Cerion ABC

One of my first sights of Neotropical land snails were very large bottles full of Cerion shells from Curaçao in the lab of the late P. Wagenaar Hummelinck. Willy de Vries, who worked at the same period in the lab, studied these shells from Aruba, Bonaire and Curaçao (in Dutch ‘ABC islands’) by taking various measurements on hundreds of shells. I recall her to be disappointed to conclude that “no obvious geographic variation in Cerion uva exists” (de Vries, 1974). This contrary to H.B. Baker, who had described various subspecies from the islands, and had concluded that Curaçao has western, central and eastern faunal regions (Baker, 1924). Wagenaar Hummelinck (1990), however, rejected this hypothesis and concurred with Gould’s (1969) partition of Curaçao in a western and eastern region.

Harasewych2014_f2

Harasewych has now published a nice paper restudying the Cerions from these islands using molecular data (Harasewych, 2014). The abstract reads: “The systematic relationships of the Cerion uva complex and its constituent taxa are reviewed based on partial sequences of the cytochrome c oxidase I and 16S rDNA genes from 19 populations spanning the geographic range of the species complex and including the type localities of 8 of the 9 subspecies and forms. Molecular data support the conclusion of prior morphometric studies that all living Cerion inhabiting Aruba, Curaçao and Bonaire are members of a single species, C. uva. Sequence variability among and within populations is not sufficiently discontinuous to segregate populations into discrete, specieslevel taxa. Three of four subspecies, proposed on the basis of geographic isolation during the Quaternary, C. uva uva (Linnaeus, 1758), the nominotypical subspecies from eastern Curaçao, C. uva knipensis Baker, 1924, from western Curaçao, and C. uva bonairensis Baker, 1924, from Bonaire, are all supported by distinctive haplotypes. Cerion uva arubanum Baker, 1924, a taxon based on living specimens from Aruba, is shown to be a synonym of C. uva uva, with which it shares a preponderance of haplotypes. It is conjectured that C. uva was widespread on Aruba during the Quaternary, but had become extinct on that island, and was reintroduced from a population near Willemstad in eastern Curaçao by humans (either by Caquetío Indians or by European settlers) within the past 800 years. Further investigation is needed to determine if Quaternary Aruban Cerion warrant subspecific recognition. On the island of Curaçao, molecular data lend support to the partition of the Cerion fauna into C. uva knipensis, which is confined to an isolated western region, as defined by Baker, and C. uva uva, which inhabits a broad, eastern region that is composed of Baker’s central and eastern regions. A population at Ronde Klip in eastern Curaçao has remained genetically isolated, and retains subspecific status as C. uva diablensis Baker, 1924. A neotype is designated for Turbo uva Linnaeus, 1758, as is necessary to provide an objective standard of reference for this species-group taxon, and for the genus- and family-level taxa based upon it.”

Harasewych2014_f7

References:

Baker, H.B., 1924. Land and freshwater molluscs of the Dutch
Leeward Islands. – Occasional papers of the Museum of Zoology.
University of Michigan 152: 1–160.
Gould, S.J., 1969. Character variation in two land snails from the
Dutch Leeward Islands: geography, environment, and evolution. –
Systematic Zoology 18: 185–200.
Harasewych, M.G., 2014. Systematics and phylogeography of Cerion sensu stricto (Pulmonata: Cerionidae) from Aruba, Curac¸ao and Bonaire. – Journal of Molluscan Studies (Advance Access): 1–19.
Vries, W. de, 1974. Caribbean land molluscs: notes on Cerionidae. –
Studies on the Fauna of Curac¸ao and other Caribbean Islands 45: 81–117
Wagenaar Hummelinck, P., 1990. About the malacological
subdivision of Curac¸ao; a review. – Contributions to Zoology 60: 181–187.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s