Variolipallium Fassio, Bouchet & Oliverio 2023
Creators: name: Fassio, Giulia
name: Stefani, Matteo
name: Russini, Valeria
name: Buge, Barbara
name: Bouchet, Philippe
name: Treneman, Nancy
name: Malaquias, Manuel António E.
name: Schiaparelli, Stefano
name: Modica, Maria Vittoria
name: Oliverio, Marco
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Velutinidae
Variolipallium

description: VARIOLIPALLIUMFASSIO, BOUCHET & OLIVERIO
GEN. NOV.
(FIGS 2, 3, 4H–J, 7B, 9D, 10E, F, 11E, F)
Zoobank registration: urn: lsid: zoobank. org:act: 170D2A4B-E62D-4612-9737-FFC39B639EFA
Type species: Variolipallium regium Fassio, Bouchet & Oliverio sp. nov.
Included species: Variolipallium cerebroides (Hutton, 1882) comb. nov., Variolipallium elatum (Strebel, 1906) comb. nov., Variolipallium leptoconcha (Bergh, 1907) comb. nov., Variolipalliumnodosum (Ev.Marcus, 1987) comb. nov., Variolipallium patagonicum (E. A. Smith, 1881) comb. nov. and Variolipallium regium Fassio, Bouchet, Oliverio sp. nov.
Description: Body of small to medium size for the subfamily, 0.5–3.0 cm total length. Shell very thin, weakly calcified to membranaceus; ear shaped, high spired, with expanded aperture; smooth or weakly sculptured by axial growth lines; completely enclosed by the mantle or presenting a small dorsal fissure. Periostracum not visible.
Protoconch of 1.24–1.70 whorls; protoconch I of 0.48– 1.20 whorls, nucleus diameter 100–150 μm, smooth, with subsutural axial folds; protoconch II with axial growth lines; protoconch–teleoconch boundary not always distinct.
Mantle flat or dome shaped, outline rounded or polygonal; thick to thin, often with a few to several dorsal tubercles; with anterior siphon fold; texture smooth to wrinkled (resembling the convolutions of a brain); colour variable, almost transparent to white, grey, yellow, orange to red, pink to violet, light blue, brown, dark green, occasionally patterned with spots. Cephalic tentacle tips can be white, lime yellow or almost transparent.
Penis to the right of the right cephalic tentacle, with or without a lateral subterminal papilla. Vas deferens without a free loop in haemocoel.
Radula reduced taenioglossate, formula 0:1:1:1:0; rachidian tooth base bifurcated; rachidian cusp with few to several, very small to pronounced external denticles; lateral teeth elongated, with a pointed triangular external cusp, with few to several, very small to pronounced denticles on both sides or only on the internal side.
Jaws homogeneous, short to elongated.
Distribution: Tropical West Pacific (South China Sea, Papua New Guinea, New Caledonia), New Zealand; Caribbean; tip of South America (Chile, Argentina, Falkland Islands), South Africa; 42–1573 m deep.
Etymology: From Variola, the Latin name for smallpox, and pallium, meaning ‘mantle’, referring to the coloured small tubercles on the mantle of the type species and other members of the group. Gender neuter.
Remarks: Variolipallium can be diagnosed by a membranaceous to weakly calcified shell with high spire (similar to that of Calyptoconcha and Marseniopsis) and a bifurcated rachidian tooth (like Lamellaria, Marsenia, etc.), although in Variolipallium the ‘V’-shaped base of the rachidian tooth can be comparatively less marked.
All the species included in this genus have been found at depths> 95 m.
The dorsal appearance of the mantle varies from wrinkled, with several tubercles (resembling the convolutions of a brain), to rather smooth and studded with fewer small tubercles of different colour, to completely smooth. Several species (Variolipallium cerebroides, Variolipallium cf. patagonicum, Variolipallium cf. elatum, Variolipallium sp. L10, Variolipallium sp. L11, Variolipallium sp. L12, Variolipallium sp. L14 and Variolipallium regium) include specimens with a small to very small dorsal mantle fissure, occasionally marked by a small black spot (visible also in preserved specimens).
Lamellaria patagonica E. A. Smith, 1881 (type locality: Trinidad Channel, Chile, in 54 m) and Lamellaria elata Strebel, 1906 (type locality: Puerto Condor, Chile) belong to this genus based on their fragile and high-spired shells, smooth mantle and radular formula and shape. Variolipallium patagonicum and Variolipallium elatum can be distinguished by a more rapidly expanding first whorl in the former and, consequently, a higher shell in the latter, also resulting in a flatter body in Variolipallium patagonicum and a more globose one in Variolipallium elatum.
Lamellariaampla Strebel, 1906 (Ushuaia, Argentina) might also belong here (based on shell shape and shell consistency), but further analysis of the type material is necessary, because the radula, in particular, is not described in the original description. However, the general description, in particular the jelly-like mantle, wrinkled, grey with darker spots, would also be compatible with a position in Marseniopsinae.
Lamellaria leptoconcha (South Africa, Cape Point, in 1097–1280 m) is included in Variolipallium based on the membranaceus texture of the shell and the shape of the rachidian tooth. Bergh (1907: pl. IX, fig. 18) sketched a rachidian tooth with a not marked but visible ‘V’-shaped base (similar to our SEM photographs; Fig. 10E, F), and in the description underlined that the difference between this species and Marsenia leptolemma (= Calyptoconcha pellucida) was the shape of the rachidian tooth (that in Calyptoconcha indeed has a squared base).
Lamellaria cerebroides (Auckland, New Zealand) is included in Variolipallium based on the radular formula and shape, and the wrinkled dorsum appearance. Lamellaria Ʋerrucosa (= Lamellaria nodosa) (Auckland Islands) is also included in this genus based on the membranaceus texture of the shell, the rugose appearance of the dorsum, and the radular formula and shape. Odhner (1924) described it as being similar to Marseniopsis mollis, but the radular formula of Lamellaria Ʋerrucosa clearly indicates that it belongs to the subfamily Lamellariinae.
The original description of Lamellaria ophione Gray, 1850 is general (fitting most lamellariine genera) and does not report any information regarding diagnostic characters. However, considering the type locality (Auckland, New Zealand), there is a chance that this species also belongs to this genus, because this is the only lamellarine genus recorded in this area so far.
description: Published as part of Fassio, Giulia, Stefani, Matteo, Russini, Valeria, Buge, Barbara, Bouchet, Philippe, Treneman, Nancy, Malaquias, Manuel António E., Schiaparelli, Stefano, Modica, Maria Vittoria & Oliverio, Marco, 2023, Neither slugs nor snails: a molecular reappraisal of the gastropod family Velutinidae, pp. 924-964 in Zoological Journal of the Linnean Society 197 (4) on pages 952-953, DOI: 10.1093/zoolinnean/zlac091, http://zenodo.org/record/7814306