Members of this family most obviously differ from related slugs in that their mantles are broadly rounded, and very large, covering the entire body. (In mollusks, the mantle consists of the tissues that normally generate the shell. Being mostly or entirely without shells, most slugs have reduced mantles.)
Pilsbry (1948) stated that "the enormously developed mantle, the large empty shell sac, and the insertions of the free retractor muscles along the margins of the foot cavity, instead of dorsally as in the Arionidae are special to the Philomycidae".[2]
A further anatomical oddity of the group, shared with certain helicid and zonitid snails, is their creation and use of calcareous love darts during mating.[2][3]
In this family, the number of haploidchromosomes lies between 21 and 30 (according to the values in this table).[4]
Acladogram based on sequences of cytochrome-c oxidase I (COI) genes showing phylogenic relations of genera in the family Philomycidae by Tsai & Wu (2008)[5] (simplified):
^Gray J. E. (November 1847). A list of genera of Recent Mollusca, their synonyma and types. Proceedings of the Zoological Society of London, 15: 129-182. Philomycidae is on the page 170.
^ abPilsbry H. A. (1948). "Land Mollusca of North America (North of Mexico)". Acad. Nat. Sci. Philadelphia, Monograph 3, 2(2): 748-750.
^Barker G. M. (2001). Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN0-85199-318-4. 1-146, cited pages: 139 and 142.
^ abcTsai C.-L. & Wu S.-K. (2008). "A New Meghimatium Slug (Pulmonata: Philomycidae) from Taiwan". Zoological Studies47(6): 759-766. PDF.
