01363nas a2200133   4500008004100000245009100041210006900132300001200201490000700213520085500220100002001075700001701095856011701112       2013                        eng d00aA new species of Isoetes with tuberculate spores from southeastern Brazil (Isoetaceae)0 anew species of Isoetes with tuberculate spores from southeastern  a869-8740 v383 aIsoetes quiririensis is described, illustrated, and compared to similar species. This species can be distinguished from other species in Brazil by a set of characters that include microphylls that are semi-cylindrical in cross section, velum covering more than 3/4 of the sporangium, tuberculate megaspores varying from 477-670 μm in diameter, echinate microspores, and a chromosome number of 2n = 22. We also include a key for species from the Atlantic Rainforest that have tuberculate megaspores, distribution maps, and spore images for all species that are discussed. Isoetes quiriensis is known only from the type locality, where it occurs as an aquatic in small streams at high elevations. We suggest it should be classified as a data deficient species based on the IUCN criteria. © Copyright 2013 by the American Society of Plant Taxonomists.1 aPereira, J.B.S.1 aLabiak, P.H.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84892771709&partnerID=40&md5=5330336025d70b7769a8178a24b91c8d02894nas a2200145   4500008004100000245009000041210006900131260001200200300001400212490000700226520236600233100001702599700001602616856011602632       2000                        eng d00aIsozymes of the Isoetes riparia complex, II. Ancestry and relationships of polyploids0 aIsozymes of the Isoetes riparia complex II Ancestry and relation  c2000///  a260 - 2800 v253 aIsoetes riparia is a complex tetraploid taxon of eastern North America that in its widest sense includes a diversity of morphotypes variously segregated, or included in a single polymorphic species. Although the diploid ancestry of I. riparia has been proposed as I. echinospora x engelmannii, it is uncertain whether this ancestry applies to all elements of the complex, here broadly defined to encompass three segregates of I. riparia and the recently described I. hyemalis (referred to informally as riparia, canadensis, saccharata and hyemalis). To help clarify relationships among these tetraploids, isozyme genotypes for 13 loci coding eight enzymes, were determined for 16 populations representing all four segregates. Duplicate gene expression, evidenced as fixed heterozygosity consistent with allopolyploidy, characterized the tetraploid genotypes of all taxa. Although exhibiting modest to no variation within populations, populations were highly differentiated, most showing a unique combination of alleles for their multilocus genotypes, with the exception of five genetically identical Canadian populations. Ancestry was evaluated through comparison to diploid genotypes previously reported. A quantitative approach was carried out to rank likelihoods for hypothetical ancestral combinations of diploids for each tetraploid population. The ancestry I. echinospora x engelmannii hypothesized for I. riparia was unequivocally supported for the six populations of the most northern segregate, canadensis. Diploid ancestries for the remaining 10 more southern populations were less certain, although the diploid I. mattaponi was implicated as a likely ancestor for most. Most likely ancestry for populations of riparia/saccharata was inferred as I. valida x mattaponi, and for hyemalis as I. mattaponi x flaccida. However, these hypotheses were only slightly more likely than other combinations. UPGMA analysis using Rogers' similarity resulted in three clusters corresponding to canadensis, riparia/saccharata, and hyemalis. However, the hyemalis cluster was weakly associated and was not supported by UPGMA using Nei's identity. These highly variable tetraploid genotypes suggest a complicated evolutionary history for the I. riparia complex that probably involved a combination of diverse ancestry, multiple origins, divergence, and gene silencing.1 aCaplen, C.A.1 aWerth, C.R.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0034046198&partnerID=40&md5=48c688dd1d8bd2bf3f8bc0a92bc0306002139nas a2200145   4500008004100000245010100041210006900142260001200211300001400223490000700237520160000244100001701844700001601861856011601877       2000                        eng d00aIsozymes of the Isoetes riparia complex, I. Genetic variation and relatedness of diploid species0 aIsozymes of the Isoetes riparia complex I Genetic variation and   c2000///  a235 - 2590 v253 aIsozymes were examined in the six aquatic (including amphibious) diploid species of Isoetes of eastern North America in order to quantify their levels and patterns of genetic variation, to determine their genetic distinctness, and to evaluate the utility of allozymes in addressing ancestry in the I. riparia complex. Twenty-six populations representing diploid species, I. echinospora, I. engelmannii, I. flaccida, I. mattaponi, I. prototypus, and I. valida were compared for eleven enzymes coded by 16 interpretable loci. Levels of genetic variation in populations tended to be low ranging from none (means: P = 0.0, A = 1.0, H = 0.0) in I. echinospora to moderate (means: P = 22.9, A = 1.4, H = 0.093) in I. flaccida. Genetic variation in polymorphic species tended to be distributed more among than within populations, as indicated by high F(st) values (F(st) > 0.607 in all polymorphic species except I. mattaponi, for which F(st) = 0.272). The genetic identities of conspecific populations were high, with mean values ranging from I = 0.779/S = 0.733 in I. flaccida to I = 1.000/S = 1.000 in I. echinospora. Interspecific genetic identities were lower, with means ranging from I = 0.438/S = 0.429 between I. mattaponi and I. prototypus to I = 0.736 between I. valida and I. flaccida, and S = 0.699 between I. valida and I. prototypus. Thus the six diploids were found to be genetically distinct, corroborating their recognition based on morphology. Evidence from this study indicates that isozymes may be informative in diagnosing ancestry of allopolyploids in the Isoetes riparia complex.1 aCaplen, C.A.1 aWerth, C.R.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0034042682&partnerID=40&md5=ed389e88047f4d191722332cdcce26a902184nam a2200205   4500008004100000245010800041210007100149260001200220300001400232490000700246520150100253653001701754653001501771653001201786653001401798100001501812700001701827700001701844856011701861       2006                        eng d00aPhylogeny and biogeography of Isoëtes (Isoëtaceae) based on nuclear and chloroplast DNA sequence data0 aPhylogeny and biogeography of Isoëtes Isoëtaceae based on nuclea  c2006///  a449 - 4600 v313 aDespite its ancient origins, worldwide distribution, and adaptation to diverse habitats, Isoëtes species have a highly conserved morphology, making it difficult to resolve phylogenetic relationships using morphological characters. In this paper, we report the results from various analyses (maximum parsimony, maximum likelihood, and Bayesian inference) for Isoëtes species from around the world based on nucleotide sequences from the nuclear internal transcribed spacer (ITS) and chloroplast atpB/rbcL intergenic spacer regions. The trees resulting from our analyses of the combined data contain six major well-supported clades (bootstrap ≥ 90%, posterior probabilities = 1.00): A clade with possible Gondwanan affinities (I. australis, I. coromandelina, I. panamensis, I. cubana, I. jamaicensis); a South African clade (I. capensis, I. toximontana, I. stellenbossiensis, I. stephansenii); a largely Northern Hemisphere clade (I. nuttallii, I. orcuttii, I. minima, I. dixitei, I. abyssinica, I. olympica, I. longissima, I. velata); an Asian/Australasian clade (I. drummondii, I. gunnii, I. pusilla, I. kirkii, I. muelleri, I. taiwanensis, I. japonica, I. yunguiensis, I. habbemensis); a Mediterranean clade (I. histrix and I. setacea); and a poorly resolved clade consisting of 12 new world species (American species complex). Our results are compared to past classifications and various biogeographical scenarios are explored. © Copyright 2006 by the American Society of Plant Taxonomists.10aBiogeography10aIsoetaceae10aIsoetes10aPhylogeny1 aHoot, S.B.1 aTaylor, W.C.1 aNapier, N.S.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-67650146436&partnerID=40&md5=c418d4b55db9dd7f2436a8d3189f155201966nas a2200217   4500008004100000245010000041210007000141260001200211300001400223490000700237520123800244653001501482653001201497653001401509653002101523653002201544653003001566100002001596700001501616856011701631       2006                        eng d00aInferring the root of Isoëtes: Exploring alternatives in the absence of an acceptable outgroup0 aInferring the root of Isoëtes Exploring alternatives in the abse  c2006///  a258 - 2700 v313 aThe ancient divergence between the lycopsid genus Isoëtes and its closest living relative (Selaginella) has resulted in considerable morphological and genetic disparity, yet within Isoëtes there is remarkable morphological and genetic uniformity. This has made it difficult to identify the phylogenetic root of the genus. In this study, we addressed this problem and characterized the early branching patterns within Isoëtes using an expanded set of taxa and three molecular markers. We assessed the saturation in the molecular data sets, tested for differences in evolutionary rate, determined the stability of the ingroup topology, and evaluated the applicability of the molecular clock. We then explored three alternative rooting approaches: outgroup, midpoint, and maximum likelihood under the assumption of a molecular clock. Attempts to infer the root of Isoëtes using the outgroup approach were severely hindered by the effects of saturation, but the results from midpoint rooting and the enforcement of the molecular clock were highly consistent among the data sets. We identify the root of Isoëtes to be located among three major, highly supported clades. © Copyright 2006 by the American Society of Plant Taxonomists.10aIsoetaceae10aIsoetes10aLycophyte10aMidpoint rooting10aPhylogenetic root10aRelative rate comparisons1 aSchuettpelz, E.1 aHoot, S.B.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-33745493624&partnerID=40&md5=8d3abb9eb77572545e97747f1aaf51a5