Search

The genus Fissidens (ca. 440 spp.) is one of the phylogenetically poorly studied groups of mosses (Bryophyta). While various classifications of this genus have been proposed, no attempt at a classification of the genus based on combined molecular and morphological evidence has been made. Here, we present for the first time a comprehensive phylogenetic tree consisting of 50 representatives of Fissidens, reconstructed using sequence data from chloroplast rbcL and rps4 genes. Ancestral state reconstructions provide three clear apomorphies within Fissidens: peristome teeth, limbidium and chromosome number. Based on the phylogeny and morphological reassessment, we recognize three subgenera, Pachyfissidens, Neoamblyothallia, and Fissidens. Subgenus Neoamblyothallia consists of two sections: Neoamblyothallia and Crispidium. Subgenus Fissidens consists of five sections: Fissidens, Polypodiopsis, Aloma, Areofissidens, and Semilimbidium. High diversity of the most derived sect. Semilimbidium in the tropics suggests that the evolutionary history of the genus is through adaptation and diversification in tropical regions., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In meiosis of basal land plants, meiotic division planes are typically predicted by quadri-lobing of the cytoplasm and/or quadri-partitioning of plastids prior to nuclear divisions. However, sporocytes of several marchantialean liverworts display no indication of premeiotic establishment of quadripolarity, as is observed in flowering plants. In these cases, the shape of sporocytes remains spherical or elliptical and numerous plastids are distributed randomly in the cytoplasm during meiosis. Through a survey of sporocyte morphology in marchantialean liverworts, we newly report the occurrence of apolar sporocytes in Sauteria japonica and Athalamia nana (Cleveaceae; Marchantiales). Molecular phylogenetic analyses revealed that the quadri-lobing of cytoplasm and quadri-partitioning of plastids were lost independently several times during the evolution of marchantialean liverworts. In addition, our phylogenetic analyses indicate that the simplified sporophytes of several marchantialean liverworts are not a primitive condition but rather represent the result of reductive evolution. The loss of the quadripolarity of sporocytes appears to correlate with the evolutionary trend of the sporophyte towards reductions. Through the evolution of the simplified sporophytes, suppression of mitotic divisions of sporogenous cells might had caused not only the modification of sporophyte ontogeny but also the drastic cytological change of sporocyte.

In northern Australia, the debris-feeding termite Amitermes laurensis builds tall, wedge-shaped mounds in the northern part of Cape York Peninsula and Arnhem Land, where their habitats are seasonally flooded, and small dome shaped mounds in the southeastern part of Cape York Peninsula, where their habitats are well-drained. Phylogeographic analyses were conducted in 238 individuals from 30 populations using the mitochondrial cytochrome oxidase II (COII) gene. DNA sequences of 50 haplotypes were used to construct NJ, MP and ML trees. Phylogenetic trees for 16 Amitermes species showed monophyly of A. laurensis and the variation of A. laurensis mounds did not strongly correspond to the intraspecific phylogeny. It was observed that mounds with the same shape were constructed by phylogenetically different groups under similar environmental conditions and different mounds shapes were built by phylogenetically closely related groups under the different environmental conditions. Thus, phylogenetically close groups of A. laurensis, in different habitats, may adapt to environmental conditions by constructing different mound shapes. We also investigated the phylogeographic structure of A. laurensis. The significant positive correlation between genetic and geographic distances indicated isolation by distance, reflecting restricted dispersal ability of alates. Although the overall genetic structure of A. laurensis showed isolation by distance, we also identified two exceptions: (i) secondary contacts of genetically divergent lineages in southern Cape York Peninsula, and (ii) low genetic differences between geographically separated populations of Cape York Peninsula and Arnhem Land. Therefore, the phylogeography of A. laurensis may reflect continuous gene flow restricted to short distances and past changes of gene flow associated with the fluctuation of environmental conditions accompanying the changing sea levels in the Quaternary.

ITS sequence data were used to estimate the phylogeny of 24 Japanese Eleocharis species and to make karyomorphological observations on 19 of these taxa. Two major clades were identified in Japanese Eleocharis molecular phylogenetic trees: (1) one including all species of section Limnochloa, and (2) another comprising two sections, Pauciflorae and Eleocharis. Phylogenetic analysis including both Japanese and North American species also shows strong support for monophyly of the Mutatae/ Limnochloa clade. The width of the spikelets in the species Mutatae/ Limnochloa is the same as that of the culms, indicating that the relative widths of spikelets and culms are useful characteristics for classification. Two major clades were supported by karyomorphological data. All taxa of section Limnochloa had very small chromosomes, while sections Pauciflorae and Eleocharis had large chromosomes. The basic chromosome number of sections Eleocharis and Pauciflorae is thought to be x=5. Chromosomal evolution in the genus Eleocharis with diffuse centromeric chromosomes may be caused by both aneuploidization and polyploidization. Our data suggest that a 3-bp insertion near the 3' end of the 5.8S gene is useful for intrageneric delimitations of the genus Eleocharis.