Tag Archives: aruba

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.

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More on Aruban Orthalicus

Gerard van Buurt (Cura??ao) send me some remarks on previous posts; today about Aruban Orthalicus.

The report of Orthalicus maracaibensis from Aruba was based on the finding of this species at two localities at the North side of the island. This led Gerard to believe it might be a case of washing ashore, caused by currents from Paraguan?? on the opposite coast of Venezuela. He had seen a similar case with a grasshopper, Tropidacris cristata, which was washed ashore at Boca Grandi in 2006. According to him “the presence [of these snails] at these localities [Boca Prins and Punta Braboe] does not point to a distribution influenced by humans; it is probably also not a relict faunal element either”. It must be noted that this species occurs on the Paraguan?? peninsula on hills (Cerro de Santa Ana and Filo de Monte Cano are mentioned by GvB), but I found it close to the sea in the National Park “Henri Pittier” (Breure, 1976, CorrBl. Ned. Malac. Ver. 172: 569-572, 585-587); this is further to the east than Paraguan??.

Orthalicus from Aruba

Bill Frank has posted new photographs on his website with Orthalicus maracaibensis forma imitator Pilsbry, 1899. 

Schermafbeelding_2011-02-04_om

This form was identified by Harry Lee, who noted “it should have microscopic spiral striation visible on the body whorl, which feature allow separation from the smooth O. floridensis“.
The shells were found on Aruba, near the top of the dunes at Boca Prins, in 1958-1960. The species was also occasionally found at Punta Braboe.

The full series of shells can be here http://www.jaxshells.org/itoo.htm