Arch. Protistenkd. 141 (1992): 119-133 Gustav Fischer Verlag lena Department of Zoology, University of Lund, Sweden; Department of Zoology, Universtiy of Cordoba, Spain On Two Hyalospora Species from Spanish Microcoryphia: Hyalospora volsella TUZET & ORMIERES, 1956 and Hyalospora gigantea sp. nov. (Eugregarinida, Hirmocystidae) By J. I. RONNY LARSSON, CARMEN BACH DE ROCA & MIGUEL GAJU-RICART With 21 Figures Key words: Hyalospora gigantea sp. nov.; Hyalospora volsella; Gregarines; Cytology; Microcoryphia, Spain Summary Gregarines of the genus Hyalospora (Eugregarinida, Hirmocystidae) are for the first time reported from Spain (Cordoba and Homachuelos). The host records, from bristletails of the families Machilidae and Meinertellidae (Microcoryphia), are new to science. Hyalospora volsella TUZET & ORMIERES, 1956 was isolated from Machilinus rupestris gallicus and Promesomachilis hispanica. The new species Hyalospora gigantea sp. nov. was found in Promesomachilis hispanica. It has a persistent, spherical epimerite, lacking holdfast structures. The protomerite is almost spherical. The shape of the deutomerite is variable (tapering posteriorly or with widest posterior end). In associated gamonts the protomerite of the satellite is retracted into the deutomerite of the satellite. Associations measure about 1000 !lm. The ultrastructural cytology, which is briefly described, conforms to the normal for eugregarines. The characteristic epicyte exhibits three types of folds, which are densely coated with fibrous projections, at least on the vertical surfaces. The new species, which is considered identical to the great morph of Hyalospora roscoviana, reported by TUZET & ORMIERES (1954), is described, and the discrimination from other Hyalospora species of bristletails is discussed. Introduction Gregarines are intimately associated with insects, but they are not equally abundant in all insect orders. Few species of Heteroptera, Hymenoptera and Lepidoptera have gregarines, while in members of Odonata, Trichoptera and Coleoptera gregarines are ubiquitous. Gregarines are also commonly found in bristletails, both of the orders Microcoryphia and Zygentoma, although only about 20 named species, belonging in 7 genera, have been reported from these hosts. The genus Lepismatophila, with about 11 species, is most commonly found. It seem to be restricted to Zygentoma and Diplura, while the genus Hyalospora, with three species from bristletails, contains species from host of the orders Neuroptera and Psocoptera as well. The Hyalospora species have never received much attention, and little is known about the cytology, host spectrum and geographic distribution. The three species from bristletails, H. ajfinis, H. roscoviana and H. volsella, were described very briefly, based on material collected in France (SCHNEIDER 1875, 1882; TUZET & ORMIERES 1956). Only H. roscoviana has been found outside France, in Germany by GEUS (1969). Identification of the species is problematic. The descriptions give few diagnostic characters, and it is unlikely that type