Innesoconcha prensa, (IREDALE, 1944)

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 : 66-67

publication ID 10.1093/zoolinnean/zlac075

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Innesoconcha prensa



( FIGS 5I View Figure 5 , 6G View Figure 6 , 21 View Figure 21 , 22A–C View Figure 22 , 23 View Figure 23 )

Melloconcha prensa Iredale, 1944: 323 View in CoL , pl. 20, fig. 9; Smith, 1992: 238; Hyman & Köhler, 2020: 111.

Type material: Holotype, AM C.63476 ( Fig. 5I View Figure 5 ), North Ridge (31°31.06′S, 159°2.97′E), September 1908, C. Hedley. GoogleMaps

was also observed on the summit of Mount Lidgbird around the same time ( Iredale, 1944), although there are no collected specimens from this locality.


Annacharis was introduced for a single species, A. miranda Iredale, 1944 . The genus was distinguished from Melloconcha and Tribocystis by its globosely turbinate shell and the presence of channelled sutures and a thickened columella, although Iredale (1944) stated that the three genera might be closely related. Annacharis was synonymized with Melloconcha by Smith (1992), a decision followed by most subsequent authors ( Schileyko, 2002b; Smith et al., 2002; Stanisic et al., 2010), although Annacharis was maintained by Hyman (2005).

It is probable that this species is extinct. It might have been affected by the introduction of rats in 1918. Alternatively, I. miranda might Material examined: See Table 1 View Table 1 .


External morphology: Shell ( Fig. 5I View Figure 5 ) small (SW 6.5– 8.0 mm, SH 3.1–4.0 mm), 4.9–5.6 whorls, glossy, pale golden brown, discoidal with spire and apex slightly raised. Protoconch and teleoconch with fine, incised spiral grooves. Whorl profile rounded above and below a rounded periphery. Animal ( Fig. 6G View Figure 6 ) cream to grey with black eye-tentacles and a darker grey neck and tail tip. Right shell lappet moderately small, narrow, finger-shaped; left shell lappet small, narrow, fingershaped; caudal horn small.

ReproductiƲe system ( Fig. 23 View Figure 23 ): Oviduct with 14 eggs and four embryos. Penis long, coiled and folded in tunica; epiphallus enters penis through a simple pore; penis internally flat, two longitudinal penis pilasters present, one at base, one at apex, apical pilaster splits into two apically, penial diverticulum absent. Penial tunica enclosing coiled and folded penis and epiphallus; penis retractor muscle attached to junction of penis and epiphallus and to parts of epiphallus. Epiphallus shorter than penis, internally with longitudinal pilasters. Spermatophore not observed.

Radula ( Fig. 22A–C View Figure 22 ): Teeth very long, slender and pointed compared with congeners. Marginal teeth with endocones absent; ectocones present, reduced to a tiny stub on early marginals and absent on remaining teeth. Radular formula ( × 66.

Range and habitat

Innesoconcha prensa was originally described from North Ridge at the extreme northern end of the island, based on a single shell collected in 1908. Another empty shell was collected from near the top of Mount Gower before 1950. Since that time, all specimens have been collected from the southern end of the island, on the walking trail leading to Mount Gower or on the summit ( Fig. 21 View Figure 21 ). This appears to indicate that the original type locality was incorrect, something that has been postulated for several other species collected at the same time ( Iredale, 1944). Live specimens have been collected on Mount Gower in 1971 (11 specimens), 2002 (four specimens), 2019 (14 specimens) and 2020 (three specimens), from leaves and branches of trees, dead leaves in the crutch between the branches and trunk or palms and from leaf litter. Innesoconcha prensa is uncommon.

This species has a limited range and has been observed and collected in very low numbers. However, after fruitless surveys from May 2016 to May 2019, multiple live specimens were found in October 2019. Live specimens were also found the following year, albeit in reduced numbers. This might have been attributable to improved weather conditions, or it might have been linked to the effects of the rodent eradication undertaken in 2019, as described in the Conservation section, above.


Australian Museum














Innesoconcha prensa

Hyman, Isabel T., Caiza, Jennifer & Köhler, Frank 2023

Melloconcha prensa

Hyman IT & Kohler F 2020: 111
Smith BJ 1992: 238
Iredale T 1944: 323
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