Tribocystis flaƲescens Iredale, 1944: 10

Hyman, Isabel T., Caiza, Jennifer & Köhler, Frank, 2023, Dissecting an island radiation: systematic revision of endemic land snails on Lord Howe Island (Gastropoda: Stylommatophora: Microcystidae), Zoological Journal of the Linnean Society 197 (1), pp. 20-75 : 61-62

Tribocystis flaƲescens Iredale, 1944: 10 , pl. 20, fig. 10.

Melloconcha flaƲescens Smith, 1992: 237 ; Stanisic et al., 2010: 344–345; Hyman & Köhler, 2020: 107.

Type material: Syntypes, AM C.40600 ( Fig. 5F ), North Ridge between North and Hunter Bays (31°31.06′S, 159°2.97′E), 1912 , R. Bell. Two specimens.

Material examined: See Table 1 .

Description

External morphology: Shell ( Fig. 5F ) small ( SW 5.0– 6.5 mm, SH 2.7–3.7 mm), glossy, 4.8–5.4 whorls, golden brown, discoidal with a low spire. Protoconch with fine spiral grooves; teleoconch with fine to obsolete spiral grooves. Whorl profile slightly flattened above and rounded below a rounded to slightly angulate periphery. Animal ( Fig. 6D, E ) cream with dark grey neck, head and eye tentacles; end of tail often with reddish, orange or yellow coloration. Right shell lappet long, narrow, finger-shaped; left shell lappet absent; caudal horn small.

Pallial caƲity: Mantle with pigmentation of white spots.

ReproductiƲe system ( Fig. 18 ): Oviduct with two eggs, two to five embryos. Penis moderately short, coiled once or twice in tunica; epiphallus enters penis through simple pore; penis internally with l o n g i t u d i n a l a n d v - s h a p e d r i d g e s; t w o m a j o r longitudinal penis pilasters present; four to five minor pilasters present apically; penial diverticulum absent. Penis retractor muscle attached to junction of penis and epiphallus. Epiphallus approximately equal to penis in length, internally with longitudinal pilasters. Spermatophore a short, soft-walled, smooth, peanut-shaped tube, closed at both ends.

Radula ( Fig. 16D–F ): Marginal teeth with ectocones approximately same length and breadth as mesocone, multicuspidate. Radular formula (56.6.1.6.56) × ~90 ( AM C.399051).

Figures

Figure 5. Shells of Innesoconcha.A,B,Innesoconcha catletti.A,AM C.101187 (syntype).B, AM C.101188 (syntype of I.catletti major). C, Innesoconcha aberrans, AM C.63475 (holotype). D, Innesoconcha delecta, AM C.63478 (holotype). E, Innesoconcha doppelganger sp. nov., AM C.592779 (holotype). F, Innesoconcha flaƲescens, AM C.40600 (syntype). G, Innesoconcha grata, AM C.63479 (lectotype). H, Innesoconcha miranda, AM C.39175 (holotype). I, Innesoconcha prensa, AM C.63476 (holotype). J, Innesoconcha princeps, AM C.38958 (syntype). K, L, Innesoconcha rosacea. K, AM C.38940 (holotype). L, AM C.63477 (holotype of Melloconcha alma). M, Innesoconcha segna, AM C.114789 (possible holotype).

Figure 6. Live individuals of Innesoconcha. A, Innesoconcha catletti, AM C.532582, Research Station. B, Innesoconcha aberrans, AM C.593857, Mount Lidgbird mid-south-western slopes. C, Innesoconcha delecta, AM C.574679, Mount Gower summit. D, Innesoconcha flaƲescens, AM C.532623, Boat Harbour. E, I. flaƲescens, AM C.574741, Mount Lidgbird lower northern slopes. F, Innesoconcha grata juvenile, AM C.593.893, Mount Lidgbird mid-south-western slopes. G, Innesoconcha prensa, AM C.583114, Mount Gower summit. H, Innesoconcha princeps, AM C.574711, Mount Gower summit. I, I. princeps juvenile, AM C.574683, Mount Gower summit. J, Innesoconcha rosacea, AM C.583117, Dinner Run. Images by A. Moussalli (A, D), C. Stehn (B, C, E, F, H, I) and F. Köhler (G, J).

Figure 16. Radulae. Column one shows central tooth and adjacent laterals, column two shows the transition between lateral and marginal teeth, and column three shows the outer marginal teeth. A–C, Innesoconcha delecta, AM C.391383, Smoking Tree Ridge. D–F, Innesoconcha flaƲescens, AM C.391761, Goat House. G–I, Innesoconcha grata, AM C.91365, Mount Gower. Scale bars: 20 µm.

Figure 18. Reproductive system of Innesoconcha flaƲescens. A, AM C.391761, Goat House, reproductive system. B, C, AM C.583104, Little Slope. B, penis with tunica removed. C, Penis interior. Scale bars: 1 mm.