Living specimens ~500 µm long and ~150 µm wide (Fig. 3A). Anterior and posterior ends rounded. Epidermis without conspicuous coloration in transmitted light. Epidermis completely ciliated. Rhabdoid glands present in distinct longitudinal rows. Frontal organ well developed. Mouth opening on ventral surface, middle of body (Fig. 5A). Ovaries paired, ventral; extends from mouth posteriorly to seminal bursa. Testes paired, lateral to ovary; extend from level of statocyst to seminal vesicle (Fig. 5A). Common gonopore ventral at posterior end of body opens to ciliated atrium surrounded on posterior and lateral sides by circularly oriented muscle fibers (Figs. 4A, 5B, C, 6A, C). Atrium branches anteriorly to male copulatory organ and dorsally to vagina (Figs. 5B, C). Behind male copulatory organ, vagina filled with large, spindle-shaped, erythrophilic glands that are grouped in a fan-like arrangement when viewed ventrally or dorsally (Figs. 3B, 4B, 5A–D). Vagina passes over male copulatory organ to seminal bursa positioned immediately anterior to seminal vesicle (Figs. 5D, 6B). Wall of seminal vesicle composed of many small cells and may contain some spots of concentrated actin (Figs. 5D, 6B). Male copulatory organ composed of seminal vesicle that surrounds sperm and penis (Figs. 3B, 4B, 5B). Muscular wall of seminal vesicle with regularly spaced circular and longitudinal fibers (Fig. 6A). Sperm fill majority of seminal vesicle space; sperm at distal end aligned in parallel. Bowl-shaped, glandular penis, composed of lamellae-like cells that stain metachromatically for glycoseaminoglycans and positioned at the distal end of seminal vesicle (Figs. 4A, B, 5B).[From Hooge MD, Tyler S (2008): 6-9]
Diagnosis for the valid (accepted) taxonomic name