Phylogenetic Characters Research Articles

Phylogenomic relationships and character evolution of the grape family (Vitaceae)

The grape family consists of 16 genera and ca. 950 species. It is best known for the economically important fruit crop – the grape Vitis vinifera. The deep phylogenetic relationships and character evolution of the grape family have attracted the attention of researchers in recent years. We herein reconstruct the phylogenomic relationships within Vitaceae using nuclear and plastid genes based on the Hyb-Seq approach and test the newly proposed classification system of the family. The five tribes of the grape family, including Ampelopsideae, Cayratieae, Cisseae, Parthenocisseae, and Viteae, are each robustly supported by both nuclear and chloroplast genomic data and the backbone relationships are congruent with previous reports. The cupular floral disc (raised above and free from ovary at the upper part) is an ancestral state of Vitaceae, with the inconspicuous floral disc as derived in the tribe Parthenocisseae, and the state of adnate to the ovary as derived in the tribe Viteae. The 5-merous floral pattern was inferred to be the ancestral in Vitaceae, with the 4-merous flowers evolved at least two times in the family. The compound dichasial cyme (cymose with two secondary axes) is ancestral in Vitaceae and the thyrse inflorescence (a combination of racemose and cymose branching) in tribe Viteae is derived. The ribbon-like trichome only evolved once in Vitaceae, as a synapomorphy for the tribe Viteae.

Current status of pinnipeds phylogeny based on molecular and morphological data

ABSTRACT The disagreement surrounding the relationship within pinnipeds as well as their phylogenetic affinities still remains unresolved. Molecular-based studies neglect significant morphological data and ignore the entire fossil record, which demonstrates why there are such contradicting results from morphology-based studies. There still remains a difference of opinion about the origin of pinnipeds, with research supporting origination from either Ursid (bear-like) or Mustelid (weasel-like) ancestors, even extending down to familial and subfamilial levels. This study examines certain morphological characters in the three pinniped families: Otariidae (sea lions and fur seals), Odobenidae (walruses), and Phocidae (true seals), with extra emphasis on the four phocid subfamilies: Phocinae, Monachinae, Cystophorinae, and Devinophocinae. Morphological characters of the cranium (skull, dentition and mandible) and post cranium (humerus and femur) are the basis for understanding pinnipeds’ movement, body size, and sexual dimorphism, and all are ignored when only molecular analyses are used. Biomolecular based studies involve larger sample sizes and incorporate more phylogenetic characters, but ignore the significant data from the fossil record (which can only be examined through morphology). Therefore, the origin of pinnipeds cannot be resolved by depending only on molecular (genetic) or morphological approaches independently and future studies need to integrate both morphology and molecular data.

The deep(er) roots of Eukaryotes and Akaryotes

Background: Locating the root node of the “tree of life” (ToL) is one of the hardest problems in phylogenetics, given the time depth. The root-node, or the universal common ancestor (UCA), groups descendants into organismal clades/domains. Two notable variants of the two-domains ToL (2D-ToL) have gained support recently. One 2D-ToL posits that eukaryotes (organisms with nuclei) and akaryotes (organisms without nuclei) are sister clades that diverged from the UCA, and that Asgard archaea are sister to other archaea. The other 2D-ToL proposes that eukaryotes emerged from within archaea and places Asgard archaea as sister to eukaryotes. Williams et al. ( Nature Ecol. Evol. 4: 138–147; 2020) re-evaluated the data and methods that support the competing two-domains proposals and concluded that eukaryotes are the closest relatives of Asgard archaea. Critique: The poor resolution of the archaea in their analysis, despite employing amino acid alignments from thousands of proteins and the best-fitting substitution models, contradicts their conclusions. We argue that they overlooked important aspects of estimating evolutionary relatedness and assessing phylogenetic signal in empirical data. Which 2D-ToL is better supported depends on which kind of molecular features are better for resolving common ancestors at the roots of clades – protein-domains or their component amino acids. We focus on phylogenetic character reconstructions necessary to describe the UCA or its closest descendants in the absence of reliable fossils. Clarifications: It is well known that different character types present different perspectives on evolutionary history that relate to different phylogenetic depths. We show that protein structural-domains support more reliable phylogenetic reconstructions of deep-diverging clades in the ToL. Accordingly, Eukaryotes and Akaryotes are better supported clades in a 2D-ToL.

Combinatorial views on persistent characters in phylogenetics

The so-called binary perfect phylogeny with persistent characters has recently been thoroughly studied in computational biology as it is less restrictive than the well-known binary perfect phylogeny. Here, we focus on the notion of (binary) persistent characters, i.e. characters that can be realized on a phylogenetic tree by at most one 0→1 transition followed by at most one 1→0 transition in the tree, and analyze these characters under different aspects. First, we illustrate the connection between persistent characters and Maximum Parsimony, where we characterize persistent characters in terms of the first phase of the famous Fitch algorithm. Afterwards we focus on the number of persistent characters for a given phylogenetic tree. We show that this number solely depends on the balance of the tree. To be precise, we develop a formula for counting the number of persistent characters for a given phylogenetic tree based on an index of tree balance, namely the Sackin index. Lastly, we consider the question of how many (carefully chosen) binary characters together with their persistence status are needed to uniquely determine a phylogenetic tree and provide an upper bound for the number of characters needed.

The deep(er) roots of Eukaryotes and Akaryotes

Background: Locating the root node of the "tree of life" (ToL) is one of the hardest problems in phylogenetics. The root-node or the universal common ancestor (UCA) divides descendants into organismal domains. Two notable variants of the two-domains ToL (2D-ToL) have gained support recently. One 2D-ToL posits that eukaryotes (organisms with nuclei) and akaryotes (organisms without nuclei) are sister clades that diverged from the UCA and that Asgard archaea are sister to other archaea, whereas the other proposes that eukaryotes emerged within archaea and places Asgard archaea sister to eukaryotes. Williams et al. ( Nature Ecol. Evol. 4: 138-147; 2020) re-evaluated the data and methods that support the competing two-domains proposals and concluded that eukaryotes are the closest relatives of Asgard archaea. Critique: We argue that important aspects of estimating evolutionary relatedness and assessing phylogenetic signal in empirical data were overlooked. We focus on phylogenetic character reconstructions necessary to describe the UCA or its closest descendants in the absence of reliable fossils. It is well known that different character types present different perspectives on evolutionary history that relate to different phylogenetic depths. Which 2D-ToL is better supported depends on which kind of molecular features - protein-domains or their component amino acids - are better for resolving common ancestors at the roots of clades. In practice, this involves reconstructing character compositions of the ancestral nodes all the way back to the UCA. We believe the criticisms of 2D-ToL focus on superficial aspects of the data and reflects common misunderstandings of phylogenetic reconstructions using protein domains (folds). Clarifications: Models of protein domain evolution support more reliable phylogenetic reconstructions. In contrast, even the best available amino acid substitution models fail to resolve the archaeal radiation, despite employing thousands of genes. Therefore, the primary domains Eukaryotes and Akaryotes are better supported in a 2D-ToL.

Hemipenial morphology of nine South American species of Mabuya (Scincidae: Lygosominae) with comments on the morphology of the family.

Species of the genus Mabuya are barely recognizable because of their highly conservative external morphology, resulting in unstable systematic and taxonomic status. Considering that hemipenial morphology has been extensively used as a source of systematic information for several groups of Squamata, we described the hemipenial morphology of nine species of Mabuya, searching for diagnostic features useful to taxonomic and systematic studies. To have comparative parameters within the family, we also presented the description of the hemipenes of two other Scincidae species (i.e., Trachylepis atlantica and Tiliqua rugosa). This information, together with the available literature, was analyzed in a comparative framework, allowing us to define some variation for the genus and family. The hemipenial morphology of the species of Mabuya studied is very conservative; features that show subtle variation were the shape of the protuberances present on the asulcate face of the hemipenial body and the presence and type of a lateral fold, on the body. Also, within the family, some variation was found in the shape and length of lobes, length of branches of the sulcus spermaticus, and in the kind of folds and protuberances in both faces of the lobes and hemipenial body. Although these features were not tested in a systematic context, this information suggested variations in hemipenial morphology that could contribute to taxonomic diagnostics and phylogenetic characters. The importance of obtaining proper preparations for gathering accurate information is emphasized, and the use of fresh-killed specimens that shows fewer difficulties for the procedures of preparation is highly recommended.

Boothiomyces angulosus and Boothiomyces elyensis: two new combinations in the Terramycetaceae (Rhizophydiales, Chytridiomycota)

The genus Rhizophydium was proposed by A. Schenk in 1858 to accommodate the inoperculate taxa previously placed in Chytridium. The morphological delineation encompassed around 235 species that have now been segregated into different genera based on molecular and zoospore ultrastructural analyses. However, some taxa have never been investigated for phylogenetic position or zoospore ultrastructural characters. The aim of this study was to use morphology, zoospore ultrastructure and molecular analyses to verify the placement of our isolates of Rhizophydium angulosum and R. elyense in the Rhizophydiales phylogeny. These isolates produced angular zoosporangia, characteristic of Terramycetaceae representatives, and grouped within the Boothiomyces clade in analyses of complete ITS and partial LSU regions of rDNA. Transmission electronic microscopy (TEM) analysis revealed that R. angulosum produces zoospores with the same ultrastructural characters described from Boothiomyces representatives. In addition, R. elyense presented sufficient characteristics that support its morphological delineation from Boothiomyces macroporosus, the type species of the genus. Based on molecular, morphological, and ultrastructural analyses, we transfer R. angulosum and R. elyense to Boothiomyces.

Description and phylogenetic relationships of a large-bodied sphagesaurid notosuchian from the Upper Cretaceous Adamantina Formation, Bauru Group, São Paulo, southeastern Brazil

In this work we describe new remains and possible gastroliths of a sphagesaurid (Mesoeucrocodylia: Notosuchia) unearthed from the Adamantina Formation (Bauru Group, Upper Cretaceous) in the municipality of Fernandópolis-SP, which add new data about the dental, dermal shield, and the post-cranial skeleton morphology of these crocodilians. Phylogenetic analyses place the studied fossil within Sphagesauridae, in a polytomy with Armadillosuchus arrudai and Caryonosuchus pricei. The anatomical comparisons are congruent to the phylogenetic analysis since they also suggest that the specimen herein described is closely related to other larger-bodied Sphagesauridae species, such as Armadillosuchus arrudai. The new skull, appendicular, and dermal elements described in this work may provide data for the elaboration of new phylogenetic characters which can improve cladistic analyses concerning Sphagesauridae species, as well as they may help to better understand the morphological complexity of this family of crocodylomorphs, especially the large-bodied species.

Evolution of endemic and sylvatic lineages of dengue virus.

Recent disease outbreaks have raised awareness of tropical pathogens, especially mosquito-borne viruses. Dengue virus (DENV) is a widely studied mammalian pathogen transmitted by various species of mosquito in the genus Aedes, especially Aedes aegypti and Aedes albopictus. The prevailing view of the research community is that endemic viral lineages that cause epidemics of DENV in humans have emerged over time from sylvatic viral lineages, which persist in wild, non-human primates. These notions have been examined by researchers through phylogenetic analyses of the envelope gene (E) from the four serotypes of DENV (serotypes DENV-1 to DENV-4). In these previous reports, researchers used visual inspection of a phylogeny in order to assert that sylvatic lineages lead to endemic clades. In making this assertion, these researchers also reasserted the model of periodic sylvatic to endemic disease outbreaks. Since that study, there has been a significant increase in data both in terms of metadata (e.g., place and host of isolation) and genetic sequences of DENV. Here, we re-examine the model of sylvatic to endemic shifts in viral lineages through a phylogenetic tree search and character evolution study of metadata on the tree. We built a dataset of nucleotide sequences for 188 isolates of DENV that have metadata on sylvatic or endemic sampling along with three orthologous sequences from West Nile virus as the outgroup for the phylogenetic analysis. In contrast to previous research, we find that there are several shifts from endemic to sylvatic lineages as well as sylvatic to endemic lineages, indicating a much more dynamic model of evolution. We propose that a model that allows oscillation between sylvatic and endemic hosts better captures the dynamics of DENV transmission.

The involvements of calcium-dependent protein kinases and catechins in tea plant [Camellia sinensis (L.) O. Kuntze] cold responses

Temperature is one of the most important environmental factors limiting tea plant growth and tea production. Previously we reported that both Ca2+ and ROS signals play important roles in tea plant cold acclimation. Here, we identified 26 CsCPK transcripts, analyzed their phylogenetic and sequence characters, and detected their transcriptions to monitor Ca2+ signaling status. Tissue-specific expression profiles indicated that most CsCPK genes were constitutively expressed in tested tissues, suggesting their possible roles in development. Cold along with calcium inhibitor assays suggested that CsCPKs are important cold regulators and CsCPK30/5/4/9 maybe the key members. Moreover, LaCl3 or EGTA pre-treatment could result in impaired Ca2+ signaling and compromised cold-responding network, but higher catechins accumulation revealed their potential positive roles in cold responses. Those findings indicated that catechins and other secondary metabolites in tea plant may form an alternative cold-responding network that closely correlated with Ca2+ signaling status.

Comparative developmental anatomy of ovary and fruit in Brazilian Velloziaceae

Abstract Morpho-anatomical studies of fruits are scarce in monocotyledons and particularly for the Brazilian species of Velloziaceae, a small family of monocots characteristic of the campo rupestre vegetation of Brazil. The main fruit types found in Velloziaceae are poricidal and loculicidal capsules, but capsule morphology is variable, which has led to discrepancies regarding fruit descriptions and terminology. In this study, we aimed to analyse fruit development in Brazilian Velloziaceae to obtain a better understanding of capsule dehiscence and to elucidate and describe in detail the fruit types occurring in the family. Based on our results, we discuss the terminology used to describe capsules of some species, e.g. capsules of Vellozia minima and V. epidendroides, previously classified as poricidal, should be called apical loculicidal, as they form three slits on the uppermost part of each carpel that are prevented from extending downwards by the precocious lignification of the pericarp. Capsules of Barbacenia purpurea, B. riparia and B. plantaginea have been classified using various terms, but they fit the definition of fissuricidal capsule and should be classified as such. We also propose an improved analysis for the character ‘fruit type’, previously used in phylogenetic reconstructions of Velloziaceae. We changed some states following the fruit reclassification proposed here and added a new state, ‘capsule opening through lateral irregular aperture’, to the character. Additionally, eight new phylogenetic characters derived from ovary and fruit characteristics are suggested.

PastView: a user-friendly interface to explore ancestral scenarios

BackgroundAncestral character states computed from the combination of phylogenetic trees with extrinsic traits are used to decipher evolutionary scenarios in various research fields such as phylogeography, epidemiology, and ecology. Despite the existence of powerful methods and software in ancestral character state inference, difficulties may arise when interpreting the outputs of such inferences. The growing complexity of data (trees, annotations), the diversity of optimization criteria for computing trees and ancestral character states, the combinatorial explosion of potential evolutionary scenarios if some ancestral characters states do not stand out clearly from others, requires the design of new methods to explore associations of phylogenetic trees with extrinsic traits, to ease the visualization and interpretation of evolutionary scenarios.ResultWe developed PastView, a user-friendly interface that includes numerical and graphical features to help users to import and/or compute ancestral character states from discrete variables and extract ancestral scenarios as sets of successive transitions of character states from the tree root to its leaves. PastView provides summarized views such as transition maps and integrates comparative tools to highlight agreements or discrepancies between methods of ancestral annotations inference.ConclusionThe main contribution of PastView is to assemble known numerical and graphical methods into a multi-maps graphical user interface dedicated to the computing, searching and viewing of evolutionary scenarios based on phylogenetic trees and ancestral character states. PastView is available publicly as a standalone software on www.pastview.org.

Phylogenetic Concepts and Tools Applied to Epidemiologic Investigations of Infectious Diseases.

In this review, which is a part of the Microbiology Spectrum Curated Collection: Advances in Molecular Epidemiology of Infectious Diseases, I present an overview of the principles used to classify organisms in the field of phylogenetics, highlight the methods used to infer the interrelationships of organisms, and summarize how these concepts are applied to molecular epidemiologic analyses. I present steps in analyses that come downstream of the assembly of a set of genomes or genes and the production of a multiple-sequence alignment or other matrices of putative orthologs for comparison. I focus on the history of the problem of phylogenetic reconstruction and debates within the field about the most appropriate methods. I illustrate methods that bridge the gap between molecular epidemiology and traditional epidemiology, including phylogenetic character evolution and geographic visualization. Finally, I provide practical advice on how to conduct an example analysis in the appendix. *This article is part of a curated collection.

Nestling-sized hadrosaurine cranial material from the Hell Creek Formation of northeastern Montana, USA, with an analysis of cranial ontogeny in <em>Edmontosaurus annectens</em>

Author(s): Wosik, Mateusz; Goodwin, Mark B.; Evans, David C. | Abstract: Despite over a century of intense collecting, the Hell Creek Formation has produced exceedingly few specimens of small juveniles and nestling-sized dinosaurs. Here, we report on the first cranial material of nestling-sized hadrosaurid dinosaurs from the formation. The specimens were recovered from the Sandstone Basin locality in Garfield County, northeastern Montana. The material consists of two dentaries, a surangular, and a quadrate from disassociated individuals, which through ontogenetically independent characters allows assignment of the surangular (UCMP 235857) and quadrate (UCMP 235859) to Hadrosaurinae and the dentary (UCMP 235860) to Edmontosaurus. Since Edmontosaurus annectens is the only known hadrosaurid in the formation, we hypothesize that these specimens represent the earliest ontogenetic growth stage of E. annectens providing a significant ontogenetic extension when assessing aspects of cranial ontogeny in this taxon. Using the newly identified nestling cranial material as end members of ontogenetic series for each element in E. annectens, we evaluated ontogenetic variability in phylogenetic characters associated with these elements that are used in assessing phylogenetic relationships among hadrosaurids. Although the quadrate and surangular generally develop isometrically and show minimal ontogenetic variation in morphology, the dentary undergoes significant ontogenetic changes. In particular, the dental battery exhibits a high degree of intraspecific variability through ontogeny. Ontogenetic variability in the dentary should reflect a commensurate degree of variation in the jaws and facial skeleton, suggesting caution should be used when taxonomically identifying small edmontosaur material, such as that known from Alaska. Taxonomic identification of new taxa should be restricted to adult individuals until enough specimens are available to adequately assess taxonomic variation in ontogenetically equivalent semaphorants/ontogimorphs for a large range of complementing taxa.

Calyx (con)fusion in a hyper-diverse genus: Parallel evolution of unusual flower patterns in Eugenia (Myrtaceae)

Eugenia has a pantropical distribution and comprises ca. 1000 species found mostly in the Neotropics. Recent DNA based phylogenies show that unusual flower morphology of ‘eugenioid’ collections, e.g. fused calices that open by tearing, consistently emerged within Eugenia. These results emphasize a demand to revaluate flower morphology in a phylogenetic context within the genus. A reassessment of calyx fusion in Eugenia and traditionally related genera is here focused on clarification of the systematic relevance of this apparently recurrent characteristic. Twenty-four Eugenia species with some level of calyx fusion in the bud were newly used (one nuclear and four plastid markers) in conjunction with a representative sample of previously sequenced species to recover a time-calibrated Eugenia phylogeny of 86 accessions. Development of the fused calyx was analysed using scanning electron microscopy, differing patterns were re-coded and subsequently phylogenetic character reconstruction was performed. Eugenia was recovered as monophyletic including the traditionally segregated genera Calycorectes and Catinga. Ancestral character reconstruction uncovered free calyx lobes as the ancestral condition. Five development patterns leading to calyx fusion are reported in Eugenia including species with apparently six petals, which contrast with the standard tetramerous flowers. This condition is interpreted as the petaloid pattern, where two external fused calyx lobes cover the bud while two internal calyx lobes are free and petaloid. The fused calyx condition is homoplastic and evolved independently, several times in Eugenia, as did the different development patterns. Data presented here show that systematic incongruence resulting from multiple, independent origins of the fused calyx in Eugenia is further aggravated by an inability to distinguish parallelism and convergence within the recovered patterns.

Antigenotoxicity and Cytotoxic Potentials of Metabiotics Extracted from Isolated Probiotic, Lactobacillus rhamnosus MD 14 on Caco-2 and HT-29 Human Colon Cancer Cells

Probiotics, the beneficial bacteria produce active metabolites which could probably mimic their anticancer effect and prevent the risk associated with live bacteria. Thus, the study was designed to isolate effective lactic acid bacteria (LAB) and monitor anticancerous potential of their metabiotic extracts. Probiotics were isolated from different sources and their cell free supernatants (CFS) were screened for antigenotoxic and cytotoxic potentials using SOS Chromo Test and MTT assay on Caco-2 and HT-29 cells. Organic extracts of CFS were prepared and dissolved in different solvents. The isolate with most effective metabiotic extract in terms of cytotoxicity was classified for probiotic and phylogenetic characters and the metabiotic extract was characterized physiochemically. Among 60 isolated LAB, CFS of only 10 isolates showed antigenotoxicity more than 30% and four exhibited 70–80% cytotoxicity. Further, organic extracts of these four CFS dissolved in carboxymethyl cellulose showed 80–90% cytotoxicity. Interestingly, the most effective isolate was found to possess probiotic attributes and phylogenetic characterization revealed it to be Lactobacillus rhamnosus MD 14. Physiochemical characterization of its metabiotic extract indicated the presence of heat sensitive organic acids and proteins. To conclude, metabiotics produced by isolated probiotic L. rhamnosus MD 14 exhibited both antigenotoxic and cytotoxic potential against colon cancer.

Geometric morphometrics for the analysis of character variation in size and shape of the sulcus acusticus of sagittae otolith in species of Gerreidae (Teleostei: Perciformes)

Sagittal otoliths are a useful structure to distinguish teleostean fishes. However, character variation in size and shape of the sulcus acusticus has not been tested among Gerreidae Gunther, 1862 species. For the first time, this paper explores the size and shape variation in the sulcus acusticus using landmark data and geometric morphometric methods. Variation in the sulcus acusticus size, as estimated with centroid size, is not a useful feature to distinguish neither the five genera nor all species in this study. However, since analyses of variance followed by Tukey a posteriori tests detect differences among groups of species, it is possible that the size of the sulcus acusticus will still be useful as a phylogenetic character. As expected, the pattern of variation in the shape of the sulcus acusticus consists of well-defined character states exclusive of each of the 18 species of Gerreidae included. All comparisons in multivariate analyses of variance of semi-landmark configurations with a CVA were statistically significant, and the rates for correct posterior classifications were all above 79%. Discriminant axes allowed to locate variation in particular regions of the sulcus acusticus outline that contribute most to the distinction among genera. Results revealed species in the same genus share a particular shape in the ostium and posterior extension of the cauda. Variation in the shape of the sulcus acusticus is, therefore, a very useful character to identify species in Gerreidae.

Answering Research Questions Using Semantic Traits

Phenoscape has developed methods to render phylogenetic characters from the systematic literature machine computable and interoperable with genetic data from model organisms, by annotating them with taxon, anatomy, quality, other ontologies. Moving these trait data into a semantic framework enables their integration with other data types and provides the potential for powerful new computational tools to aid discovery. For example, trait similarities can be quantified, assessed against phylogenetic trees to determine whether they are based in homology or homoplasy, and linked back to candidate genes. Another example is the ability to automatically construct a matrix on the fly, for a user-selected set of traits and taxa. Guidelines for consistent representation of characters have been developed through manual annotation of over 20,000 systematic characters. These represent a limited number of design patterns that are applicable to traits from any source. The level of detail to which characters are annotated will influence how they may be used in research; a minimal approach will still enable basic trait aggregation. Manual curation effort is substantial and does not scale well to biodiversity traits. Natural Language Processing (NLP) methods, using our newly developed Gold Standard for semantic traits, can accelerate annotation from published text, particularly with well-provisioned ontologies. Efforts to establish new trait databases might profitably explore machine learning for morphological discrimination and semantic annotation from digitized images for a high-throughput approach.

Kinetid Structure of Aphelidium and Paraphelidium (Aphelida) Suggests the Features of the Common Ancestor of Fungi and Opisthosporidia.

The aphelids (phylum Aphelida) are phagotrophic parasitoids of algae and represent the most basal branch in superphylum Opisthosporidia, which contains the Microsporidia, Rozellosporidia and Aphelida. Being the closest group to traditional fungi, the aphelids should have ancestral features of both phyla. As in chytrids and other zoosporic fungi, the structure of zoospores is the most informative and important morphological feature for the phylogeny and taxonomy of aphelids. Though a general zoospore description exists for some aphelid species, their flagellar apparatus (kinetid) structure, which contains pivotal taxonomic and phylogenetic characters, has not been studied. Here we represent the kinetid structure in two genera, Aphelidium and Paraphelidium, and demonstrate independent reduction in the kinetid in each genus. The kinetid-mitochondrion connection found in Aphelidium and Paraphelidium is rare for opisthokonts in general, but present in the most basal branches of Fungi and Opisthosporidia. We suggest, therefore, that this connection represents an ancestral character for both these phyla.

Phylogenetic interrelationships of the eel families Derichthyidae and Colocongridae (Elopomorpha: Anguilliformes) based on the pectoral skeleton.

A cladistic analysis of the eel families Derichthyidae and Colocongridae is herein proposed for the first time on the basis of morphological data. We discovered dozens of new phylogenetic characters derived from a detailed analysis of the pectoral skeleton, an anatomical system neglected by most previous studies. Our maximum parsimony analysis indicates that Colocongridae sensu lato is paraphyletic, with its two constituent genera Coloconger and Congriscus appearing as successive sister groups of derichthyids. Monophyly of the family Derichthyidae, which has been questioned by some studies, is herein strongly supported by 10 unambiguous synapomorphies. We also stress the importance of the appendicular skeleton as a useful source of phylogenetic information for the resolution of systematic problems within Anguilliformes.