Host Genera Research Articles

Morphology and phylogeny reveal two novel Coryneum species from China.

Coryneum is currently the sole genus of Coryneaceae in Diaporthales, distinguished from other diaporthalean genera by transversely distoseptate brown conidia. However, Coryneum species are presently difficult to identify because of variability and overlap of morphological characters and the lack of sequence data for most described species. During fungal collection trips in China, 13 Coryneum isolates were obtained from cankered branches of Ilex and Quercus. Morphological and phylogenetic analyses (ITS, LSU, TEF1-α and RPB2) revealed that these strains belong to two new species (viz. Coryneumilicissp. nov. and C.songshanensesp. nov.), and three known species, C.gigasporum, C.sinense, and C.suttonii. Coryneumilicis has larger conidia and more distosepta than most Coryneum species. Coryneumsongshanense was similar to C.sinense from the same host genus, Quercus, in conidial length, but distinct in conidial width and by molecular data.

The salivary transcriptome ofLimnobdella mexicana(Annelida: Clitellata: Praobdellidae) and orthology determination of major leech anticoagulants

Bloodfeeding requires several adaptations that allow the parasite to feed efficiently. Leeches and other hematophagous animals have developed different mechanisms to inhibit hemostasis, one of the main barriers imposed by their hosts. Limnobdella mexicana is a member of the leech family Praobdellidae, a family of host generalists known for their preference to attach on mucosal membranes of mammals, such as those in nasopharyngeal cavities, bladders and ocular orbits. Previous studies have hypothesized a positive relationship between diversity of anticoagulants and diversity of hosts in bloodfeeding leeches. However, orthology determination of putative anticoagulants and the lack of standardization of sequencing effort and method hinder comparisons between publicly available transcriptomes generated in different laboratories. In the present study, we examine the first transcriptome of a praobdellid leech and identify 15 putative anticoagulants using a phylogeny-based inference approach, amino-acid conservation, Pfam domains and BLAST searches. Our phylogenetic analyses suggest that the ancestral leech was able to inhibit factor Xa and that some hirudins that have been reported in previous studies on leech anticoagulants may not be orthologous with the archetypal hirudin.

Drivers of parasite community structure in fishes of the continental shelf of the Western Mediterranean: the importance of host phylogeny and autecological traits

We explored the relationships between features of host species and their environment, and the diversity, composition and structure of parasite faunas and communities using a large taxonomically consistent dataset of host-parasite associations and host-prey associations, and original environmental and host trait data (diet, trophic level, population density and habitat depth vagility) for the most abundant demersal fish species off the Catalonian coast of the Western Mediterranean. Altogether 98 species/taxa belonging to seven major parasite groups were recovered in 683 fish belonging to 10 species from seven families and four orders. Our analyses revealed that (i) the parasite fauna of the region is rich and dominated by digeneans; (ii) the host parasite faunas and communities exhibited wide variations in richness, abundance and similarity due to a strong phylogenetic component; (iii) the levels of host sharing were low and involved host generalists and larval parasites; (iv) the multivariate similarity pattern of prey samples showed significant associations with hosts and host trophic guilds; (v) prey compositional similarity was not associated with the similarity of trophically transmitted parasite assemblages; and (vi) phylogeny and fish autecological traits were the best predictors of parasite community metrics in the host-parasite system studied.

Population structure of avian malaria parasites.

The geographic distribution of genetic diversity in malaria parasite populations (Apicomplexa: Haemosporida) presumably influences local patterns of virulence and the evolution of host‐resistance, but little is known about population genetic structure in these parasites. We assess the distribution of genetic diversity in the partial Domain I of apical membrane antigen 1 (AMA1) in three mtDNA‐defined lineages of avian Plasmodium to determine spatial population structure and host–parasite genetic relationships. We find that one parasite lineage is genetically differentiated in association with a single host genus and among some locations, but not with respect to other hosts. Two other parasite lineages are undifferentiated with respect to host species but exhibit geographic differentiation that is inconsistent with shared geographic barriers or with isolation‐by‐distance. Additional differentiation within two other lineages is unassociated with host species or location; in one case, we tentatively interpret this differentiation as the result of mitochondrial introgression from one of the lineages into a second lineage. More sampling of nuclear genetic diversity within populations of avian Plasmodium is needed to rule out coinfection as a possible confounding factor. If coinfections are not responsible for these findings, further assessment is needed to determine the frequency of mitonuclear discordance and its implications for defining parasite lineages based on mitochondrial genetic variation.OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at Genbank https://www.ncbi.nlm.nih.gov/genbank/, accession numbers MK965548‐MK965653 and MK929797‐MK930264.

Molecular and morphological reappraisal of Spyridiocolax capixabus (Spyridiaceae, Rhodophyta), a rare endemic parasite from Brazil

Abstract The monotypic red algal parasite genus Spyridiocolax was proposed from material from the coast of Espírito Santo to accommodate Spyridiocolax capixabus, endemic from Brazil. The species is rare, and we performed a morphological reappraisal and the first molecular characterization of S. capixabus. Parasite specimens growing on Spyridia clavata were collected in the type locality, Itaoca Beach, Espírito Santo. Spyridiocolax capixabus forms colorless warts on the branches of S. clavata, and the secondary pit connections were described for the first time. Male, female and tetrasporophytic structures were observed growing in the same host plant. The plastid rbcL sequences of parasite and host were identical. A divergence of one nucleotide was found to the nuclear SSU rRNA gene, suggesting that the parasite retains the chloroplast of its host. Both plastidial and nuclear phylogenies supported the close relationship of S. capixabus and S. clavata. The data obtained corroborate other studies with rhodophycean parasites, which show morphological and molecular similarities between parasites and hosts. To maintain the monophyly of the host genus, the transfer of S. capixabus to Spyridia is proposed here on the basis of morphological and molecular evidence. Our study constitutes a starting point for reinvestigating the red algal parasites in Brazil.

Systematic review and meta-analysis of 50 years of coral disease research visualized through the scope of network theory.

Coral disease research encompasses five decades of undeniable progress. Since the first descriptions of anomalous signs, we have come to understand multiple processes and environmental drivers that interact with coral pathologies. In order to gain a better insight into the knowledge we already have, we explored how key topics in coral disease research have been related to each other using network analysis. We reviewed 719 papers and conference proceedings published from 1965 to 2017. From each study, four elements determined our network nodes: (1) studied disease(s); (2) host genus; (3) marine ecoregion(s) associated with the study site; and (4) research objectives. Basic properties of this network confirmed that there is a set of specific topics comprising the majority of research. The top five diseases, genera, and ecoregions studied accounted for over 48% of the research effort in all cases. The community structure analysis identified 15 clusters of topics with different degrees of overlap among them. These clusters represent the typical sets of elements that appear together for a given study. Our results show that while some coral diseases have been studied considering multiple aspects, the overall trend is for most diseases to be understood under a limited range of approaches, e.g., bacterial assemblages have been considerably studied in Yellow and Black band diseases while immune response has been better examined for the aspergillosis-Gorgonia system. Thus, our challenge in the near future is to identify and resolve potential gaps in order to achieve a more comprehensive progress on coral disease research.

Local habitat, not phylogenetic relatedness, predicts gut microbiota better within folivorous than frugivorous lemur lineages.

Both host phylogenetic placement and feeding strategy influence the structure of the gut microbiome (GMB); however, parsing their relative contributions presents a challenge. To meet this challenge, we compared GMB structure in two genera of lemurs characterized by different dietary specializations, the frugivorous brown lemurs ( Eulemur spp.) and the folivorous sifakas ( Propithecus spp.). These genera sympatrically occupy similar habitats (dry forests and rainforests) and diverged over similar evolutionary timescales. We collected fresh faeces from 12 species (six per host genus), at seven sites across Madagascar, and sequenced the 16S rRNA gene to determine GMB membership, diversity and variability. The lemurs' GMBs clustered predominantly by host genus; nevertheless, within genera, host relatedness did not predict GMB distance between species. The GMBs of brown lemurs had greater evenness and diversity, but were more homogeneous across species, whereas the GMBs of sifakas were differentiated between habitats. Thus, over relatively shallow timescales, environmental factors can override the influence of host phylogenetic placement on GMB phylogenetic composition. Moreover, feeding strategy can underlie the relative strength of host-microbiome coadaptation, with Madagascar's folivores perhaps requiring locally adapted GMBs to facilitate their highly specialized diets.

Generalist host species drive Trypanosoma cruzi vector infection in oil palm plantations in the Orinoco region, Colombia

BackgroundOil palm plantation establishment in Colombia has the potential to impact Chagas disease transmission by increasing the distribution range of Rhodnius prolixus. In fact, previous studies have reported Trypanosoma cruzi natural infection in R. prolixus captured in oil palms (Elaeis guineensis) in the Orinoco region, Colombia. The aim of this study is to understand T. cruzi infection in vectors in oil palm plantations relative to community composition and host dietary specialization by analyzing vector blood meals and comparing these results to vectors captured in a native palm tree species, Attalea butyracea.MethodsRhodnius prolixus nymphs (n = 316) were collected from A. butyracea and E. guineensis palms in Tauramena, Casanare, Colombia. Vector blood meals from these nymphs were determined by amplifying and sequencing a vertebrate-specific 12S rRNA gene fragment.ResultsEighteen vertebrate species were identified and pigs (Sus scrofa) made up the highest proportion of blood meals in both habitats, followed by house mouse (Mus musculus) and opossum (Didelphis marsupialis). Individual bugs feeding only from generalist mammal species had the highest predicted vector infection rate, suggesting that generalist mammalian species are more competent hosts for T. cruzi infection .ConclusionsOil palm plantations and A. butyracea palms found in altered areas provide a similar quality habitat for R. prolixus populations in terms of blood meal availability. Both habitats showed similarities in vector infection rate and potential host species, representing a single T. cruzi transmission scenario at the introduced oil palm plantation and native Attalea palm interface.

Bedbugs Evolved before Their Bat Hosts and Did Not Co-speciate with Ancient Humans

All 100+ bedbug species (Cimicidae) are obligate blood-sucking parasites [1, 2]. In general, blood sucking (hematophagy) is thought to have evolved in generalist feeders adventitiously taking blood meals [3, 4], but those cimicid taxa currently considered ancestral are putative host specialists [1, 5]. Bats are believed to be the ancestral hosts of cimicids [1], but a cimicid fossil [6] predates the oldest known bat fossil [7] by >30 million years (Ma). The bedbugs that parasitize humans [1, 8] are host generalists, so their evolution from specialist ancestors is incompatible with the "resource efficiency" hypothesis and only partially consistent with the "oscillation" hypothesis [9-16]. Because quantifying host shift frequencies of hematophagous specialists and generalists may help to predict host associations when vertebrate ranges expand by climate change [17], livestock, and pet trade in general and because of the previously proposed role of human pre-history in parasite speciation [18-20], we constructed a fossil-dated, molecular phylogeny of the Cimicidae. This phylogeny places ancestral Cimicidae to 115 mya as hematophagous specialists with lineages that later frequently populated bat and bird lineages. We also found that the clades, including the two major current urban pests, Cimex lectularius and C.hemipterus, separated 47 mya, rejecting the notion that the evolutionary trajectories of Homo caused their divergence [18-21]. VIDEO ABSTRACT.

Identification and pathogenicity of Cryphonectriaceae species associated with chestnut canker in China

Cryphonectriaceae species cause serious canker diseases on chestnut, oak and eucalypt trees. Recently, canker symptoms with typical orange fruiting bodies were observed on Chinese chestnut and oak trees in Hebei, Hubei, Shaanxi and Shandong Provinces in China. In the present study, isolates of these fungi were identified based on phylogenetic and morphological evidence, and their pathogenicities were tested on detached chestnut (Castanea mollissima) branches. DNA sequence comparisons of the internal transcribed spacer (ITS) regions and two regions of β‐tubulin (TUB1/TUB2) indicate that these isolates represent five species in the Cryphonectriaceae, viz. Cryphonectria japonica, Cryphonectria parasitica, Aurantiosacculus castaneae sp. nov., Cryphonectria neoparasitica sp. nov. and Endothia chinensis sp. nov. The sexual morph of Aurantiosacculus is discovered for the first time and can be distinguished from the other genera in Cryphonectriaceae by dark brown ascospores and tubiform appendages at both ends. Cryphonectria neoparasitica sp. nov. is different from the other Cryphonectria species by its aseptate ascospores. Endothia chinensis sp. nov. is the sole species in Endothia infecting the host genus Castanea. Additionally, it is much smaller than E. gyrosa and narrower than E. singularis in ascospores. The inoculation results showed that these five Cryphonectriaceae fungi isolated from chestnut or oak are all pathogenic to tested chestnut branches. Cryphonectria parasitica appears to be the most aggressive fungus, followed by C. neoparasitica sp. nov., C. japonica, E. chinensis sp. nov. and A. castaneae sp. nov.

Two new species of Pucciniastrum producing dimorphic sori and spores from northeast of China

During field surveys for rust fungi in northeast of China, rust specimens on Galium (Rubiaceae), Aster, and Kalimeris (Compositae) were found in Jilin and Heilongjiang Provinces. Comparative morphology and phylogenetic analyses with 28S and ITS regions of rDNA showed that these specimens belong to Pucciniastrum, although no telial stage was found and they were different to Pucciniastrum species previously reported from the same host genera. Therefore, the rust fungus on Galium and another on Aster and Kalimeris are described as P. coronisporum and P. verruculosum, respectively. Both new species are mainly characterized by having two types of uredinia producing morphologically different urediniospores, which are intermingled in most of the uredinia. Pucciniastrum coronisporum has echinulate and coronate urediniospores, while those of P. verruculosum are echinulate and verrucose to nail-headed.

Contrasting effects of habitat discontinuity on three closely related fungivorous beetle species with diverging host-use patterns and dispersal ability.

Understanding how landscape structure influences biodiversity patterns and ecological processes are essential in ecological research and conservation practices. Forest discontinuity is a primary driver affecting the population persistence and genetic structure of forest‐dwelling species. However, the actual impacts on populations are highly species‐specific. In this study, we tested whether dispersal capability and host specialization are associated with susceptibility to forest discontinuity using three closely related, sympatric fungivorous ciid beetle species (two host specialists, Octotemnus assimilis and O. crassus; one host generalist, O. kawanabei). Landscape genetic analyses and the estimation of effective migration surfaces (EEMS) method consistently demonstrated contrasting differences in the relationships between genetic structure and configuration of forest land cover. Octotemnus assimilis, one of the specialists with a presumably higher dispersal capability due to lower wing loading, lacked a definite spatial genetic structure in our study landscape. The remaining two species showed clear spatial genetic structure, but the results of landscape genetic analyses differed between the two species: while landscape resistance appeared to describe the spatial genetic structure of the specialist O. crassus, genetic differentiation of the generalist O. kawanabei was explained by geographic distance alone. This finding is consistent with the prediction that nonforest areas act more strongly as barriers between specialist populations. Our results suggest that differences in host range can influence the species‐specific resistance to habitat discontinuity among closely related species inhabiting the same landscape.

Local host-tick coextinction in neotropical forest fragments

Ticks are obligatory parasites with complex life cycles that often depend on larger bodied vertebrates as final hosts. These traits make them particularly sensitive to local coextinction with their host. Loss of wildlife abundance and diversity should thus lead to loss of tick abundance and diversity to the point where only generalist tick species remain. However, direct empirical tests of these hypotheses are lacking, despite their relevance to our understanding of tick-borne disease emergence in disturbed environments. Here, we compare vertebrate and tick communities across 12 forest islands and peninsulas in the Panama Canal that ranged 1000-fold in size (2.6–2811.3 ha). We used drag sampling and camera trapping to directly assess the abundance and diversity of communities of questing ticks and vertebrate hosts. We found that the abundance and species richness of ticks were positively related to those of wildlife. Specialist tick species were only present in fragments where their final hosts were found. Further, less diverse tick communities had a higher relative abundance of the generalist tick species Amblyomma oblongoguttatum, a potential vector of spotted fever group rickettsiosis. These findings support the host-parasite coextinction hypothesis, and indicate that loss of wildlife can indeed have cascading effects on tick communities. Our results also imply that opportunities for pathogen transmission via generalist ticks may be higher in habitats with degraded tick communities. If these patterns are general, then tick identities and abundances serve as useful bioindicators of ecosystem health, with low tick diversity reflecting low wildlife diversity and a potentially elevated risk of interspecific disease transmission via remaining host species and generalist ticks.

Stress-related gene transcription in fish exposed to parasitic larvae of two freshwater mussels with divergent infection strategies.

Freshwater unionoid mussels have a unique life cycle involving a temporary parasitic phase. Their larvae (glochidia) attach to the gills or fins of fish hosts where they remain encysted until metamorphosis into free-living juveniles. The physiological response of fish during the critical period of glochidial attachment is not well understood, but recent work suggests that glochidia retention and survival is enhanced in stressed and cortisol-injected hosts. In this study, the early changes induced by glochidiosis were investigated for the first time at the transcriptional level. In 2 separate experiments, juvenile yellow perch Perca flavescens were inoculated with glochidia of Elliptio complanata (a host generalist) and Lampsilis radiata (a host specialist) following a standardized procedure. The transcriptional levels of 5 genes involved in the fish response to stress were assessed in the host liver and gills 24 h post-infection using quantitative real-time PCR. The number of encysted glochidia did not significantly differ between fish inoculated with E. complanata and L. radiata. Both species induced a 3-fold increase of 70 kDa heat-shock protein gene (hsp70) transcription in host liver. However, only E. complanata influenced the transcription of cortisol-regulated genes, notably glucocorticoid receptor DNA-binding factor 1 (grlf1). This gene, known to modulate tissue responsiveness to cortisol, was downregulated in infected fish compared to controls. Our findings suggest that different glochidia species interact with their fish host in distinct ways. Additional studies are required to address this hypothesis and further investigate the significance of the observed host transcriptional responses.

Anthropogenic and soil environmental drivers of arbuscular mycorrhizal community composition differ between grassland ecosystems

Interactions between arbuscular mycorrhizal fungi (AMF) and plants are sensitive to a myriad of underlying factors, including soil chemistry and land-use disturbances. Here we address how two grassland ecosystems (Ozark glades vs. tallgrass prairies) in south-central USA have been impacted by legacy effects from land-use disturbances (e.g., fire suppression in glades and tillage, fertilizer, row cropping, and grazing in prairies) and geological substrate (acidic versus calcareous bedrock). We surveyed AMF on the roots of two native generalist host species [Ruellia humilis Nutt. and Schizachyrium scoparium (Michx.) Nash] as well as plants randomly selected from the plant community. Glades on calcareous bedrock had a higher pH than those on acidic bedrock, and AMF communities on all three root sample types varied between acidic and calcareous bedrock locations. In prairies, both bedrock types had a similar soil pH, and AMF communities on all three root sample types varied across remnant and disturbed prairies. Shifts in AMF composition across land-use history included shifts in dominant AMF genera, and some unique rare AMF taxa were restricted to only calcareous glades or remnant prairies. Our findings suggest that reseeding prairie plant communities on cultivated lands does not restore AMF communities. Restoration projects need to address the soil environment and community.

The first record of genus Bruggmanniella (Diptera: Cecidomyiidae) from Taiwan with description of a new species inducing bud galls on Neolitsea parvigemma (Lauraceae)

Abstract The genus Bruggmanniella Tavares is newly discovered from Taiwan and Bruggmanniella brevipes sp. n. is described as new to science. This is the southernmost species of Bruggmanniella found in the Old World. Furthermore, the gall midge induces bud galls on Neolitsea parvigemma (Hayata) Kaneh (Lauraceae), an endemic species in Taiwan, and the plant genus Neolitsea is the third host genus of Lauraceae-associated Bruggmanniella in East Asia. The knowledge of its distribution and host information provide us to shed the light on evolutionary and biogeography issue of East Asian Bruggmanniella. www.zoobank.org/urn:lsid:zoobank.org:pub:820320EC-17BC-4E00-A401-2DBDA3EEE9C4

Mortality and Flowering of Great Basin Perennial Forbs After Experimental Burning: Implications for Wild Bees

The fates of native bee communities in the Great Basin sagebrush steppe are linked with the susceptibilities of their floral hosts to increasingly frequent wildfires. Postfire survival and subsequent flowering of six prevalent perennial wildflowers representing five families were quantified across a range of realistic fire severities created using a calibrated propane burn barrel. Five burn prescriptions of varying intensity and duration were applied to cultivated rows of basalt milkvetch (Astragalus filipes Torr. ex A. Gray), Blue Mountain prairie clover (Dalea ornata Eaton & J. Wright), sulphur-flower buckwheat (Eriogonum umbellatum Torr.), fernleaf biscuitroot (Lomatium dissectum Nutt.), blue penstemon (Penstemon cyaneus Pennell), and gooseberryleaf globemallow (Sphaeralcea grossularifolia Hook. & Arn.). Overall differences in their fire sensitivities were maximal at peak fire severity, ranging from 80% survival (L. dissectum) to complete mortality (E. umbellatum and P. cyaneus). Although A. filipes survived well (85%), half of the 95 burn survivors then failed to flower the year after burning. The postfire fate of plant-pollinator interactions is a function of the bees’ nesting habits, their floral host’s sensitivity to a given burn intensity (both in terms of survival and flowering), and the reproductive interdependence of bee and floral host (taxonomic specialists vs. generalists).

Avian malaria on Madagascar: prevalence, biodiversity and specialization of haemosporidian parasites

Previous studies about geographic patterns of species diversity of avian malaria parasites and others in the Order Haemosporida did not include the avian biodiversity hotspot Madagascar. Since there are few data available on avian malaria parasites on Madagascar, we conducted the first known large-scale molecular-based study to investigate their biodiversity. Samples (1067) from 55 bird species were examined by a PCR method amplifying nearly the whole haemosporidian cytochrome b gene (1063 bp). The parasite lineages found were further characterized phylogenetically and the degree of specialization was determined with a newly introduced host diversity index (Hd). Our results demonstrate that Madagascar indeed represents a biodiversity hotspot for avian malaria parasites as we detected 71 genetically distinct parasite lineages of the genera Plasmodium and Haemoproteus. Furthermore, by using a phylogenetic approach and including the sequence divergence we suspect that the detected haemosporidian lineages represent at least 29 groups i.e. proposed species. The here presented Hd values for each parasite regarding host species, genus and family strongly support previous works demonstrating the elastic host ranges of some avian parsites of the Order Haemosporida. Representatives of the avian parasite genera Plasmodium and Leucocytozoon tend to more often be generalists than those of the genus Haemoproteus. However, as demonstrated in various examples, there is a large overlap and single parasite lineages frequently deviate from this rule.

A new species of Rosenscheldia (Dothideomycetes) from Brazil

AbstractA fungus forming black stromata with several immersed ascomata was found associated with living branches of Protium warmingianum (Burseraceae) in the Mata da Biologia, city of Viçosa, Minas Gerais, Brazil. The new species differs from all five species found on literature and is fully described, illustrated and compared with the other species described in the genus. This is the first species of Rosenscheldia found on burseraceae hosts in Brazil and the first species on the host genus Protium.

Can interaction specificity in the fungus-farming termite symbiosis be explained by nutritional requirements of the fungal crop?

Fungus-growing termites are associated with genus-specific fungal symbionts, which they acquire via horizontal transmission. Selection of specific symbionts may be explained by the provisioning of specific, optimal cultivar growth substrates by termite farmers. We tested whether differences in in vitro performance of Termitomyces cultivars from nests of three termite species on various substrates are correlated with the interaction specificity of their hosts. We performed single-factor growth assays (varying carbon sources), and a two-factor geometric framework experiment (simultaneously varying carbohydrate and protein availability). Although we did not find qualitative differences between Termitomyces strains in carbon-source use, there were quantitative differences, which we analysed using principal component analysis. This showed that growth of Termitomyces on different carbon sources was correlated with termite host genus, rather than host species, while growth on different ratios and concentrations of protein and carbohydrate was correlated with termite host species. Our findings corroborate the interaction specificity between fungus-growing termites and Termitomyces cultivars and indicate that specificity between termite hosts and fungi is reflected both nutritionally and physiologically. However, it remains to be demonstrated whether those differences contribute to selection of specific fungal cultivars by termites at the onset of colony foundation.