· Lagenophrys Stein, 1852

is the largest genus, with 62 known species. The lorica is usually hemispheroidal (Fig. 2–3) but is ovoid (Fig. 4) in a few species as an adaptation for attaching to setae of the host1. The lorica aperture is an invaginated tube (loricastome) closed by drawing the outer edges (lips) together (Fig. 2 B–C). Characteristics of the lorica aperture, especially the lips, are remarkably diverse among species of Lagenophrys (Fig. 4). Details of the lorica aperture are species-specific and, usually, show relatively little intraspecific variation (Clamp 1990); however, the lips of the lorica aperture are highly variable in a few species (Clamp 1990, 1992). Other than their distinctive lorica aperture, members of Lagenophrys are unique in undergoing a special sequence of asexual divisions (second-type division) to abandon the exoskeleton of the host.