Molecular phylogeny of major lineages of Trichadenotecnum and a review of diagnostic morphological characters (Psocoptera: Psocidae)

Abstract. Phylogenetic relationships among species groups of Trichadenotecnum were inferred based on morphology and the partial sequences of five gene regions (mitochondrial 12S rDNA, 16S rDNA, cytochrome oxidase I, NADH dehydrogenase subunit 5 and nuclear 18S rDNA). All analyses supported the monophyly of Trichadenotecnum and all previously proposed species groups, except that T. circularoides was excluded from the spiniserrulum group. To examine the phylogenetic usefulness of morphological data, the morphological characters used in the construction of an earlier taxonomic system for Trichadenotecnum were mapped parsimoniously on the molecular tree. As a result: (1) commonly used forewing marking features (sparsely or extensively spotted) are considered to be very homoplastic and less informative of higher‐level phylogenetic relationships; (2) a broadly expanded epiproct lobe is considered to be independently evolved at least two or three times, and a detailed morphological re‐examination allows recognition of these convergent structures; (3) the short ventral valve of gonapophyses independently evolved at least three or four times, although this character was used initially to diagnose the spiniserrulum group.     

A Cladistic Analysis of Mitochondrial Ribosomal DNA from the Bovidae

There is a huge data base of genetic information for the domestic artiodactyl speciesBos taurus(cow),Ovis aries(sheep), andCapra hircus(goat). However, the phylogenetic relationships of these economically critical taxa and their close relatives, family Bovidae, remain for the most part unresolved. In this report, we aligned new mitochondrial (mt) 12S and 16S ribosomal (r) DNA sequences from 26 bovid taxa with published sequences. Phylogenetic analyses of the more than 64 kilobases of mt rDNA from 57 taxa support a basal division in the Bovidae that separatesBosand its close relatives fromCapra, Ovis,and their kin. As suggested by previous molecular and morphological studies, “antelopes” are a paraphyletic assemblage. Caprinae (sheep, goats, goat antelopes, and musk oxen) groups consistently with hippotragine and alcelaphine antelopes, while Bovini (cattle and buffaloes) clusters with tragelaphine and boselaphine antelopes. The traditional tribal subdivisions of Bovidae are supported in most cases, but there are exceptions within Caprinae and Antilopinae (gazelles and close relatives). The rDNA data consistently place the enigmatic generaPelea, Pantholops,andSaiga,but the origin ofAepyceros,the impala, remains obscure. Combined phylogenetic analyses of the rDNA data with the skeletal characters of Gentry (1992) were used to assess the stability of the molecular results.     

Using 18S rDNA to resolve diaptomid copepod (Copepoda: Calanoida: Diaptomidae) phylogeny: an example with the North American genera

The phylogenetic relationships among the numerous genera of diaptomid copepods remain elusive due to difficulties in obtaining sufficient numbers of phylogenetically informative morphological characters for cladistic analysis. Molecular phylogenetic techniques offer high potential to resolve phylogenetic relationships in the absence of sufficient morphological characters because of the ease in which many characters can be unambiguously coded. I present the first molecular phylogeny for diaptomid copepod genera using 18S rDNA. Specifically, I test Light’s (1939) hypothesis regarding the interrelationships among the North American diaptomid genera. The 18S phylogeny is remarkably consistent with Light’s hypothesis. The endemic North American genera represent a monophyletic group exclusive of the non-endemic genera. Moreover, his hypothesized basal genus for the North America genera, Hesperodiaptomus, is the basal genus in this analysis. However, his Leptodiaptomus group is not reciprocally monophyletic with his Hesperodiaptomus group, but is rather a derived member of the latter group. Finally, the genus Mastigodiaptomus is found to be more closely allied with the non-endemic genera, as Light suggested. This phylogeny contributes heavily to the understanding of phylogenetic relationships among North American diaptomids and has large implications for the systematics of diaptomids in general. The use of 18S rDNA sequences in phylogenetic analyses of diaptomid copepods can be used to confirm the monophyly of recognized genera, the interrelationships among genera, and subsequent biogeographic interpretation of the family’s diversification. The use of molecular data, such as 18S rDNA sequences, to test phylogenetic hypotheses based on a very limited number of morphological characters will be a particularly useful approach to phylogenetic analysis in this system.     

Phylogenetic relationships of Chalara and allied species inferred from ribosomal DNA sequences

The phylogenetic relationships of Chalara and allied taxa are studied based on ribosomal DAN sequences. Partial 28S rDNA and 18S rDNA regions from 26 strains were sequenced in this study. These and related sequences from GenBank were analyzed using parsimony and Bayesian analyses. Most of the Chalara species clustered in a strongly supported monophyletic lineage representing Helotiales. However, a few Chalara species appeared closely related to Xylariales. The phylogenetic significance of morphological characters observed in Chalara species are evaluated based on our sequence analyses. Conidial septation, conidial width and conidiophore pigmentation are thought to be indicative in understanding their evolutionary relationships. Sterile setae, which traditionally have been used to delimitate Chaetochalara from Chalara, are phylogenetically insignificant.     

Phylogenetic relationships of Steinernema Travassos, 1927 (Nematoda: Cephalobina: Steinernematidae) based on nuclear, mitochondrial and morphological data

Entomopathogenic nematodes of the genus Steinernema are lethal parasites of insects that are used as biological control agents of several lepidopteran, dipteran and coleopteran pests. Phylogenetic relationships among 25 Steinernema species were estimated using nucleotide sequences from three genes and 22 morphological characters. Parsimony analysis of 28S (LSU) sequences yielded a well-resolved phylogenetic hypothesis with reliable bootstrap support for 13 clades. Parsimony analysis of mitochondrial DNA sequences (12S rDNA and cox 1 genes) yielded phylogenetic trees with a lower consistency index than for LSU sequences, and with fewer reliably supported clades. Combined phylogenetic analysis of the 3-gene dataset by parsimony and Bayesian methods yielded well-resolved and highly similar trees. Bayesian posterior probabilities were high for most clades; bootstrap (parsimony) support was reliable for approximately half of the internal nodes. Parsimony analysis of the morphological dataset yielded a poorly resolved tree, whereas total evidence analysis (molecular plus morphological data) yielded a phylogenetic hypothesis consistent with, but less resolved than trees inferred from combined molecular data. Parsimony mapping of morphological characters on the 3-gene trees showed that most structural features of steinernematids are highly homoplastic. The distribution of nematode foraging strategies on these trees predicts that S. hermaphroditum, S. diaprepesi and S. longicaudum (US isolate) have cruise forager behaviours.     

Phylogeny of Glaucosomatidae inferred from molecular evidence

Most species of glaucosomatids (Teleostei: Glaucosomatidae) are endemic to Australia, except Glaucosoma buergeri that is widely distributed from Australia to Japan. This study elucidated phylogenetic relationships among glaucosomatids based on the morphological characters of the saccular‐otolith sagitta, in addition to molecular evidence of mitochondrial 16S rDNA, cytochrome oxidase I (COI) and cytochrome b (cyt b) sequences, and nuclear rhodopsin sequences. The topologies of individuals' phylogenetic trees, based on 16S rDNA, COI and cyt b sequences, were statistically indistinguishable from one another, and were only slightly different from a tree based on rhodopsin sequences. These molecular tree topologies, however, differed from species relationships in morphology‐based phylogenetic hypothesis proposed in previous studies. Specimens of G. buergeri from Australia and Taiwan showed differences in the sagitta and molecular differentiation at the four genes, suggesting a possible speciation event. Both molecular and morphological evidences indicate that Glaucosoma magnificum is the plesiomorphic sister species of other glaucosomatid species. Glaucosoma hebraicum is the sister species of a clade composed of G. buergeri and Glaucosoma scapulare. Molecular and morphological evidences also support the species status of G. hebraicum.     

基于叶绿体16S rRNA的绿色裸藻类系统发育及性状进化研究

该研究基于叶绿体16S rRNA基因序列,构建绿色裸藻类的系统发育树,并对绿色裸藻类植物8个形态性状进行祖先重建分析,以明确绿色裸藻类植物的系统演化关系,为研究该类植物的起源提供理论依据。结果表明：(1)贝叶斯法构建的绿色裸藻类系统发育树显示,双鞭藻属与拟双鞭藻属互为姐妹群,扁裸藻属、鳞孔藻属和盘裸藻属亲缘关系较近,而囊裸藻属和陀螺藻属亲缘关系较近,裸藻属、隐裸藻属、柄裸藻属和旋形藻属亲缘关系较近,表明裸藻属不是一个单系类群。(2)基于形态性状的祖先重建结果显示,绿色裸藻类相对原始的7个性状包括：表质柔软易变形,出现螺旋形线纹,细胞后端渐尖或尖尾刺状,无囊壳,叶绿体为片状、盾状或大盘状,具无鞘蛋白核,副淀粉粒为小颗粒状且数量不定,而鞭毛长度不能推断可能的祖先状态。(3)综合8种性状祖先重建结果发现,裸藻属和眼裸藻属植物具有所有原始性状,可能是最先出现的绿色裸藻类的祖先。     

Evolution of 28S Ribosomal DNA in Chaetognaths: Duplicate Genes and Molecular Phylogeny

The chaetognaths are an extraordinarily homogeneous phylum of animals at the morphological level, with a bauplan that can be traced back to the Cambrian. Despite the attention of zoologists for over two centuries, there is little agreement on classification within the phylum. We have used a molecular biological approach to investigate the phylogeny of extant chaetognaths. A rapidly evolving expansion segment toward the 5′ end of 28S ribosomal DNA (rDNA) was amplified using the polymerase chain reaction (PCR), cloned, and sequenced from 26 chaetognath samples representing 18 species. An unusual finding was the presence of two distinct classes of 28S rDNA gene in chaetognaths; our analyses suggest these arose by a gene (or gene cluster) duplication in a common ancestor of extant chaetognaths. The two classes of chaetognath 28S rDNA have been subject to different rates of molecular evolution; we present evidence that both are expressed and functional. In phylogenetic reconstructions, the two classes of 28S rDNA yield trees that root each other; these clearly demonstrate that the Aphragmophora and Phragmophora are natural groups. Within the Aphragmophora, we find good support for the groupings denoted Solidosagitta, Parasagitta, and Pseudosagitta. The relationships between several well-supported groups within the Aphragmophora are uncertain; we suggest this reflects rapid, recent radiation during chaetognath evolution. Received: 19 March 1996 / Accepted: 5 August 1996     

DNA‐based phylogeny of the marine genus Heterodrilus (Annelida,Clitellata, Naididae)

Heterodrilus is a group of marine Naididae, common worldwide in subtropical and tropical areas, and unique among the oligochaetes by their tridentate chaetae. The phylogenetic relationships within the group are assessed from the nuclear 18S rDNA gene, and the mitochondrial cytochrome c oxidase subunit I (COI) and 16S rDNA genes. Sequence data were obtained from 16 Heterodrilus species and 13 out‐group taxa; 48 sequences are new for this study. The data were analysed by Bayesian inference. Monophyly of the genus is corroborated by the resulting tree, with Heterodrilus ersei (a taxon representing a small group of species with aberrant male genitalia) proposed to be outside all other sampled species. Although earlier regarded as a member of the subfamily Rhyacodrilinae, both molecular and morphological data seem to support that Heterodrilus is closely related to Phallodrilinae. However, the results are not conclusive as to whether the genus is the sister group of, or a group nested inside, or separate from this latter subfamily. The studied sample of species suggests at least two major clades in Heterodrilus with different geographical distributions, in one of the clades, most species are from the Indo‐West Pacific Ocean, while in the other, the majority are from the Western Atlantic Ocean. Morphological characters traditionally used in Heterodrilus taxonomy are optimized on the phylogenetic tree, revealing a high degree of homoplasy.     

绣球属(Hydrangea L.)植物分子系统学及系统发育分析

该研究基于对绣球属(Hydrangea L.)的大尺度取样,选取国内外61种绣球属和近缘属植物,分别基于核基因片段(ITS)和叶绿体基因片段(rbcL,trnL-F,atpB)重建了绣球属及其近缘种属的系统发育关系。结果表明:(1)核基因与叶绿体基因树之间在树形上没有明显的冲突,进而基于核基因和叶绿体基因联合数据重建了绣球属及其近缘种属的系统发育关系。(2)基于联合数据构建的系统树确认了2个大分支,并得到了果实顶端截平与否这一形态学证据的强力支持;每个大分枝又分为4个类群,共确定了8个类群。部分类群也得到了广义宏观形态性状的支持,如第1类群得到了叶形、花粉以及种子形态的支持。因此,该系统发育关系的重建对于全面理解绣球属及其近缘种属的演化关系具有重要的启发。     

New taxa refresh the phylogeny and classification of pleurostomatid ciliates (Ciliophora,Litostomatea)

A high diversity of pleurostomatid ciliates has been discovered in the last decade, and their systematics needs to be improved in the light of new findings concerning their morphology and molecular phylogeny. In this work, a new genus, Protolitonotus gen. n., and two new species, Protolitonotus magnus sp. n. and Protolitonotus longus sp. n., were studied. Furthermore, 19 novel nucleotide sequences of SSU rDNA, LSU rDNA and ITS1‐5.8S‐ITS2 were collected to determine the phylogenetic relationships and systematic positions of the pleurostomatid ciliates in this study. Based on both molecular and morphological data, the results demonstrated that: (i) as disclosed by the sequence analysis of SSU rDNA, LSU rDNA and ITS1‐5.8S‐ITS2, Protolitonotus gen. n. is sister to all other pleurostomatids and thus represents an independent lineage and a separate family, Protolitonotidae fam. n., which is defined by the presence of a semi‐suture formed by the right somatic kineties near the dorsal margin of the body; (ii) the families Litonotidae and Kentrophyllidae are both monophyletic based on both SSU rDNA and LSU rDNA sequences, whereas Amphileptidae are non‐monophyletic in trees inferred from SSU rDNA sequences; and (iii) the genera Loxophyllum and Kentrophyllum are both monophyletic, whereas Litonotus is non‐monophyletic based on SSU rDNA analyses. ITS1‐5.8S‐ITS2 sequence data were used for the phylogenetic analyses of pleurostomatids for the first time; however, species relationships were less well resolved than in the SSU rDNA and LSU rDNA trees. In addition, a major revision to the classification of the order Pleurostomatida is suggested and a key to its families and genera is provided.     

New insight into the identification and molecular phylogeny of dagger nematodes of the genus Xiphinema (Nematoda: Longidoridae) with description of two new species

The genus Xiphinema constitutes a large group of about 260 species of plant‐ectoparasitic nematodes. The group is polyphagous and distributed almost worldwide. Some of the species of this genus damage agricultural crops by direct feeding on root cells as well as by transmitting nepoviruses. Species discrimination in Xiphinema is complicated by phenotypic plasticity leading to potential misidentification. We conducted nematode surveys in cultivated and natural environments in Spain from 2009 to 2012, from which we identified 20 populations of Xiphinema species morphologically close to the virus‐vector nematode species Xiphinema diversicaudatum, three apomictic populations tentatively identified as species from the complex Xiphinema aceri‐pyrenaicum group, and one population morphologically different from all others that is characterized by a female tail elongate to conical and absence of uterine differentiation. We developed comparative multivariate analyses for these related species by using morphological and morphometrical features together with molecular data from nuclear ribosomal DNA genes [D2‐D3 expansion segments of large ribosomal subunit 28S, internal transcribed spacer 1 (ITS1), and partial small ribosomal subunit (18S)]. The results of multivariate, molecular, and phylogenetic analysis confirmed the morphological hypotheses and allowed the delimitation and discrimination of two new species in the genus described herein as Xiphinema baetica sp. nov. and Xiphinema turdetanensis sp. nov. , and ten known species: Xiphinema adenohystherum, Xiphinema belmontense, Xiphinema cohni, Xiphinema coxi europaeum, Xiphinema gersoni, Xiphinema hispidum, Xiphinema italiae, Xiphinema lupini, Xiphinema nuragicum, and Xiphinema turcicum. Multivariate analyses based on quantitative and qualitative characters and phylogenetic relationships of Xiphinema spp. based on the three molecular ribosomal markers resulted in a partial consensus of these species grouping as nematode populations were maintained for the majority of morphospecies groups (e.g. morphospecies groups 5 and 6), but not in some others (e.g. position of Xiphinema granatum), demonstrating the usefulness of these analyses for helping in the diagnosis and identification of Xiphinema spp. The clade topology of phylogenetic trees of D2‐D3 and partial 18S regions in this study were congruent in supporting the polyphyletic status of some characters, such as the female tail shape and the degree of development of the genital system in species with both genital branches equally developed. This is the most complete phylogenetic study for Xiphinema non‐americanum‐group species. Agreement between phylogenetic trees and some morphological characters (uterine spines, pseudo‐Z organ, and tail shape) was tested by reconstruction of their histories on rDNA‐based trees using parsimony and Bayesian approaches. Thus, integrative taxonomy, based on the combination of multivariate, molecular analyses with morphology, constitutes a new insight into the identification of Xiphinema species. © 2013 The Linnean Society of London     

Molecular Systematics of Zopfiella and allied genera: evidence from multi-gene sequence analyses

This study aims to reveal the phylogenetic relationships of Zopfiella and allied genera in the Sordariales. Multiple gene sequences (partial 28 S rDNA, ITS/5.8 S rDNA and partial β-tubulin) were analysed using MP and Bayesian analyses. Analyses of different gene datasets were performed individually and then combined to infer phylogenies. Phylogenetic analyses show that currently recognised Zopfiella species are polyphyletic. Based on sequence analyses and morphology, it appears that Zopfiella should be restricted to species having ascospores with a septum in the dark cell. Our molecular analysis also shows that Zopfiella should be placed in Lasiosphaeriaceae rather than Chaetomiaceae. Cercophora and Podospora are also polyphyletic, which is in agreement with previous studies. Our analyses show that species possessing a Cladorrhinum anamorph are phylogenetically closely related. In addition, there are several strongly supported clades, characterised by species possessing divergent morphological characters. It is difficult to predict which characters are phylogenetically informative for delimiting these clades.     

Improved phylogenetic resolution of toxic and non-toxic Alexandrium strains using a concatenated rDNA approach

Dinoflagellates of the genus Alexandrium are known producers of paralytic shellfish toxins. Species within the genus have similar phenotypes making morphological identification problematical. The use of Alexandrium rDNA sequence data is therefore increasing, resulting in the improved resolution of evolutionary relationships by phylogenetic inferences. However, the true branching pattern within Alexandrium remains unresolved, with minimal support shown for the main phylogentic branch. The aim of this study is to improve phylogenetic resolution via a concatenated rDNA approach with a broad sample of taxa, allowing inference of the evolutionary pattern between species and toxins. 27 Alexandrium strains from 10 species were tested with HPLC for PSP toxin presence and additionally sequenced for 18S, ITS1, 5.8S, ITS2 and 28S rDNA before being phylogenetically inferred together with all available orthologous sequences from NCBI. The resulting alignment is the largest to date for the genus, in terms of both inferred characters and taxa, thus allowing for the improved phylogenetic resolution of evolutionary patterns there in. No phylogenetic pattern between PSP producing and non-producing strains could be established, however the terminal tamarense complex was shown to produce more PSP analogues than basal clades. Additionally, we distinguish a high number of polymorphic regions between the two copies of A. fundyense rDNA, thus allowing us to demonstrate the presence of chimeric sequences within GenBank, as well as a possible over estimation of diversification within the tamarense complex.     

Phylogeny in Echinocereus (Cactaceae) based on combined morphological and molecular evidence: taxonomic implications

Echinocereus is a morphologically diverse genus that includes 64 species grouped into eight taxonomic sections based on morphological traits. In previous molecular phylogenetic analyses, the relationships amongst Echinocereus species were not entirely revealed and useful characters to recognize clades were not provided. The inclusion of several sources of evidence in a phylogenetic analysis is likely to produce more supported hypotheses. Therefore, we performed a combined phylogenetic analysis with a set of 44 morphological characters and six chloroplast DNA sequences. Topologies from parsimony and Bayesian analyses were mostly congruent. However, the relationships of E. poselgeri were not consistent between analyses. A second Bayesian analysis using a long-branch extraction test resulted in a topology with the morphological position of E. poselgeri congruent with that in parsimony analysis. Parsimony and Bayesian analyses corroborated the monophyly of Echinocereus, which included eight monophyletic groups. The combined phylogeny integrated into different clades those taxa that were not determined in previous analyses and changed the relationships of some recognized clades. The clades did not recover the recent infrageneric classification. In the present study, a new sectional classification for Echinocereus is proposed based on the eight recovered clades, which is supported by a combination of morphological and molecular characters. An identification key for sections in the genus is included.     

Phylogenetic relationships in rhinonyssid mites (Acari: Rhinonyssidae) based on mitochondrial 16S rDNA sequences

A 390 bp region of the 16S rDNA gene was sequenced from six species ofrhinonyssid mites (Tinaminyssus columbae, T. minisetosum, Sternostomaturdi, S. sternahirundo, S. fulicae and Ptilonyssus euroturdi) andtwo subspecies (Tinaminyssus melloi melloi andTinaminyssus melloi streptopeliae) to examine the level ofsequence variation and the taxonomic levels to show utility in phylogenyestimation. Furthemore, two different geographic locations of T. m.melloi and T. m. streptopeliae were analyzed todetect variation between populations. Molecular data revealed the existence oftwo distinct groups in the genus Tinaminyssus parasitic oncolumbiform birds. These results are in agreement with those reported by someauthors using morphological characters. Sternostoma turdi parasitizing aerial birds appeared to be phylogenetically separated from otherspecies of this genus isolated from aquatic birds. Moreover, our studyaddressesthe validity of the subspecies status of T. melloistreptopeliae. This region of the mitochondrial 16S rDNA gene is auseful marker for inferring phylogenetic relationships among closely relatedrhinonyssid species, but not for more distantly related taxa.     

Phylogenetic Classification at Generic Level in the Absence of Distinct Phylogenetic Patterns of Phenotypical Variation: A Case Study in Graphidaceae (Ascomycota)

Molecular phylogenies often reveal that taxa circumscribed by phenotypical characters are not monophyletic. While re-examination of phenotypical characters often identifies the presence of characters characterizing clades, there is a growing number of studies that fail to identify diagnostic characters, especially in organismal groups lacking complex morphologies. Taxonomists then can either merge the groups or split taxa into smaller entities. Due to the nature of binomial nomenclature, this decision is of special importance at the generic level. Here we propose a new approach to choose among classification alternatives using a combination of morphology-based phylogenetic binning and a multiresponse permutation procedure to test for morphological differences among clades. We illustrate the use of this method in the tribe Thelotremateae focusing on the genus Chapsa, a group of lichenized fungi in which our phylogenetic estimate is in conflict with traditional classification and the morphological and chemical characters do not show a clear phylogenetic pattern. We generated 75 new DNA sequences of mitochondrial SSU rDNA, nuclear LSU rDNA and the protein-coding RPB2. This data set was used to infer phylogenetic estimates using maximum likelihood and Bayesian approaches. The genus Chapsa was found to be polyphyletic, forming four well-supported clades, three of which clustering into one unsupported clade, and the other, supported clade forming two supported subclades. While these clades cannot be readily separated morphologically, the combined binning/multiresponse permutation procedure showed that accepting the four clades as different genera each reflects the phenotypical pattern significantly better than accepting two genera (or five genera if splitting the first clade). Another species within the Thelotremateae, Thelotrema petractoides, a unique taxon with carbonized excipulum resembling Schizotrema, was shown to fall outside Thelotrema. Consequently, the new genera Astrochapsa, Crutarndina, Pseudochapsa, and Pseudotopeliopsis are described here and 39 new combinations are proposed.     

Reconciling taxonomy and phylogeny in the bristleworm family Eunicidae (polychaete,Annelida)

Eunicid annelids inhabit diverse marine habitats worldwide, have ecological and economic importance and have been pictured in the news as giant predator worms. They compose a traditional stable taxon recently supported as monophyletic but characterized by plesiomorphies. Most genera within the family have been recovered as paraphyletic in previous studies. We present a phylogenetic hypothesis for eunicid based on molecular (COI, 16S rDNA, 18S rDNA) and morphological data (213 characters), including an explicit attempt to account for serial homology. Eunicidae as well as monophyletic genera Marphysa sensu stricto and Lysidice is redefined based on synapomorphies. Nematonereis is synonymized to Lysidice. Leodice and Nicidion are resurrected to name monophyletic groups including species previously included in Eunice and Marphysa sensu lato. Traditional diagnostic characters such as the absence/presence of peristomial cirri, lateral antennae and branchiae are homoplasies and not informative at the generic level. Different coding of traditional characters (i.e. articulation of prostomial appendages) and novel characters of prostomial features and regionalization of the body support the monophyly of the family and genera level clades. Thus, the phylogenetic hypothesis presented here and the evolution of characters provided background information for taxonomic changes yielding evolutionary meaningful classification and diagnoses for the family and genera.     

Reconstructing the evolution of agarics from nuclear gene sequences and basidiospore ultrastructure

Traditional classifications of agaric fungi involve gross morphology of their fruit bodies and meiospore print-colour. However, the phylogeny of these fungi and the evolution of their morphological and ecological traits are poorly understood. Phylogenetic analyses have already demonstrated that characters used in traditional classifications of basidiomycetes may be heavily affected by homoplasy, and that non-gilled taxa evolved within the agarics several times. By integrating molecular phylogenetic analyses including domains D1–D3 and D7–D8 of nucLSU rDNA and domains A–C of the RPB1 gene with morphological and chemical data from representative species of 88 genera, we were able to resolve higher groups of agarics. We found that the species with thick-walled and pigmented basidiospores constitute a derived group, and hypothesize that this specific combination of characters represents an evolutionary advantage by increasing the tolerance of the basidiospores to dehydration and solar radiation and so opened up new ecological niches, e.g. the colonization of dung substrates by enabling basidiospores to survive gut passages through herbivores. Our results confirm the validity of basidiospore morphology as a phylogenetic marker in the agarics.