The life cycle of Gregarina ronderosi n. sp. (Apicomplexa: Gregarinidae) in the Argentine grasshopper Dichroplus elongatus (Orthoptera: Acrididae)

Gregarina ronderosi n. sp. is described based on life cycle observations conducted on nymphs and adults of its natural host, the grasshopper Dichroplus elongatus. Following ingestion of oocysts by the host, parasite development occurs between the epithelium and the food mass in the midgut and gastric caeca. Gametocysts are liberated in the faeces. Natural prevalence in the type locality, Girondo, northwestern Buenos Aires Province, was 39.7% (n=131). The earliest trophozoites seen were small (< or = 10 microm), somewhat ovoid, unsegmented bodies. Fully developed trophozoites (the body is divided into epimerite, protomerite, and deutomerite) were slender, with conical or globular epimerites in attached or unattached forms, respectively. Trophozoites varied greatly in size [total length: 10.4-275.1 microm; mean (+/-S.E.): 126.3+/-78.9]. Gamonts, which were the most common stages observed and filled the midgut and gastric caeca in grasshoppers kept in rearing rooms, had a stocky appearance and also varied greatly in size (total length: 80-348 microm; 205+/-13). Association of gamonts was precocious, biassociative, and caudofrontal. Gametocysts were spherical and highly variable in size (96-376 microm in diameter; 202.8+/-52.5), and normally have 14 sporoduct basal discs. Everted sporoducts were up to 60 microm long. Oocysts were uniformly doliform in shape, measured (5+/-0.08 by 3.2+/-0.06 microm) and contained eight sporozoites. Wall reinforcements (carinae) were present. No infection resulted in experimentally inoculated Locusta migratoria, which is a host of Gregarina acridiorum. G. ronderosi is strikingly similar to G. acridiorum, but has larger oocysts.