PROC. ENTOMOL. SOC. WASH. 97(3), 1995, pp. 666-688 A REVISION OF THE SHORE-FLY GENUS RHYSOPHORA CRESSON (DIPTERA: EPHYDRIDAE) Navin Rao and Wayne N. Mathis Department of Entomology, Smithsonian Institution, Washington, D.C. 20560. Abstract.— T\it New World genus Rhysophora Cresson, now placed in the tribe Dis-comyzini (subfamily Discomyzinae), is revised. Four species, including R. griseola (type locality: Costa Rica. Guanacaste: Colorado), which is newly described, are included. The phylogenetic relationships of the species of Rhysophora are reanalyzed, and brief com-ments are provided on the relationships of the genus within the tribe. A key to the genera of the tribe is included. Key Words: Diptera, Ephydridae, shore flies, Rhysophora, phylogeny The subfamily Discomyzinae, presently comprising two tribes, 22 genera, and nearly 200 species (Zatwamicki 1992, Mathis and Zatwamicki, in preparation), is one of the smaller subfamilies of shore flies. One of the tribes, Discomyzini, with half of the gen-era (11) but only one-fourth of the species (ca. 50), includes the genus Rhysophora Cresson, the subject of this revision. Cresson (1924) described Rhysophora as a monotypic genus with R. robusta Cresson as its type species. Cresson (1946) later transferred two previously described spe-cies, Psilopa umbrosa Loew and P. caeru-leiventris Loew, to Rhysophora. Mathis and Wirth (1977), however, placed the latter two species in Nesopsilopa Mathis and Wirth, which is now recognized as a subgenus of Guttipsilopa Wirth (Mathis and Zatwar-nicki 1990). Since the original description o{ Rhysophora, most references to the genus have been part of generalized studies, such as keys to genera (Cresson 1942, Sturtevant and Wheeler 1954, Wirth and Stone 1956) or regional catalogs (Wirth 1965, 1968). An exception is Mathis' (1977) revision of the genus, which included two new species, R. ardeoceras and R. liropus, and provided the first phylogeny for the species. Mathis' phy-logenetic analysis resulted in two basal lin-eages that were recognized as species groups: the ardeoceras group {R. ardeoceras) and the robusta group {R. robusta and R. liropus) as sister groups. A sister group to Rhysophora was not identified. The phylogenetic relationships Rhyso-phora has with related genera within Dis-comyzini remain largely unresolved, al-though Zatwamicki (in litt.) is now inves-tigating them. Previously, Zatwamicki (1992) accorded subfamilial status to Dis-comyzinae and reconstituted the two in-cluded tribes with Rhysophora and 1 other genera being moved from Psilopini to Dis-comyzini. Information on the natural history and distribution o{ Rhysophora is meager. Adults are collected infrequently, resulting in a paucity of specimens and locality records. Some species are associated with plants of the family Pontederiaceae, perhaps as her-bivores. Virtually nothing is known about the larval stages, behavior, or life history of Rhysophora. The species o^ Rhysophora are known thus far only from the New World. The purpose of this study is to revise the
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