Achaetorisa Papp, 1980

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 : 13

Subgenus Achaetorisa Papp

Achaetorisa Papp, 1980: 420 , 421 [as a genus]. Type species: Achaetorisa brevicornis Papp, 1980: 421 [monotypy]; 1984: 178 [Palearctic catalog].

Diagnosis. The subgenus Achaetorisa is distinguished from the nominate subgenus Risa by the following combination of characters: Head: Face with a medial carina, in lateral view carina rounded.

Thorax: Prescutellar acrostichal setae absent, only setulae present; scutellar disc lacking setulae. Costal section III (between R 2+3 and R 4+5) bearing approximately 10–35 setulae along anterior margin.

Abdomen: Male terminalia: Cercus elongate, separate from epandrium; gonostylus evident as distinct lobe at ventral margin of epandrial arm ( Figs 42 , 55 ); hypandrium in ventral view plate like, longer than wide, shallowly pocket-like. Female terminalia: subanal plate absent ( Fig. 34 ); sternite 8 entire but lacking a sclerotized, protrusion, posterior portion lacking hooked setulae, but bearing 12–22 short, straight setae along anterior margin; cerci short and rounded; stalk of ventral receptacle with paired, tubular processes ( Figs 47, 48 ). Discussion. Achaetorisa is given status here as a wellcorroborated, monophyletic subgenus. As a terminal clade, however, its recognition as a subgenus leaves the nominate subgenus as a paraphyletic group that includes, among other lineages, Achaetorisa .

Papp (1980) described Achaetorisa and distinguished it from Risa using several characters. The discovery of additional species of Risa , and thus an enhanced opportunity to study critically characters for this group, revealed that Achaetorisa brevicornis is congeneric with other species of Risa and that Achaetorisa should therefore be consigned to subgeneric status within Risa . Papp (1980), however, did not emphasize the distinctive and paired ventral appendages of the female ventral receptacle in R. brevicornis . These appendages appear to be unique to the Achaetorisa group.

We recognize the following five species in the subgenus Achaetorisa : Risa (Achaetorisa) brevicornis (Papp) comb. nov., R. (A.) brevirostris sp. nov., R. (A.) flavicoxa Krivosheina & Ozerov , R. (A.) nettae sp. nov., and R. (A.) salsolae (Mathis & Zatwarnicki) comb. nov.

Figures

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.

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.

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 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).