Molecular Synapomorphies Research Articles

Complete mitochondrial genomes of two blattid cockroaches, Periplaneta australasiae and Neostylopyga rhombifolia, and phylogenetic relationships within the Blattaria.

Complete mitochondrial genomes (mitogenomes) of two cockroach species, Periplaneta australasiae and Neostylopyga rhombifolia, 15,605 bp and 15,711 bp in length, respectively, were determined. As reported for other cockroach mitogenomes, the two mitogenomes possessed typical ancestral insect mitogenome gene composition and arrangement. Only several small intergenic spacers were found: one, which was common in all sequenced cockroach mitogenomes except for the genus Cryptocercus, was between tRNA-Ser (UCN) and ND1 and contained a 7bp highly conserved motif (WACTTAA). Three different types of short tandem repeats in the N. rhombifolia control region (CR) were observed. The homologous alignments of these tandem repeats with other six cockroach mitogenome CRs revealed a low similarity. Three conserved sequence blocks (CSB) were detected in both cockroach mitochondrial CRs. CSB1 was specific for blattinine mitogenomes and was highly conserved with 95% similarity, speculating that this block was a possible molecular synapomorphy for this subfamily. CSB3 located nearby downstream of CSB1 and has more variations within blattinine mitogenomes compared with CSB1. The CSB3 was capable of forming stable stem-loop structure with a small T-stretch in the loop portion. We assessed the influence of four datasets and two inference methods on topology within Orthopteroidea. All genes excluding the third codon positions of PCGs could generate more stable topology, and higher posterior probabilities than bootstrap values were presented at some branch nodes. The phylogenetic analysis with different datasets and analytical methods supported the monophyly of Dictyoptera and supported strongly the proposal that Isoptera should be classified as a family (Termitidae) of the Blattaria. Specifically, Shelfordella lateralis was inserted in the clade Periplaneta. Considering the K2P genetic distance, morphological characters, and the phylogenetic trees, we suggested that S. lateralis should be placed in the genus Periplaneta.

Constraints on Phylogenetic Interrelationships among Four Free-living Litostomatean Lineages Inferred from 18S rRNA gene-ITS Region sequences and Secondary Structure of the ITS2 molecule

We investigated interrelationships between four free-living litostomatean lineages, using 18S rRNA gene and ITS region sequences as well as the secondary structure of the ITS2 molecules. Our phylogenetic analyses confirmed the deep split of free-living litostomateans into Rhynchostomatia and Haptoria represented here by Haptorida, Pleurostomatida, and Spathidiida. This bifurcation is also corroborated by the signature of the rhynchostomatian and haptorian ITS2 molecules. Specifically, the consensus stems of helices II and III are longer by one base pair in Rhynchostomatia, while the terminal loops of both helices are longer by one or two nucleotide/-s in Haptoria. A close relationship of Pleurostomatida and Haptorida is favored by quartet likelihood-mapping and supported by a 5’-AG vs. CU-3’ motif in the variable part of helix II and by two morphological apomorphies, i.e., meridionally extending somatic kineties and a non-three-rowed dorsal brush. Although monophyletic origin of Spathidiida is poorly supported in phylogenetic trees, the unique motif 5’-GA vs. UC-3’ present in the consensus helix II stem could be an important molecular synapomorphy of spathidiids, apart from the ancestrally anteriorly curved somatic kineties and the three-rowed dorsal brush. The peculiar family Pseudoholophryidae has very likely found its phylogenetic home among spathidiids, as an early branching lineage.

A Partial Taxonomic Revision of the Rhynchocarpa Clade of Commiphora (Burseraceae) Endemic to Madagascar

Recent molecular phylogenetic studies of Commiphora (Burseraceae) have revealed a complex history of species evolution in this genus, which includes four separate invasions of Madagascar. Two of these invasions have resulted in radiations of species that are not wellcharacterized taxonomically due in part to a lack of sufficient herbarium collections. Recent work has also revealed that morphological characters that have been used historically to circumscribe species of this genus have proven insufficient for distinguishing the closely related Malagasy species of these radiations. In this study we present a partial taxonomic revision for the most species-rich of these clades, the ‘Rhynchocarpa’ clade, which contains at least 26 species united by numerous molecular synapomorphies yet lack a shared, derived suite of morphological traits. Here, we revise seven ‘Rhynchocarpa’ species that are united by the presence of stellate pubescence on vegetative and reproductive parts of the plant, a trait that is uncommon in the genus and a practical metric for limiting the scope of the revisionary work. We include five new species, including four new names (Commiphora andranovoryensis, Commiphora elliptica, Commiphora morondavensis, and Commiphora razakamalalae) and a name currently in use, correctly published (Commiphora falcata). We provide morphological descriptions, distributional information, and conservation assessments for these as well as Commiphora aprevalii and Commiphora stellulata. We designate a lectotype for Commiphora stellulata. A key to the seven species is included. We envision this contribution as the first in a series of clade-based revisions that clarify the taxonomy of Malagasy Commiphora.

Phylogenetic relationships of enigmatic Sphingiphila (Bignoniaceae) based on molecular and wood anatomical data

AbstractSphingiphila is a monospecific genus, endemic to the Bolivian and Paraguayan Chaco, a semi‐arid lowland region. The circumscription of Sphingiphila has been controversial since the genus was first described. Sphingiphila tetramera is perhaps the most enigmatic taxon of Bignoniaceae due to the presence of very unusual morphological features, such as simple leaves, thorn‐tipped branches, and tetramerous, actinomorphic flowers, making its tribal placement within the family uncertain. Here we combined molecular and wood anatomical data to determine the placement of Sphingiphila within the family. The analyses of a large ndhF dataset, which included members of all Bignoniaceae tribes, placed Sphingiphila within Bignonieae. A second, smaller ndhF and pepC dataset, which included only members of tribe Bignonieae, placed the genus within Tanaecium. Unlike most macro‐morphological traits, Sphingiphila is not unusual within Bignoniaceae from a wood anatomical point of view. Sphingiphila shares the presence of narrow vessels and vasicentric to aliform confluent parenchyma with the rest of the family. In addition, Sphingiphila has several specific wood anatomical traits, such as vessels in a diagonal to tangential arrangement, small intervessel pits, and non‐storied heterocellular rays with occasional perforated ray cells. These features suggest that the genus is best placed either in Tecomeae s.str. or Bignonieae, with a better placement in Bignonieae due to its abundant parenchyma, despite lacking the cambial variant synapomorphic for this group. Sphingiphila and Tanaecium form a clade that is strongly supported by molecular characters, including two indels that are molecular synapomorphies of this clade. In addition, careful morphological inspections show that S. tetramera shares with Tanaecium the subulate, bromeliad‐like prophylls, the most evident synapomorphy of this genus apart from long, tubular, villose corollas, and a lepidote ovary. Given the molecular phylogenetic placement of S. tetramera and its macro‐morphological and wood anatomical similarities with Tanaecium, we propose the new combination Tanaecium tetramerum.

Peltigera islandica, a new cyanolichen species in sectionPeltigera(‘P. caninagroup’)

AbstractA new cyanolichen,Peltigera islandicasp. nov. in the sectionPeltigera(‘P. caninagroup’) is described from Iceland. This species is similar in general appearance toP. rufescensandP. membranacea, but may be recognized by its downturned lobe tips and narrow lobes, respectively. Most thalli are bright emerald green in colour when moist, although a dark khaki green colourmorph is also documented. Monophyly ofP. islandicas. lat. (i.e. includingP. sp. AsensuO’Brienet al., from Canada) is significantly supported based on ITS sequences and corroborated by molecular synapomorphy (absence of the ITS1 hypervariable region). Analysis of therbcLX locus indicates the cyanobiont ofP. islandica(Nostocsp.) comprises strains belonging to a pool of Icelandic genotypes, some of which are present in otherPeltigeraspecies, includingP.“neorufescens”, another taxon new to Iceland collected during this study. Association with photobionts that are shared by other local species suggestsP. islandicamay be well established in Iceland, but a review of herbarium collections as well as broader field surveys are needed to better characterize its geographical distribution.

300 million years of diversification: elucidating the patterns of orthopteran evolution based on comprehensive taxon and gene sampling.

Orthoptera is the most diverse order among the polyneopteran groups and includes familiar insects, such as grasshoppers, crickets, katydids, and their kin. Due to a long history of conflicting classification schemes based on different interpretations of morphological characters, the phylogenetic relationships within Orthoptera are poorly understood and its higher classification has remained unstable. In this study, we establish a robust phylogeny of Orthoptera including 36 of 40 families representing all 15 currently recognized superfamilies and based on complete mitochondrial genomes and four nuclear loci, in order to test previous phylogenetic hypotheses and to provide a framework for a natural classification and a reference for studying the pattern of divergence and diversification. We find strong support for monophyletic suborders (Ensifera and Caelifera) as well as major superfamilies. Our results corroborate most of the higher-level relationships previously proposed for Caelifera, but suggest some novel relationships for Ensifera. Using fossil calibrations, we provide divergence time estimates for major orthopteran lineages and show that the current diversity has been shaped by dynamic shifts of diversification rates at different geological times across different lineages. We also show that mitochondrial tRNA gene orders have been relatively stable throughout the evolutionary history of Orthoptera, but a major tRNA gene rearrangement occurred in the common ancestor of Tetrigoidea and Acridomorpha, thereby representing a robust molecular synapomorphy, which has persisted for 250Myr.

Phylogeny of the shore crab family Grapsidae (Decapoda: Brachyura: Thoracotremata) based on a multilocus approach

The Grapsidae are a thoracotreme crab family with 40 species in eight genera (in their strict definition), and possess a number of morphological and molecular synapomorphies. Previous phylogenetic studies based on mitochondrial DNA markers established the monophyly of this family, but suggested possible paraphyly or polyphyly of some of the constituent genera. To test the validity of previous hypotheses, the present study reconstructed a molecular phylogeny of the grapsid crabs based on five molecular markers, including mitochondrial DNA markers and the first use of nuclear protein-coding markers to address this issue. Monophyly of Grapsidae was confirmed, with the exception of the position of the monotypic genus Leptograpsodes. The polyphyly of the genus Pachygrapsus is consistent with previous molecular phylogenies, as members from this genus are dispersed throughout our gene tree. Grapsus and Planes were shown to be paraphyletic, with species of Pachygrapsus nested within them. Our study found incongruences between the currently adopted classification of the family, and hence taxonomic revisions will be needed. We hereby demonstrate the use of nuclear protein-coding markers for high confidence reconstruction of decapod phylogenies, resolving most of the early splits that mitochondrial DNA markers alone are unable to tackle.

Taxonomic updates in Dolichandra Cham. (Bignonieae, Bignoniaceae).

Dolichandra is a genus of lianas found in dry and wet Neotropical forests. The genus currently includes eight species and is well characterized by molecular and morphological synapomorphies. Here, Macfadyena hispida (DC.) Seemann is removed from synonomy with Dolichandra uncata (Andrews) L.G. Lohmann based on the presence of the hispid indument, vinaceus ovary, long fruits, and winged seeds. The combination Dolichandra hispida (DC.) L.H. Fonseca & L.G. Lohmann, comb. nov. is proposed, increasing the number of accepted species of Dolichandra to nine. A taxonomic key for all species of Dolichandra is presented.

ITS rDNA sequence comparisons resolve phylogenetic relationships in Orostachys subsection Appendiculatae (Crassulaceae)

Orostachys (Crassulaceae) is a small genus of succulent plants having a predominantly East Asian distribution. Recent DNA sequence comparisons revealed polyphyletic nature of the genus and found distant relationship between its infrageneric taxa. Here we present the first molecular phylogeny of Orostachys subsection Appendiculatae based on a large number of ITS rDNA sequences representing most currently recognized members of the subsection and utilizing secondary structure information. Ribosomal spacer was a highly informative marker and provided a phylogenetic signal sufficient to resolve relationships at different scales, from affinities between species to a fine geographic structure in broadly sampled species. It was also conservative enough to allow unambiguous alignment and construction of consensus secondary structure models for ITS1 and ITS2. These models displayed a number of molecular synapomorphies defining most lineages established in our analyses. We revealed a major split in the subsection placing three species, O. spinosa, O. japonica and O. chanetii, into a strongly supported clade to the exclusion of O. thyrsiflora. Phenotypically distinct monotypic genus Meterostachys was also resolved as a part of the subsection’s clade and showed affinity to O. thyrsiflora. Our data suggested that morphology-based species concept for O. thyrsiflora requires reassessment.

Molecular Evidence for β-tubulin Neofunctionalization in Retaria (Foraminifera and Radiolarians)

Foraminifera and radiolarians are closely related amoeboid protists (i.e., retarians) often characterized by their shells and pseudopodia. Previous studies hypothesized that the unusual "Type 2" β-tubulin (β2) is critically involved in forming helical filaments (HFs), a unique microtubule (MT) assembly/disassembly intermediate found in foraminiferan reticulopodia. Such noncanonical β-tubulin sequences have also been found in two radiolarian species and appear to be closely related to the foraminiferan β2. In this study, we report 119 new β-tubulin transcript sequences from six foraminiferans, four radiolarians, and a related non-retarian species. We found that foraminiferan and radiolarian β2-tubulins share some of the unusual substitutions in the structurally essential and usually conserved domains. In the β-tubulin phylogeny, retarian β2-tubulin forms a monophyletic clade, well separated from the canonical β-tubulin (β1) ubiquitous in eukaryotes. Furthermore, we found that foraminiferan and radiolarian β2-tubulin lineages were under positive selection, and used homology models for foraminiferan α- and β-tubulin hexamers to understand the structural effect of the positively selected substitutions. We suggest that the positively selected substitutions play key roles in the transition of MT to HF by altering the lateral and longitudinal interactions between α- and β-tubulin heterodimers. Our results indicate that the unusual β2-tubulin is a molecular synapomorphy of retarians, and the β-tubulin gene duplication occurred before the divergence of Foraminifera and radiolarians. The duplicates have likely been subjected to neofunctionalization responsible for the unique MT to HF assembly/disassembly dynamics, and/or other unknown physiological processes in retarian protists.

Secondary structure models of 18S and 28S rRNAs of the true bugs based on complete rDNA sequences of Eurydema maracandica Oshanin, 1871 (Heteroptera,Pentatomidae).

The sequences of 18S and 28S rDNAs have been used as molecular markers to resolve phylogenetic relationships of Heteroptera for two decades. The complete sequences of 18S rDNAs have been used in many studies, while in most studies only partial sequences of 28S rDNAs have been used due to technical difficulties of amplifying the complete lengths. In this study, we amplified the complete 18S and 28S rDNA sequences of Eurydema maracandica Oshanin, 1871, and reconstructed the secondary structure models of the corresponding rRNAs. In addition, and more importantly, all of the length variable regions of 18S rRNA were compared among 37 families of Heteroptera based on 140 sequences, and the D3 region of 28S rRNA was compared among 51 families based on 84 sequences. It was found that 8 length variable regions could potentially serve as molecular synapomorphies for some monophyletic groups. Therefore discoveries of more molecular synapomorphies for specific clades can be anticipated from amplification of complete 18S and 28S rDNAs of more representatives of Heteroptera.

Phylogenetic analysis of Astragalus sect. Ammodendron (Fabaceae) based on nrDNA ITS and two cpDNAs, psbA-trnH and trnT-trnY sequences

Phylogenetic relationships among species of Astragalus sect. Ammodendron were reconstructed using nrDNA ITS and two cpDNAs trnT-trnY and psbA-trnH, separately and in combination. The present analyses do not support the monophyly of section Ammodendron at the current status. Astragalus griffithii and Astragalus ovalis were nested in separate clades apart from the well supported Ammodendron s. str. clade. The members of Ammodendron s. str. are characterized by shrubby/sub-shrubby habit and imparipinnate leaves of mostly 1–3 pairs of leaflets. Two molecular synapomorphies for this clade are a deletion of 36-bp in ITS1 and a 6-bp deletion in psbA-trnH regions. Resolution within the sect. Ammodendron s. str. is very poor due to the low rate of evolutionary change in nucleotides.

Systematics and Molecular Phylogeny of the Family Oscarellidae (Homoscleromorpha) with Description of Two New Oscarella Species

The family Oscarellidae is one of the two families in the class Homoscleromorpha (phylum Porifera) and is characterized by the absence of a skeleton and the presence of a specific mitochondrial gene, tatC. This family currently encompasses sponges in two genera: Oscarella with 17 described species and Pseudocorticium with one described species. Although sponges in this group are relatively well-studied, phylogenetic relationships among members of Oscarellidae and the validity of genus Pseudocorticium remain open questions. Here we present a phylogenetic analysis of Oscarellidae using four markers (18S rDNA, 28S rDNA, atp6, tatC), and argue that it should become a mono-generic family, with Pseudocorticium being synonymized with Oscarella, and with the transfer of Pseudocorticium jarrei to Oscarella jarrei. We show that the genus Oscarella can be subdivided into four clades, each of which is supported by either a small number of morphological characters or by molecular synapomorphies. In addition, we describe two new species of Oscarella from Norwegian fjords: O. bergenensis sp. nov. and O. nicolae sp. nov., and we compare their morphology, anatomy, and cytology with other species in this genus. Internal anatomical characters are similar in both species, but details of external morphology and particularly of cytological characters provide diagnostic features. Our study also confirms that O. lobularis and O. tuberculata are two distinct polychromic sibling species. This study highlights the difficulties of species identification in skeleton-less sponges and, more generally, in groups where morphological characters are scarce. Adopting a multi-marker approach is thus highly suitable for these groups.

Molecular phylogenetics and biogeography of Neotropical Paepalanthoideae with emphasis on BrazilianPaepalanthus(Eriocaulaceae)

Subfamily Paepalanthoideae encompass the largest generic diversity in Eriocaulaceae. In the present study, the main goals were to infer the phylogeny of this subfamily focusing on Paepalanthus, to evaluate recent classifications and morphological characters in a phylogenetic context and to reconstruct the historical biogeography of the group. Sampling involved 94 ingroup species corresponding to all recognized genera and three outgroup species. Two molecular data sets, nuclear ribosomal internal transcribed spacer (nrITS) and plastid trnL-trnF, were analysed under parsimony and Bayesian methods. Rondonanthus is monophyletic and confirmed as sister to the remaining Paepalanthoideae. Leiothrix and Actinocephalus are each monophyletic, whereas Syngonanthus may be either monophyletic or paraphyletic with the recognition of Philodice. Four subgenera of Paepalanthus are monophyletic, but P. subgenus Paepalanthus is polyphyletic. Morphological characters used in previous classifications are assessed as putative synapomorphies for recognized genera. Some of the characters employed in defining Paepalanthus subcategories appear to have evolved multiple times, and many clades may be exclusively defined by molecular synapomorphies. Biogeographical reconstructions suggest that the current distribution patterns may be related to vicariance and a few long-distance dispersal events. Furthermore, some clades are restricted to narrow geographical areas, perhaps important as a means of conserving evolutionary processes. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ●●, ●●–●●.

A mitochondrial genome phylogeny of termites (Blattodea: Termitoidae): Robust support for interfamilial relationships and molecular synapomorphies define major clades

Despite their ecological significance as decomposers and their evolutionary significance as the most speciose eusocial insect group outside the Hymenoptera, termite (Blattodea: Termitoidae or Isoptera) evolutionary relationships have yet to be well resolved. Previous morphological and molecular analyses strongly conflict at the family level and are marked by poor support for backbone nodes. A mitochondrial (mt) genome phylogeny of termites was produced to test relationships between the recognised termite families, improve nodal support and test the phylogenetic utility of rare genomic changes found in the termite mt genome. Complete mt genomes were sequenced for 7 of the 9 extant termite families with additional representatives of each of the two most speciose families Rhinotermitidae (3 of 7 subfamilies) and Termitidae (3 of 8 subfamilies). The mt genome of the well supported sister-group of termites, the subsocial cockroach Cryptocercus, was also sequenced. A highly supported tree of termite relationships was produced by all analytical methods and data treatment approaches, however the relationship of the termites+Cryptocercus clade to other cockroach lineages was highly affected by the strong nucleotide compositional bias found in termites relative to other dictyopterans. The phylogeny supports previously proposed suprafamilial termite lineages, the Euisoptera and Neoisoptera, a later derived Kalotermitidae as sister group of the Neoisoptera and a monophyletic clade of dampwood (Stolotermitidae, Archotermopsidae) and harvester termites (Hodotermitidae). In contrast to previous termite phylogenetic studies, nodal supports were very high for family-level relationships within termites. Two rare genomic changes in the mt genome control region were found to be molecular synapomorphies for major clades. An elongated stem-loop structure defined the clade Polyphagidae + (Cryptocercus+termites), and a further series of compensatory base changes in this stem-loop is synapomorphic for the Neoisoptera. The complicated repeat structures first identified in Reticulitermes, composed of short (A-type) and long (B-type repeats) defines the clade Heterotermitinae+Termitidae, while the secondary loss of A-type repeats is synapomorphic for the non-macrotermitine Termitidae.

Molecular systematics of the ‘Navanax aenigmaticus’ species complex (Mollusca, Cephalaspidea): coming full circle

Ornelas‐Gatdula, E., Camacho‐García, Y., Schrödl, M., Padula, V., Hooker, Y., Gosliner, T. M. & Valdés, Á. (2012). Molecular systematics of the ‘Navanax aenigmaticus’ species complex (Mollusca, Cephalaspidea): Coming full circle. —Zoologica Scripta, 41, 374–385.Molecular evidence from the mitochondrial COI and 16S genes and the nuclear H3 gene indicate that the traditionally recognized cephalaspidean sea slug species Navanax aenigmaticus consists of three deeply divergent lineages with disjunct ranges in the eastern Pacific, western Atlantic and eastern Atlantic. Each of these allopatric lineages is highly variable in colour and body size, which hampers identification of some possible consistent differences between them. Some conchological differences between the three lineages seem to be correlated with the groupings resulting from the analyses of molecular data, but the results of the morphological studies are inconclusive. Because of the presence of well‐supported divergences and molecular synapomorphies, these lineages are herein considered to be three separate cryptic species. A review of the literature and available type material was conducted to determine the valid name for each of the three species. In other to promote nomenclatural stability, the oldest name with a description that allows a positive identification was selected over older, taxonomically ambiguous names. The conclusion of this revision is that the valid names for the species are Navanax nyanyanus (Edmunds 1968) – eastern Atlantic, Navanax gemmatus (Mörch 1863) – western Atlantic and Navanax aenigmaticus (Bergh 1893) – eastern Pacific.

Color pattern variation in Cichla temensis (Perciformes: Cichlidae): resolution based on morphological, molecular, and reproductive data

Morphological variants of Cichla temensis, readily differentiated by their striking color pattern differences, are found in several Amazon basin flood pulse river systems. The adult variants have at times been thought to represent different species or sexual dimorphism. A three part study was performed in two regions in Brazil (rio Igapó Açú and rio Caures) to elucidate the nature of the variants. In part one; selected diagnostic morphometric characters were compared intraspecifically among the variants and interspecifically with C. monoculus and C. orinocensis. All of the C. temensis variants were found to differ significantly from their sympatric congeners while not differing among each other. In part two, mitochondrial DNA samples were compared intraspecifically among the variants and interspecifically with their sympatric congeners. There were no diagnostic molecular synapomorphies that would unambiguously distinguish the variants and all C. temensis variants were clearly diagnosable and divergent from their sympatric congeners. In part three, color pattern variation in both sexes was compared to a gonadosomatic index (GSI). A significant correlation between color pattern variation and gonadosomatic index was found. The results of this study demonstrate that Cichla temensis variants are confirmed to be members of a single species and that the variation does not represent a sexual dimorphism. The color pattern variation is a cyclically occurring secondary sexual characteristic and is indicative of the specific degree of an individual's seasonal sexual maturation.

A genomic survey shows that the haloarchaeal type tyrosyl tRNA synthetase is not a synapomorphy of opisthokonts

The haloarchaeal-type tyrosyl tRNA synthetase (tyrRS) have previously been proposed to be a molecular synapomorphy of the opisthokonts. To re-evaluate this we have performed a taxon-wide genomic survey of tyrRS in eukaryotes and prokaryotes. Our phylogenetic trees group eukaryotes with archaea, with all opisthokonts sharing the haloarchaeal-type tyrRS. However, this type of tyrRS is not exclusive to opisthokonts, since it also encoded by two amoebozoans. Whether this is a consequence of lateral gene transfer or lineage sorting remains unsolved, but in any case haloarchaeal-type tyrRS is not a synapomorphy of opisthokonts. This demonstrates that molecular markers should be re-evaluated once a better taxon sampling becomes available.

Nucleotide sequence data confirm diagnosis and local endemism of variable morphospecies of Andean astroblepid catfishes (Siluriformes: Astroblepidae)

Phylogenetic analysis based on nuclear and mitochondrial DNA sequences was used to test the validity of morphospecies of catfishes of the family Astroblepidae inhabiting the southern-most limit of their Andean distribution in the upper Ucayali and upper Madre de Dios river basins. Population samples of morphospecies designated a priori on the basis of morphological features were further diagnosed by the presence of unique and unreversed molecular synapomorphies, thereby confirming species validity for seven of nine cases. Although each are distinguished by unique combinations of morphological features, two morphospecies (designated F and H) cannot be diagnosed on the basis of apomorphic changes in molecular sequence that did not also occur in other astroblepid morphospecies or outgroup taxa. Further, one morphospecies (species G) was recovered as nested within the assemblage of populations sampled from morphospecies F, whose morphological diagnosis does not involve unique or apomorphic characters. In contrast, the absence of corroborating molecular apomorphies for species H, otherwise recognized by distinctive and uniquely derived morphological characters, suggests a history of rapid divergence and insufficient time for fixation of genetic differences. Species sharing syntopic distributions were not recovered as sister groups, and in some cases species distributed in adjacent river drainage basins were not more closely related to one another than to species distributed in more distant drainages. Three independent instances were observed of sister-group relationships involving species distributed in both the Apurimac and Urubamba rivers (Ucayali drainage). These observations combine to suggest that the current distribution of astroblepid species in the southern region may have arisen via a complex history involving both divergence between and dispersal amongst drainage basins that is probably repeated numerous times throughout the Andean distribution of the group. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 90–102.

POLYPHYLY OF CHAETOPHORA AND STIGEOCLONIUM WITHIN THE CHAETOPHORALES (CHLOROPHYCEAE), REVEALED BY SEQUENCE COMPARISONS OF NUCLEAR-ENCODED SSU rRNA GENES(1).

Previously published molecular phylogenetic analyses of the Chaetophorales (Chlorophyceae) suffered from limited taxon sampling (six genera with only a single species per genus). To test the monophyly of species-rich genera, and to analyze the phylogenetic relationships among families and genera in the Chaetophorales, we determined nuclear-encoded SSU rDNA sequences from 30 strains of Chaetophorales, performed phylogenetic analyses using various methods, and screened clades for support by unique molecular synapomorphies in the SSU rRNA secondary structure. The Schizomeridaceae and the weakly supported Aphanochaetaceae were recovered as basal lineages. The derived family Chaetophoraceae diverged into two clades: the "Uronema clade" containing unbranched filaments, and a sister clade designated as "branched Chaetophoraceae" comprising Chaetophora, Stigeoclonium, Draparnaldia, Caespitella, and Fritschiella. Although some terminal clades corresponded to genera described (e.g., Caespitella and Draparnaldia), other clades were in conflict with traditional taxonomic designations. Especially, the genera Stigeoclonium and Chaetophora were shown to be polyphyletic. The globose species Chaetophora elegans was unrelated to lobate Chaetophora spp. (e.g., Chaetophora lobata). Since the original description of Chaetophora referred to a lobate thallus organization, the latter clade represented Chaetophora sensu stricto. In consequence, C. lobata was designated as lectotype of Chaetophora. Two Stigeoclonium species, Stigeoclonium farctum Berthold and Stigeoclonium'Longipilus', diverged independently from the type species of Stigeoclonium, Stigeoclonium tenue (C. Agardh) Kütz. These results indicated that some commonly used taxonomic characters are either homoplasious or plesiomorphic and call for a reevaluation of the systematics of the Chaetophorales using novel morphological and molecular approaches.