The grass megagametophyte and its possible phylogenetic implications

The structure of the grasses megagametophyte is considered to be characteristic enough as to deserve a particular place in the megagametophyte typology. Furthermore, it is compared with those of other Monocotyledonous families to point out embryological affinities.Both are members of the Carrera del Investigador (Conicet, Argentina).     

Variation of pollen morphology, and its implications in the phylogeny of Clematis (Ranunculaceae)

Clematis s.l. (including Archiclematis and Naravelia) is a genus of approximately 300 species with cosmopolitan distribution. The diversity of its pollen was surveyed in 162 taxa belonging to all infrageneric groups of Clematis s.l. Pollen morphology was investigated by use of scanning electron microscopy to identify useful characters, test taxonomic and systematic hypotheses, and elucidate pollen character evolution on the basis of the molecular phylogeny. Clematis pollen is small to medium (14.8–32.1?μm?×?14.2–28.7?μm), oblate to prolate (P/E?=?0.9–1.4) in shape. The apertures may be tricolpate and pantoporate sometimes with 4-zonocolpate and pantocolpate pollen grains as transitional forms. The tricolpate pollen grains are predominant and occur in all the sections of the genus, whereas pantoporate pollen grains can be found in sect. Tubulosae, sect. Viorna, sect. Viticella, and Naravelia only. Phylogenetic mapping of aperture types reveals that the pantoporate pollen type may be the apomorphy in the genus and evolved several times. The surface ornamentation in all taxa studied is similar and characterized by microechinae evenly distributed on the microperforate tectum. The size and density of spinules on the tectum vary greatly but successive in the whole genus. According to the character syndromes of the ornamentation, separating sect. Brachiata from sect. Meclatis is supported. Though pollen morphology may contribute to investigation of problematic taxa, the taxonomic value of pollen morphology is limited at the species level.     

The phylogeny of the Praomys complex (Rodentia: Muridae) and its phylogeographic implications

Among the African Murinae (Rodentia, Muridae), the Praomys complex, whose systematics has been studied by different approaches, has raised numerous taxonomic problems. Different taxa, namely Praomys, Mastomys , Myomys and Hylomyscus have been considered either as separate genera or subgenera of Praomys . In order to understand the relationships within the Praomys complex and to test the monophyly of the genus Praomys , a cladistic analysis was conducted, based on morpho-anatomical factors involving different species of Praomys , Mastomys , Myomys and Hylomyscus. The results indicate that the Praomys complex is monophyletic, as are the genera Hylomyscus , Mastomys and Myomys , whereas the genus Praomys appears paraphyletic. Indeed, a group of species including Praomys jacksoni was found to be more closely related to the genera Mastomys and Myomys than to a Praomys tullbergi -group. The biotopes and the distribution areas of the species were mapped on the phylogeny. It appears that the different clades each present a relative ecological cohesion and are arranged according to a gradient from closed to open habitats. From there, an evolutionary scenario is proposed for the emergence of the different clades and species of the genus Praomys sensu stricto.     

Anatomy of Afropomus balanoideus (Mollusca,Gastropoda, Ampullariidae) and its implications for phylogeny and ecology

Summary The hitherto unknown anatomy of Afropomus balanoideus is described. Its systematic position within the Ampullariidae is indicated by the possession of the following autapomorphic characters of the Ampullariidae: presence of a lung sac, an ampulla-shaped aorta anterior, a bipartite copulatory organ of pallial origin, a left-sided zygoneur nervous system, a bipartite kidney, a lamellate osphradium, labial tentacles, an ingestion and an egestion sipho and a radula with strong teeth. The pallial vas deferens is completely closed, while the pallial oviduct is anatomically open in its distal part but functionally closed, because it is embedded in the surrounding mantle tissue. The copulatory organ is of pallial origin and innervated by the right pleural ganglion. The plesiomorphic states of some characters indicate that Afropomus balanoideus might represent the adelphotaxon of the remaining Ampullariidae. The morphological structures show that this species is adapted to an amphibious mode of life and to aestivation, as has been shown for other species of Ampullariidae.     

Pollen Morphology of Xyridaceae Systematic (Poales) and its Potential

Xyridaceae are a predominantly tropical family of five genera that exhibit two pollen morphologies often considered to be of taxonomic importance. Xyris comprises about 95% of the species and is characterized by medium to large, elliptic, sulcate pollen grains. The other pollen class is spheroidal grains without an evident aperture. Many of the species with spheroidal grains have remarkably large and ornamented pollen found to be species specific in earlier research. A scanning electron microscopy investigation of 23 taxa representing all genera with spheroidal pollen revealed new data to further distinguish the genera based on pollen characters. Reliable specific pollen characters need to be evaluated in a statistical study.     

The pregenital abdominal musculature in phasmids and its implications for the basal phylogeny of Phasmatodea (Insecta: Polyneoptera)

Recently several conflicting hypotheses concerning the basal phylogenetic relationships within the Phasmatodea (stick and leaf insects) have emerged. In previous studies, musculature of the abdomen proved to be quite informative for identifying basal taxa among Phasmatodea and led to conclusions regarding the basal splitting events within the group. However, this character complex was not studied thoroughly for a representative number of species, and usually muscle innervation was omitted. In the present study the musculature and nerve topography of mid-abdominal segments in both sexes of seven phasmid species are described and compared in detail for the first time including all putative basal taxa, e.g. members of Timema, Agathemera, Phylliinae, Aschiphasmatinae and Heteropteryginae. The ground pattern of the muscle and nerve arrangement of mid-abdominal segments, i.e. of those not modified due to association with the thorax or genitalia, is reconstructed. In Timema, the inner ventral longitudinal muscles are present, whereas they are lost in all remaining Phasmatodea (Euphasmatodea). The ventral longitudinal muscles in the abdomen of Agathemera, which span the whole length of each segment, do not represent the plesiomorphic condition as previously assumed, but might be a result of secondary elongation of the external ventral longitudinal muscles. Sexual dimorphism, common within the Phasmatodea, also applies to the muscle arrangement in the abdomen of some species. Only in the females of Haaniella dehaanii (Heteropteryginae) and Phyllium celebicum (Phylliinae) the ventral external longitudinal muscles are elongated and span the length of the whole segment, possibly as a result of convergent evolution.     

Nuclear ribosomal DNA phylogeny and its implications for evolutionary trends in Mexican Bursera (Burseraceae)

The genus Bursera (Burseraceae) is one of the most diversified and abundant groups of plants of the tropical dry forests of Mexico. In order to provide a basis for better understanding of its evolutionary biology, we reconstructed a phylogeny of 57 species and varieties using the nucleotide sequences of the internal transcribed spacer regions (ITS1 and ITS2) of 18S–26S and the 5.8S coding region of nuclear ribosomal DNA. We used four species of the allied genera Commiphora and Boswellia and one species of Spondias (Anacardiaceae) as outgroups. Our results support the views that Bursera is monophyletic and more closely related to Commiphora than to Boswellia. The division of Bursera into sections Bullockia and Bursera is also strongly supported by our phylogeny. Several other subclades also had high bootstrap values, especially within section Bursera. We use the phylogeny as a basis for discussing evolutionary tendencies in bark, leaves, breeding systems, and fruits.     

The phylogeny of the 'higher' temnospondyls (Vertebrata: Choanata) and its implications for the monophyly and origins of the Stereospondyli

A parsimony analysis of 'higher' temnospondyls (all temnospondyls descended from the common ancestor of Eryops and Parotosuchus ) was performed using 37 terminal taxa and 121 osteological characters. Bremer support values for each internal node were calculated as a measure of clade strength. Additionally, the shortest trees that conformed to some alternative hypotheses were searched for. The following new taxa are established on the basis of the results: Euskelia (the clade containing the Eryopoidea and Dissorophoidea), Limnarchia (the clade containing Trimerorhachidae, Dvinosauroidea, Archegosauroidea and Stereospondyli), Dvinosauria (the clade containing Trimerorhachidae and Dvinosauroidea), Stereo-spondylomorpha (the clade containing Archegosauroidea and Stereospondyli), Capitosauria (the clade containing Lydekkerina and 'capitosauroids'), and Trematosauria (the clade containing Trematosauroidea, Rhytidosteidae, Plagiosauroidea, Metoposauroidea and Brachyopoidea). The monophyly of the assemblage of Mesozoic families called the Stereospondyli by Romer is supported. The dominance of the Stereospondyli in the Mesozoic and its rarity in the Palaeozoic is discussed. It is suggested that the radiation of the diverse stereospondyl clades, the Capitosauria and Trematosauria, began in the Late Permian of Gondwana, in a 'safe haven' that was less severely affected by the Late Permian extinction event. It is further speculated that the 'safe haven' was located in Antarctica, or possibly Australia.     

A new species of fungus-growing ant and its implications for attine phylogeny (Hymenoptera: Formicidae)

Abstract. Apterostigma megacephala, a new species of attine ant, is described from Peru and Colombia. It is diagnosed by the following combination of worker characters: flattened compound eyes partially wrapped around conical tubercles, mesonotal denticles and erect rigid pilosity on the head, mesosoma and gaster. It is thought to be a basal species in relation to the rest of Apterostigma. Phylogenetic relationships among basal genera of the tribe Attini are discussed.     

Columnal ontogeny in articulate crinoids and its implications for their phylogeny

Simms, Michael J. 1969 01 15: Columnal ontogeny in articulate crinoids and its implications for their phylogeny. Lethaia , Vol. 22, pp. 61–68. Oslo. ISSN 0024–1164.
Detailed doamentation of columnal ontogeny in several Lower Jurassic isocrinids reveals a number of features which are of phylogenetic significance. Columnal proportions are determined by two largely independent growth vectors. Columnal diameter is primarily a function of cup size at the time of formation, though it may subsequently undergo considerable increase through lateral accretion. Columnal height is largely independent of cup size except for a gradual increase with the growth of the whole animal. Columnal diameter increases at a much greater rate than columnal height and so columnals are relatively lower in large individuals. Heterochronous variation in vertical growth rate or the extent of lateral accretion in columnals may significantly alter their shape. The smallest isocrinid columnals found (0.35 mm diameter) have synarthrial articula. The transformation to a typical pentaradiate symplexy, via a triradiate stage, occurs at a diameter of about 0.75 mm. Synarthrial articula are unknown in millericrinid columnals, which instead have symplectial articula at small diameters (0.45 mm). The presence of synarthrial articula in the stems of juvenile isocrinids, and their absence in millericrinids. supports previous hypotheses concerning derivation of bourgueticrinids from an isocrinid, rather than a millericrinid, ancestor.     

The first mitochondrial genome for Brahmin moths (Brahmaeidae) and implications for the higher phylogeny of Bombycoidea

Bombycoidea comprises 10 families and 4723 species, and the phylogenetic relationships among families are still in debate. In this study, we have determined the complete mitochondrial genome (mitogenome) of Brahmaea porphyria. The 15,429-bp mitogenome contains a common set of 37 mitochondrial genes including 13 protein-coding genes, 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and an inferred control region, and shares the conserved gene rearrangement (trnM-trnI-trnQ) in most ditrysian mitogenomes. Moreover, we analysed the secondary structure for all the tRNA genes of B. porphyria and the preference of codon usage in the PCGs of B. porphyria. The putative 373-bp control region (CR) possesses three types of conserved elements, including ATAGA, Ploy-T stretch, and microsatellite-like elements. A phylogenetic analysis among available Bombycoidea mitogenomes using the concatenated 37 mitochondrial genes appears to support the hypothesis of (Sphingidae+Bombycidae)+Saturniidae and the relatively basal phylogenetic position of Brahmaeidae within Bombycoidea.     

A molecular phylogeny for the leaf-roller moths (Lepidoptera: Tortricidae) and its implications for classification and life history evolution

Background

Tortricidae, one of the largest families of microlepidopterans, comprise about 10,000 described species worldwide, including important pests, biological control agents and experimental models. Understanding of tortricid phylogeny, the basis for a predictive classification, is currently provisional. We present the first detailed molecular estimate of relationships across the tribes and subfamilies of Tortricidae, assess its concordance with previous morphological evidence, and re-examine postulated evolutionary trends in host plant use and biogeography.

Methodology/Principal Findings

We sequenced up to five nuclear genes (6,633 bp) in each of 52 tortricids spanning all three subfamilies and 19 of the 22 tribes, plus up to 14 additional genes, for a total of 14,826 bp, in 29 of those taxa plus all 14 outgroup taxa. Maximum likelihood analyses yield trees that, within Tortricidae, differ little among data sets and character treatments and are nearly always strongly supported at all levels of divergence. Support for several nodes was greatly increased by the additional 14 genes sequenced in just 29 of 52 tortricids, with no evidence of phylogenetic artifacts from deliberately incomplete gene sampling. There is strong support for the monophyly of Tortricinae and of Olethreutinae, and for grouping of these to the exclusion of Chlidanotinae. Relationships among tribes are robustly resolved in Tortricinae and mostly so in Olethreutinae. Feeding habit (internal versus external) is strongly conserved on the phylogeny. Within Tortricinae, a clade characterized by eggs being deposited in large clusters, in contrast to singly or in small batches, has markedly elevated incidence of polyphagous species. The five earliest-branching tortricid lineages are all species-poor tribes with mainly southern/tropical distributions, consistent with a hypothesized Gondwanan origin for the family.

Conclusions/Significance

We present the first robustly supported phylogeny for Tortricidae, and a revised classification in which all of the sampled tribes are now monophyletic.     

Morphology and anatomy of inflorescence and inflorescence axis in Paepalanthus sect. Diphyomene Ruhland (Eriocaulaceae,Poales) and its taxonomic implications

Paepalanthus sect. Diphyomene has inflorescences arranged in umbels. The underlying bauplan seems however to be more complex and composed of several distinct subunits. Despite appearing superficially very similar, the morphology and anatomy of the inflorescences can supply useful information for the understanding of the phylogeny and taxonomy of the group. Inflorescences of Paepalanthus erectifolius, Paepalanthus flaccidus, Paepalanthus giganteus, and Paepalanthus polycladus were analyzed in regard to branching pattern and anatomy. In P. erectifolius, P. giganteus and P. polycladus the structure is a tribotryum, with terminal dibotryum, and with pherophylls bearing lateral dibotrya. In P. flaccidus, the inflorescence is a pleiobotryum, with terminal subunit, and without pherophylls. Secondary inflorescences may occur in all species without regular pattern. Especially when grown in sites without a pronounced seasonality, the distinction between enrichment zone (part of the same inflorescence) and new inflorescences may be obscured. The main anatomical features supplying diagnostic and phylogenetic information are as follows: (a) in the elongated axis, the thickness of the epidermal cell walls and the cortex size; (b) in the bracts, the quantity of parenchyma cells (c) in the scapes, the shape and the presence of a pith tissue. Therefore, P. sect. Diphyomene can be divided in two groups; group A is represented by P. erectifolius, P. giganteus and P. polycladus, and group B is represented by P. flaccidus. The differentiation is based in both, inflorescence structure and anatomy. Group A presents a life cycle and anatomical features similar to species of Actinocephalus. Molecular trees also point that these two groups are closely related. However, inflorescence morphology and blooming sequence are different. Species of group B present an inflorescence structure and anatomical features shared with many genera and species in Eriocaulaceae. The available molecular and morphology based phylogenies still do not allow a precise allocation of the group in the bulk of basal species of Paepalanthus collocated in P. sect. Variabiles. The characters described and used here supply however important information towards this goal.     

Sperm morphology of salamandrids (Amphibia, Urodela): implications for phylogeny and fertilization biology

Mature spermatozoa belonging to four salamander species, Salamandrina terdigitata, Triturus alpestris, Triturus carnifex and Triturus vulgaris, have been investigated by electron microscopy. The sperm ultrastructure of these species was compared with that of previously examined urodeles (36 species and 20 genera) and with that of anurans and caecilians. Many phylogenetic considerations may be inferred as a consequence of comparative spermatology. Urodela appears to be a monophyletic order characterized by three sperm synapomorphies: the acrosomal barb, nuclear ridge and marginal filament. Cryptobranchoidea are confirmed to form a monophyletic suborder having two synapomorphic characters: absence of mitochondria in the tail, and cylindrical shape of the tail axial rod. Within the family Salamandridae, sperm morphology confirms the phylogenetic distance between Salamandrina and Triturus, as already pointed out on the basis of molecular and morphological characters. The very complex ultrastructure of spermatozoa confirms a previous opinion that internal fertilization is the ancestral condition of the Amphibia.     

Delimitation and phylogeny of Aletris (Nartheciaceae) with implications for perianth evolution

Aletris,containing approximately 21 species,is the largest genus in Nartheciaceae,and is disjunctively distributed in eastern Asia and eastern North America.Its delimitation has been controversial beca...     

The mitochondrial genomes of the iguana (Iguana iguana) and the caiman (Caiman crocodylus): implications for amniote phylogeny

The complete mitochondrial genomes of two reptiles, the common iguana (Iguana iguana) and the caiman (Caiman crocodylus), were sequenced in order to investigate phylogenetic questions of tetrapod evolution. The addition of the two species allows analysis of reptilian relationships using data sets other than those including only fast-evolving species. The crocodilian mitochondrial genomes seem to have evolved generally at a higher rate than those of other vertebrates. Phylogenetic analyses of 2889 amino-acid sites from 35 mitochondrial genomes supported the bird-crocodile relationship, lending no support to the Haematotherma hypothesis (with birds and mammals representing sister groups). The analyses corroborated the view that turtles are at the base of the bird-crocodile branch. This position of the turtles makes Diapsida paraphyletic. The origin of the squamates was estimated at 294 million years (Myr) ago and that of the turtles at 278 Myr ago. Phylogenetic analysis of mammalian relationships using the additional outgroups corroborated the Marsupionta hypothesis, which joins the monotremes and the marsupials to the exclusion of the eutherians.