The genus Fusconaia Simpson, 1900, as currently recognized, includes ~12 species in the tribe Pleurobemini. Two species are federally listed and several more are imperiled in part or all of their ranges; one species is probably extinct. However, classification at the species and genus level has been problematic, and it is unknown whether imperiled populations represent merely local ecophenotypic variations or endemic species. To provide additional evidence on the systematics of this group and to help establish conservation priorities, we sequenced two mitochondrial genes for all available species of Fusconaia as well as representatives of other genera of Pleurobemini and several outgroups. Both cox1 and nad1 provided well-resolved phytogenies. Some putative species show little molecular differentiation, supporting their synonymization. In particular, Fusconaia flava (Rafinesque, 1820), F. cerina (Conrad, 1838), and the easternmost populations previously assigned to F. askewi (Marsh, 1896) are not differentiated by our data. Although the majority of Fusconaia places in a well-supported clade that includes F. flava, the type species, others do not. “Fusconaia” barnesiana (Lea, 1838), the type of Pleuronaia Frierson, 1927, places with “Lexingtonia” dollabelloides (Lea, 1840) and “Pleurobema” gibberum (Lea, 1838). “Fusconaia” ebenus (Lea, 1831) and “F.” rotulata (Wright, 1899) form a distinct clade outside of Pleurobemini. “Fusconaia” succissa (Lea, 1852) is assigned to the pustulosa group of Quadrula (subgenus Rotundaria), along with Quincuncina infucata (Conrad, 1834). Conversely, the type species of Quincuncina, Quincuncina burkei Walker, 1922, is assigned to Fusconaia. Populations in the Ozark region assigned to F. flava and populations in the Suwannee River system assigned to Quincuncina infucata probably deserve species-level recognition.

The unionid tribe Pleurobemini is diverse but poorly-understood phylogenetically. Current classification recognizes two highly diverse genera, Elliptio Rafinesque, 1819 and Pleurobema Rafinesque, 1820, besides the moderately diverse Fusconaia Simpson, 1900, and several genera with one to three species. However, classification at the species and genus level has been problematic. Molecular data and re-examination of shell morphology and anatomy indicate new groupings of these taxa. Several genera proposed by early workers such as Rafinesque and Swainson are available, but are poorly-characterized and are often overlooked. We analyzed two mitochondrial genes, cox1 and nad1, for 50 species assigned to Pleurobemini, including the type species of each genus and as many other species as possible. Although the majority of studied species in Elliptio, Pleurobema, and Fusconaia show close affinities to the respective type species, the affinities of others are problematic. Genera or subgenera such as Eurynia Rafinesque, 1819, Sintoxia Rafinesque, 1820, and Pleuronaia Frierson, 1927, generally regarded as subjective synonyms, apply to some clades. Other clades or unaffiliated species have no available name. Quincuncina burkei (Walker, 1922), the type of the genus Quincuncina Ortmann, 1922, is assigned to Fusconaia Simpson, 1900. Fusconaia apalachicola (Williams and Fradkin, 1999), F. ebenus (Lea, 1831), F. rotulata (Wright, 1899) (also listed as Obovaria rotulata), F. succissa (Lea, 1852), Cyclonaias tuberculatus (Rafinesque, 1820), Uniomerus Conrad, 1853, and the Quincuncina infucata (Conrad, 1834) complex are all excluded from Pleurobemini. The first three are placed in the new genus Reginaia Campbell and Lydeard; Uniomerus Conrad, 1853 is assigned to Quadrulini; and the remainder belong in the pustulosa Lea, 1831 group of Quadrulini (genus Rotundaria Rafinesque, 1820).

Diverse strategies have evolved in freshwater mussels to promote the transfer of their parasitic larvae to host fish. Among these, modification of the mantle as a host attracting lure has been well-documented in the Tribe Lampsilini, but only recently reported in the Tribe Quadrulini. Here we describe mantle modifications and glochidia release behaviors in five quadruline species, including members of the Quadrula quadrula (Rafinesque, 1820), Q. pustulosa (Lea, 1831), and Q. metanevra (Rafinesque, 1820) species groups. Displays were motionless and consisted of inflated mantle tissue surrounding the excurrent aperture. Gross display morphology was largely variable among species: Q. fragosa (Conrad, 1835) and Tritogonia verrucosa (Rafinesque, 1820) had relatively large, uniquely shaped displays; Cyclonaias tuberculata (Rafinesque, 1820) and Q. pustulosa had smaller, stomate-shaped displays; and Q. metanevra had a diminutive, polyp-like display. Cyclonaias tuberculata exhibited a bimodal host infection strategy where individuals had either a mantle display or released a gelatinous conglutinate. Quadrula pustulosa and Q. metanevra expelled glochidia in a forceful burst when their displays were touched. Quadruline mantle displays do not clearly mimic identifiable aquatic organisms suggesting they may represent non-specific food items to their fish hosts.

Early life history information on the federally endangered winged mapleleaf (Quadrula fragosa (Conrad, 1835)) mussel is needed by natural resource managers to improve conservation and propagation programs. We conducted four studies to obtain some of this information. First, we observed Q. fragosa in the St. Croix River, Wisconsin between 1997–2010 and found females brood larvae (glochidia) for a unique period, between 8 September to 8 October at water temperatures ranging between 15–21 °C Second, we tested 67 fish species and Necturus maculosus for their ability to transform glochidia into juveniles. Nearly 30,000 juvenile Q. fragosa were produced, but only on Ictalurus furcatus and I. punctatus. Unlike most mussel species, Q. fragosa glochidia grew 3 to 4-fold while attached. Third, using scanning electron microscopy we were able to distinguish Q. fragosa glochidia height and length from six other mussel species that also produce small glochidia (<120 µm in height). Finally, we recovered 535 juveniles from 15 naturally infested fish species to determine if any were Q. fragosa based on glochidia morphology. We identified one juvenile from an I. punctatus as a Q. fragosa. To improve conservation efforts we suggest monitoring not only Q. fragosa beds but also associated Ictalurus populations, whose ranges may extend beyond mussel populations.

Freshwater mussels in the family Unionidae have suffered severe population declines because of severe anthropogenic disturbances, such as habitat destruction and habitat alteration. Understanding the genetic diversity of healthy unionid populations is crucial to developing informed management plans for imperilled mussels. Here, we characterize the genetic diversity of two common species, Lampsilis cardium Rafinesque, 1820 and Quadrula pustulosa (I. Lea, 1831), using the mitochondrial gene ND1. Populations of Q. pustulosa contained more numerous and more highly divergent haplotypes than populations of L. cardium. This disparity in genetic diversity could be because of several factors, including differences in population size and location and extent of refugia during the Last Glacial Maximum. For both species, AMOVA analysis indicated no genetic structuring based on location within the river, with genetic diversity concentrated within rather than between populations. This finding is consistent with patterns seen for other common mussel species characteristic of large rivers.

The glochidia of Diplodon (Diplodon) suavidicus (Lea, 1856), D. (D.) obsolescens F. Baker, 1914, Diplodon (Rhipidodonta) hylaeus (d'Orbigny, 1835), Prisodon obliquus Schumacher, 1817, Paxyodon syrmatophorus (Meuschen, 1781), Triplodon corrugatus (Lamarck, 1819, and Castalia ambigua Lamarck, 1819 were redescribed based on comparisons of external morphology and morphometric measurements of larval shells. The outline of the glochidial valves was classified into three types. The morphological comparison was based on light and scanning electron microscopy. Details of the shell, hooks and external sculpture allowed a redescription of the larvae, transferring D. suavidicus and D. obsolescens to the subgenus Diplodon and, within the Prisodontini, the genus Triplodon Spix, 1827 was separated from Prisodon Schumacher, 1817 and Paxyodon Schumacher, 1817. The glochidium of Prisodon obliquus is described for the first time. The larvae of the latter species and those of Paxyodon syrmatophorus present projections on the external sculpture in the form of spikes that have not yet been seen in the larvae of other South American Hyriidae. This unique ornamentation indicates closer proximity of Prisodon obliquus to Paxyodon syrmatophorus, a result also supported by multivariate analysis that allowed separation of the glochidia of the different species, using morphometric measurements such as length, height, length of the dorsal line and angle of obliquity formed between the position of the base edge in relation to the center of the dorsal line. Considering the angle of obliquity, the glochidium of Castalia Lamarck, 1819 was observed to diverge greatly in relation to those of other genera. The sampling dates of adults containing glochidia in the marsupium and an illustrated glossary are provided.

Living bivalves of the family Mactridae from Northern Argentina and Uruguay are herein revised. A bibliographical research yielded 22 nominal species reported from this area. Material from several institutions as well as fieldwork from La Paloma, Uruguay to San Blas, Argentina was studied. In addition, all type material were illustrated and redescribed. Descriptions of the soft and hard parts including ultrastructure of the shell, hinge and ligament using the Scanning electronic microscope (SEM) were carried out. We consider Mactra guidoi Signorelli and Scarabino, 2010, Mactra isabelleana d'Orbigny, 1846, Mactra marplatensis Doello-Jurado, 1949, Mactra petitii d'Orbigny, 1846, Mactrella janeiroensis (Smith, 1915), Raeta plicatella (Lamarck, 1818) and Darina solenoides (King, 1832) as valid species. In addition, a list of synonyms as well as the corroborated distribution is proposed for each species.

The morphology of the fasciolariid gastropods Leucozonia nassa (Gmelin, 1791), L. ocellata (Gmelin, 1791) and L. ponderosa Vermeij and Snyder, 1998 from Brazil is described. Examination of several shells from the oceanic island of Trindade, off southeastern Brazil confirmed the conchological differences between L. ponderosa and L. nassa. In addition, the first occurrence of L. ponderosa is documented from the Fernando de Noronha Archipelago, off northeastern Brazil. The anatomy of L. ponderosa is shown to be identical to L. nassa, except for minor radular features; however, the male genital system was not examined because of the lack of male specimens of L. ponderosa available for study. Leucozonia ocellata differs from L. nassa and L. ponderosa in having a proportionally smaller seminal receptacle and bursa copulatrix, a rhynchostome with lip-like margins, a curved anterior esophagus, and a cement gland with a posteriorly folded branch. Anatomic characters of the species studied here agree with the previous descriptions of fasciolariid anatomy.

A revision of the genus Pazinotus from Brazil revealed the occurrence of three species: Pazinotus stimpsonii (Dall, 1889a), with a wide geographical range in the western Atlantic, including Florida, the Caribbean, and the southeast coast of Brazil; Pazinotus bodarti (Costa, 1993), restricted to the southeast coast of Brazil; and Pazinotus gili new species, restricted to the Canopus Bank on the northeast coast of Brazil. Pazinotus gili new species is distinguished by its smaller size, less-pronounced teeth on the outer lip, and the absence of spiral sculpture on the teleoconch whorls. A microscopic sculpture is described for species of Pazinotus, consisting of microgranules on the protoconch and series of spiral pitted lines on the teleoconch surface or in the intritacalx of Pazinotus gili new species.

We examined covariation of morphology with local and regional environmental variables in the widespread North American freshwater gastropod Elimia livescens (Menke, 1830). Geometric morphometrics was used to quantify shape of individuals collected at sites in Indiana, U.S.A. We used the Procrustes superimposition method and relative warp analysis to examine variation among individuals. We found that shape of E. livescens covaried significantly with flowing versus non-flowing habitats, drainage area, latitude and longitude, water temperature, conductivity, substrate type, and the presence of woody debris. Individuals with smaller apertures and streamlined shape occurred in smaller watersheds in the southeastern regions of Indiana, and in local habitats with low water flow, low conductivity, large, coarse substrate (rip-rap), low frequency of woody debris, and higher dissolved oxygen. We suggest that morphological variation is an integral part in maintaining a wide distribution and maximizing local success for an aquatic gastropod that occurs in a variety of environments.

Changes in the distributional ranges of marine indicator species have been used to support hypotheses of climate change on NE Atlantic shores. One such indicator species, Osilinus lineatus (da Costa, 1778) (a trochid gastropod), recently colonized the Lough Hyne Marine Reserve in SW Ireland and spread around the lough shores in the last two decades. The incursion and local spread of O. lineatus was documented during annual intertidal community surveys of the lough from 1994 to 2010. This species is presently an abundant member of the lough's biota. Although the tidal rapids connecting the lough to the open ocean may have acted as a partial barrier to incursion, substantial populations of the trochid have been noted within the lough from 2003 to the present. Climate change may have enabled this primarily Lusitanien species to penetrate and flourish in the lough. However, based on environmental variables measured and other species surveyed, changes in the semi-enclosed lough may be more complex.

Although non-native species have been implicated as a major factor in the decline of the native Hawaiian land snail fauna, little attention has been focused on understanding how colonization by non-native plants influences Hawaiian land snail populations. The plant preferences of native Hawaiian succineids in the Kohala Forest Reserve were examined where native plant species and invasive non-native ginger species are present to understand how changes in the understory plant composition may influence succineid populations. Surprisingly, native succineid land snails preferred non-native ginger species to native plant species. This finding suggests that native succineid populations may not be negatively affected when the understory plant assemblage changes from a native plant community to one composed primarily of non-native ginger species. However, this preference also indicates that native succineids may be vulnerable to the effects of ginger control efforts. As such, managers should proceed cautiously with ginger removal efforts if they intend not to harm native succineid populations. Hopefully, future efforts to control non-native ginger species will adapt and minimize any negative effects on native succineid species.

The predatory snail Euglandina rosea (Férussac, 1821) is native to the southeastern U.S.A. and has been widely introduced as an attempted biological control agent for agricultural pest gastropods, often targeting the giant African snail Achatina fulica Bowdich, 1822. However, E. rosea may impact native land snails rather than A. fulica, particularly in Hawaii. Laboratory prey preference trials for E. rosea were conducted using three prey taxa, including the endemic endangered Oahu tree snail Achatinella lila Pilsbry, 1914, the giant African snail A. fulica, and the introduced Asian trampsnail Bradybaena similaris (Rang, 1831). Trials were conducted in the laboratory on branches of ohia lehua trees, Metrosideros polymorpha, an important habitat component for Hawaiian tree snails. Y-shaped ohia branches were used to simulate tree snail habitat and test E. rosea's ability to track and pursue prey via slime trails on branches, and to evaluate prey choice by offering trails of two different species simultaneously and slime trail vs. water. Euglandina rosea significantly favored branches with slime trails vs. water, choosing the branch with slime trail 90% of the time (P < 0.001). Predatory snails exhibited no significant preference between B. similaris and A. fulica (P = 0.820), or B. similaris and A. lila (P = 0.260). However, E. rosea showed a significant preference for native Achatinella lila over invasive Achatina fulica (P = 0.040), the intended target species of the biological control program.

Comparative studies of egg size and larval morphological characteristics coupled with estimates of dispersal abilities enabled Kohn and Perron (1994) to predict attributes of geographic distribution patterns of Indo-West Pacific Conus species that vary widely in developmental mode. However, because at that time, no species-level phylogenetic hypothesis had ever been proposed for Conus, we were constrained to treat each species as an independent entity. During the past decade, however, molecular phylogenetics of Conus has progressed to the point where character mapping and the method of phylogenetically independent contrasts can evaluate the importance of phylogenetic relatedness to biogeographic patterns. Analyses of species in two well-supported clades with data on ranges of trait variations suggest that significant evolutionary associations remain among developmental traits that affect dispersal ability after accounting for phylogenetic relationships. These are clades of molluscivorous and piscivorous Conus species, both exclusively in the Indo-Pacific region. As yet inadequate data on both development types and biogeography exist to determine whether phylogenetic relatedness predicts biogeographic patterns elsewhere in this hyperdiverse genus.

We compared patterns of genetic population structure and historical demography of several tropical Pacific Conus species that have similar though not completely overlapping distributions. Although these species possess similar life histories with planktonic larval durations of at least three weeks and exhibit genetic homogeneity across broad expanses of their distributions, they show distinct patterns of genetic population structure that are largely associated with genetic differentiation of geographically isolated populations. While previous analyses of C. ebraeus (Linnaeus, 1758) and C. miliaris (Hwass in Bruguière, 1792) detected high levels of genetic differentiation among isolated locations in the eastern Pacific and at Easter Island for each species, respectively, C. chaldaeus (Röding, 1798) does not show robust evidence of population differentiation across the East Pacific Barrier, albeit the sample size from the eastern Pacific is small. In addition, unlike C. chaldaeus and C. ebraeus, C. sanguinolentus (Quoy and Gaimard, 1834) exhibits a strong genetic break at Hawaii. Analyses of mismatch distributions suggest recent population expansion of C. chaldaeus and C. sanguinolentus as well as the Hawaiian endemic species C. abbreviatus (Reeve, 1843) during the past one million years as was observed previously for tropical Pacific populations of C. ebraeus and C. miliaris. Taken together, these results show that although high dispersal rates appear to genetically homogenize broadly distributed species in the tropical Pacific, stochasticity in long-distance dispersal likely instigates genetic differentiation of geographically isolated and peripheral populations and results in discordant phylogeographic patterns among even closely related species. Thus, population divergence and speciation in the tropical Pacific likely occur among populations at isolated locations though gene flow tends to prevent differentiation at broad geographic scales in species with high potentials for dispersal.

Morphological variation in shell shape was quantitatively evaluated among newly identified cryptic species in two species complexes (coronata and cinerea groups) belonging to the gastropod genus Lunella (Turbinidae) using elliptic Fourier descriptors (EFDs). Sympatric species of the coronata group show greater phenotypic diversity than the entirely allopatric cinerea group. We suggest that if morphological divergence is driven most strongly in sympatry, cryptic species are more likely to occur in taxa with allopatric speciation. Discriminant analysis showed that one species (L. aff. coronata ophiolite) was significantly different and could be distinguished from its two sister species (L. coronata (Gmelin, 1791), L. aff. coronata Oman) by shell outline with a high degree of success. In pairwise analyses two pairs from the cinerea group were also significantly different and species could be determined with a modest degree of success: L. aff. cinerea Fiji with L. aff. cinerea SW Pacific and L. aff. cinerea Indian Ocean with L. aff. cinerea central Indo-West Pacific (cIWP). The remaining species could not be accurately identified by shell shape alone in this study. We also used a combination of shell shape and shell sculpture to determine that the coronate form of L. coronata, which occurs along the east coast of Africa and along the Arabian Peninsula into India, corresponds to L. coronata sensu stricto. We were unable to assign either a holotype for L. cinerea (Born, 1778) or a figured specimen of L. versicolor (Gmelin, 1791) to genetic lineages with any statistical confidence, although the shell outline of the former is most similar to L. aff. cinerea cIWP and the latter to L. aff. cinerea SW Pacific. Finally, using morphometrics, in combination with other shell characters, two fossil species, one from the cinerea group from the Pleistocene and one Japanese species from the Eocene, were compared with extant species. Using this method in combination with other characters, we suggest that the Japanese L. kurodai Itoigawa, 1955 is most likely a member of the coronata group and the Pleistocene cinerea fossil is most similar to L. cinerea cIWP.

The equilibrium theory of island biogeography as originally proposed by R. MacArthur and E. O. Wilson relied on the ecological processes of colonization and extinction to determine the species diversity of islands. Although they were well aware of the potential contribution of speciation within-island to species diversity, MacArthur and Wilson's equilibrium model was purely ecological and did not incorporate the evolutionary process of diversification. This might seem surprising given that the best-known examples of adaptive radiation, the diversification of a single ancestral species into descendant species occupying a wide variety of ecological niches, are found on island systems. Recently, it has become possible to quantify the relative contribution of between-island colonization and within-island speciation to species diversity with the use of molecular phylogenies. By providing an estimate of the historical relationship among species, phylogenies can be used in combination with information on species' geographical distributions to infer the geographical zone of origin of species. Here I use this process-oriented analysis to determine the main predictors of diversification in three unique insular land snail lineages: the Galapagos Bulimulidae, the Hawaiian Succineidae and the Hawaiian Achatinellinae. I find that in Galapagos bulimulid land snails, species richness resulting from between-island colonization is mainly driven by island area and insularity, whereas species richness resulting from withinisland speciation is mainly determined by habitat heterogeneity. In contrast, I find that within-island species diversification is driven by island area in Hawaiian succineids, and the probability of speciation via between-island colonization in this group is significantly greater on younger islands. None of best multiple regression models proposed to explain variation in Hawaiian Achatinellinae species diversity were significant.