliptical, elongate, with fused phallapodeme as a fish tail, in lateral view ( Fig. 54 ) elongate, narrow, curved, with phallapodeme as a basal, thumb-like extension; pregonite in lateral and ventral views ( Figs 51, 52, 56 ) fused to apical arch of subepandrial plate, as triangular projections ( Figs 52, 56 ); subepandrial plate in lateral view ( Fig. 52 ) longer than wide, basal and apical margins rounded, apical one more so; postgonite in ventral view ( Fig. 53 ) somewhat triangular with base broadly rounded, apex pointed and bearing setulae, in lateral view ( Fig. 54 ) ovate, longer than wide, base rounded, apex pointed and setulose; hypandrium in ventral view ( Fig. 53 ) a symmetrical plate, about as wide as long, basal margin evenly and shallowly concave, posterior margin slightly narrowed and broadly rounded, in lateral view ( Fig. 54 ) elongate, length 4 times width, shallowly angulate, pointed at anterior and posterior margins. Female: subanal plate lacking; ventral receptacle with paired tubular appendages ( Figs 47, 48 ).

Type material. The holotype ♂ of Risa (Achaetorisa) nettae is labelled “ ISRAEL [.] Ẕomet Zohar [,] [31°08.5'N 35°21.6'E,] 21. vii. 1998 [21 Jul 1998,] A. FREIDBERG/ HOLOTYPE ♂ Risa (Achaetorisa) nettae Mathis & Zatwarnicki SMNH [red.].” Thirty-nine paratypes bear the same locality, collection date, and collector as the holotype and was taken on the plant Seidlitzia rosmarinus (29♂, 10♀; SMNH, USNM) .

Other specimens are as follows (listed alphabetically; some specimens in poor condition or in alcohol): Israel. Deir Hijleh (near Jericho; 31°49.2'N 35°30.1'E), 19 May 1998, A. Freidberg (16♂, 28♀; SMNH, USNM) . Ne’ot haKikkar (30°56'N 35°22.7'E), 4 Apr–1 May 1997, 1998, A. Freidberg (17♂ ♀; SMNH) . Ẕomet Zohar (31°08.5'N 35°21.6'E), 4 Apr–14 Oct 1997, 1998, A. Freidberg, I. Yarom (90♂ ♀; SMNH, USNM) .

Type locality. Israel. Ẕomet Zohar (31°08.5'N 35°21.6'E) .

Distribution. Palearctic: Israel (Dead Sea Area).

Natural history. This species is associated with Seidlitzia rosmarinus Bunge ex Boiss (Amaranthaceae) .

Etymology. The specific epithet, nettae , is a genitive patronym to honor our friend and colleague, Dr Netta Dorchin, for discovering and rearing numerous specimens of Risa from plants of the familyAmaranthaceae. This discovery greatly facilitated collecting greater numbers of specimens.

Figures

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 51–56. Male terminalia of Risa nettae sp. nov. (51) Epandrium, cerci, gonostylus, subepandrial plate with pregonites, ventral view. (52) Same, lateral view. (53) Internal structures (postgonite, hypandrium and aedeagus fused with phallapodeme), ventral view. (54) Same, lateral view. (55) Anterior section of epandrium and cerci, gonostylus (without supepandrial plate and pregonites), ventral view. (56) Subepandrial plate and pregonites, lateral view. Scale bar = 0.1 mm.