PACIFICA LENTIGINOSA FASSIO, BOUCHET & 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 : 954

PACIFICA LENTIGINOSA FASSIO, BOUCHET & OLIVERIO SP. NOV.

( FIGS 2 , 3 , 5A , 7C , 9E , 10G , 11G )

Zoobank registration: urn: lsid: zoobank. org:act: 210F01F5-C95D-4F27-A63D-9715015E67EE

Type material: Holotype: MNHN-IM-2009-16140 (Sud Madagascar, Lavanono West sector, ATIMO VATAE/ BP21, 25°23.1–23.2ʹS, 44°51.4–51.6ʹE, 20 m deep, female).

Material examined: MNHN-IM-2009-16140 (Sud Madagascar, Lavanono West sector, ATIMO VATAE/ BP21, 25°23.1–23.2ʹS, 44°51.4–51.6ʹE, 20 m deep, female).

Description: Body of medium size for the genus, 1 cm total length. Shell very thin, weakly calcified; ear shaped, low spire, with expanded aperture; weakly sculptured by axial growth lines; completely enclosed by the mantle. Periostracum not visible.

Protoconch of 1.6 whorls; nucleus diameter 110 μm; protoconch I 1.2 whorls, smooth, with subsutural axial folds; protoconch II with axial growth lines; protoconch–teleoconch boundary distinct.

Mantle dome shaped, outline rounded; thin; with anterior siphon folds; texture slightly wrinkled; dorsal mantle colour light violet, patterned with several small white and beige spots, fewer bigger orange spots and some brown patches.

Penis unknown; vas deferens unknown.

Radula reduced taenioglossate, formula 0:1:1:1:0; rachidian tooth base bifurcated; rachidian cusp with three external long denticles on each side; lateral teeth elongated, with a pointed triangular external cusp, with four or five long denticles on each side.

Jaws short; with an external protrusion on the upper side.

Distribution: So far known only from the type locality (southern Madagascar), 20 m deep.

Etymology: From the Latin adjective lentiginosa , meaning ‘freckled’, referring to the dorsal coloration of the holotype.

Remarks: This species is known only from shallow waters of southern Madagascar. Owing to the high variability in shell shape and mantle coloration in this family, the most reliable way to identify this species remains by molecular analysis.

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 7. Velutinidae shells. A, Calyptoconcha pellucida, BAU 3758. B, Variolipallium cerebroides, NIWA 74086.A. C, Pacifica lentiginosa sp. nov., MNHN-IM-2009-16140, holotype. D, Pacifica sp. (L16), MNHN-IM-2013-58543. Scale bars: A, B, 5 mm; C, D, 1 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.