Although the family is itself reasonably recognizable by its generally elongate, thin, rather featureless shells, genera and species are not well differentiated by their shells. Characters of the reproductive anatomy (and sometimes jaw) are used to distinguish the genera and subgenera. Perhaps the gastropods most superficially similar to the succineids are some members of the family Lymnaeidae; these are predominantly freshwater living snails but there are a few that are more amphibious, and therefore come in close proximity with hygrophilous succineids and might be confused with them. Succineids are often thought of amphibious in their habits, but there are also species living in surprisingly xeric habitats, even under brittle prickly-pear cactus [Opuntia fragilis (Nutt.) Haw.] at Kamloops in the hot, dry BC interior. The generally translucent, yellowish shells of succineids give rise to the common name, “ambersnails”. The family occurs worldwide, and there are five genera in Canada.
Key to genera of Succineidae in Canada
- 1a Penis sheath absent. Penis with a rather large, blunt (rounded or bulge-like) appendix midway along its length — Mediappendix
- 1b Penis (and sometimes epiphallus) wholly or partially enclosed in a sheath of connective tissue. Penis without a medial appendix (appendix absent or small, terminal and enclosed within the penial sheath) — 2
- 2a Oviduct twisted 360° around the stalk of the bursa copulatrix. Penis projecting from the penis sheath in the form of a loop. Epiphallus absent — Novisuccinea
- 2b Oviduct not twisted 360° around the stalk of the bursa copulatrix. Penis enclosed in the sheath and not forming a loop. Epiphallus present (although not always well differentiated from the penis) — 3
- 3a Penial retractor attached to the vas deferens — Succinella
- 3b Penial retractor attached to the penis sheath — 4
- 4a Penial appendix present, terminal on the penis. Epiphallus straight, sinuous, or tightly convoluted inside the penial sheath — Oxyloma
- 4b Penial appendix absent. Epiphallus partially or fully external to the penial sheath and not tightly coiled — Succinea
Subfamily Succineinae Beck, 1837
Genus Novisuccinea Schileyko & Likharev, 1986
- Novisuccinea Schileyko & Likharev 1986: 211; type species by original designation: Succinea ovalis Say, 1817.
Although described by Pilsbry (1948) as a North American group, several other species were included in this genus by Schileyko & Likharev (1986) from Central Asia and the Russian Far East. However, not all of these would seem to be Novisuccinea (Forsyth 2017); those without the 360° coiling of the oviduct around the stalk of the bursa copulatrix would not belong, as this is a very distinctive character of Novisuccinea (Hoagland & Davis 1987). Novisuccinea is available from Schileyko & Likharev (1986), not Pilsbry (1948), following Articles 13.3 and 67.4.1 of the ICZN (1999); Pilsbry did not designate a type species and so the genus name was not validly published at that time.
Species of Novisuccinea are rather large-bodied animals, and more characteristically woodland species, although in the far north, it occurs in tundra-shrub habitats.
There are about eight species known, but it is uncertain how many occur in Canada. Russian and American (i.e., Schileyo & Likharev 1986 and Hoagland & Davis 1987) concepts of the genus differ, and some Siberian species attributed to Novisuccinea by Schileyo & Likhaarev almost certainly do not belong in Novisuccinea (Forsyth 2017). Two species are described in full here.
Etymology. Latin: novi, new + Succinea; feminine.
Novisuccinea ovalis (Say, 1817)
Novisuccinea strigata (L. Pfeiffer, 1855)
Genus Succinea Draparnaud, 1801
- Succinea Draparnaud : 55; type species (ICZN 1926, Opinion 94): Succinea putris (Linnaeus, 1758).
There are about 10 species distributed around the Holarctic realm. It is uncertain how many species of Succinea occur in Canada, and due this problematic taxonomy, the group is only given cursory treatment here.
Etymology. Latin: “amber”.
Genus Succinella Mabille, 1871
- Succinea Mabille 1871: 82, 92; type species by monotypy: Succinea oblonga Draparnaud, 1801.
Once considered a synonym or subgenus of Succinea, Succinella is now generally used as a separate, valid genus. There is only one species, which is broadly distributed over Europe and western and central Siberia (Schileyko 2007) and introduced to Ontario.
Etymology. Succinea + the Latin diminutive suffix -ella.
Genus Oxyloma Westerlund, 1885
- Oxyloma Westerlund 1885 (1884–1890): 1; type species by monotypy: Succinea hungarica Hazay, 1881 (= Succinea dunkeri L. Pfeiffer, 1865).
There are about 30 species of this genus are distribution around the Holarctic. It is uncertain how many species of Oxyloma occur in Canada, and due this problematic taxonomy, the group is only given cursory treatment here
Etymology. Greek: oxys, sharp + loma, edge.
Subgenus Oxyloma Westerlund, 1885
Subgenus Neoxyloma Pilsbry, 1948
- Neoxyloma Pilsbry 1948: 775; type species by original designation: Succinea effusa L. Pfeifer, 1853.
Etymology. Greek: neo, new + oxys, sharp + loma, edge.
Subfamily Catinellinae Odhner, 1950
Genus Mediappendix Pilsbry, 1948
- Mediappendix Pilsbry 1948: 843; type species by original designation: Succinea campestris vagans Pilsbry, 1900 (= Mediappendix vagans).
Shell small (adult shells under 13 mm high), subovate, translucent, thin-shelled, rather coarsely wrinkled, and greenish or yellowish. In general, these are small, short-spired succineids, more rotund than Oxyloma or Succinea. See Table 1 for anatomical distinctions between genera of succineids in Canada.
There are about 15 nominal species. It is uncertain how many species occur in Canada, but it is expected that there are more than the single species presented here.
Although frequently treated as a subgenus of the genus Catinella Pease, 1871 (following Odhner 1950), this group of succineids show anatomical features consistently different from European Quickella Boettger, 1939, and Hawaiian Catinella (sensu stricto). Catinella species lack a penial appendix; Quickella has an indistinct penial appendix in the “upper” part of the penis sac and entocones are present in both the lateral and marginal radular teeth; and Mediappendix has a rather prominent penial appendix placed mid-length on the penis and entocones are only present on the marginal radular teeth (Odhner 1950). Thus, Mediappendix is regarded here as a full genus, as was previously by Schileyko (2007). Etymology. Latin: media, the middle + appendix, for the blunt appendix that arises about midway along the length of the penis (Pilsbry 1948); feminine.