Genus

About: Genus is a research topic. Over the lifetime, 68921 publications have been published within this topic receiving 590966 citations. The topic is also known as: monospecies genus & genus (zoology).

Revision of Entrophospora and description of Kuklospora and Intraspora , two new genera in the arbuscular mycorrhizal Glomeromycetes

Abstract: Five mycorrhizal fungal species of the Glomeromycetes which were organized in the genus Entrophospora are revised. They all form their spores within the hyphal stalk directly beneath or in some distance of a sporiferous saccule formed intercalary or terminally in the mycelium. Based on differences respective similarities in spore morphologies and root infection characteristics only Entrophospora infrequens and Entrophospora baltica remain in this genus. The genus is the type genus for the new family Entrophosporaceae. The other three species are organized in two new genera. Kuklospora gen. nov. with Kuklospora colombiana and Kuklospora kentinensis (formerly Entrophospora colombiana and Entrophospora kentiniensis ) is placed into the family of the Acaulosporaceae. Intraspora gen. nov. so far contains only Intraspora schenckii (the former Entrophospora schenckii ) and is included into the family of the Archaeosporaceae. The morphological differences between the genera and the distribution of these fungal species in ecosystems are discussed.

The South American annual killifish genus Austrolebias (Teleostei: Cyprinodontiformes: Rivulidae): phylogenetic relationships, descriptive morphology and taxonomic revision

Abstract: The annual fish genus Austrolebias is redefined to include species previously placed in Megalebias, and is revised based on characters of osteology, external morphology, the latero-sensory system and color patterns. Monophyly of Austrolebias is supported by the absence of scales between the corner of the mouth and anterior portion of the preopercular region and ventral portion of the opercular region, a deep urohyal, presence of a dark gray supraorbital spot, dorsal and anal fins rounded in males, a long urogenital papilla in males, and reduced ventral process of the angulo-articular. Thirty-eight species are recognized as valid: A. cinereus, A. robustus, A. nonoiuliensis, and A. bellottii, from the lower de La Plata River basin and adjacent areas; A. varzeae, A. melanoorus, A. apaii Costa, Laurino, Recuero & Salvia, new species, A. alexandri, A. ibicuiensis, A. affinis, A. duraznensis, and A. periodicus, from the Uruguay River basin; A. nigripinnis and A. elongatus n. comb., from both the lower de La Plata and Uruguay river basins; A. viarius, A. univentripinnis, A. charrua, A. minuano, A. adloffi, A. nigrofasciatus, A. nachtigalli Costa & Cheffe, new species, A. salviai Costa, Litz & Laurino, new species, A. luteoflammulatus, A. gymnoventris, A. jaegari, A. cheradophilus n. comb., A. wolterstorffi n. comb., and A. prognathus n. comb., A. cyaneus, and A. litzi new species, from the dos Patos lagoon system and adjacent areas to the south; A. vazferreirai, A. arachan, and A. juanlangi Costa, Cheffe, Salvia & Litz, new species, from both the dos Patos lagoon system and Uruguay River basin; A. paranaensis, new species, A. vandenbergi, A. monstrosus n. comb., A. patriciae, from the Paraguay and middle Parana river basins; and, A. carvalhoi, from the rio Iguacu basin. A key to the identification of species is provided. A phylogenetic hypothesis based on morphology for species of Austrolebias is compared to a recent hypothesis based on molecular data, demonstrating partial or full congruence between the two sets of characters.

Allozyme Divergence and the Evolution of Dendroseris (Compositae: Lactuceae) on the Juan Fernandez Islands

Abstract: The genus Dendroseris, consisting of rosette trees or shrubs, is endemic to the Juan Fernandez Islands, Chile. With 11 species it is the largest genus on the Islands. The considerable morphological diversity among the species is reflected by the recognition of three subgenera. The relatively young age of the Islands, ca. four million years for Masatierra and one to two million for Masafuera, indicates that speciation may have occurred recently and rapidly in Dendroseris. An electrophoretic study of 14 enzymes revealed little divergence among the six species examined. The three species in subgenus Dendroseris and the three in subgenus Rea are all monomorphic for the same allele at 21 of the 34 genes. The two subgenera are fixed for different alleles at two genes, which supports their recognition as monophyletic lines. The lack of divergence among the species at genes specifying soluble enzymes is concordant with the hypothesis of rapid speciation, perhaps the result of adaptive radiation into a variety of habitats. The chromosome number of n = 18 in Dendroseris suggests it is a tetraploid. Enzyme electrophoresis revealed extensive gene duplication in Dendroseris indicating the genus likely consists of relatively "young" tetraploids. Data from gene number indicate that polyploidy may have been associated with the origin of Dendroseris from a diploid progenitor, or that polyploidy was established shortly after the origin of the genus.

A revision of the Mexican and Central American species of Vanilla Plumier ex Miller with a characterization of their ITS region of the nuclear ribosomal DNA

Abstract: We present a revision of the Mexican and Central American species of Vanilla. There are 15 different species in the area; Vanilla costaricensis, V. cribbiana, V. dressleri, V. martinezii and V. sarapiquensis are here proposed as new taxa, and V. pompona subsp. pittieri and V. pompona subsp. grandiflora are recognized at subspecific rank. Vanilla calyculata, V. hartii, V. helleri, V. inodora, V. insignis, V. odorata, V. phaeantha, V. planifolia, V. pompona and V. trigonocarpa are also described, illustrated, and their nomenclature, typification, distribution, and other aspects of interest are discussed. Additionally, we include a key to the species. Several Mexican and Central American species of Vanilla are closely related to V. planifolia, V. x tahitensis, and V. pompona, the cultivated species of the genus, and these are thus important in plant breeding. We also include a cladistic analysis of nucleotidic sequences of the internal transcribed spacer region of the nuclear ribosomal DNA, showing that this popular molecular marker is of sufficient variation to allow for species discrimination, permitting, with some exceptions that are discussed, the recognition of sterile samples and indicating that it is a good molecular marker to infer the phylogeny of this group. The similarity and relationship between V. x tahitensis* and V. odorata is discussed.