Freshwater mites of the family Unionicolidae are associated with freshwater mussels and snails in lakes and streams on all continents except Antarctica. The majority of the currently known 265 Unionicolidae species are associated with molluscs during at least one stage of their life cycle. A new host record is presented here from India: Unionicola (Myanamaratax) savadiensis from the host Lamellidens corrianus. In addition to L. corrianus, U. savadiensis was also found associated with two other mussel species, i.e., Lamellidens marginalis and Corbicula cashmiriensis, but DNA evidence confirms parasite-host association between U. (M.) savadiensis and L. corrianus, indicating that its findings in the two other mussel species should be considered as 'vagrant' associations. This report is thus significant for two reasons: (i) the record of the new host and geographic associations of the mite and mussels extends our knowledge on the known mite-mussels associations, and (ii) the study emphasized the importance of including experts from acarology, malacology, and molecular biology, to ascertain the nature of mite-mussel associations.

Here we describe a new subgenus and three new species of parasitic water mites in the genus Unionicola (Acari: Hydrachnidia) from Myanmar: Myanmaratax subgen. nov., Unionicola (Myanmaratax) savadiensis subgen. and sp. nov. (hosts: Lamellidens savadiensis and L. generosus), U. (My.) generosa sp. nov. (the same hosts), and U. (My.) trapezidens sp. nov. (hosts: Trapezidens dolichorhynchus and T. angustior). These taxa were identified based on a two-gene phylogenetic analysis (COI + 28S), which also confirms the division of the genus Unionicola into numerous subgenera. The new species are cryptic species, which are morphologically indistinguishable but strongly resemble U. (Prasadatax) brandti Vidrine, 1985 described from Thailand (hosts: Lens spp. and Ensidens spp.). We also transfer the latter taxon from Prasadatax to Myanmaratax based on a set of morphological evidence and propose U. (My.) brandti comb. nov. The new subgenus contains a total of five species, one of which needs future sampling efforts and will be described elsewhere. Additionally, 56 valid subgenera, which were placed in the synonymy of the genus and in one case raised to the genus level, are restored here until robust phylogenetic evidence on their taxonomic status is available. Our results also confirm that Unionicola mites are narrow host specialists that are associated with either one or a few closely related freshwater mussel species belonging to one or two sister genera.

Freshwater pearl mussels (Bivalvia: Margaritiferidae) are among the most imperiled groups of animals globally. While the parasites and symbionts of the Margaritiferidae are rather poorly known, these mussels were thought to be free of parasitic mites (Acari: Unionicolidae: Unionicola). Here, we report on the discovery of a mite species being associated with the endangered freshwater pearl mussel Gibbosula laosensis (Lea, 1863) from Myanmar. This species, Unionicola (Gibbosulicola) sella subgen. & sp. nov., morphologically resembles mites belonging to the subgenera Coelaturicola and Fulleratax (African and Southeast Asian groups, respectively). Our novel discovery expands the host range of Unionicola mites and reveals that all freshwater mussel families of the order Unionida host these aquatic mites. Our phylogenetic research and available published data reveal that the mussel-associated mite assemblage in Southeast and South Asia contains not less than 17 species and 8 subgenera. Currently, the regional taxonomic richness of this group seems to be largely underestimated. We found that mussel mites from Southeast Asia are narrow host specialists, which are known to occur in a single or a few closely related species belonging to one or two sister genera of freshwater mussels. Finally, our results indicate that mussel mites share generally restricted ranges and that their distribution patterns in Southeast Asia are largely congruent with the boundaries of biogeographic subregions delineated on the basis of phylogenetic studies of freshwater mussels.

Water mites of the genus Unionicola are common parasites of freshwater mussels, living on the gills or mantle of their hosts and using these tissues as sites of oviposition. Although surveys of this mite fauna among North American unionid mussels indicate that these mites represent highly diverse assemblages, we know very little regarding the determinants of Unionicola species diversity among their molluscan hosts. The present study addresses the relationship between host diversity and mite diversity for Unionicola assemblages associated with unionid mussels of North America. The results of this study found a significantly positive relationship between host species richness and mite species richness, adding to a growing body of evidence that host diversity is an important determinant of parasite diversity. In recent years, molecular sequence data have discovered cryptic biodiversity among unionid mussels, yielding revisions in the nomenclature and systematic taxonomy of the group. DNA sequence variation has also revealed cryptic species complexes among Unionicola mites. Collectively, these findings suggest that the results of the present study may be underestimating species richness among mites and their host mussels. Unfortunately, human perturbations are known to have caused high recent rates of extinction in the mussel and mite faunas of North America and could play a major role in influencing patterns of species richness for this host-parasite system moving forward.

Water mites of Unionicola species are common symbionts of freshwater mussels, living on the gills or mantle and foot of their hosts and using these tissues as sites of oviposition. Although surveys of the mite fauna among North American mussels suggest that these mites represent highly diverse assemblages, there are currently no quantitative data characterizing Unionicola species diversity among their molluscan hosts. The present study addresses patterns of species richness of Unionicola assemblages from freshwater mussels, including the relationship between richness and host specificity among these mites. Results from this study indicate that mite species richness increased significantly with an increase in the number of host individuals sampled. When corrected for sampling effort, there was a positive relationship between host size and mite species richness. Results from this study also reveal a significant relationship between mite species richness and the geographical distribution of host mussels. Overall, the patterns of species richness observed for this study are consistent with those examining the richness of parasitic helminth communities. Because the phylogenetic history of host taxa can have a significant influence on patterns of parasite species richness, studies that correct for the phylogenetic history among host mussels will be required to better understand the role that evolutionary processes have in determining Unionicola species richness. The present study did not indicate a significant relationship between species richness and host specificity and, in not doing so, suggests that the dispersal ability of mites may also play a role in influencing Unionicola species richness. The host recognition behavior and swimming abilities for a larger sample of mites will be required to substantiate this hypothesis.

Water mites of the genus Unionicola Haldeman, 1842 are common symbionts of molluscs, living on the gills or mantle and foot of their hosts and using these tissues as sites of oviposition. Phylogenetic relationships among species that comprise the genus are poorly understood and what is known has been based on a limited number of morphological and life history characters or molecular sequence data using closely-related taxa. The present study uses sequence data from the cytochrome oxidase subunit I (cox1) gene (664 bp) to reconstruct evolutionary relationships among representative species of North American Unionicola from eight subgenera that occur in symbiotic association with freshwater mussels. Maximum parsimony and maximum likelihood analysis yielded trees with similar topologies, and most of the branches have moderate to high bootstrap support. The topologies of these gene trees are mostly congruent with a previously published morphologically-derived tree. Specifically, the gene trees support monophyly among mites from subgenera that occur in association with the gill tissues of host mussels. The molecular trees of Unionicola mites generated by this study must, however, be interpreted with caution, given that the analysis is based exclusively on Unionicola subgenera from North America. A more robust phylogeny of Unionicola mussel-mites will require the addition of molecular sequence data from taxa outside of North America.

The genus Unionicola Haldeman, 1842 contains 56 subgenera (Smit, 2008). The subgenus Polyatacides Lundblad, 1941 a was originally created as a genus. Cook (1974) reduced the taxon to subgenus. Vidrine (1986a) eliminated the subgenus, and placed its only species, U. prominens Koenike, 1914, into the subgenus Atacella Lundblad, 1937. Vidrine (1996) resurrected the subgenus Polyatacides in the genus Unionicola. This paper supports that change and re-evaluates Polyatacides, Atacella, and Berezatax Vidrine 1986b: the three subgenera have dorsoventrally flattened pedipalps and form a distinctive Artenkreis of gill mites in the Americas.

Unionicola (Wolcottatax) weni n. sp. (Acari: Hydrachnidia: Unionicolidae) is described from freshwater mussels Arconaia lanceolata from Nanchang, Jiangxi Province, China. The new mite resembles U. fengchengensis Wen and Zhu, 1996, but it can be distinguished by the number of genital acetabula and the morphology of the tarsus of the fourth walking legs. Both species are readily distinguished from U. arcuata (Wolcott, 1898) and U. arcuatoides Vidrine, 1986 by the shape of the tarsal claws and the morphology of the walking legs. Unionicola arcuatoides, previously known only from Japan, is reported from Acuticosta chinensis from Nanchang, Jiangxi Province, China.

Unionicola (Coelaturicola) edwardsi n. sp. (Acari: Hydrachnidia: Unionicolidae) is described from freshwater mussels, Chambardia moutai (Dartevelle, 1939) (Unionoida: Iridinidae), from the Cunene River Basin, Provincia da Huila, Cape Longo, upper Onquenha River, Angola, Africa. The new species has unique and distinctive male genital field morphology. The species illustrates sexual dimorphism in the chaetotaxy of the first and fourth walking legs. It further extends our knowledge of host-specificity among the Unionicola. Also, new host and geographic records are reported for Unionicola (Mutelicola) blayi Gledhill and Vidrine, 2002, and U. (Coelaturicola) gledhilli Vidrine et al., 2007b.

Water mites of the subgenus Dimockatax (Unionicolidae: Unionicola) are common inhabitants of anodontine bivalve molluscs. Morphological differences among the five species that comprise the subgenus are minor and based primarily on subtle differences in one or two characters. The newly described species Unionicola ernstingi (Edwards et al., 2008) is distinguished from its sibling species U. tumida (Wolcott, 1898) by the number of clawlets on the tarsus of the pedipalps. These mites have been reported from the same locality, although they inhabit distinct species of host mussels. Unionicola ernstingi occurs with Anodontoides radiatus (Conrad, 1834), and U. tumida is found in association with Strophitus subvexus (Conrad, 1834). Taxonomic delineations among Unionicola mussel-mites parasitizing different species of hosts have, however, been challenged by the suggestion that morphological differences between mites may be influenced by the host species in which they metamorphosed. To test the validity of the species status for Dimockatax mites from A. radiatus and S. subvexus, heterogeneity in sequence data of the cox1 gene was examined. A comparison of cox1 sequences for U. tumida from S. subvexus and U. ernstingi from A. radiatus revealed a high degree of differentiation (12.7%). The genetic differences observed for U. ernstingi and U. tumida are consistent with those observed for other closely related, yet morphologically distinct species of Unionicola reported from different species of host mussel and thus complement morphological data recognizing them as valid species.

Unionicola (Dimockatax) ernstingi n. sp. (Acari: Hydrachnidia: Unionicolidae) is described from freshwater mussels, Anodontoides radiates (Conrad, 1834), from Twelve Mile Creek, St. Helena Parish, Louisiana, USA. The suspected sibling species, U. tumida (Wolcott, 1898), occurred in the same locality in another mussel species, Strophitus subvexus (Conrad, 1834). Unionicola ernstingi is distinguished from other North American members of the subgenus by the number of clawlets on the tarsus of the pedipalps. It closely resembles U. tumidoides (Vidrine, 1986) from Asia, but it is distinctive in body size and chaetotaxy of the first walking legs. The pedipalp morphology, body size, and chaetotaxy of the first walking legs are used to separate the five currently known species in the subgenus Dimockatax Vidrine, 1992.

Abstract Unionicola (Coelaturicola) gledhilli n. subgen., n. sp. (Hydrachnida: Unionicolidae) is described from freshwater mussels, Coelatura kunenensis Mousson, 1887 (Unionoida: Unionidae) from the Okavango River, Botswana, and Chambardia nyassaensis (Lea, 1864) (Unionoida: Iridinidae) from Lake Malawi, Malawi, East Africa. The new species has distinctive coxal plate and genital field morphologies. This new mite extends our understanding of the morphology and biogeography of the genus in Africa and the Southern Hemisphere. It further extends our knowledge of host selection and host-specificity among the Unionicola.

The genus Unionicola Haldeman in the family Unionicolidae is distributed worldwide, with more than half of the known species recorded as parasites of freshwater mussels (Mollusca: Bivalvia: Unionoida). Re-evaluation of the morphology and biogeography of the genus in Africa, Australia and South America extends our knowledge of host selection and host-specificity among Unionicola. New host and geographic records for Unionicola (Kovietsatax) walkeri Viets are Velesunio angasi in Western Australia The subgenus Australatax Vidrine is re-evaluated. A new subgenus, Hyricola n. subgen., is erected for Australian members of the subgenus Australatax sensu lato. Discrete differences in leg chaetotaxy, pedipalp morphology, and female genital field chaetotaxy clearly separate the newly redefined Australatax from Hyricola. These changes provide an opportunity to re-evaluate all the gill mites in the Southern Hemisphere.

Morphological differences among species of parasitic water mites in subgenus Parasitatax (Unionicolidae: Unionicola) are comparatively minor, with taxonomic distinctions among most members of the taxon based on subtle differences in one or two morphological characters. Two species of the subgenus, Unionicola formosa Dana and Whelpley, 183 6 and U. foili Edwards and Vidrine, 1994 are morphologically indistinguishable and have been designated separate species on the basis of host specificity and allozyme analysis. The present study examines heterogeneity in sequence data of the mitochondrial cytochrome oxidase subunit I (COI) gene among four putative species of the subgenus Parasitatax: U. dimocki Vidrine, 1986, U.foili, U.formosa, and U.ypsilophora Bonz, 1783. Because populations of U.formosa from different species of host mussels are genetically divergent, intraspecific diversity of the COI gene among host-associated populations of U. formosa was also examined. DNA sequence data was used to construct a phylogenetic hypothesis for the group and assess the degree to which a phylogeny based on molecular data is consistent with traditional taxonomy. Maximum parsimony and maximum likelihood analysis each yielded a single tree with the same topology and high bootstrap support. The gene tree indicates two major clades, with U. dimocki and U.ypsilophora forming one clade and U. foili along with host-associated populations of U. formosa forming the other. The latter clade resolved into two branches and indicated that one host-associated population of U. formosa is more closely related to U. foili than it is to other host-associated populations of U. formosa.

Water mites of Unionicola spp. are common parasites of freshwater mussels as adults, living on the gills, or mantle and foot of their hosts and using these tissues as sites of oviposition. The present study addresses specialization among North American Unionicola mussel-mites using 2 measures of host specificity: (1) the number of host species used by a species of mite; and (2) a measure that considers the taxonomic distinctness of the hosts utilized by mites, weighted for their prevalence in the different hosts. Results of this study indicate the Unionicola spp. mussel-mites are highly host specific, with most species occurring in association with 1 or 2 species of hosts. If 2 or more host species are utilized, they are typically members of the same genus. These data are consistent with studies examining the dispersal abilities and host recognition behavior for members of the group. When the average values of host specificity for Unionicola subgenera were mapped on a phylogenetic tree for these taxa, a clade comprised of gill mites appeared to be more host specific than a clade consisting of mantle mites. There were, however, no apparent patterns of host specificity within each of the clades. Differences in specificity between the 2 lineages may reflect either a long evolutionary history that gill mites have had with host mussels or the intense competition among gill mites for oviposition sites within unionid mussels, leading to increased host specialization.

Unionicola (Iridinicola) botswaniana n. subgen., n. sp. (Hydrachnida: Unionicolidae) is described from freshwater mussels, Mutela zambesiensis and Aspatharia pfeifferiana, from Okavango River, Botswana, Africa. The new species is a unique mite with distinctive female genital field anatomy and leg chaetotaxy. This new mite extends our understanding of the morphology and biogeography of the genus in Africa. It further extends our knowledge of host selection and host-specificity among African Unionicola.

ABSTRACT This paper focused on the evaluation of undergraduate study programs in agriculture for a selected group of universities from Louisiana and Texas in the US, and France and Italy. Eight samples of graduating students (n = 20) from each institution participated in a quantitative survey. Qualitative data were collected through interviews with sixteen respondents (one faculty member and one administrator of each university). A document analysis review provided more qualitative data on the foundations of agricultural curricula at these institutions and other schools around the world. Such a variety of data collection methodologies allowed for a triangulation of the results, which enhanced the validity of the study. Every university recognized the emergence of a sustainable agriculture model, despite the curricular diversity across national borders and the different levels of sensitivity toward the issue. Although more work is needed to incorporate sustainable agriculture principles in the agricultural curriculum, various recommendations are suggested. This work contributes to the promotion of an emerging sustainable agriculture philosophy.