Freshwater mussels (Mollusca: Bivalvia: Unionoida) are a species-rich group of parasitic bivalves comprising approximately 843 nominal species in six families, including 300 species of Unionidae and ...five of Margaritiferidae in North America. Unionid shells have been studied extensively for the purposes of taxonomy, but less information exists about the cellular anatomy of their “soft tissues” (mantle cavity tissues and visceral tissues). No systematic histological atlas of any unionid has been published in the peer-reviewed literature, and this lack of information hinders basic and applied research topics involving freshwater mussels. Herein, we describe the tissue and cell anatomy of a representative species from each of three lineages (tribes) of Unionidae sensu Graf & Cummings (2006) ranging in North America: Villosa nebulosa (Ambleminae: Lampsilini), Fusconaia cerina (Ambleminae: Pleurobemini) and Strophitus connasaugaensis (Unioninae: Anodontini). Based on necropsy observations and light microscopy of serial histological sections, for each species we describe and compare mantle cavity tissues (i.e., tissue enclosed by mantle: mantle, adductor muscle, pedal protractor, pedal retractor, gill, foot, labial palp) and visceral organs (i.e., internal organs: esophagus, digestive diverticulum, stomach, crystalline style sac, intestine, heart, nephridium, cerebral ganglia, pedal ganglia, visceral ganglia, ovaries and testes). We also present a synoptical review of pertinent literature on histological anatomy of unionids. The present study (i) represents the first histological atlas for freshwater mussels, (ii) comprises a baseline for monitoring mussel health in aquatic ecosystems, and (iii) could assist future workers studying freshwater mussel physiology, life history, toxicology, pathology, systematics and ecology.
Summary
1. Life histories of the highly diverse and endangered North American freshwater mussel fauna are poorly known. We investigated reproductive traits of eight riverine mussel species in Alabama ...and Mississippi, U.S.A.: Amblema plicata, Elliptio arca, Fusconaia cerina, Lampsilis ornata, Obliquaria reflexa, Pleurobema decisum, Quadrula asperata and Q. pustulosa, and compare our results with existing life history information for other species.
2. These eight species had reproductive traits characteristic of large, outcrossing populations: hermaphrodites were rare, we found no evidence of protandry, and sex ratios were even or slightly male‐biased.
3. Age at sexual maturity varied among species, ranging from <1 to 2 years for L. ornata to 3–9 years for Q. asperata. In all species, most mature females participated in reproduction and fertilisation success was high.
5. Fecundity was related positively to both length and age, but length was the best predictor. In six species, fecundity increased exponentially with increasing size; in two species the rate of increase in fecundity declined in larger animals. In four species, fecundity declined in older animals. These latter results indicate weak reproductive senescence; however, in all species, older individuals continued to produce large numbers of offspring. Mean annual fecundity differed widely among species ranging from 9647 to 325 709. Within‐species differences in fecundity were found among rivers and among populations within a river.
6. The wide variation in reproductive traits among species indicates the existence of widely divergent life history strategies in freshwater mussels.
The new agaricoid species Inocybe aureocitrina , belonging to section Rimosae , is described and illustrated based on morphological and ecological characters. It is recognized by the pale citrine ...yellow when young to golden yellow or orange yellow pileus colour at maturity, habitat in evergreen oak calcareous forests and especially by the rather small spores, broadly ellipsoid and not reniform in profile. A comparison with the holotypes of two close taxa with yellowish colours, e.g. Inocybe obsoleta var. lutea and Inocybe fastigiata var. cerina , is presented. Illustrations of the macro- and micro-morphological features of this new species are given.
The following new taxa are described from China: Direnaia, n. gen., with one new species, D. quadripunctata, n. sp. and Xaniona, n. gen., with two new species, Xaniona galacta, n. sp. (type species) ...and X. cerina, n. sp.
The micropropagation of Gentiana cerina and G. corymbifera was investigated. Cultures were initiated from axillary shoots or seed. Seeds of G. corymbifera germinated on a Murashige & Skoog (MS) ...medium containing 100 mg/litre gibberellic acid (GA3) with 54% of the seed germinating within 70 days. In the absence of GA3 germination did not exceed 5%. Both species proliferated shoots on MS medium supplemented with 6-benzylaminopurine (BAP). For G. cerina there was no significant difference in proliferation rates for BAP concentrations between 0.05 and 0.5 mg/litre. In contrast G. corymbifera gave highest multiplication rates on 0.2 mg/litre BAP. Addition of 1 mg/litre GA3 to the medium gave improved proliferation compared to treatments in which GA3 was absent. The best treatment for G. cerina resulted in a shoot multiplication rate in excess of 7-fold after 50 days whereas for G. corymbifera this increase was more than 3-fold. Root initiation occurred on MS medium supplemented with indole-3-butyric acid (IBA). In both species the frequency of explants with roots increased with increasing IBA concentration, but at IBA ≥ 1 mg/litre and 3 mg/ litre for G. cerina and G. corymbifera respectively a high proportion of the plants developed a basal callus. Survival of the G. cerina plants during acclimatisation was related to IBA concentration but survival was unrelated to IBA concentration for G. corymbifera. G. cerina survival rates decreased from 80% with up to 0.3 mg/litre IBA to c. 5% at the highest rate of IBA. For G. corymbifera average survival of plants after acclimatisation was just over 20%. Thus root initiation with 0.3 mg/litre IBA can be recommended for both species.
The results of a preliminary antifungal screening of the methanol extracts and the major anthraquinone aglycones, alizarin and emodin, of
Rubia tinctorum and
Rhamnus frangula in comparison with the ...antifungal activity of the anthraquinone-containing lichen
Caloplaca cerina and its main secondary metabolite parietin are reported.
We examined seasonal patterns of abundance of mussel larvae (glochidia) in stream drift in a diverse, large-stream mussel assemblage in the Sipsey River, Alabama, across 1 y. We used recently ...developed techniques for glochidial identification combined with information about mussel fecundity and benthic assemblages to evaluate how well observed glochidial abundance corresponded to expected abundance based on glochidial production. Glochidia from short-term brooding species (Amblema plicata, Elliptio arca, Fusconaia cerina, Pleurobema decisum, Obliquaria reflexa, and Quadrula asperata) were abundant from May to August but did not occur in drift between November and the end of April. Long-term brooders (Lampsilis spp., Medionidus acutissimus, Obovaria unicolor, and Villosa spp.) occurred in several short peaks in spring, summer, and autumn, but generally were less abundant than short-term brooders. We estimated that the benthic assemblage at our study site produced >500,000 glochidia/m2 annually and production varied widely among species. Abundance of species in the drift was positively related to benthic abundance but was only weakly related to glochidial production. The poor relationship between glochidial production and abundance in the drift suggests that release and transport of glochidia are influenced by a wide variety of abiotic and biotic factors.
We investigated host fishes, timing and modes of glochidial release, and host-attraction strategies for 7 species of freshwater mussels from the Buttahatchee and Sipsey rivers (Mobile Basin), Alabama ...and Mississippi, USA. We determined hosts as fish species that produced juvenile mussels from laboratory-induced glochidial infections. We established the following primary mussel/host relationships:Elliptio arcawithEtheostoma artesiaeandPercina nigrofasciata;Fusconaia cerinawith 6 species of minnows (Cyprinidae);Lampsilis ornatawithMicropterus salmoides;Medionidus acutissimuswith 8 species of darters (Percidae);Obovaria unicolorwithAmmocrypta beani,A. meridiana, andEtheostoma artesiae;Pleurobema decisumwithCyprinella venusta; andQuadrula asperatawithIctalurus punctatus. For most mussel species, host use was similar to that of closely related species, indicating that, in general, this trait is highly conserved at the generic level. Four mussel species used host-attraction strategies that targeted their specific host fish.Fusconaia cerinaandP. decisumreleased glochidia in conglutinates that elicited feeding responses from fishes in the field and in the laboratory. Gravid femaleLampsilis ornataandM. acutissimusdisplayed mantle lures. Host-attraction strategies were less apparent forE. arcaandQ. asperata, but these species released glochidia in association with copious mucous secretions, which may serve to entangle fishes, facilitating host infection. No host-attraction strategy was apparent forO. unicolor.
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