Lymnaea affinis, Souleyet, 1852

Cowie, Robert H., Héros, Virginie, Yeung, Norine W. & Hayes, Kenneth A., 2016, Annotated catalogue of types of Hawaiian land and freshwater snails (Mollusca: Gastropoda) in the Muséum national d’Histoire naturelle, Paris, with lectotype designations. Addendum: lectotype designation for Lymnaea affinis Souleyet, 1852, Zoosystema 38 (3), pp. 389-391 : 390

affinis Souleyet, 1852 , Lymnaea

( Fig. 1 )

Lymnaea affinis Souleyet, 1852: 528 , pl. 29, figs 42-44.

CURRENT TAXONOMIC STATUS. — Lymnaeidae , Lymnaea (Pseudisidora) producta Lea, 1841 , synonym ( Cowie et al. 1995: 32).

TYPE MATERIAL. — Lectotype (here designated) MNHN IM-2000- 32500 (ex MNHN IM-2000-2636); paralectotypes: MNHN IM- 2000-2636 (2 spms).

TYPE LOCALITY. — “Nous avons recueilli cette Lymnée dans les mêmes lieux que la précédente” [“…les ruisseaux de l’île Oahou (îles Sandwich)”].

REMARKS

The original description indicates that this species is always sinistral and all three of the MNHN specimens are indeed sinistral. The three specimens are similar in size and overall appearance. However, one of them most closely resembles the illustration of Souleyet (1852: pl. 29, fig. 44) of a presumed life-size shell in both size and shape, especially in the depiction of the columellar region of the aperture and the shape of the aperture. It also resembles Souleyet’s more detailed illustrations of the shell ( Souleyet 1852: fig. 43) and of the shell of the living animal ( Souleyet 1852: fig. 42). The specimen is 6.25 mm in height (Souleyet’s description says 7 mm) and 4.2 mm in width (Souleyet’s description says 4 mm). This specimen is here designated as the lectotype; the remaining two specimens are paralectotypes.Those in MNHN IM-2000-2636 (from which the lectotype was segregated as MNHN IM-2000-32500) are explicitly labelled as having been obtained from the voyage of La Bonite in 1838, the year after its return.

Hubendick (1952: 321), in his review of Hawaiian Lymnaeidae , considered there to be only one sinistral species, Lymnaea reticulata Gould, 1847 . He placed affinis Souleyet, 1852 in the synonymy of reticulata Gould, 1847 , also including Physa producta Mighels, 1845 in synonymy, but with a question mark. Morrison (1968: 32) considered affinis to be a “short-spired sinistral species” distinct from reticulata . However, Cowie et al. (1995: 32) treated all taxa synonymized under reticulata by Hubendick (1952: 321) as synonyms of producta on the basis that Morrison had synonymized reticulata and producta , although such practice is not generally deemed appropriate. Nonetheless, other authors have considered L. producta to be the only sinistral Hawaiian lymnaeid species, indeed the only sinistral lymnaeid species globally (e.g. Burch & Patterson 1971: 209; Burch 1982: 247; Christensen 2015: 54), although sinistral individuals or populations of normally dextral lymnaeids are occasionally encountered (e.g. Pierce 1996; Vinarksi & Vodyanitskaja 2008) and the genetics of the dimorphism is well studied ( Liu et al. 2013).

Confusion in the literature between native Hawaiian sinistral lymnaeids ( L. producta ) and introduced physids (all physid species are sinistral) was noted by Cowie (1997: 8), and exemplified by curation of the specimens noted here among Physidae in the MNHN. It is possible that additional specimens of sinistral Hawaiian lymnaeids may be found curated among the Physidae in other museums.

Figures

FIG. 1. — Lymnaea affinis Souleyet, 1852, lectotype MNHN IM-2000-32500, shell height 6.25 mm, width 4.2 mm; reproductions of figs 42-44 of Souleyet (1852), to the same relative scale as they were in the original publication.