Hiromi Tsubota

Ordinal Phylogeny within the Hypnobryalean Pleurocarpous Mosses Inferred from Cladistic Analyses of Three Chloroplast DNA Sequence Data Sets: trnL-F, rps4, and rbcL

Abstract Classification of families of hypnobryalean mosses into the Hypnales, Leucodontales, and Hookeriales has been taxonomically difficult. Several researchers have sequenced different genes for independent phylogenetic studies of these three pleurocarp groups. Our goal is to summarize available molecular data and compile the largest data set to infer phylogenetic relationships among families as basis for classification at ordinal level. Sequences of rbcL, trnL-F, and rps4 loci for 38 exemplars of most families of Hypnales, Leucodontales, and Hookeriales were analyzed to evaluate whether or not each of the three orders is monophyletic. Cladistic analyses of combined sequences, using five taxa in the Bryales as outgroups, reveal a robust clade (decay > 5) including all hypnobryalean pleurocarps. Within this group, one clade (decay = 2) includes only taxa of the Hookeriales, and is sister to a large monophyletic group (Hypnales sensu lato) containing all other taxa (decay = 2) previously in the Leucodontales and Hypnales. These relationships suggest that the ordinal level taxonomy needs to be reconsidered since major lineages detected do not correspond to the traditional Leucodontales or Hypnales. These two orders are not supported by any molecular evidence from rbcL, trnL-F, or rps4, either analyzed singly or in different combinations. Additionally, present results indicate the need for changes to the current system of three suborders of Hypnales and four of the Leucodontales. Phylogenetic reconstructions based on molecular data emphasize the need for a re-examination of the taxonomic relevance of morphological characters and corroborate previous interpretations of sporophytic morphological similarities as multiple transitions to similar solutions to epiphytism among the pleurocarps.

Molecular phylogeny of Japanese Eleocharis (Cyperaceae) based on ITS sequence data, and chromosomal evolution

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.

A new aerial alga, Stichococcus ampulliformis sp. nov. (Trebouxiophyceae, Chlorophyta) from Japan

A new aerial alga, Stichococcus ampulliformis S. Handa sp. nov. (Trebouxiophyceae, Chlorophyta) is described based on a clone isolated from the bark of Cephalotaxus harringtonia (Knight ex Forbes) K. Koch collected from Taishaku‐kyo Gorge, Hiroshima Prefecture, south‐west Japan. This alga was examined by light microscopy and transmission electron microscopy and subjected to molecular phylogenetic analysis. Based on its morphological features and life‐cycle, especially short filament formation, the alga was assigned to the genus Stichococcus Nägeli. However, this alga differs from other described Stichococcus species in that it reproduces by a form of ‘budding’, producing two daughter cells of different sizes. The larger cell, enclosed within the mother cell wall, soon reaches the size of a normal vegetative cell. The smaller cell is extruded and takes longer to reach full vegetative size. A phylogenetic tree constructed using 18S rRNA sequences indicated that, within the Trebouxiophyceae, S. ampulliformis is closely related to S. bacillaris Nägeli and some species of Prasiola Meneghini.

The New Genus Benitotania (Daltoniaceae, Bryopsida) from Mt. Kinabalu

Abstract A new monospecific genus, Benitotania, is described on the basis of B. elimbata H. Akiyama, T. Yamag, & M. Suleiman, collected in the northern part of Sabah, Malaysia. It appears to be most closely related to Adelothecium and Bryobrothera.

Evolution of apolar sporocytes in marchantialean liverworts: implications from molecular phylogeny

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.

A reappraisal of Pylaisiopsis (Sematophyllaceae)

Abstract Pylaisiopsis (Broth.) Broth. is revised based on the molecular phylogenetic analysis and detailed morphological investigation. The genus is considered to be synonymous with Pylaisia (Hypnaceae). An older combination, Pylaisia speciosa (Mitt.) Wilson ex A. Jaeger, is selected for Pylaisiopsis speciosa (Mitt.) Broth. A description and illustrations of the species are provided. The taxonomic position of Foreauella orthothecia (Schwägr.) Dixon & P. de la Varde is also discussed.

Phylogenetic and morphological reevaluation of Leucobryum boninense (Leucobryaceae), endemic to the Bonin Islands

Abstract Leucobryum boninense is an enigmatic species distributed in southeast China and islands of the northwestern Pacific and is the only species of Leucobryum known from the Bonin Islands which are typical oceanic islands. Molecular phylogenetic analysis using internal transcribed spacer (ITS) of nrDNA sequences was performed to resolve phylogenetic relationships among geographically isolated populations of L. boninense and its related species. The analysis showed that L. boninense is divided into two distinct clades, which correspond to geographical regions: an oceanic island clade (Bonin clade) and a continental region clade (Ryukyu clade). These two clades were also distinguished from each other by the ratio of the length of the prorate apex region to the whole leaf length, ecological preference and the colony habit. Plants of the Ryukyu clade proved to correspond to L. scaberulum, previously treated as a synonym of L. boninense. Molecular and morphological evidence strongly suggests that L. boninense is endemic to the Bonin Islands, and that L. scaberulum should be treated as a distinct species. Endemism of L. boninense on the oceanic islands may be result of allopatric speciation.

Lectotypification and Taxonomic Identity of Astomum japonicum G. Roth (Pottiaceae, Bryophyta)

Abstract Astomum japonicum G. Roth is a cleistocarpous moss species but its taxonomic placement remains uncertain because the type material has not been re-examined since being described in 1911. We have examined type specimens and selected the specimen in PC as the lectotype. Based on a morphological study of the type material, we also propose the transfer of the species to the genus Weissia Hedw.: W. japonica (G. Roth) Y. Inoue & H. Tsubota comb. nov. Taxonomic notes on W. japonica and a key to the cleistocarpous species of Weissia in Japan are also provided.

Geographical origin of Leucobryum boninense Sull. & Lesq. (Leucobryaceae, Musci) endemic to the Bonin Islands, Japan.

Leucobryum boninense is endemic to the Bonin Islands, Japan, and its related species are widely distributed in Asia and the Pacific. We aimed to clarify the phylogenetic relationships among Leucobryum species and infer the origin of L. boninense. We also describe the utility of the chloroplast trnK intron including matK for resolving the phylogenetic relationships among Leucobryum species, as phylogenetic analyses using trnK intron and/or matK have not been performed well in bryophytes to date. Fifty samples containing 15 species of Leucobryum from Asia and the Pacific were examined for six chloroplast DNA regions including rbcL, rps4, partial 5′ trnK intron, matK, partial 3′ trnK intron, and trnL-F intergenic spacer plus one nuclear DNA region including ITS. A molecular phylogenetic tree showed that L. boninense made a clade with L. scabrum from Japan, Taiwan and, Hong Kong; L. javense which is widely distributed in East and Southeast Asia, and L. pachyphyllum and L. seemannii restricted to the Hawaii Islands, as well as with L. scaberulum from the Ryukyus, Japan, Taiwan, and southeastern China. Leucobryum boninense from various islands of the Bonin Islands made a monophylic group that was closely related to L. scabrum and L. javense from Japan. Therefore, L. boninense may have evolved from L. scabrum from Japan, Taiwan, or Hong Kong, or L. javense from Japan. We also described the utility of trnK intron including matK. A percentage of the parsimony-informative characters in trnK intron sequence data (5.8%) was significantly higher than that from other chloroplast regions, rbcL (2.4%) and rps4 (3.2%) sequence data. Nucleotide sequence data of the trnK intron including matK are more informative than other chloroplast DNA regions for identifying the phylogenetic relationships among Leucobryum species.

Molecular phylogeny of the genus Fissidens (Fissidentaceae, Bryophyta) and a refinement of the infrageneric classification

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.