Halongella Pall-Gergely

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 : 44

Taxon classification Animalia Stylommatophora Plectopylidae

Genus Halongella Pall-Gergely gen. n.

Type species.

Helix (Plectopylis) Schlumbergeri Morlet, 1886.

Diagnosis.

Shells do not differ from those of Gudeodiscus ; small to very large, body whorl rounded, callus and apertural fold; Parietal wall with two lamellae or the anterior one is reduced or absent; parietal side with straight, slightly curved, or depressed Z-shaped plicae.

Penial caecum absent. Penis internally with longitudinal, parallel folds, with tiny, flat, T-shaped calcareous granules between the folds, all along the penis; there are no determined “pockets” for the granules at the apical part of the penis. Epiphallus internally with longitudinal folds having several perpendicular projections which overlap with those of the neighbouring fold. Radula similar to Gudeodiscus (Veludiscus) subgen. n. by the smaller central tooth than the ectocone of the first laterals and the marginals which are bicuspid or tricuspid with blunt innermost cups and shallow incision between the two inner cusps.

Differential diagnosis.

Sinicola species have a keeled body whorl, whereas it is rounded in Halongella gen. n. Moreover, all Sinicola species have a penial caecum, a central tooth which is as large as or larger than the ectocone of the first laterals and clearly tricuspid marginals with deep incision between the innermost two, sharp cusps. The same radular morphology has been observed in Sicradiscus species. Additionally, “eastern” Sicradiscus species possess keeled shells, whereas the rounded shelled “western” species of the genus have determined pockets on the inner penial wall, similar to that of Gudeodiscus . For comparison with Gudeodiscus , see there.

Included taxa.

fruhstorferi Möllendorff, 1901 and schlumbergeri Morlet, 1886.

Etymology.

This generic name derives from the name of the Halong Bay, where both species occur. The genus is gender feminine.

Remarks.

Calcareous granules of complicated shape have been found in the vagina of Halongella schlumbergeri , and some granules not having characteristic shapes have been found in the vaginal lumen of Halongella fruhstorferi . The taxonomic value of these granules are unknown. No granules of characteristic shape have been found in the vaginas of Gudeodiscus species, therefore this can be a synapomorphy of Halongella gen. n.