Galerina Earle: A polyphyletic genus in the consortium of dark-spored agarics

The basidiomycete genus Galerina Earle accommodates more than 300 small brown-spored agarics worldwide, predominantly described from the Northern hemisphere. The delimitation of species and infrageneric units hitherto has been based on morphological and, to some extent, ecological characters. In this study we have analyzed nuclear ribosomal LSU and ITS sequences to reveal infrageneric phylogeny and the phylogenetic placement of Galerina among the dark-spored agarics. Sequences from 36 northern hemisphere Galerina species and 19 other dark-spored taxa were analyzed, some of them obtained from EMBL/GenBank. Our results, received from Bayesian and distance methods, strongly suggest that Galerina is a polyphyletic genus. The LSU analysis shows that Galerina is composed of three or four separate monophyletic main groups. In addition, a few species cluster together with other dark-spored agarics. The same groups are recognized in the ITS tree and they correspond roughly to previously recognized subgenera or sections in Galerina. With high support our LSU analysis suggests that Gymnopilus is a monophyletic genus and that Gymnopilus and one of the Galerina lineages ("mycenopsis") are sister groups. The analyses further indicate that the Galerina lineages, as well as the genus Gymnopilus, could be referred to a strongly emendated family Strophariaceae, which corresponds largely to the family as circumscribed by Kühner (1980). Our results affirm that morphological characters often are highly homoplastic in the agarics. At the present stage formal taxonomic consequences or nomenclatural changes are not proposed.     

Mitochondrial and nuclear phylogenies of Cervidae (Mammalia, Ruminantia): Systematics, morphology, and biogeography

The family Cervidae includes 40 species of deer distributed throughout the northern hemisphere, as well as in South America and Southeast Asia. Here, we examine the phylogeny of this family by analyzing two mitochondrial protein-coding genes and two nuclear introns for 25 species of deer representing most of the taxonomic diversity of the family. Our results provide strong support for intergeneric relationships. To reconcile taxonomy and phylogeny, we propose a new classification where the family Cervidae is divided in two subfamilies and five tribes. The subfamily Cervinae is composed of two tribes: the tribe Cervini groups the genera Cervus, Axis, Dama, and Rucervus, with the Père David's deer (Elaphurus davidianus) included in the genus Cervus, and the swamp deer (Cervus duvauceli) placed in the genus Rucervus; the tribe Muntiacini contains Muntiacus and Elaphodus. The subfamily Capreolinae consists of the tribes Capreolini (Capreolus and Hydropotes), Alceini (Alces), and Odocoileini (Rangifer + American genera). Deer endemic to the New World fall in two biogeographic lineages: the first one groups Odocoileus and Mazama americana and is distributed in North, Central, and South America, whereas the second one is composed of South American species only and includes Mazama gouazoubira. This implies that the genus Mazama is not a valid taxon. Molecular dating suggests that the family originated and radiated in central Asia during the Late Miocene, and that Odocoileini dispersed to North America during the Miocene/Pliocene boundary, and underwent an adaptive radiation in South America after their Pliocene dispersal across the Isthmus of Panama. Our phylogenetic inferences show that the evolution of secondary sexual characters (antlers, tusk-like upper canines, and body size) has been strongly influenced by changes in habitat and behaviour.     

Global chloroplast phylogeny and biogeography of bracken (Pteridium; Dennstaedtiaceae)

Bracken ferns (genus Pteridium) represent an ancient species complex with a natural worldwide distribution. Pteridium has historically been treated as comprising a single species, but recent treatments have recognized several related species. Phenotypic plasticity, geographically structured morphological variation, and geographically biased sampling have all contributed to taxonomic confusion in the genus. We sampled bracken specimens worldwide and used variable regions of the chloroplast genome to investigate phylogeography and reticulate evolution within the genus. Our results distinguish two major clades within Pteridium, a primarily northern hemisphere Laurasian/African clade, which includes all taxa currently assigned to P. aquilinum, and a primarily southern hemisphere Austral/South American clade, which includes P. esculentum and P. arachnoideum. All European accessions of P. aquilinum subsp. aquilinum appear in a monophyletic group and are nested within a clade containing the African P. aquilinum taxa (P. aquilinum subsp. capense and P. aquilinum subsp. centrali-africanum). Our results allow us to hypothesize the maternal progenitors of two allotetraploid bracken species, P. caudatum and P. semihastatum. We also discuss the biogeography of bracken in the context of the chloroplast phylogeny. Our study is one of the first to take a worldwide perspective in addressing variation in a broadly distributed species complex.     

Molecular phylogeny and systematics of the pseudoxyrhophiine snake genus Liopholidophis (Reptilia, Colubridae): evolution of its exceptional sexual dimorphism and descriptions of new taxa

The pseudoxyrhophiine snake genus Liopholidophis Mocquard, 1904 is endemic to Madagascar and consists of two distinct species groups. We performed molecular phylogenetic analyses using nucleotide sequences of c . 2200 bp from two mitochondrial genes (16S rRNA, cyt b ) and one nuclear gene (c-mos) to test the monophyly of the genus Liopholidophis and to investigate the relationships of the known species and an unidentified Liopholidophis population. Our phylogeny strongly supports the polyphyly of the genus Liopholidophis , confirms the monophyly of both species groups, and reveals that the unidentified population belongs to a new species. We therefore transfer the species of the former L. stumpffi group ( L. epistibes , L. infrasignatus , L. lateralis , L. martae , and L. stumpffi ) to a new genus Bibilava gen. n. and describe Liopholidophis dimorphus sp. n. from the rainforests of Montagne d'Ambre National Park in northern Madagascar. Finally, we compare our phylogeny with previous hypotheses and discuss the evolution of the extreme sexual dimorphism in tail length of Liopholidophis s. str.     

Phylogenetic relationships among Thunnus species inferred from rDNA ITS1 sequence

Intra and interspecific nucleotide sequence variation of rDNA first internal transcribed spacer (ITS1) was analysed using all eight species of the genus Thunnus plus two out‐group species within the same family, skipjack tuna Katsuwonus pelamis and striped bonito Sarda orientalis . Intraspecific nucleotide sequence variation in ITS1, including intra‐genomic variation, was low, ranging from 0·003 to 0·014 [Kimura's two parameter distance (K2P)], whereas variation between species within the genus Thunnus ranged from 0·009 to 0·05. The Atlantic and Pacific northern bluefin tunas Thunnus thynnus thynnus and Thunnus thynnus orientalis , recently proposed to be distinct species, were found to share nearly identical ITS1 sequences (mean K2P = 0·006) well within the range of intraspecific variation. The northern bluefin tuna appeared to be a sister group to albacore Thunnus alalunga , with all other Thunnus species in a distinct clade. The ITS1 phylogeny was consistent with mtDNA phylogeny in clustering the three tropical Thunnus species ( T. albacares , T. atlanticus and T. tonggol ). Southern bluefin Thunnus maccoyii and bigeye Thunnus obesus tunas showed a closer affinity to this tropical tuna group than to the northern bluefin tuna and albacore. The molecular data supported mitochondrial introgression between species and contradicted morphological subdivision of the genus into two subgenera Neothunnus and Thunnus .     

Contrasting patterns of postglacial range shifts between the northern and southern hemisphere in Herbertus (Herbertaceae,Marchantiophyta)

The leafy liverwort genus Herbertus exhibits considerably variable morphology and widely disjunct distributions in both hemispheres. Here, the biogeographic history of the genus and its phylogenetic relationships with the focus on the taxonomically difficult, northern hemispheric disjunct species, were investigated. We conducted a time-calibrated, molecular-based phylogenetic analysis using psbA, trnL-F, and ITS1-2 loci and different approaches for ancestral range inference of the genus. Herbertus is inferred to have originated in the Cenozoic era about 51 million years ago, in an ancestral area including southern South America, the Neotropics, Oceania, and South-east Asia. The current distribution of the genus is supported to have resulted from long-term in situ persistence, short and long distance dispersals, extinctions and recolonizations. Postglacial range shifts between the southern and northern hemisphere in the genus show distinct patterns. In the southern hemisphere, Herbertus is characterized by in situ persistence, not showing further dispersal until the uplift of the Andean Cordillera. Species of the northern hemisphere showed wide range expansions and repeated recolonizations, including north- and southward dispersals, recolonizations and extinctions. Our results support that the ancestor of South-east Asiatic Herbertus had a Gondwanan origin and arrived in Asia via Indian Plate migration. The uplift of high mountains must have had a strong influence in the diversification and dispersal of the genus. Our results further suggest that climate changes must have had a profound effect on the evolution and biogeography of the species of Herbertus in the northern hemisphere, and might also have influenced the reproductive strategies of the genus. Few genetic differentiations amongst currently recognized species H. aduncus, H. dicranus, H. hutchinsiae, H. stramineus, H. delavayi, and H. kurzii, and amongst H. sendtneri, H. armitanus, and H. circinatus were shown, suggesting that the morphological characters that are currently used for delimiting species should be re-evaluated.     

Nodulation of Cyclopia spp. (Leguminosae, Papilionoideae) by Burkholderia tuberum

BACKGROUND AND AIMS: Species of the genus Burkholderia, from the Betaproteobacteria, have been isolated from legume nodules, but so far they have only been shown to form symbioses with species of Mimosa, sub-family Mimosoideae. This work investigates whether Burkholderia tuberum strains STM678 (isolated from Aspalathus carnosa) and DUS833 (from Aspalathus callosa) can nodulate species of the South African endemic papilionoid genera Cyclopia (tribe Podalyrieae) and Aspalathus (Crotalarieae) as well as the promiscuous legume Macroptilium atropurpureum (Phaseoleae). METHODS: Bacterial strains and the phylogeny of their symbiosis-related (nod) genes were examined via 16S rRNA gene sequencing. Seedlings were grown in liquid culture and inoculated with one of the two strains of B. tuberum or with Sinorhizobium strain NGR 234 (from Lablab purpureus), Mesorhizobium strain DUS835 (from Aspalathus linearis) or Methylobacterium nodulans (from Crotalaria podocarpa). Some nodules, inoculated with green fluorescence protein (GFP)-tagged strains, were examined by light and electron microscopy coupled with immunogold labelling with a Burkholderia-specific antibody. The presence of active nitrogenase was checked by immunolabelling of nitrogenase and by the acetylene reduction assay. B. tuberum STM678 was also tested on a wide range of legumes from all three sub-families. KEY RESULTS: Nodules were not formed on any of the Aspalathus spp. Only B. tuberum nodulated Cyclopia falcata, C. galioides, C. genistoides, C. intermedia and C. pubescens. It also effectively nodulated M. atropurpureum but no other species tested. GFP-expressing inoculant strains were located inside infected cells of C. genistoides, and bacteroids in both Cyclopia spp. and M. atropurpureum were immunogold-labelled with antibodies against Burkholderia and nitrogenase. Nitrogenase activity was also shown using the acetylene reduction assay. This is the first demonstration that a beta-rhizobial strain can effectively nodulate papilioinoid legumes. CONCLUSIONS: Papilionoid legumes from widely different tribes can be nodulated by beta-rhizobia, forming both indeterminate (Cyclopia) and determinate (Macroptilium) nodules.     

Phylogenetic and biogeographic relationships of the mouse opossum Thylamys (Didelphimorphia,Didelphidae) in southern South America

Nucleotide sequence data from the mitochondrial cytochrome b gene were used to evaluate the phylogenetic relationships among mouse opossum species of the genus Thylamys. Based on approximately 1000 bp in five of the six species of the genus and including different localities for some of the species, we concluded that T. macrura from the subtropical forests of eastern Paraguay is the most primitive taxon. Subsequent radiation of the genus is explained mainly via founder effect speciation. This evolutionary scenario would account for the speciation of T. pusilla, T. venusta, T. pallidior, and T. elegans in the Chaco, southern Bolivia and northern Argentina, the Andean Altiplano, the Coastal Desert of Chile, and coastal Perú, respectively. Calibration of a molecular clock set the Pleistocene as the period for the differentiation of Thylamys species. The molecular results confirm the strong genetic connection between populations that inhabit the "pre-cordillera" of northern Chile (T. pallidior) and the canyons that run through the Atacama Desert to the lowlands in northern Chile. Our results confirm the occurrence of two Thylamys species in Chile, T. pallidior and T. elegans, within and south to the Atacama Desert, respectively.     

A phylogeny of the northern temperate leafy liverwort genus Scapania (Scapaniaceae, Jungermanniales)

Scapania is a northern temperate genus with a few disjunctions in the south. Despite receiving considerable attention, the supraspecific classification of this genus remains unsatisfactorily solved. We use three molecular markers (nrITS, cpDNA trnL-F region, atpB-rbcL spacer) and 175 accessions belonging to 50 species (plus eight outgroup taxa) to estimate the phylogeny and to test current classification systems. Our data support the classification of Scapania into six rather than three subgenera, rearrangements within numerous sections, and inclusion of Macrodiplophyllum microdontum. Scapania species with a plicate perianth form three early diverging lineages; the most speciose subgenus, Scapania s.str., represents a derived clade. Most morphological species concepts are supported by the molecular topologies but classification of sect. Curtae requires further study. Southern lineages are nested in northern hemispheric clades. Palearctic-Nearctic distribution ranges are supported for several species.     

Molecular phylogeny illuminates Amblyopinini (Coleoptera: Staphylinidae) rove beetles as a target for systematic and evolutionary research

The rove beetle tribe Amblyopinini (Coleoptera: Staphylinidae: Staphylininae) is a recently discovered monophyletic lineage comprising an estimated 1000 or more species of mainly leaf- and log litter-dwelling predatory insects found throughout the southern hemisphere. Of these, a single genus Heterothops Stephens somehow conquered all continents in the northern hemisphere as well. A few lineages of amblyopinines independently evolved into highly derived predators of mammal ectoparasites from free-living ancestors. In return, they are tolerated in the mammal fur and nests, which is a unique example of cleaning symbiosis between insects and vertebrates. For over a century the great majority of free-living southern amblyopinines were incorrectly placed in the northern hemisphere-restricted, and superficially similar, rove beetle genera from the subtribe Quediina. Only their mammal-associated derived forms were understood as amblyopinines, a nonmonophyletic taxon of volatile status and enigmatic sister-group relationships of its various members. Here we present the first comprehensive phylogeny of Amblyopinini inferred with Bayesian analysis of a six-gene molecular dataset (4672 bp) across a broad sample of taxa (90 species). This phylogeny provides a framework for the badly needed taxonomic inventory of this group and, in particular, reveals at least two independent origins of mammal association within the tribe. It frames the upcoming in-depth interdisciplinary exploration of a variety of phenomena such as evolution of the austral biota in response to continental drift and climate change, biotic exchange between southern and northern continents, origin and evolution of beetle–mammal symbiosis, and pathways and constraints of the evolutionary parallelisms.     

Genus delimitation,biogeography and diversification of Choristoneura Lederer (Lepidoptera: Tortricidae) based on molecular evidence

Widely known for pest species that include major modulators of temperate forests, the genus Choristoneura is part of the species‐rich tribe Archipini of leafroller moths (Tortricidae). Delimitation of the genus has remained unresolved because no phylogeny has included species endemic to Africa and studies have often omitted the type species of the genus. Further taxonomic confusion has been generated by the transfer of Archips occidentalis (Walsingham) to Choristoneura, creating a homonym with Choristoneura occidentalis Freeman, an important defoliator of North American forests. To define the limits of the genus, we reconstructed a phylogeny using DNA sequences for mitochondrial cytochrome oxidase subunit I and nuclear ribosomal 28S genes. Our ingroup included 23 Choristoneura species‐level taxa, complemented by a large sample of outgroups comprising 82 species of Archipini and other Tortricidae. We generated a time‐calibrated tree using fossil and secondary calibrations and we inferred biogeographic and diversification processes in Choristoneura. Our analysis recovered the genus as polyphyletic, with Archips occidentalis, Choristoneura simonyi and Choristoneura evanidana excluded from the main clade. Based on the recovered phylogenies and a redefinition, we restrict Choristoneura primarily to species with a northern hemisphere distribution. Our analysis supports A. occidentalis as the sister group of Cacoecimorpha pronubana, C. simonyi as the sister of ‘Xenotemna’ pallorana, and C. evanidana as the sister of Archips purpurana. A new combination is proposed: Archips evanidana comb.n. ; the availability of ‘Xenotemna’ as a valid name is discussed and A. occidentalis is considered as an orphaned name within the Archipini. We found support for a Holarctic origin of Choristoneura about 23 Ma, followed by early divergence in the Palearctic region. The main divergence occurred at 16 Ma, with one clade in the Nearctic and another in the Palearctic. Subsequent cladogenetic events were synchronous and related to herbivorous specialization, with each clade divided into coniferophagous and polyphagous lineages. Their specialization as conifer feeders temporally matched the expansion of boreal forest during the Miocene.     

Phylogenetic relationships and ecological speciation in the mistletoe Tristerix (Loranthaceae): the influence of pollinators, dispersers, and hosts

Phylogenies can provide valuable information on biotic and abiotic factors associated with speciation. We examined species relationships in Tristerix (Loranthaceae), a genus of 11 species with an Andean distribution from Colombia to Chile. A previous classification divided Tristerix into subgenera Tristerix (two species) and Metastachys (nine species). We tested this classification by generating a molecular phylogeny of the genus using nuclear ribosomal DNA ITS and chloroplast atpB-rbcL intergenic spacer and trnL-F regions. All partitions generally gave congruent trees, thus a combined analysis was conducted. Tristerix was composed of a northern clade (six species) and a southern clade (four species). Tristerix verticillatus and T. penduliflorus (Metastachys) were strongly supported as members of the (southern) subgenus Tristerix clade. Speciation appears to be correlated with the emergence of matorral and cloud forest biomes and is driven by interactions with pollinators and seed dispersers. Tristerix aphyllus is sister to T. corymbosus of the matorral, not to neighboring temperate forest populations, thus rendering the latter species paraphyletic. This ecological speciation event may have occurred in sympatry. Tristerix provides excellent examples of how, during the orography of the Andes, many dynamic and interacting ecological factors have influenced their speciation.     

First phylogenetic and biogeographical study of the southern bluebells (Wahlenbergia, Campanulaceae)

Wahlenbergia is a largely southern hemisphere genus of at least 260 species; within Campanulaceae only Campanula is larger. This first phylogeny of Wahlenbergia was reconstructed using about 20% of the 260 species in the genus based on the nuclear ribosomal ITS marker and the chloroplast trnL-F marker with samples from South Africa, Europe, Australia and New Zealand. Wahlenbergia was confirmed to be non-monophyletic, though most of the species form a clade. Our tree topology and date estimates indicate that Wahlenbergia diverged in South Africa about 29.6 mya, then dispersed to Australasia about 4.8 mya, thus indicating the radiation of Wahlenbergia occurred relatively recently. Radiations occurred in both of these main centres; there are currently about 170 species in South Africa and 45 species and subspecies in Australasia. New Zealand species comprise two clades, both rooted within the Australasian clade. We thus propose two dispersals from Australia to New Zealand, one leading to a radiation of species with the rhizomatous herbaceous growth form ca. 1.6 mya, and the other leading to a radiation of species with the radicate growth form 0.7 mya. Dispersals from Australia to New Zealand match the expected direction, following the west wind drift and ocean currents. The herbaceous growth form was shown to be ancestral for the genus as a whole, and polyploidy has been a mechanism of the evolution of the genus in Australasia.     

Genetic divergence, speciation and biogeography of Mustelus (sharks) in the central Indo-Pacific and Australasia

The shark genus Mustelus is speciose, commercially important and systematically troublesome. We use a molecular approach combining inter and intra-specific data to investigate Mustelus species in the central Indo-Pacific and Australasia. Our analysis supports two Mustelus clades, one comprising species with no white spots and a placental reproductive mode and a second clade of white spotted, aplacental species. Levels of genetic divergence are low, especially among species in the white spotted, aplacental clade and this should be taken into account when employing molecular data to delineate species. Our data support the hypothesis of a radiation following dispersal from a northern hemisphere ancestor. Molecular dating suggests that localised speciation in Australasia may have occurred during the Pleistocene. We propose that some of the difficulties associated with Mustelus systematics relate to a recent radiation, particularly in the Australasian region.     

The biogeography of Hoffmannseggia (Leguminosae, Caesalpinioideae, Caesalpinieae): a tale of many travels

Aim The flowering plant genus Hoffmannseggia consists of 21 species distributed amphitropically between the arid regions of the south‐western United States and adjacent Mexico, and west‐central South America. This pattern of geographical disjunction is shared by numerous other angiosperm genera and has been the subject of discussions for more than a century with various authors advocating a northern origin for particular taxa and others advocating a southern origin. This study uses a well‐supported phylogeny of a genus with numerous species in each area to address the issues of a northern or southern origin and the facility with which organisms move between the two continents. Location South‐western United States and northern Mexico, northern Chile and Argentina, southern Bolivia, and western Peru. Methods Using DNA sequence data from the nuclear and chloroplast genomes, we generated a phylogenetic hypothesis for all species of Hoffmannseggia rooted with Zuccagnia and Balsamocarpon. Geographical data were optimized on the resultant tree to assess the probable continent of origin for the genus, the pattern of disjunctions between North and South America, and species radiations within the genus. Main conclusions Hoffmannseggia arose in South America and initially split into a suffrutescent (somewhat woody) and an herbaceous clade. Within each of these major clades, there have been at least two exchanges between North and South America. There are no data to support an ancestral pan‐American range for Hoffmannseggia and we therefore ascribe the amphitropical disjunctions to long‐distance dispersal. The phylogeny clearly shows that all dispersals were from South to North America and they occurred at different times and thus the pattern is not the result of a single simultaneous set of dispersals.     

线粒体D-loop序列变异与东方鲀属鱼类系统发育

东方鲀属的红鳍东方鲀（Takifugu rubripes）是后基因组时代的一种重要模式生物。本研究中,利用东方鲀属11种鱼类（18尾）的D-loop基因序列,对东方鲀属鱼类的系统发育关系进行研究。经序列比对排定后,分析中D-loop序列有841个位点,其中395个位点为可变位点,267个位点为系统发育信息位点。分别采用邻接法（NJ）、最大简约法（MP）、最大似然法（ML）和贝叶斯方法构建了分子系统树。研究结果表明：（1）东方鲀属鱼类为一单系类群;（2）由横纹东方鲀（T. oblongus）和铅点东方鲀（T. alboplumbeus）构成的姊妹群位于这个类群的基部。此外,本属鱼类物种分类现状还需要进一步的澄清。     

Evolutionary history of tree squirrels (Rodentia,Sciurini) based on multilocus phylogeny reconstruction

Pe?nerová, P. & Martínková, N. (2012). Evolutionary history of tree squirrels (Rodentia, Sciurini) based on multilocus phylogeny reconstruction. —Zoologica Scripta, 41, 211–219. Tree squirrels of the tribe Sciurini represent a group with unresolved phylogenetic relationships in gene trees. We used partial sequences of mitochondrial genes for 12S rRNA, 16S rRNA, cytochrome b and d‐loop, and nuclear irbp, c‐myc exon 2 and 3 and rag1 genes to reconstruct phylogenetic relationships within the tribe, maximizing the number of analysed species. Bayesian inference analysis of the concatenated sequences revealed common trends that were similar to those retrieved with supertree reconstruction. We confirmed congruence between phylogeny and zoogeography. The first group that diverged from a common ancestor was genus Tamiasciurus, followed by Palaearctic Sciurus and Indomalayan Rheithrosciurus macrotis. Nearctic and Neotropical Sciurus species formed a monophyletic group that included Microsciurus and Syntheosciurus. Neotropical Sciurini were monophyletic with a putative exception of Syntheosciurus brochus that was included in a polychotomy with Nearctic Sciurus in supertree analyses. Our data indicate that Sciurini tree squirrels originated in the northern hemisphere and ancestors of contemporary taxa attained their current distribution through overland colonization from the nearest continent rather than through trans‐Pacific dispersal.     

A new species of Deinsdorfia (Soricidae, Insectivora, Mammalia) from the Pliocene of Spain

A new species of Deinsdorfia is defined using new material coming from the karstic fissure infilling of Almenara-Casablanca 4 (Castelló, Spain), which shows important differences with the rest of the previously known species of the genus. The definition of a new species is supported by the characters found in extra material coming from the localities of Valdeganga, in the Albacete Province (Spain). The stratigraphical occurrence of this genus of pigmented-toothed shrews reinforces the idea of the Iberian Peninsula as a sink area during the Pliocene, where some Central-European soricids expanded their distribution. Most of those migrations or distributional expansions coincide with moments of climatic changes in the northern hemisphere.     

Phylogenetic distance of Thelohania butleri Johnston, Vernick, and Sprague, 1978 (Microsporidia; Thelohaniidae), a parasite of the smooth pink shrimp Pandalus jordani, from its congeners suggests need for major revision of the genus Thelohania Henneguy, 1892

Thelohania butleri, a microsporidian that causes mortality and commercial losses in the smooth pink shrimp Pandalus jordani, is of taxonomic interest as a species resembling the poorly studied type species, Thelohania giardi, of the large, polyphyletic genus Thelohania. We examined the ultrastructure of T. butleri to confirm its identity and reconstructed phylogenies using ribosomal DNA to find the relationship of T. butleri with other Thelohania species in crayfish and ants. Light and transmission electron microscopy from specimens collected from the type locality, the Pacific coast of Canada, confirmed the identity and demonstrated a development similar to that of T. giardi, involving a series of binary fissions without formation of a plasmodium. Phylogenetic analyses consistently showed T. butleri to be distantly related to other Thelohania species, and closely related to species from marine decapods within a larger fish-parasitic clade. Together, features such as host group and habitat, developmental morphology, and phylogeny suggest T. butleri may be a closer relative to T. giardi than any other Thelohania species represented by DNA data so far, and thus imply species from crayfish and ants may not belong in this genus. Results also confirm that genus Thelohania and family Thelohanidae are in need of revision.