Dasyrhicnoessa Hendel

Mathis, Wayne N. & Marinoni, Luciane, 2012, A conspectus on the Canacidae (Diptera) of Brazil, ZooKeys 162, pp. 59-92 : 76-77

Genus Dasyrhicnoessa Hendel (25 species worldwide; 1 from Brazil)

Dasyrhicnoessa Hendel 1934:38. Type species: Rhicnoessa fulva Hendel, original designation. Malloch 1935:93 [discussion]. Mathis and Munari 1996:11-13 [world catalog]. Munari and Mathis 2010: 43-46 [world catalog].

Diagnosis.

Dasyrhicnoessa is distinguished from other genera of the family by the following combination of characters: Head: Frons bearing some setulae in addition to larger setae; fronto-orbital and orbital setae usually with similar orientation, mostly reclinate or lateroclinate; fronto-orbital setae 3-4; paravertical setae more or less convergent. Head: Face lacking shiny tubercle above vibrissal pore; vibrissal seta present on apex of vibrissal angle. Eye mostly densely covered with small, pale, interfacetal setulae. Gena bare except for a ventral or nearly ventral row of setae (peristomal setae); gena narrow, about 1/8-1/3 eye height. Palpus and proboscis usually normally developed; clypeus small, if exposed not protruding anteriad beyond oral margin. Thorax: Scutum with numerous rows of coarse setulae arising from punctures; scutellar disc bare; postpronotum with 3 main setae, ventral seta curved upward; acrostichal setulae in two or more complete or nearly complete rows; prescutellar acrostichal setae present; scutellar disc bare except for marginal setae. Wing with costa not spinose; vein A1+CuA2 short, much shorter than discal cell; wing usually short, about twice as long as wide (less often 2.5-3.0 times); cell bm and discal cell distinct. Forefemur generally bearing an anteroventral ctenidial comb on distal third; mid and hind tibiae evenly setulose, lacking anterodorsal or posterodorsal setae. Abdomen: Tergites wider than long; tergite 6 well differentiated from short syntergosternite 7+8, the latter forming a dorsal pregenital sclerite. Male terminalia: Epandrium with a posterior (true) surstylus, articulating with sternite 10. In some species, articulating broadly with ventral margin of epandrium, in others, reduced and positioned more dorsad, along posterior margin of epandrium. Anterior process a surstylarlike lobe, not articulating with sternite 10 but only with anterior margin of epandrium. This lobe much reduced in some species (absent in Dasyrhicnoessa platypes Sasakawa) and positioned more or less medially along anterior margin of epandrium. Aedeagus long, sinuous, ribbonlike.

Discussion.

In the New World, a single species, Dasyrhicnoessa insularis (Aldrich), is known, and was probably introduced through human commerce. Woodley and Hilburn (1994) and Mathis and Munari (1996) first recorded this genus from the New World (as Dasyrhicnoessa ferruginea (Lamb)), and here we provide detailed locality data and descriptive documentation for the genus and the only known species that occurs there. We first discovered the genus and species on barrier islands off the coast of Belize and at the western margin of the Caribbean. Since then, we have found it in the United States (Florida), Mexico (Tabasco), on the Lesser Antilles (Dominica, St. Lucia, St. Vincent), and Bermuda in the western North Atlantic. The genus was probably introduced through human commerce and is now widespread throughout the Caribbean Region and perhaps beyond. Elsewhere, the genus occurs primarily within the Pacific and Indian Ocean basins where 25 species have been described thus far ( Munari and Mathis 2010).

Dasyrhicnoessa is distinctive and is easily distinguished, especially from other genera of the subfamily Tethininae , by the densely setulose eyes, prominent oral vibrissal seta, vibrissal angle lacking a shiny tubercle, an anterior surstylarlike lobe, and a posterior (true) surstylus in males.