Akorhexoza Cook

Amorim, Dalton De Souza, 2007, Two new genera of Swammerdamellini (Diptera, Scatopsidae), with a discussion of the position of the species of Rhexoza, Zootaxa 1640, pp. 41-53 : 44

Akorhexoza Cook

( Figs. 6–7 )

Akorhexoza Cook, 1978:31 .

Type –species. Scatopse dampfi Duda (orig. des.).

Diagnosis. Shiny thoracic and abdominal sclerites. A single whorl of setae on flagellomeres, maxillary palpus large, cardo–stipes mesally fused. Distal end of postmentum projected between the labella. Pronotal apodeme curved, katepisternum setose along anterior margin. No incomplete false r–m vein on M1. No pretergites 3, sternites 2–4 unsclerotized. Male sternite 7 trapezoid, with a posterior mesal incision and a pair of lateral projections. Male terminalia well developed; aedeagus base enlarged, with a pair of distinctive lateral projections on which the parameres articulate, aedeagal usually sword–like; gonostylus lost; tergite 9 well sclerotized and developed, with a posterior mesal incision ( Figs. 6–7 ).

Discussion. Akorhexoza was described by Cook (1978) to include S. dampfi Duda , placed by him ( Cook, 1956a) in the group dampfi , and a species described from Mexico, A. cactivora Cook, 1978 . The genus has some very obvious synapomorphies –shiny thoracic and abdominal sclerites, a large and well sclerotized male terminalia, well developed lateral projections of the aedeagus, on which the parameres articulate etc.–, showing that those species clearly compose a small monophyletic group within the tribe. The genus presents a combination of features that indicates its species do not fit into any of the remaining genera. They have, e.g., the fused cardostipes, well developed spiracular sclerite, aedeagal distal projection, and tergite 9 projected posteriorly and laterally. None of the present species of Rhexoza fit in Akorhexoza , and there are some few new Neotropical species to be described in the genus.

Species included. Nearctic: A. dampfi (Duda, 1928) . Neotropical: A. cactivora Cook, 1978 ; Akorhexoza sp. 1 ( Mexico), Akorhexoza sp. 2 ( Mexico), Akorhexoza sp. 3 ( Panama).

Figures

FIGURES 1 – 7. Male terminalia of Swammerdamellini genera. 1 – 3. Pararhexosa chelata (Cook), 1971. Male paratype (1, ventral; 2, lateral, 3, dorsal). 4 – 5. Rhexoza subnitens (Verrall). 6 – 7. Akorhexoza sp. 1 (4, ventral, 5, dorsal).