Gudeodiscus Pall-Gergely , 2013

Pall-Gergely, Barna, Hunyadi, Andras, Ablett, Jonathan, Lương, Hao Văn, Fred Naggs, & Asami, Takahiro, 2015, Systematics of the family Plectopylidae in Vietnam with additional information on Chinese taxa (Gastropoda, Pulmonata, Stylommatophora), ZooKeys 473, pp. 1-118 : 8-9

Taxon classification Animalia Stylommatophora Plectopylidae

Genus Gudeodiscus Pall-Gergely, 2013

Gudeodiscus Páll-Gergely in Páll-Gergely & Hunyadi 2013, Archiv für Molluskenkunde, 142 (1): 4, 8.

Type species.

Plectopylis phlyaria Mabille, 1887, by original designation.

Included taxa.

Subgenus Gudeodiscus and subgenus Veludiscus subgen. n.

Diagnosis.

Shell rarely small, usually middle sized or large, dextral, body whorl rounded, without periostracal folds on the "upper keel" of the whorls. The whole protoconch is usually very finely, regularly ribbed (see Figure 10A). The only known exceptions are Gudeodiscus villedaryi (see Figure 10B) and Gudeodiscus dautzenbergi . Teleoconch usually has a reticulated sculpture; more prominent on the dorsal side; sometimes with very small periostracal filaments, but these are always arranged radially, never in spiral lines. A short apertural fold is present in the majority of the species. Palatal plicae usually 6, sometimes 5 or 7, they are usually free, very rarely connected by a ridge. Middle palatal plicae can be horizontal, oblique or almost vertical, they are usually depressed “Z” or “V” -shaped. The first plica is always straight and parallel with the suture, the last is slightly curved or oblique. On the parietal wall there are two vertical lamellae or the anterior one is missing or dissolved into small denticles or parallel horizontal plicae. Usually horizontal plicae are visible above and below the anterior lamella, near the sutures.

Penial caecum usually present (very rarely absent). Penis internally with longitudinal folds; the middle or proximal portion of the penis can have transverse or reticulated sculpture; the longitudinal folds are thickened on the apical part of the penis and form “pockets”, each of which holds a calcareous, usually hook- or claw-like translucent granule; these granules are probably present seasonally when the snails are reproductively active and disappear when embryos develop in the uterus; the pockets stand in one row or rarely in two rows on the opened penis wall. Epiphallus with simple internal longitudinal folds.

Differential diagnosis.

The body whorl of the species belonging to Sinicola is keeled or shouldered, often with flat, deciduous periostracal folds arranged in one row on the keel. In contrast, all Gudeodiscus species have rounded body whorl and never have periostracal folds arranged in a spiral line. Moreover, in Sinicola there are no “pockets” on the inner wall of the penis. The shells of Halongella gen. n. are indistinguishable from those of Gudeodiscus . Halongella gen. n. species have parallel, longitudinal folds on the inner wall of the penis with tiny, flat calcareous granules between the folds, all along the penis; there are no determined “pockets” for the granules at the apical part of the penis, which are so characteristic for Gudeodiscus . Additionally, the longitudinal folds inside the epiphallus of Halongella gen. n. species have characteristic transverse projections which overlap with those of neighbouring folds. In contrast, Gudeodiscus species have parallel folds on the inner wall of the epiphallus. Additionally, most anatomically examined Gudeodiscus specimens had a penial caecum, which is missing in both Halongella gen. n. species. See also under Sicradiscus .