On the Taxonomic Status of the Family Pfeifferinellidae (Coccidia), with a Description of Pfeifferinella gugleri sp. n.

SYNOPSIS. Pfeifferinella gugleri sp. n. was found in the liver of each of 2 land snails, Triodopsis albolabris (Say), in Iowa. The stages found, their average length × width dimensions (in μm), and their principal features were as follows: oocysts (21 × 14.5) ovoid, with micropyle and oocyst residuum; meronts (20 × 15) with 24–32 merozoites: microgametocytes (15 × 11.5) with many small microgametes; macrogametes (20 × 10.5) with 1–5 nucleoli and 1–2 wall‐forming bodies, but without a “vaginal [fertilization] tube.” This tube, originally described by Léger & Hollande, 1912, from Pfeifferinella impudica , has since been considered a principal taxonomic feature of the family Pfeifferinellidae. In the absence of this structure, the taxonomic status of this monogeneric family is reexamined with the recommendation that the family be retained as distinct, but redefined to exclude the “vaginal tube” as a valid characteristic. The discovery of P. gugleri brings to 3 the number of pfeifferinellids reported, the other 2 being P. impudica Léger & Hollande, 1912, and P. ellipsoides Wasielewski, 1904, all from gastropods.