With the AMS (and COA) meetings scheduled for next week, the book with the program and abstracts for the AMS meeting is now available. Several topics of interest to Neotropical land snails are highlighted here.
Phylogenetics and evolution of Jamaican Pleurodontidae
Makiri Sei & Gary Rosenberg
The pulmonate family Pleurodontidae (formerly placed in Camaenidae) is one of eight endemic-rich families of land snails in Jamaica. Thirty endemic Jamaican pleurodontid species are currently classified in the genera Pleurodonte, Dentellaria, Thelidomus and Eurycratera, but their evolutionary history within the family has not been rigorously examined with molecular phylogenetics. We obtained partial sequences of mitochondrial cytochrome c oxidase subunit II (COII) gene, 16S ribosomal RNA (rRNA) gene, and nuclear 28S rRNA gene from 70 Jamaican pleurodontid individuals, 24 non-Jamaican pleurodontid individuals, and twelve outgroups including Cochlicellidae, Helminthoglyptidae, Hygromiidae, Sagdidae, and Scolodontidae.
Phylogenetic analysis strongly supports the monophyly of Jamaican species and the polyphyly of the genus Pleurodonte. Jamaican Pleurodonte did not group with Pleurodonte (sensu stricto) from the Lesser Antilles, but with Dentellaria from Jamaica. These results suggest that a single colonization event with subsequent radiation established the Jamaican pleurodontid fauna. The large degree of sequence divergence within some Jamaican pleurodontid species suggests some taxa described at the varietal level need to be elevated to full species status. In addition, some supposed ingroup taxa (Caracolus, Solaropsis, Zachrysia and Parthena) grouped strongly with Jamaican Sagdidae. This suggests that Pleurodontidae is not monophyletic and that the subfamily Polydontinae might be more closely related to Sagdidae.
Exploration at the verge of extinction ??? estimating diversity in the tropical land snail family Helicinidae (Neritopsina)
Helicinids represent a family of classic tropical land snails with a distribution range limited to the subtropical and tropical zones of the New World, the Australasian and the Pacific region. Hot spots of helicinid diversity are typically found on different island sites, e. g. the Greater Antilles and certain Indo-Pacific islands.
Although not as severely threatened as other tropical land snail families such as Endodontidae, Partulidae and Achatinellidae, the Helicinidae are faced with extinction in some areas. As almost exclusively forest dwelling species with often high requirements for suitable habitats they suffer almost everywhere at least a dramatic loss of habitat. This not only results in limited available material, but highly fragmentary data on distribution, the documented range of variation etc.
Against this background, and based on case studies in the different parts of the world (Costa Rica, the Lesser Antilles, New Caledonia and Pacific islands), specific and general challenges in approaching diversity estimates are discussed. A critical review of the available data from the different regions will be presented with a new estimate of the worldwide diversity, which will help to expose poorly studied areas and highlight the main sources of new species.
In helicinids, the greatest specific drawbacks to systematic work, and thus to judging diversity, include: a limited number of recognised differentiating characters; still-questionable systematic concepts and the absence of a robust higher phylogeny, and intergrading shell morphologies and multiple cases of convergence, not only in shell shape but in radula characteristics as well. An annotated outline of the past research on Helicinidae will round off the presentation.
Gal??pagos bulimulids: diversification amongst a vanishing tribe
Christine E. Parent
Why are island systems inhabited by remarkable adaptive radiations? Finches in Gal??pagos, Honeycreepers in Hawaii, Cichlids in the Great Lakes of East Africa–these species display a range of phenotypic variation equivalent to that of many vastly larger taxonomic groups. On Gal??pagos, bulimulid land snails have diversified to an unprecedented density of species richness. In this group there are over 70 described species representing a vast array of variation in form and ecology. This variation is the result of evolution in a fragmented landscape. Phenotypic diversity in these snails results from the combination of within-island speciation, between-island colonization and extinction.
During this talk I will first present a general overview of my research work on Gal??pagos bulimulid land snails. I will then focus on my latest work which aims at bridging the gap between the observed patterns of biodiversity at and above the species level and our understanding of how diversification proceeds at the population level. Although the patterns of adaptive radiations are increasingly well described, and the process of intraspecific diversification leading to speciation is better understood, the link between them remains to be studied in detail.
Populations of abnormally-shelled giant African snails Lissachatina fulica (Bowdich) in Barbados
Anton Norville & Angela Fields
The giant African snail, Lissachatina fulica (Bowdich 1822), first reported from the parish of St. Michael, Barbados in 2000, is now well established in all parishes on the island.
In 2006, specimens of giant African snails possessing abnormally shaped shells were observed. A survey of the island was initiated in 2007 to document the distribution of populations of abnormally shelled (AS) snails. Collection of snails were made at 16 sites to determine the prevalence of AS-snails, the shell lengths of snails displaying shell abnormalities and the whorl at which abnormalities could first be seen. To catalogue the types of abnormality observed, 746 shells were inspected and differences from Bequaert???s description of the shell of Lissachatina fulica were noted.
Of the 78 locations surveyed, 32% were found to have populations containing abnormally shelled snails. The prevalence of AS-snails in these populations ranged from 1% to 70%. The first appearance of an abnormality could be as early as in the third whorl of a neonate shell (shell length, 9 mm) or as late as in the eighth whorl of an adult shell (shell length, 103 mm). Abnormalities found included a reflexed apex, uneven whorls, a disjunct body whorl, an umbilicus, two outer lips and a non-truncated columella.
An ereynetid mite has been found at all sites where AS-snails are present. An investigation as to whether this mite is implicated in the shell abnormalities seen in Lissachatina fulica is under way.
Diversity, phylogeography and relationships of the Cerion (Gastropoda: Cerionidae) of the Dutch Leeward Islands
M. G. Harasewych
Long known for its exceptionally high diversity, the family Cerionidae ranges from the barrier islands of southern Florida to the Dutch Leeward Islands, usually inhabiting terrestrial vegetation with a few hundred meters of the shore. The nominotypical subgenus Cerion is restricted to the Dutch Leeward Islands, and separated from all living congeners by the Caribbean tectonic plate.
Nine taxa have been proposed for this fauna based exclusively on shell morphology. Several have been supported by subsequent, detailed morphometric analyses. Phylogenetic relationships of the subgenus and its constituent taxa are reviewed based on the first molecular studies of this fauna [partial 16S and CO I sequences]. Samples from the type localities of all named taxa are included in the analyses to infer patterns of interrelatedness among populations on Aruba, Cura??ao and Bonaire, and to evaluate biogeographic hypotheses.
Morphological and molecular analysis of the Andean land slugs Colosius n. sp., a newly recognized pest of cultivated flowers and coffee from Colombia and Ecuador, and Colosius pulcher (Colosi, 1921) (Gastropoda: Veronicellidae).
Suzete R. Gomes, David G. Robinson, Frederick J. Zimmerman, Oscar Obregon & Norman B. Barr
In this study we identify a new species of Colosius, recognizing it as pest of coffee and cultivated flowers from Colombia and Ecuador. We compare it with C. pulcher, a species with which it has been confused. In order to analyze the genetic relationship of Colosius n. sp., C. pulcher, C. propinquus (currently synonymized with C. pulcher) and C. lugubris (type species), fragments of COI, 16S rRNA, and 28S rRNA genes are analyzed.
Genetic variability within Colosius n. sp. and C. pulcher is also analyzed based on COI and 16S rRNA. In Colosius n. sp. the phallus has a deep longitudinal groove from the base, near the retractor muscle, to its distal region, close to the papilla. In C. pulcher there is an oval to rectangular swelling on the basal region of the phallus. Some important differences between both species are also found in the digitiform gland and bursa copulatrix.
Colosius n. sp. is a distinct lineage within the genus Colosius. It is not a sister species of C. pulcher, which has C. propinquus as a sister species, here confirmed as valid. Colosius n. sp. is closer to the clade that includes C. pulcher and C. propinquus than it is to C. lugubris. Based on the phylogenetic reconstruction, C. lugubris is sister to all the other Colosius. Genetic diversity within Colosius n. sp. and C. pulcher is low.
We describe, illustrate and discuss the color variation, morphological similarities, diagnostic characters and variability, habitat and distribution for Colosius n. sp. and C. pulcher. Associated imports and number of interceptions per year of Colosius n. sp. by federal agricultural inspectors are also presented.
Land mollusks in northern South America: biogeographic and ecological studies in megadiverse hotspots
Francisco J. Borrero & Timothy A. Pearce
The terrestrial malacofauna of northern South America is very poorly known. As a team of Colombian, European, and USA scientists (6 institutions total) we are studying the land snails of Colombia to enhance knowledge of systematics, distribution, and phylogeography of terrestrial mollusks and to address broader questions regarding the origin and maintenance of Neotropical biotic diversity. We will assess relations of the northern South America fauna with those of North and Central America, the Caribbean, and the rest of South America. We focus on Colombia because (1) it is at the crossroads of multiple biogeographic provinces and of the inter-American faunal exchange that was facilitated by joining previously separated faunas at Panama, and (2) it includes two megadiverse hotspots (Biogeographic Choco and Northern Andes). Land snails are uniquely well suited for these analyses as they are ancient, diverse, abundant, and, due to their limited dispersal ability, they address our questions better than more mobile taxa.
We outline the rationale, main methodology, and preliminary results of this first modern, comprehensive survey program of any non-arthropod invertebrate animal group in Colombia and northern South America. A species accumulation curve for Colombia continues climbing steeply, indicating that many species remain to be described; a sharp climb since year 2000 (including work by us and others), shows that relatively little effort can markedly increase the known biodiversity.
Suitably collected material will allow us to (1) compare diversity and endemism in various ecosystems, (2) study influences of dispersal limitation and habitat specificity in snail distributions, (3) assess whether snails are as diverse as other invertebrates in leaf litter and canopies, (4) study how the American interchange of land snails differs from that of other groups, and (5) examine the contributions of in situ speciation and accumulation of fauna from other regions to Colombia???s land snail diversity.