Fanulena imitatrix

The shell is small, measuring 5.6–6.8 mm in width and 4.9–6.0 mm in height, with 6.0–6.5 whorls. It is dark golden brown to chocolate brown with cream flammulations, conical in shape with a domed, strongly raised spire and apex. The protoconch is sculptured with moderately closely spaced radial ribs, faint to obsolete on the early whorl but becoming stronger towards the teleoconch. The teleoconch is sculptured with strong, moderately closely spaced radial ribs ornamented with long periostracal hairs arranged in spiral rows — four rows on early whorls and five to seven rows on outer whorls. This distinctive hair-like sculpture gives the species its common name. The whorl profile is rounded above and below a keeled periphery. The aperture is ovate, with a small, indistinct columellar tooth. The animal is grey with a white sole. Unlike many other Norfolk Island microcystids, F. imitatrix completely lacks shell lappets.

Reproductive anatomy. Fanulena imitatrix possesses a short penis that is not coiled within the penial tunica, with a small blind tip that narrows significantly towards the penis–epiphallus boundary. The inner penial wall is flat with v-shaped grooves in the upper half and a single longitudinal pilaster in the lower half. …

This species is endemic to Norfolk Island, a volcanic island situated approximately 1,500 km from the Australian mainland and 1,000 km from New Zealand in the South Pacific Ocean. The historical distribution of F. imitatrix is poorly understood; the original 1900 description lacked locality data. The species is common in subfossil deposits at Emily Bay and Cemetery Bay, indicating it was once more widespread. A single specimen was reportedly recorded from Mount Pitt by Neuweger et al. (2001), but the identity could not be confirmed. As of the most recent surveys, the species is known only from a single population in Selwyn Reserve, where it inhabits remnant subtropical rainforest and shelters under logs and palm fronds in leaf litter.