Risa (Achaetorisa) brevirostris, 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 : 14-17

Risa (Achaetorisa) brevirostris sp. nov.

urn:lsid:zoobank.org:act:53C1FDA1-4A7B-4890-95B0-0ABB8EDF0FA3

Figs 28, 32 , 34 , 38, 39 , 42–45

Diagnosis. This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.48–1.70 mm.

Head: Structure: Face moderately low, with prominent carina ( Figs 38, 39 ); antennal ratio ⅓–⅖; basal flagellomere ratio 1.5; aristal hairs very short; labellar ratio about 1 ( Fig. 28 ). Coloration: Antenna as for genus; palpus black; head otherwise black, without distinct microtomentum. Chaetotaxy: Medial-to-lateral vertical setal ratio 2; fronto-orbital setae 3 (rarely 2 or 4), proclinate, small, hair-like, equal or subequal in size ( Figs 38, 39 ).

Thorax: Scutum sparsely microtomentose. Prescutellar acrostichal setae lacking; 1 anepisternal seta present; scutellar disc lacking setulae. Wing: costal setulae few and sparse. Wing length: 1.08–1.32 mm. Halter knob yellow. Legs as in generic description.

Abdomen: Often extensively basally yellow, otherwise dark. Male: Male terminalia ( Figs 42–45 ): Epandrium in posterior view ( Fig. 42 ) as an inverted U, dorsal arch and lateral arms thin, latter becoming slightly wider ventrally, in lateral view ( Fig. 43 ) with posterior margin nearly straight, anterior scalloped with a pointed projection at midlength between scallops; cercus in posterior view ( Fig. 42 ) narrowly rectangular, thumb-like, dorsal margin rounded, uniformly setulose, in lateral view ( Fig. 43 ) elongate, narrow, tapered to point dorsally; gonostylus in posterior view ( Fig. 42 ) triangular, somewhat fused basally with ventral epandrial margin, thereafter ventrally tapered to narrowly rounded point, oriented ventrally, bearing 2–3 setulae toward apex along medial margin, in lateral view ( Fig. 43 ) narrowly triangular, ventral apex narrowly rounded; subepandrial plate in lateral view ( Fig. 43 ) an irregularly elliptical plate, anterior and posterior margin tapered to broadly rounded apices; in ventral view ( Fig. 42 ) somewhat rectangular plates, bearing cluster of setulae at medioposterior corner; aedeagus in ventral view ( Fig. 44 ) elliptical, elongate, in lateral view ( Fig. 45 ) very slender, curved, slightly expanded apically; phallapodeme partially fused to base of aedeagus, in ventral view ( Fig. 44 ) T-shaped with robust crossbar, in lateral view ( Fig. 45 ) perpendicular to aedeagus with short, narrow keel; pregonite moderately long, gently curved in lateral view; postgonite in ventral view ( Fig. 44 ) somewhat trapezoidal with even base, anteroventral margin rounded and bearing 3 setulae, in lateral view ( Fig. 45 ) ovate; hypandrium in ventral view ( Fig. 44 ) a wide plate, especially basally, lateral margins evenly curved and tapered to broad, medial margin, in lateral view ( Fig. 45 ) elongate, curved, pointed at anterior and posterior apices. Female: tergites 6–7 bearing a few small setulae, lacking row of long, fringe-like setulae along posterior margin ( Fig. 34 ); tergite 8 interrupted dorsomedially; sternite 8 more or less pentagonal (length/ width ca 0.7) with pointed apex directed anteriorly, evenly sclerotized, lacking protrusion; posterior margin with shallow notch medially; anterior third bearing about 22 very short, stout, black setae, these not arranged in distinct rows; posterior third bearing sparse setulae submarginally ( Fig. 34 ); subanal plate lacking; ventral receptacle with paired tubular appendages; cerci short, rounded.

Type material. The holotype ♂ of Risa (Achaetorisa) brevirostris is labelled “ ISRAEL [.] Ẕomet Zohar [31°08.5'N 35°21.6'E,] 9. vi. 1997 [9 Jun 1997,] A. FREIDBERG [white]/ HOLOTYPE ♂ Risa (Achaetorisa) brevirostris Mathis & Zatwarnicki SMNH [red].” Twenty-four paratypes are as follows: ISRAEL. Ẕomet Zohar (31°08.5'N 35°21.6'E; on Seidlitzia rosmarinus ), 9 Jun 1997, A. Freidberg (2♂, 1♀; SMNH) ; 9 Sep 1997, A. Freidberg (on Seidlitzia rosmarinus ) (14♂, 7♀; additional specimens in alcohol; SMNH) . Deir Hijleh (near Jericho; 31°49.2'N 35°30.1'E; ex Seidlitzia rosmarinus ), 25 Sep 1997, A. Freidberg (5♂, 18♀; SMNH) .

Other specimens examined. EGYPT. Sinai: Ras Umm Burká (on Seidlitzia rosmarinus ), 1–9 May 1996, A. Freidberg (5♂ ♀, SMNH) .

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

Distribution. Palearctic: Israel (Dead Sea Area), Egypt (eastern Sinai).

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

Etymology. The specific epithet, brevirostris , is named for this species’ comparatively short mouthparts.

Figures

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).

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 42–45. Male terminalia of Risa brevirostris sp. nov. (42) Epandrium, cerci, gonostylus, subepandrial plate with pregonites, ventral view. (43) Same, lateral view. (44) Internal structures (postgonite, hypandrium and aedeagus fused with phallapodeme), ventral view. (45) Same, lateral view. Scale bar = 0.1 mm.