Searching for natural lineages within the Cerylonid Series (Coleoptera: Cucujoidea)

Phylogenetic relationships within the diverse beetle superfamily Cucujoidea are poorly known. The Cerylonid Series (C.S.) is the largest of all proposed superfamilial cucujoid groups, comprising eight families and representing most of the known cucujoid species diversity. The monophyly of the C.S., however, has never been formally tested and the higher-level relationships among and within the constituent families remain equivocal. Here we present a phylogenetic study based on 18S and 28S rDNA for 16 outgroup taxa and 61 C.S. ingroup taxa, representing seven of the eight C.S. families and 20 of 39 subfamilies. We test the monophyly of the C.S., investigate the relationships among the C.S. families, and test the monophyly of the constituent families and subfamilies. Phylogenetic reconstruction of the combined data was achieved via standard static alignment parsimony analyses, Direct Optimization using parsimony, and partitioned Bayesian analysis. All three analyses support the paraphyly of Cucujoidea with respect to Tenebrionoidea and confirm the monophyly of the C.S. The C.S. families Bothrideridae, Cerylonidae, Discolomatidae, Coccinellidae and Corylophidae are supported as monophyletic in all analyses. Only the Bayesian analysis recovers a monophyletic Latridiidae. Endomychidae is recovered as polyphyletic in all analyses. Of the 14 subfamilies with multiple terminals in this study, 11 were supported as monophyletic. The corylophid subfamily Corylophinae and the coccinellid subfamilies Chilocorinae and Scymninae are recovered as paraphyletic. A sister grouping of Anamorphinae+Corylophidae is supported in all analyses. Other taxonomic implications are discussed in light of our results.     

基于18S基因序列的姬小蜂分子系统发育

本文基于18S rDNA部分序列,用MP和Baysian方法研究了姬小蜂科的系统发育,对姬小蜂科的单系性及其与其它小蜂科间的关系进行了讨论。姬小蜂亚科、灿姬小蜂亚科和啮姬小蜂亚科形成三个独立的支系,研究结果支持它们各自的单系性,但本结果没有明确姬小蜂科的单系性。研究结果同时还支持瑟姬小蜂族、扁股姬小蜂族和狭面姬小蜂族三个族的地位,但不支持姬小蜂族的地位。姬小蜂科的单系性及其与其它小蜂间的关系还需更多的形态学数据和更多的基因序列来进一步研究[动物学报52 (2) : 288 -301 , 2006]。     

A phylogeny of robber flies (Diptera: Asilidae) at the subfamilial level: molecular evidence

We present the first formal analysis of phylogenetic relationships among the Asilidae, based on four genes: 16S rDNA, 18S rDNA, 28S rDNA, and cytochrome oxidase II. Twenty-six ingroup taxa representing 11 of the 12 described subfamilies were selected to produce a phylogenetic estimate of asilid subfamilial relationships via optimization alignment, parsimony, and maximum likelihood techniques. Phylogenetic analyses support the monophyly of Asilidae with Leptogastrinae as the most basal robber fly lineage. Apocleinae+(Asilinae+Ommatiinae) is supported as monophyletic. The laphriinae-group (Laphriinae+Laphystiinae) and the dasypogoninae-group (Dasypogoninae+Stenopogoninae+Stichopogoninae+ Trigonomiminae) are paraphyletic. These results suggest that current subfamilial classification only partially reflects robber fly phylogeny, indicating the need for further phylogenetic investigation of this group.     

Community effects of praying mantids: a meta-analysis of the influences of species identity and experimental design

Abstract 1. Generalist arthropod predators are ubiquitous in terrestrial ecosystems but experimental studies have yielded little agreement as to their effects on prey assemblages. Drawing on results from a suite of experimental field studies, a meta‐analysis was conducted of the impact of praying mantids (Mantodea: Mantidae) on arthropod assemblages in order to identify predictable and unpredictable effects of these extremely generalised predators. 2. Results across different experiments were synthesised using the log response ratio framework, with a focus on quantifying net mantid impacts on arthropod density across taxonomic orders and trophic levels of arthropods, paying special attention to the contribution of mantid species identity and experimental design variables, such as the use of cages, length of experiment, and manipulated mantid density. 3. Calculated on a per mantid‐day basis, the net impacts of Tenodera sinensis on arthropod density were generally weaker but more predictable than the effects of Mantis religiosa. Mantids in general had weak negative effects on density for most taxa but exhibited strong negative and positive effects on some taxa. Tenodera sinensis tended to have negative effects on Homoptera, Diptera, and Hemiptera and herbivores as a group, however M. religiosa exhibited greater variation in response of different taxa that appeared to be affected more strongly by experimental design. The effects of Stagmomantis carolina tended to be negative or non‐significant. 4. Experimental cages had little influence on either the sign or magnitude of net community impacts for T. sinensis, however cage experiments reversed the sign of the mean effect for two of six taxonomic orders when the experimental predator was M. religiosa. Cages also increased the variability of effect size greatly for M. religiosa but not for T. sinensis. 5. It was concluded that it is possible to use log response ratios to determine general, predictable trends in a well‐studied system. Similar meta‐analyses of generalist predator effects in other systems should produce predictions of how these predators influence food webs, an important step towards defining more clearly the influences of generalist predators on community structure and dynamics.     

Structural alignment of 18S and 28S rDNA sequences provides insights into phylogeny of Phytophaga (Coleoptera: Curculionoidea and Chrysomeloidea)

We performed a comparative study of partial rDNA sequences from a variety of Coleoptera taxa to construct an annotated alignment based on secondary structure information, which in turn, provides improved rRNA structure models useful for phylogenetic reconstruction. Subsequent phylogenetic analysis was performed to test monophyly and interfamilial relationships of the megadiverse plant feeding beetle group known as ‘Phytophaga’ (Curculionoidea and Chrysomeloidea), as well as to discover their closest relatives among the Cucujiformia. Parsimony and Bayesian analyses were performed based on the structural alignment of segments of 18S rRNA (variable regions V4‐V5, V7‐V9) and 28S rRNA (expansion segment D2). A total of 104 terminal taxa of Coleoptera were included: 96 species of Cucujiformia beetles, representing the families and most ‘subfamilies’ of weevils and chrysomeloids (Phytophaga), as well as several families of Cleroidea, Tenebrionoidea and Cucujoidea, and eight outgroups from three other polyphagan series: Scarabaeiformia, Elateriformia and Bostrichiformia. The results from the different methods of analysis agree — recovering the monophyly of the ‘Phytophaga’, including Curculionoidea and Chrysomeloidea as sister groups. The curculionoid and chrysomeloid phylogeny recovered from the aligned 18S and 28S rDNA segments, which is independent of morphological data, is in agreement with recent hypotheses or concepts based on morphological evidence, particularly with respect to familial relationships. Our results provide clues about the evolutionary origin of the phytophagan beetles within the megaclade Cucujiformia, suggesting that the sister group of ‘Curculionoidea + Chrysomeloidea’ is a clade of the ‘Cucujoidea’, represented in this study by species in Boganiidae, Erotylidae, Nitidulidae, Cucujidae and Silvanidae. The Coccinellidae and Endomychidae are not grouped with the latter, and the remaining terminal taxa are nested in Tenebrionoidea and Cleroidea. We propose that the combination of structurally aligned ribosomal RNA gene regions 18S (V4‐V5, V7‐V9) and 28S (D2) are useful in testing monophyly and resolving relationships among beetle superfamilies and families.     

Initial results on the molecular phylogeny of the Nudibranchia (Gastropoda, Opisthobranchia) based on 18S rDNA data

This study investigated nudibranch phylogeny on the basis of 18S rDNA sequence data. 18S rDNA sequence data of 19 taxa representing the major living orders and families of the Nudibranchia were analyzed. Representatives of the Cephalaspidea, Anaspidea, Gymnomorpha, Prosobranchia, and Pulmonata were also sequenced and used as outgroups. An additional 28 gastropod sequences taken from GenBank were also included in our analyses. Phylogenetic analyses of these more than 50 gastropod taxa provide strong evidence for support of the monophyly of the Nudibranchia. The monophyly of the Doridoidea, Cladobranchia, and Aeolidoidea within the Nudibranchia are also strongly supported. Phylogenetic utility and information content of the 18S rDNA sequences for Nudibranchia, and Opisthobranchia in general, are examined using the program SplitsTree as well as phylogenetic reconstructions using distance and parsimony approaches. 0Results based on these molecular data are compared with hypotheses about nudibranch phylogeny inferred from morphological data.     

Molecular phylogenetics of Meliaceae (Sapindales) based on nuclear and plastid DNA sequences

Phylogenetic analyses of Meliaceae, including representatives of all four currently recognized subfamilies and all but two tribes (32 genera and 35 species, respectively), were carried out using DNA sequence data from three regions: plastid genes rbcL, matK (partial), and nuclear 26S rDNA (partial). Individual and combined phylogenetic analyses were performed for the rbcL, matK, and 26S rDNA data sets. Although the percentage of informative characters is highest in the segment of matK sequenced, rbcL provides the greatest number of informative characters of the three regions, resulting in the best resolved trees. Results of parsimony analyses support the recognition of only two subfamilies (Melioideae and Swietenioideae), which are sister groups. Melieae are the only tribe recognized previously that are strongly supported as monophyletic. The members of the two small monogeneric subfamilies, Quivisianthe and Capuronianthus, fall within Melioideae and Swietenioideae, respectively, supporting their taxonomic inclusion in these groups. Furthermore, the data indicate a close relationship between Aglaieae and Guareeae and a possible monophyletic origin of Cedreleae of Swietenioideae. For Trichilieae (Melioideae) and Swietenieae (Swietenioideae) lack of monophyly is indicated.     

Cladistic analysis of Aradidae (Insecta,Heteroptera) based on morphological and molecular characters

In this study, we present for the first time a cladistic analysis of the subfamilies of Aradidae, using molecular and morphological characters. Eighty‐three taxa, including 79 species representing eight subfamilies, are treated. The analyses were performed using 72 morphological characters and approximately 1650 bp corresponding to three molecular loci (CO1, 16S and 28S). Characters were analysed using parsimony and Bayesian methods. Based on the combined analyses, we find support for the monophyly of Aradidae, including the subfamilies Aradinae, Aneurinae, Calisiinae, Isoderminae, and Mezirinae and the paraphyly of Prosympiestinae and Chinamyersiinae. In all analyses, Prosympiestinae includes Isoderminae. The Termitaphididae were not found sister to the Aradidae in the Aradoidea.     

Phylogenetic relationships among the Braconidae (Hymenoptera: Ichneumonoidea) inferred from partial 16S rDNA, 28S rDNA D2, 18S rDNA gene sequences and morphological characters

Phylogenetic relationships among the Braconidae were examined using homologous 16S rDNA, 28S rDNA D2 region, and 18S rDNA gene sequences and morphological data using both PAUP* 4.0 and MRBAYES 3.0B4 from 88 in-group taxa representing 35 subfamilies. The monophyletic nature of almost all subfamilies, of which multiple representatives are present in this study, is well-supported except for two subfamilies, Cenocoelinae and Neoneurinae that should probably be treated as tribal rank taxa in the subfamily Euphorinae. The topology of the trees generated in the present study supported the existence of three large generally accepted lineage or groupings of subfamilies: two main entirely endoparasitic lineages of this family, referred to as the "helconoid complex" and the "microgastroid complex," and the third "the cyclostome." The Aphidiinae was recovered as a member of the non-cyclostomes, probably a sister group of Euphorinae or Euphorinae-complex. The basal position of the microgastroid complex among the non-cyclostomes has been found in all our analyses. The cyclostomes were resolved as a monophyletic group in all analyses if two putatively misplaced groups (Mesostoa and Aspilodemon) were excluded from them. Certain well-supported relationships evident in this family from the previous analyses were recovered, such as a sister-group relationships of Alysiinae+Opiinae, of Braconinae+Doryctinae, and a close relationship between Macrocentrinae, Xiphozelinae, Homolobinae, and Charmontinae. The relationships of "Ichneutinae + ((Adeliinae + Cheloninae) + (Miracinae + (Cardiochilinae + Microgastrinae)))" was confirmed within the microgastroid complex. The position of Acampsohelconinae, Blacinae, and Trachypetinae is problematic.     

基于线粒体Cyt b,16S rDNA和核28S rDNA的中国斑腿蝗科(直翅目,蝗总科)九亚科间的系统发育关系研究

基于线粒体Cytb、16S rDNA和核28S rDNA的部分序列的联合数据集,重建了中国斑腿蝗科9亚科26种蝗虫和癞蝗科笨蝗(外群)间的系统发育关系。结果显示:1)除黑蝗亚科、秃蝗亚科和切翅蝗亚科外,其余6亚科的单系性都得到支持;2)黑蝗亚科似乎应当与秃蝗亚科合并为一个亚科,且与其他几个亚科亲缘关系相对较远;3)凸额蝗属应该由切翅蝗亚科中独立出来;4)卵翅蝗亚科和稻蝗亚科是姐妹群;5)星翅蝗亚科、黑背蝗亚科、斑腿蝗亚科、刺胸蝗亚科及切翅蝗亚科中的凸额蝗属间的关系较近。     

Insights into the phylogenetic relationships within Cixiidae (Hemiptera: Fulgoromorpha): cladistic analysis of a morphological dataset

Abstract.  According to the most recent classifications proposed, the planthopper family Cixiidae comprises three subfamilies, namely Borystheninae, Bothriocerinae and Cixiinae, the latter with 16 tribes. Here we examine morphological characters to present the first phylogenetic reconstructions within Cixiidae derived from a cladistic analysis. We scored 85 characters of the head, thorax, and male and female genitalia for 50 taxa representative of all cixiid subfamilies and tribes and for six outgroup taxa. Analyses were based on maximum parsimony – using both equally weighted and successive weighting procedures – and Bayesian inferences. The monophyly of most currently accepted tribes and subfamilies was investigated through Templeton statistical tests of alternative phylogenetic hypotheses. The cladistic analyses recover the monophyly of Cixiidae, the subfamily Bothriocerinae, and the tribes Pentastirini, Mnemosynini, and Eucarpiini. Successive weighting and Bayesian inference recover the monophyly of the tribe Gelastocephalini, but only Bayesian inference supports the monophyly of Semoniini. The relationships recovered support the groups [Stenophlepsini (Borystheninae + Bothriocerinae)] arising from the tribe Oecleini, and [Andini + Brixiidini + Brixiini (polyphyletic) + Bennini]. Templeton tests reject the alternative hypothesis of a monophyletic condition for the tribe Pintaliini as presently defined.     

Dracula ant phylogeny as inferred by nuclear 28S rDNA sequences and implications for ant systematics (Hymenoptera: Formicidae: Amblyoponinae)

Ants are one of the most ecologically and numerically dominant families of organisms in almost every terrestrial habitat throughout the world, though they include only about 1% of all described insect species. The development of eusociality is thought to have been a driving force in the striking diversification and dominance of this group, yet we know little about the evolution of the major lineages of ants and have been unable to clearly determine their primitive characteristics. Ants within the subfamily Amblyoponinae are specialized arthropod predators, possess many anatomically and behaviorally primitive characters and have been proposed as a possible basal lineage within the ants. We investigate the phylogenetic relationships among the members of the subfamily, using nuclear 28S rDNA sequence data. Outgroups for the analysis include members of the poneromorph and leptanillomorph (Apomyrma, Leptanilla) ant subfamilies, as well as three wasp families. Parsimony, maximum likelihood, and Bayesian analyses provide strong support for the monophyly of a clade containing the two genera Apomyrma+Mystrium (100% bpp; 97% ML bs; and 97% MP bs), and moderate support for the monophyly of the Amblyoponinae as long as Apomyrma (Apomyrminae) is included (87% bpp; 57% ML bs; and 76% MP bs). Analyses did not recover evidence of monophyly of the Amblyopone genus, while the monophyly of the other genera in the subfamily is supported. Based on these results we provide a morphological diagnosis of the Amblyoponinae that includes Apomyrma. Among the outgroup taxa, Typhlomyrmex grouped consistently with Ectatomma, supporting the recent placement of Typhlomyrmex in the Ectatomminae. The results of this present study place the included ant subfamilies into roughly two clades with the basal placement of Leptanilla unclear. One clade contains all the Amblyoponinae (including Apomyrma), Ponerinae, and Proceratiinae (Poneroid clade). The other clade contains members from subfamilies Cerapachyinae, Dolichoderinae, Ectatomminae, Formicinae, Myrmeciinae, and Myrmicinae (Formicoid clade).     

History of canids in Chile and impacts on prey adaptations

Artiodactyl prey species of Chile, especially guanacos (Lama guanicoe), are reported to be very susceptible to predation by pack‐hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack‐hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies, and hunting behavior. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviors of guanacos: predator inspection of ambush predators, for example, Puma concolor, and rushing at and kicking smaller cursorial predators, for example, Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group‐hunting canids east of the Andes, there were no native species creating group‐hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group‐hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.     

Molecular phylogeny of Clupeiformes (Actinopterygii) inferred from nuclear and mitochondrial DNA sequences

The taxonomy of clupeiforms has been extensively studied, yet phylogenetic relationships among component taxa remain controversial or unresolved. Here we test current and new hypotheses of relationships among clupeiforms using mitochondrial rRNA genes (12S and 16S) and nuclear RAG1 and RAG2 sequences (total of 4749bp) for 37 clupeiform taxa representing all five extant families and all subfamilies of Clupeiformes, except Pristigasterinae, plus seven outgroups. Our results, based on maximum parsimony, maximum likelihood, and Bayesian analyses of these data, show that some traditional hypotheses are supported. These include the monophyly of the families Engraulidae, consisting of two monophyletic subfamilies, Engraulinae (Engraulis and Anchoa) and Coilinae (Coilia and Setipinna), and Pristigasteridae (here represented only by Ilisha and Pellona). The basal position of Denticeps among clupeiforms is consistent with the molecular data when base compositional biases are accounted for. However, the monophyly of Clupeidae was not supported. Some clupeids were more closely related to taxa assigned to Pristigasteridae and Chirocentridae (Chirocentrus). These results suggest that a major revision in the classification of clupeiform fishes may be necessary, but should await a more complete taxonomic sampling and additional data.     

DNA barcoding identifies Eimeria species and contributes to the phylogenetics of coccidian parasites (Eimeriorina, Apicomplexa, Alveolata)

Partial (～ 780 bp) mitochondrial cytochrome c oxidase subunit I (COI) and near complete nuclear 18S rDNA (～ 1,780 bp) sequences were directly compared to assess their relative usefulness as markers for species identification and phylogenetic analysis of coccidian parasites (phylum Apicomplexa). Fifteen new COI partial sequences were obtained using two pairs of new primers from rigorously characterised (sensu Reid and Long, 1979) laboratory strains of seven Eimeria spp. infecting chickens as well as three additional sequences from cloned laboratory strains of Toxoplasma gondii (ME49 and GT1) and Neospora caninum (NC1) that were used as outgroup taxa for phylogenetic analyses. Phylogenetic analyses based on COI sequences yielded robust support for the monophyly of individual Eimeria spp. infecting poultry except for the Eimeria mitis/mivati clade; however, the lack of a phenotypically characterised strain of E. mivati precludes drawing any firm conclusions regarding this observation. Unlike in the 18S rDNA-based phylogenetic reconstructions, Eimerianecatrix and Eimeria tenella formed monophyletic clades based on partial COI sequences. A species delimitation test was performed to determine the probability of making a correct identification of an unknown specimen (sequence) based on either complete 18S rDNA or partial COI sequences; in almost all cases, the partial COI sequences were more reliable as species-specific markers than complete 18S rDNA sequences. These observations demonstrate that partial COI sequences provide more synapomorphic characters at the species level than complete 18S rDNA sequences from the same taxa. We conclude that COI performs well as a marker for the identification of coccidian taxa (Eimeriorina) and will make an excellent DNA 'barcode' target for coccidia. The COI locus, in combination with an 18S rDNA sequence as an 'anchor', has sufficient phylogenetic signal to assist in the resolution of apparent paraphylies within the coccidia and likely more broadly within the Apicomplexa.     

Evolution of fossil and living spider flies based on morphological and molecular data (Diptera,Acroceridae)

The phylogeny of spider flies is presented based on an analysis of DNA sequence data combined with morphological characters for both living and fossil species. We sampled 40 extant and extinct genera across all major lineages of Acroceridae, which were compared with outgroup taxa from various lower brachyceran families. In all, 81 morphological characters of 60 extant and 10 extinct ingroup species were combined with 7.1 kb of DNA sequences of two nuclear (CAD and 28S rDNA) and two mitochondrial genes (COI and 16S rDNA). Results strongly support the monophyly of Acroceridae, with major clades contained within classified here in five extant subfamilies (Acrocerinae, Cyrtinae stat. rev. , Ogcodinae stat. rev. , Panopinae and Philopotinae) and one extinct subfamily, Archocyrtinae. The evolution of important spider fly traits is discussed, including genitalia and wing venation. The status of the enigmatic Psilodera Gray and Pterodontia Gray as members of the Panopinae is confirmed based on both molecular and morphological data.     

Family‐level relationships of the spittlebugs and froghoppers (Hemiptera: Cicadomorpha: Cercopoidea)

The spittlebug superfamily Cercopoidea (Hemiptera: Cicadomorpha) comprises approximately 3000 phytophagous species (including some economically important pests of grass crops) classified among the families Cercopidae, Aphrophoridae, Epipygidae, Clastopteridae and Machaerotidae. However, the monophyly of these taxa has never been tested and the evolutionary relationships among these major lineages are unknown. Presented here are the results of the first ever phylogenetic investigation of the higher‐level relationships within Cercopoidea, based on DNA nucleotide sequence data from six loci (18S rDNA, 28S rDNA, histone 3, wingless, cytochrome oxidase I and cytochrome oxidase II) generated from exemplars of 109 spittlebug species representing all five described families, seven of eight subfamilies and 61 genera (eight additional exemplars, representing a selection of other Auchenorrhyncha taxa, were included as outgroups). The resulting topologies are used to evaluate the monophyly of each cercopoid family, and further to calculate divergence date estimates to examine the chronological origins and historical diversification of Cercopoidea. The results of this investigation suggest that: (i) four of the five described families are monophyletic; Epipygidae was recovered consistently as originating within Aphrophoridae; (ii) the exclusively Old World Machaerotidae is the most anciently diversified family of extant spittlebugs; (iii) New World Cercopidae (i.e. Ischnorhininae) constitute a derived monophyletic lineage; (iv) the genus Microsargane Fowler, classified currently within Aphrophoridae, actually belongs within Cercopidae; and (v) the origins of the major spittlebug lineages probably coincided with the breakup of Pangaea and, subsequently, Gondwana, as well as major floristic diversification such as the rise of angiosperms.     

Molecular phylogeny of land and freshwater planarians (Tricladida, Platyhelminthes): from freshwater to land and back

The suborder Tricladida (phylum Platyhelminthes) comprises the well-known free-living flatworms, taxonomically grouped into three infraorders according to their ecology: Maricola (marine planarians), Paludicola (freshwater planarians), and Terricola (land planarians). Molecular analyses have demonstrated that the Paludicola are paraphyletic, the Terricola being the sister group of one of the three paludicolan families, the Dugesiidae. However, neither 18S rDNA nor COI based trees have been able to resolve the relationships among species of Terricola and Dugesiidae, particularly the monophyly of Terricola. Here, we present new molecular data including sequences of nuclear genes (18S rDNA, 28S rDNA) and a mitochondrial gene (COI) of a wider sample of dugesiid and terricolan species. The new sequences have been analyzed, together with those previously obtained, in independent and concatenated analyses using maximum likelihood and bayesian methods. The results show that, although some parts of the trees remain poorly resolved, they support a monophyletic origin for Terricola followed by a likely return of some species to freshwater habitats. Relationships within the monophyletic group of Dugesiidae are clearly resolved, and relationships among some terricolan subfamilies are also clearly established and point to the need for a thorough revision of Terricola taxonomy.     

DIVERSITY AMONG TETRASPORALEAN TAXA: EVIDENCE FROM ULTRASTRUCTURE AND MOLECULES

Recent phylogenetic studies of tetrasporalean exemplars using 18S rDNA revealed the extent of diversity among taxa in this non-monophyletic group (Booton et al. 1998). In particular, two distinct tetrasporalean lineages were identified; one group allied with chlamydomonadalean taxa and the other group comprising taxa now placed in a separate order, the Chaetopeltidales. Using these observations as a framework, a new investigation of diversity among a broader sampling of putative tetrasporalean genera (e.g. Asterococcus , Chloranomala , Chlorophysema , Gloeocystis , Gloeodendron , Palmella , Paulschulzia , Physocytium , Schizochlamys and Tetraspora ) was undertaken. Phylogenetic studies of both 18S and 26S rDNA were compared with ultrastructural investigations of vegetative cells. Molecular phylogenetic analyses corroborate the earlier 18S rDNA results, but also reveal additional diversity. The new data raise doubts regarding the monophyly of two genera, Palmella and Tetraspora. The new data also link two enigmatic green algal genera, Physocytium and Heterochlamydomonas , in a long-branch lineage within the Chlamydomonadales. Another enigmatic genus, Schizochlamys , is allied with Bracteacoccus in the Sphaeropleales. Lastly, Chloranomala is resolved as an ally of Paulschulzia , Tetraspora sp., and the green flagellate, Lobomonas. Comparison of pyrenoid ultrastructure generally supports the molecular phylogenetic analyses, suggesting that this non-molecular character will be a useful marker for broad phylogenetic studies of chlamydomonadalean taxa. (Supported by NSF grant, DEB 9726588)