PROC. ENTOMOL. SOC. WASH. 103(3), 2001, pp. 655-665 SUBMERGED STILOBEZZIA RABELLOI LANE (DIPTERA: CERATOPOGONIDAE) PUPAE OBTAIN OXYGEN FROM THE AQUATIC FERN SALVINIA MINIMA BAKER Art Borkent and Douglas A. Craig (AB) Research Associate, Royal British Columbia Museum and the American Museum of Natural History, 1171 Mallory Road, Enderby, British Columbia, VOE 1V3, Canada (email:
[email protected]); (DAC) Dept. of Biological Sciences, CW-405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9 (email:
[email protected]). Abstract. — Pupae of the predaceous midge Stilobezzia rabelloi Lane have sharply point-ed, anteriorly directed respiratory organs which they insert into the underside of floating leaves or into the dangling submerged leaves of Salvinia minima Baker. They also have extremely elongate body setae and apicolateral processes which help them to insert their respiratory organs and to remain immobile amongst the highly branched submerged leaves once they have pierced the plant tissue. These features are shared by the African Stilob-ezzia poikiloptera (Ingram and Macfie) and are synapomorphic character states. Sharply pointed respiratory organs and elongate apicolateral processes are known in more distantly related Ceratopogonidae and these represent instances of homoplasy. Resumen. — Las pupas de Stilobezzia rabelloi Lane presentan organos respiratorios pun-tiagudos dirigidos hacia adelante, los que insertan en la faz inferior de las hojas flotantes o dentro de la hojas sumergidas de Salvinia minima Baker. Tambien presentan setas cor-porales extremadamente elongadas y procesos apicolaterales, los que ayudan a insertar los organos respiratorios, asi como a permanecer inmoviles entre las hojas sumergidas una vez que han perforado el tejido vegetal. Estas caracteristicas son compartidas por la especie africana Stilobezzia poikiloptera (Ingram & Macfie), y son estados sinapomorficos del caraacter. Tanto organos respiratorios puntiagudos como procesos apicolaterales elon-gados son conocidos para Ceratopogonidae mas lejanamente emparentados, y estos re-presentan instancias de homoplasia. Key Words: biting midges, immatures, behavior, phylogeny, morphology, Costa Rica, Neotropical, Dasyhelea While collecting Ceratopogonidae in mained submerged for most of their devel-Costa Rica in 1993, the senior author was opment, as do those of a few species of puzzled to discover adults of a species of Dasyhelea Kieffer and Culicoides Latreille Stilobezzia Kieffer emerging from samples (Dyce and Murray 1966, Lee and Chan of a floating fern (Salvinia minima Baker) 1985), samples of Salvinia minima were even though these had been previously more carefully examined and it was discov-checked for free floating pupae on a re-ered that the pupae had their respiratory or-peated basis. Thinking that the pupae re-gans firmly embedded in the underside of
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