Richmondaropa, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 82

Richmondaropa n. gen.

Gyrocochlea Hedley, 1924: 215 (in part); Iredale 1937: 322 (in part); Iredale 1941a: 267 (in part); Smith 1992: 190 (in part); Stanisic et al. 2010: 196 (in part).

Roblinella Iredale, 1941b: 1 (in part); Smith 1992: 203 (in part).

Type species. Gyrocochlea prava Hedley, 1924 —here designated.

Etymology. For the Richmond River district, north-eastern NSW.

Diagnosis. Shell very small, cinnamon brown, planispiral to slightly biconcave with spire flat to slightly concave. Whorls tightly coiled, the last inflated and descending strongly in front. Protoconch sculpture primarily spiral consisting of 17 to 21 prominent, widely spaced, narrow, continuous spiral cords; vague, very weak, underlying radial ridges present. Teleoconch sculpture of numerous, prominent, widely and uniformly spaced, slightly sinuate, orthocline to strongly prosocline radial ribs; microsculpture cancellate with prominent microradial ribs and low microspiral cords. Aperture shape broadly ovately-lunate. Umbilicus wide, U-shaped to cup-shaped. Epiphallus longer than penis, entering penis through a simple pore (i.e. verge absent). Penis tubular with an expanded apical portion, internally with 2–3 longitudinal pilasters.

Distribution and habitat. Sub-coastal volcanics, alluvial flood plains and coastal habitats between the Richmond and Tweed Rivers, north-eastern NSW; found in rainforests, living on undersides of logs.

Remarks. Richmondaropa n. gen. is distinguished by having a predominantly spiral protoconch with widely spaced, continuous narrow, spiral cords. Gyrocochlea Hedley, 1924 differs chiefly in having finely cancellate protoconch sculpture with numerous, extremely crowded, beaded spiral cords; Dictyoropa has a reticulate protoconch sculpture with continuous, widely spaced spiral cords; and Macphersonea n. gen. has distinctly latticelike protoconch sculpture and channelled sutures. Richmondaropa appears confined to the coastal and sub-coastal areas of north-eastern NSW area between the Richmond and Tweed Rivers. However, the hinterland, particularly rainforests of the upper Richmond and Nightcap Ranges needs to be further explored to circumscribe fully the geographic range of the genus and constitute species.