Marseniopsis is a genus of small slug-like sea snails, marine gastropod molluscs in the subfamily Velutininae within the family Velutinidae.MolluscaBase eds. (2021). MolluscaBase. Marseniopsis Bergh, 1886. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=196957 on 2021-06-25
Characteristics The members in the genus Marseniopsis differ strikingly from other genera in the family Velutinidae. They form a beautiful transitional link between the diclinous (unisexual) and the androgynous (hermaphroditic) groups, such as Marsenina and Onchidiopsis. This connection distinctly demonstrates a unity of relationship.
In their general form, these animals agree with Onchidiopsis. The superior part of the body is hemispherical, appearing as if it were distended, while the mantle margin is thick and swollen. The external mouth lies far forward on the body. However, these specimens possess no right exhalent fold nor any associated semi-canal, and their branchial folia (gills) rather resemble those of the genus Lamellaria.
The mandibular plates are narrower and, on the whole, smaller than those found in other Velutinidae species. The radula, on the other hand, agrees exactly with that of the androgynous forms; notably, outside the lateral teeth, there are two additional hooked plates.
Unlike their androgynous relatives, the species in Marseniopsis have the sexes separate. Their anatomical relations resemble most closely those of the Coriocella. For instance, the inferior portion of the vas deferens does not lie freely within the lower body cavity. Furthermore, the penis most nearly resembles that of the Marsenia proper, and the shell is also, on the whole, like that of the typical Marsenia. Bergh [L.S.] R. (1886). Report on the Marseniadae collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873–76. Zoology. 15 (part 41):1-24, pl. 1
Species Marseniopsis antarctica Vayssière, 1906 Marseniopsis conica (E. A. Smith, 1902) Marseniopsis hexalateratus Egorova, 2007 Marseniopsis innominatus Iredale, 1936 Marseniopsis mollis (E. A. Smith, 1902) Marseniopsis pacifica Bergh, 1886 Marseniopsis soliditesta Numanami, 1996 Marseniopsis spherica Numanami, 1996 Marseniopsis syowaensis Numanami & Okutani, 1991 Taxa inquirenda Marseniopsis charcoti Vayssière, 1917 Marseniopsis murrayi Bergh, 1886
References
Vayssière A., 1906 - Mollusques Nudibranches et Marseniadés. (in) Expédition Antarctique Francaise (1903-1905) commandée par le Dr Jean Charcot. Documents Scientifiques. Sciences Naturelles, p. p. 34-51, 4 pls
External links Index to Organism Names (ION)