Taxonomy and ecology of the Philobryidae and Limopsidae (Mollusca: Pelecypoda)

The Philobryidae (Eocene-Recent; order Arcoida) are redefined to include nine genera: Adacnarca, Aupouria, Cosa, Gratis, Limarca, Limopsilla, Lissarca, Neocardia, and Philobrya. Philobryids are generally small (2-10 mm), mytiliform, and have a ligament pit that lies between two series of interlocking denticles. Philobryids are most common and widely distributed in the Southern Hemisphere. They are epibyssate but also are efficient epifaunal crawlers. The Limopsidae (Jurassic-Recent; order Arcoida) are redefined to include two genera: Empleconia and Limopsis. Limopsids are small (10-60 mm), ovate, and have a ligament pit that lies in a dorsal area above numerous teeth. Limopsids are endobyssate and are cosmopolitan at shelf depths. Unlike the gill of other arcoids, the philobryid gill is composed of short, stubby filaments and has few ciliary junctures. These features of the philobryid gill represent adaptations for cleansing, strengthening the gill, and viviparity. Some philobryids have an anterior inhalant area. The presence of this feature in taxonomically remote pelecypod groups and in groups of Recent, highly specialized pelecypods shows that, contrary to prevalent opinion, its presence does not necessarily indicate primitiveness or taxonomic affinity. Morphological, distributional, and temporal evidence suggests that limopsids probably arose from grammatodonts and in turn gave rise to glycymerids and philobryids. Neoteny may have played a role in philobryid and limopsid evolution

An Analysis of Diversity in Freshwater Mussels (Bivalvia: Unionidae) of the Cuyahoga and Rocky River Watersheds (Ohio, USA) Based on the 16S rRNA Gene

The continued loss of freshwater unionid mussel species in the Great Lakes region, and particularly from Lake Erie, raises the question of how much phylogenetic and genetic variation remain in the watershed. The introduction of molecular markers into population biology offers one reproducible technique for assessing this variation. A fragment of the 16S rRNA gene of mitochondrial DNA has previously been used to infer phylogenetic relationships in the family Unionidae. Therefore, we reanalyzed these published molecular data with the addition of 12 species from the Cuyahoga and Rocky rivers in northeast Ohio. Both rivers drain to Lake Erie. The species assessed were Pyganodon grandis, Lasmigona complanata, Lasmigona compressa, Lampsilis radiata luteola, Fusconaia flava, Potamilus alatus, Strophitus undulatus, and Toxolasma parvus, for which published data were unavailable, and northern specimens of four wide ranging species, Lasmigona costata, Leptodea fragilis, Utterbackia imbecillis, and Quadrula quadrula. The resulting phylogenetic tree remained consistent with the accepted major taxonomic divisions in the Unionidae, and it indicates that these rivers still contain a phylogenetically diverse assemblage. However, the most abundant species all are members of the Anodontinae. Intraspecific variation in these unionid species was low, even where results were compared to published sequences on individuals from distant watersheds. One exception was a unique haplotype of Q. quadrula that differed at more base sites than is generally found for many congeneric species

Changes in the Freshwater Mussel (Bivalvia: Unionidae) Fauna of the Cuyahoga River, Ohio, Since Late Prehistory

We provide new information from archaeological samples on the historical freshwater mussel fauna (Mollusca: Bivalvia: Unionoidea) of the Cuyahoga River (South Park site: occupied between ca. A.D. 950 and 1650) and Black River (White Fort site, occupation centered at ca. A.D. 1350), northeast Ohio. Data from these prehi storic sites are compared with information on extant mussel populations of the Cuyahoga River published between 1890 and 2000. The high representation at both archaeological sites of the species Actinonaias ligamentina, Elliptio dilatata, and Ptychobranchus fasciolaris suggests that these were· among the important clean water species in northeast Ohio prior to European settlement. By comparison, the modem mussel fauna of the lower Cuyahoga River (between Cleveland and Akron) contains none of these relatively abundant species, or any of the species represented in the archaeological material. The modern fauna of the lower river was established during the 20\u27 century. This fauna is a low diversity assemblage of pollution tolerant species represented by rare live individuals. The modem mussel fauna of the upper Cuyahoga River (between Akron and the source) suggests that the upper and lower reaches are effectively isolated from each other. Published records indicate little change in the fauna during the last three quarters of the 20\u27 century. Nevertheless, overall diversity, although substantially higher than that of the lower river, is considerably lower than that of the Grand River, which is located to the east of the Cuyahoga. Overall, the mussel fauna of the Cuyahoga River has changed greatly over time, most notably in terms of losses in diversity of clean water species and overall abundance

An Analysis of Diversity in Freshwater Mussels (Bivalvia: Unionidae) of the Cuyahoga and Rocky River Watersheds (Ohio, USA) Based on the 16S rRNA Gene

The continued loss of freshwater unionid mussel species in the Great Lakes region, and particularly from Lake Erie, raises the question of how much phylogenetic and genetic variation remain in the watershed. The introduction of molecular markers into population biology offers one reproducible technique for assessing this variation. A fragment of the 16S rRNA gene of mitochondrial DNA has previously been used to infer phylogenetic relationships in the family Unionidae. Therefore, we reanalyzed these published molecular data with the addition of 12 species from the Cuyahoga and Rocky rivers in northeast Ohio. Both rivers drain to Lake Erie. The species assessed were Pyganodon grandis, Lasmigona complanata, Lasmigona compressa, Lampsilis radiata luteola, Fusconaia flava, Potamilus alatus, Strophitus undulatus, and Toxolasma parvus, for which published data were unavailable, and northern specimens of four wide ranging species, Lasmigona costata, Leptodea fragilis, Utterbackia imbecillis, and Quadrula quadrula. The resulting phylogenetic tree remained consistent with the accepted major taxonomic divisions in the Unionidae, and it indicates that these rivers still contain a phylogenetically diverse assemblage. However, the most abundant species all are members of the Anodontinae. Intraspecific variation in these unionid species was low, even where results were compared to published sequences on individuals from distant watersheds. One exception was a unique haplotype of Q. quadrula that differed at more base sites than is generally found for many congeneric species

Changes in the Freshwater Mussel (Bivalvia: Unionidae) Fauna of the Cuyahoga River, Ohio, Since Late Prehistory

We provide new information from archaeological samples on the historical freshwater mussel fauna (Mollusca: Bivalvia: Unionoidea) of the Cuyahoga River (South Park site: occupied between ca. A.D. 950 and 1650) and Black River (White Fort site, occupation centered at ca. A.D. 1350), northeast Ohio. Data from these prehi storic sites are compared with information on extant mussel populations of the Cuyahoga River published between 1890 and 2000. The high representation at both archaeological sites of the species Actinonaias ligamentina, Elliptio dilatata, and Ptychobranchus fasciolaris suggests that these were· among the important clean water species in northeast Ohio prior to European settlement. By comparison, the modem mussel fauna of the lower Cuyahoga River (between Cleveland and Akron) contains none of these relatively abundant species, or any of the species represented in the archaeological material. The modern fauna of the lower river was established during the 20\u27 century. This fauna is a low diversity assemblage of pollution tolerant species represented by rare live individuals. The modem mussel fauna of the upper Cuyahoga River (between Akron and the source) suggests that the upper and lower reaches are effectively isolated from each other. Published records indicate little change in the fauna during the last three quarters of the 20\u27 century. Nevertheless, overall diversity, although substantially higher than that of the lower river, is considerably lower than that of the Grand River, which is located to the east of the Cuyahoga. Overall, the mussel fauna of the Cuyahoga River has changed greatly over time, most notably in terms of losses in diversity of clean water species and overall abundance