MARSENIOPSINAE FASSIO, BOUCHET, SCHIAPARELLI & OLIVERIO, 2023

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, Zoological Journal of the Linnean Society 197 (4), pp. 924-964 : 949

MARSENIOPSINAE FASSIO, BOUCHET, SCHIAPARELLI & OLIVERIO SUBFAM. NOV.

( FIGS 2 , 3 , 4A, B , 6A , 9A , 10A , 11A, M )

Zoobank registration: urn: lsid: zoobank. org:act: 0FF5505F-49D2-4814-8E81-CA559340917E

Type genus: Marseniopsis Bergh, 1866 .

Included genera: Marseniopsis Bergh, 1866, Lamellariopsis Vayssière, 1906 (probably a synonym of Marseniopsis Bergh, 1866 ).

Description: Body of small to medium size for the family, 0.5–11.5 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; enclosed by the mantle. Periostracum thin to not visible.

Protoconch of 0.76–1.9.0 whorls; protoconch I of 0.25–0.73 whorls, with or without granular sculpture, nucleus diameter 150–875 μm; protoconch II with or without marked longitudinal ribs; protoconch– teleoconch boundary not always distinct.

Mantle flat or dome shaped, outline rounded or polygonal; often thick, but sometimes thin, with or without warts; with anterior siphonal fold; texture smooth to wrinkled or jelly-like; colour highly variable, almost transparent to white, grey, beige, yellow, orange, red or brown, frequently patterned with dots and/or polygonal lines.

Penis to the right of the right cephalic tentacle; with or without a lateral subterminal papilla. Vas deferens with a free loop in haemocoel.

Radula taenioglossate, formula 2: 1:1: 1: 2; rachidian tooth elongated, with rectangular base, elongated; rachidian cusp with three or four small to pronounced external denticles on each side; lateral teeth elongated, with pointed triangular external cusp, with two or three small to pronounced denticles on the internal side and one or two small to large denticles on the external side; marginals narrow, without denticles.

Jaws elongated, composed of scale-like elements.

Distribution: Southern Ocean and south Argentinian waters; 75–668 m deep.

Remarks: Fassio et al. (2019) suggested that the radiation of velutinids in Antarctica might represent a lineage worthy of taxonomic recognition at subfamily level. This is here confirmed, and the geographical range is now extended outside the Southern Ocean to Argentina, with the record of M5 (= new MOTU P) from north of Isla de los Estados (USNM 1137366, 54°27ʹ19.1″S, 63°52ʹ39.4″W, 108 m depth). Marseniopsinae can be diagnosed by the radular formula combined with the elongated shape of the rachidian tooth with a rectangular base, and by an ear-shaped shell, not well calcified, with a high spire.

Lamellariopsis is probably a synonym of Marseniopsis , but the genetic analysis of type or topotypical material is needed to check it. Two types of protoconchs, potentially indicating a difference in the length of the larval phase, have been described for this subfamily (see Fassio et al., 2019).

Figures

Figure 2. Phylogenetic relationships of the family Velutinidae (Bayesian tree based on the combined dataset), with clades (A–L) collapsed by genera. Numbers at nodes indicate branch support values [posterior probability (PP) and ultrafast bootstrap (UFb) values, respectively]; support values are shown only when at least one of them is ≥ 80%; white circles at nodes indicate maximum support (PP = 1, Ufb = 100). On the right side of the tree, for each genus is reported a representative photograph of the shell, a schematic representation of the radula, the depth range (in metres) and the geographical distribution.

Figure 3. Phylogenetic relationships of the family Velutinidae (Bayesian tree based on the combined dataset) showing clades A–L expanded. Numbers at nodes indicate branch support values [posterior probability (PP) and ultrafast bootstrap (UFb) values, respectively]; support values are shown only when at least one of them is ≥ 80%; white circles at nodes indicate maximum support (PP = 1, Ufb = 100). Boxes indicate hypothetical species; dashed lines indicate possible alternative species partitions. Coloured boxes on the right indicate genera, and white boxes indicate subfamilies. Letters at the end of sample codes broadly indicate the area of origin:AK, Alaska; ANT, Antarctica; AR, Argentina; BC, British Columbia; BRE, Bretagne; CA, California; CH, China; COR, Corse; CR, Costa Rica; FL, Florida; GF, French Guiana; GP, Guadeloupe; HI, Hawaii; IT, Italy; MG, Madagascar; MQ, Martinique; MX, Mexico; MZ, Mozambique; NC, New Caledonia; NL, Newfoundland; NO, Norway; OR, Oregon; PA, Panama; PF, French Polynesia; PG, Papua New Guinea; PH, Philippines; QLS, Queensland; RE, Reunion; SA, Saudi Arabia; SP, Spain; TAS, Tasmania; TW, Taiwan; VU, Vanuatu; WA, Washington State; ZNZ, Zanzibar.

Figure 4. A, Marseniopsis sp. (M9), MNA 5376. B, Marseniopsis conica, MNA 5361. C, Marsenina zadei, LACM 182861. D, Marsenina rhombica, LACM 182862. E, Limneria prolongata, LACM 182858. F, Velutina sp., LACM 182869. G, Hainotis sharonae. H, Variolipallium regium sp. nov., MNHN-IM-2013-69285, holotype. I, Variolipallium sp. (L3), MNHN-IM-2013-69605. J, Variolipallium sp. (L10), MNHN-IM-2013-69280. Photograph credits: A, B, MNA, Stefano Schiaparelli; C–F, Nancy Treneman; G, iNaturalist, Robin Gwen Agarwal; H–J, MNHN, Philippe Maestrati. For the sequenced specimens, the corresponding species code (see Fig. 3) is reported in parentheses.

Figure 6. Velutinidae shells. A, Marseniopsis conica, BAS 03-764. B, Hainotis sharonae, LACM 1059, holotype (after Willet, 1939: fig. 1 and 1a). C, Marsenina rhombica, BAU 4229. D, Limneria prolongata, BAU 4228. Scale bars: A, 1 mm; C, D, 5 mm; B, shell maximum diameter = 5.5 mm, shell height 7.4 mm.

Figure 9. Velutinidae protoconchs. A, Marseniopsis conica, BAS 03-764. B, Marsenina rhombica, BAU 4229. C, Calyptoconcha pellucida, BAU 3758. D, Variolipallium cerebroides, NIWA 74086.A. E, Pacifica lentiginosa sp. nov., MNHN-IM-2009-16140, holotype.F, Pacifica sp. (L16), MNHN-IM-2013-58543. G, Djiboutia sp. (L22), MNHN-IM-2019-9053. H, Coriocella sp. (L27), MNHN-IM-2013-84230. I, Lamellaria latens complex (L41), MNHN-IM-2019-14179. J, Lamellaria mopsicolor, MNHN-IM-2013-73086. K, Marsenia perspicua complex (L55), MNHN-IM-2019-14574. L, Marsenia sp. (L42), MNHN-IM-2019-7641. Scale bars: A–L, 500 µm. For the sequenced specimens, the corresponding species code (see Fig. 3) is reported in parentheses. Arrows indicate protoconch I – protoconch II boundary.

Figure 10. Velutinidae radulae. A, Marseniopsis mollis, CE 6137. B, Marsenina rhombica, BAU 4229. C, Velutina cf. coriacea, LACM 182870. D, Calyptoconcha pellucida, BAU 3751. E, Variolipallium regium sp. nov., MNHN-IM-2013-69285, holotype. F, Variolipallium sp. (L10), MNHN-IM-2013-69280. G, Pacifica lentiginosa sp. nov., MNHN-IM-2009-16140, holotype. H, Pacifica sp. (L15), MNHN-IM-2013-59969. I, Djiboutia sp. (L22), MNHN-IM-2019-9053. J, Coriocella sp. (L27), MNHN-IM-2013-84230. K, Lamellaria mopsicolor, MNHN-IM-2013-73086. L, Lamellaria latens complex (L41), MNHN-IM-2019-14113. M, Marsenia herberti, MNHN-IM-2019-8503. N, Marsenia sp. (L45), MNHN-IM-2013-59960. O, Marsenia perspicua complex (L55), MNHN-IM-2019-5980. Scale bars: A–O, 100 µm. For the sequenced specimens, the corresponding species code (see Fig. 3) is reported in parentheses.

Figure 11. Velutinidae jaws. A, M, Marseniopsis mollis, CE 6152. B, N, O, Marsenina rhombica, BAU 2339. C, Limneria prolongata, BAU 4228. D, Calyptoconcha pellucida, BAU 3758. E, Variolipallium regium sp. nov., MNHN-IM-2013-69285, holotype. F, Variolipallium sp. (L10), MNHN-IM-2013-69280. G, Pacifica lentiginosa sp. nov., MNHN-IM-2009-16140, holotype.H, Pacifica sp. (L19), MNHN-IM-2009-16136.I,Djiboutia sp.(L22), MNHN-IM-2019-9053.J,Coriocella cf.jayi (L28), MNHN-IM-2009-16119. K, Lamellaria latens complex (L40), BAU 2536.2. L, Marsenia sp. (L45), MNHN-IM-2013-59960. Scale bars: H, M–O, 100 µm; A–G, I–L, 500 µm. For the sequenced specimens, the corresponding species code (see Fig. 3) is reported in parentheses.