Marsenia, OKEN, 1823

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 : 956-957

MARSENIA OKEN, 1823

( FIGS 2 , 3 , 5H, I , 8D , 9K, L , 10M–O , 11L )

Marsenia Oken, 1823 : columns 458, 460;

type species Bulla haliotoidea Montagu, 1803 = Helix perspicua Linnaeus, 1758 by monotypy.

Included species: Marsenia herberti (Drivas & Jay, 1990) comb. nov., Marsenia perspicua (Linnaeus, 1758) , Marsenia affinis Bergh, 1886 [taxon inquirendum], Marsenia cabulana Bergh, 1886 [taxon inquirendum], Marsenia dubia Bergh,1886 [taxoninquirendum], Marseniagemma Bergh, 1875 [taxon inquirendum], Marsenia isabellina Bergh, 1875 [taxon inquirendum], Marsenia perspicua var. lara Bergh, 1899 [taxon inquirendum].

Description: Body of small to medium size for the subfamily, 0.3–10.0 cm total length. Shell thin, weakly calcified; ear shaped, low to high spire, 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 1.2–1.6 whorls; protoconch I 0.6–0.75 whorls, nucleus diameter 100–250 μm, smooth, with subsutural axial folds; protoconch II with or without axial growth lines; protoconch–teleoconch boundary not always distinct.

Mantle flat or dome shaped, outline rounded; thick or thin, with or without tubercles on dorsum; with anterior siphon folds; texture smooth/wrinkled/jellylike; colour highly variable, almost transparent to white, grey, beige, yellow, orange, red, violet, brown, often patterned with dots, streaks or patches of colour.

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

Radula reduced taenioglossate, with formula 0:1:1:1:0; rachidian tooth base bifurcated; rachidian cusp with several external denticles; lateral teeth elongated, with a pointed triangular external cusp, with several denticles on both sides.

Jaws short to elongated.

Distribution: Indo-West Pacific ( Madagascar, Reunion, Red Sea, Taiwan, Philippines, Papua New Guinea, Tasmania, New Caledonia, Hawaii), Mediterranean Sea ( Corsica and Alboran Sea), Caribbean Sea (Martinique and French Guiana); 0–214 m deep.

Remarks: The type species, Marsenia perspicua , is part of a complex of at least two cryptic species.

This widely distributed lineage is present in the tropical areas of the Indo-Pacific and the Atlantic, and in the Mediterranean Sea. It would be difficult to recognize this genus from other lamellarines with a low spire and moderately calcified shell, if it was not for its radula, characterized by a rachidian tooth bifurcated at the base, with small denticles on both sides and elongated lateral teeth with pointed, triangular and external cusps, with small denticles on both sides.

In one species ( Marsenia sp. L45), a specimen with a shell not completely enclosed by the mantle but presenting a small dorsal fissure (similar to that of some Variolipallium specimens) was observed.

We think that, based on the original descriptions, several taxa inquirenda described by Bergh (1886b) from Philippines and Cape Verde material ( Marsenia affinis , Marsenia cabulana , Marsenia dubia , Marsenia gemma , Marsenia isabellina and Marsenia perspicua var. lara ) might belong to this genus.

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 5. A, Pacifica lentiginosa sp. nov., MNHN-IM-2009-16140, holotype. B, Pacifica sp. (L18), MNHN-IM-2007-33407. C, Djiboutia sp. (L22), MNHN-IM-2019-9053. D, Coriocella sp., UF-IZ-523481. E, Coriocella sp., MNHN-IM-2019-26097. F, Lamellaria mopsicolor, MNHN-IM-2013-73086. G, Lamellaria latens complex (L41), MNHN-IM-2019-6391. H, Marsenia herberti, MNHN-IM-2019-8219. I, Marsenia perspicua complex (L55), MNHN-IM-2019-13522. Photograph credits: A–C, F, MNHN, Philippe Maestrati; D, Florida Museum of Natural History—Invertebrate Zoology, Gustav Paulay; E, MNHN, Giulia Fassio; G, I, MNHN, Gilles Devauchelle; H, MNHN, Laurent Charles. For the sequenced specimens, the corresponding clade code (see Fig. 3) is reported in parentheses.

Figure 8. Velutinidae shells. A, Djiboutia sp. (L26), MNHN-IM-2019-7668. B, Coriocella sp. (L27), MNHN-IM-2013-84230. C, Lamellaria latens complex (L41), MNHN-IM-2019-14179. D, Marsenia perspicua complex (L55), MNHN-IM-2019-14574. Scale bars: A, C, D, 1 mm; B, 5 mm. For the sequenced specimens, the corresponding species code (see Fig. 3) is reported in parentheses.

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.