Peloparion helenae (Godwin-Austen, 1883)
Material examined. Holotype (Peloparion submissus). AM C.101142 (Scone, NSW, 32°3’ S, 150°52’ E, pre-1941; Fig. 35A).
Non-type material. See Table S1.
Diagnosis. Animal. Pale grey with faint spots on sides of body and lappets; appearing red from mucus. Sole uniformly pale, foot border red; caudal horn large, edged with dark grey. Slime network visible. Mantle lobes and shell lappets well developed, lappets stained red and joined by a narrow collar; right lappet moderately large, rounded, edged with black, with a raised ridge on lower side; left lappet slightly shorter, rounded at tip, with a raised ridge on lower side (Fig. 32C).
Genitalia. Bursa copulatrix moderately short, sac tear-shaped and distinguishable from duct. Penis cylindrical, fully enclosed in penial tunica, internally with two main longitudinal pilasters broken up at proximal end into several smaller zigzagging threads; additional smaller longitudinal pilasters present; transverse ridges at proximal end; epiphallus moderately short, less than twice penis length, with numerous internal cryptae adjacent to flagellum; entering penis through thick, moderately long verge sculptured with transverse ridges. Spermatophore with approximately six branching spines present on capsule in a spiraling pattern and one spine on tail-pipe (Fig. 36).
Peloparion helenae is only known from Barrington Tops are in the Hunter Valley, living arboreally in beech forest and snow gum woodland. It is easily distinguished from other helicarionid semislugs by its small size and bright red mucus. It was previously grouped with Ubiquitarion iridis, another small semislug with rounded, dark-edged shell lappets. However, while some elements of the genitalia appear to be quite similar, there are considerable differences in the penial complex and spermatophore. In Peloparion helenae there are numerous internal cryptae in the epiphallus but none in the flagellum, giving rise to a spermatophore with long branching spines on the capsule but very few on the tail-pipe. In contrast, U. iridis has a thick muscular tunica obscuring the flagellum and adjacent part of the epiphallus, and a spermatophore with only a single branching spine on the capsule but a double row of numerous short, branching spines on the tail-pipe. The two species are also not grouped together based on mitochondrial DNA sequences, and as a consequence we have erected a new genus for Peloparion iridis. Peloparion helenae appears to be most closely related to Mysticarion, but is too anatomically divergent to be included in this group.