Diancta quadrata (Mousson, 1870) Mousson, 1870

Neubert, Eike & Bouchet, Philippe, 2015, The Diplommatinidae of Fiji - a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea), ZooKeys 487, pp. 1-85 : 7-10

Taxon classification Animalia Mesogastropoda Diplommatinidae

Diancta quadrata (Mousson, 1870) comb. n. Figs 11-12

Diplommatina quadrata Mousson 1870, Journal de Conchyliologie, 18: 187, pl. VIII, fig. 1. Type locality: Viti Levu.

Palaina (Palaina) quadrata , - Kobelt 1902, Cyclophoridae : 404.

Type data.

The holotype (by monotypy) could be found neither in MNHN nor in the Mousson collection in Zurich, the SMF, the collection of Charpentier in Lausanne or the Shuttleworth collection in NMBE. The species was not present in the 1989-1999 material. However, the Mousson collection contains a lot of one specimen, which agrees well with the original description (see below). Because of the need to unambiguously stabilize the taxonomic extension of this nominal species, this specimen (ZMZ 526690a; Fig. 11) is here selected as neotype.

Original description.

"T. sinistrorsa, oblique lineatim rimata, ovata, confertim costulato-striata, pallide flavula. Spira convexoconica; summo minuto, obtusulo; sutura vix profunda. Anfr. 5, celeriter accrescentes, convexi; primi laevigati; sequentes striati; tertius subinflatus; penultimus in dorso inflatus, in ventre retractus; ultimus fortiter ascendens, attenuatus, infra utrimque compressiusculus, cervice subangulata. Apert. verticalis, tangentialis, intus anguste elliptica, extus magna, subpatula, oblique et obtuse quadrata. Perist. expansum, vix incrassatum; marginibus lamina breviter solutu junctis, lateralibus super medium anfractus penultimi insertis, hic expansiusculis, antrorsum irregulariter undulatis. - Long, 4,6, diam. 2,9 mill. - Rat. apert. 1: 1. Viti Levu ex Graeffe, one specimen".

Diagnosis.

Shell large, yellowish, teleoconch sculpture with narrowly spaced ribs on the entire shell, last whorl with shallow furrow, aperture quadrate to subrectangular, peristome disconnected from last whorl.

Description

(based on neotype). Shell large, sinistral, oval, yellowish, partly translucent; last whorl only slightly constricted, with a broad and shallow furrow; protoconch large, 1-1.5 whorls, bulbous obtuse, pitted; umbilicus closed, periomphalum narrow; teleoconch sculpture of narrowly spaced ribs on the entire teleoconch; last whorl ascending; aperture quadrate to subrectangular, reinforced by a labial callus, peristome disconnected from the last whorl; apertural rims connected by a large polished callus; aperture with a slightly enlarged process over the left edge; no pleats visible in the aperture; internal lamellar structure not investigated.

Operculum unknown.

Measurements.

Neotype (Fig. 11): H = 4.56; D = 3.53; PH = 2.24; PD = 2.16; W = 6.

Distribution.

Viti Levu, precise locality unknown.

Remarks.

This species is placed here in Diancta , because the neotype shows the typical contraction of the teleoconch, described by Mousson as “anfractus… penultimus in dorso inflatus, in ventre retractus".