Novel morphology in Enteromorpha (Ulvophyceae) forming green tides

"Green tides" are vast accumulations of unattached green macroalgae associated with eutrophicated marine environments. They have major ecological and economic impacts globally, so an understanding of their origin and persistence is required in order to make management decisions. Blooms predominantly consist of two common fouling genera of the Ulvales, Ulva (distromatic sheets) and Enteromorpha (monostromatic tubes). In the Baltic Sea and elsewhere green tides have increased over the last few decades. On the west coast of Finland, summer blooms consist of monostromatic sheets resembling Monostroma (Codiolales). We identified these as Enteromorpha intestinalis by comparative analyses of rDNA internal transcribed spacer 1 (ITS1), 5.8S, and ITS2 sequences, the first time monostromatic sheets have been found in the genus Enteromorpha. Ordinary attached E. intestinalis sporulated freely in culture, but the sheets reproduced only by cell regeneration into typical tubular thalli. The ITS sequences were identical to those of attached E. intestinalis populations in southwestern Finland, but differed by two substitutions from other Baltic sequences. We infer that this bloom originated from local attached populations and now reproduces clonally by fragmentation. This study provides further evidence of radical changes in gross morphology of green algae under eutrophicated conditions and the need for molecular identification.     

EXTENSIVE INTRASPECIFIC MORPHOLOGICAL VARIATION IN ENTEROMORPHA MUSCOIDES (CHLOROPHYTA) REVEALED BY MOLECULAR ANALYSIS

Enteromorpha muscoides (Clemente y Rubio) Cremades and E. clathrata Roth (Greville) are morphologically variable species that can easily be distinguished from other Enteromorpha species but not from each other. The key morphological character separating the two species is the presence or absence of spine-like branches: E. muscoides has small spine-like branches throughout the thallus, whereas E. clathrata lacks spines. The spiny branches in E. muscoides are not as obvious in summer as in winter, so summer samples may be difficult to distinguish from those of E. clathrata. In this study, molecular data were used to investigate whether these two species, as defined by morphological characters, might be conspecific. The sequences of the internal transcribed spacers ITS1 and ITS2 and the 5.8S gene differed by 0%–0.6% between all samples of both E. muscoides and E. clathrata. Phylogenetic analysis of these sequences in an alignment with 13 other representatives of both Enteromorpha and Ulva showed that this highly supported monophyletic E. muscoides / E. clathrata clade is separated by long branch lengths from other Enteromorpha and Ulva clades. Based on these results, we suggest that Enteromorpha muscoides (Clemente y Rubio) Cremades and Enteromorpha clathrata Roth (Greville) are conspecific, with the older name E. muscoides taking priority.     

Molecular systematics of the Catesbaeeae-Chiococceae complex (Rubiaceae): flower and fruit evolution and biogeographic implications

The classification of the Catesbaeeae and Chiococceae tribes, along with that of the entire Rubiaceae, has long been debated. The Catesbaeeae-Chiococceae complex (CCC) includes approximately 28 genera and 190 species primarily concentrated in the Greater Antilles (nearly 70% of the species), Central and South America, and in the western Pacific (three genera). Previous molecular studies, with broad sampling of the Rubiaceae, have shown the CCC to be a monophyletic group. The present study is a more detailed examination of the generic relationships within the CCC using two data sets, the nuclear ribosomal ITS regions and the trnL-F chloroplast intron and spacer. Maximum parsimony analyses lend further support to the previous hypotheses that the CCC is monophyletic and sister to Strumpfia maritima. However, within the complex several genera do not form monophyletic groups. Previous studies of the Rubiaceae suggest that the ancestral fruit type in the CCC is a multiseeded capsule. Indehiscent, fleshy fruits appear to have evolved three to four times within this lineage. Changes in floral morphologies within the complex tend to correspond to cladogenesis among and within genera. Finally, molecular analyses suggest one or possibly two long-distance dispersals from the Americas to the western Pacific.     

Molecular systematics and radiation of western North American nymphophiline gastropods

Three mitochondrial DNA (mtDNA) markers were used to infer the phylogenetic relationships of the morphologically diverse, species rich, and poorly understood western North American aquatic gastropod genus Pyrgulopsis (Hydrobiidae: Nymphophilinae). Sequences were obtained from 62 of 124 currently recognized species of Pyrgulopsis and representatives of four related genera of North American nymphophilines. Separate and combined analyses of the mtDNA datasets recovered a well supported clade composed of Pyrgulopsis and two other North American nymphophiline genera (Floridobia, Nymphophilus) consistent with the results of a prior study based on a single gene and with anatomical evidence suggesting that these taxa form a monophyletic group. Phylogenetic relationships among lineages of Pyrgulopsis were little resolved in our analyses and provided no obvious basis for splitting this large genus into multiple genera. The little differentiated Mexican genus Nymphophilus was consistently placed within Pyrgulopsis in our trees and is formally synonymized with it herein. Pyrgulopsis was also depicted as paraphyletic with respect to Floridobia in some of our trees while in others the latter was sister to a Nymphophilus + Pyrgulopsis clade. Based on these equivocal results and the morphological and geographical divergence of eastern North American Floridobia relative to Pyrgulopsis, we recommend that the former be maintained as a separate genus. The short, weakly supported branches within Pyrgulopsis and the noncongruence between our molecular phylogenetic hypotheses and geographical groupings of species are attributed to an early rapid diversification of the genus, perhaps triggered by the complex changes in western topography which occurred during the late Tertiary. Our results also indicate that penial morphologies used to define species groups of Pyrgulopsis have been subject to striking convergence throughout the West, suggesting another compelling facet of the radiation of these snails.     

DIVERSITY OF EUKARYOTIC PICOPLANKTON IN COASTAL WATERS

Van Alstyne, K. L. Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Road, Anacortes, WA 98221 USA Ulvoid green macroalgae, such as Enteromorpha and Ulva, can form large blooms that have deleterious impacts on the local biota. These algae are often assumed to be very palatable for most invertebrate and vertebrate herbivores because they lack obvious physical defenses, and because there have been few reports of their producing chemical defenses. However, in laboratory feeding preference assays, the ulvoid macroalgae Enteromorpha linza and Ulva fenestrata were low preference foods for green sea urchins, Strongylocentrotus droebachiensis. Both these algae and several other species of green algae produce large quantities of dimethylsulphoniopropionate (DMSP), which is enzymatically converted to dimethyl sulfide (DMS) and acrylic acid when the algae are physically damaged. In laboratory bioassays, both DMS and acrylic acid were potent feeding deterrents towards urchins at concentrations that the urchins would be likely to encounter in the field. The precursor in this system, DMSP, was a feeding attractant. Our data provide evidence that DMSP functions as a precursor in an activated defense system in marine macroalgae and suggests a similar function in phytoplankton. The presence of this activated defense system may contribute to the persistence of macroalgal blooms by making these algae unpalatable to some species of herbivores.     

Research note: Identity of the Qingdao algal bloom

In early July 2008, news agencies worldwide reported on a vast algal bloom that was threatening the upcoming Olympic sailing events in Qingdao, China. The identity of the culpable alga, however, remained undiscussed. We have identified the alga that caused the bloom by means of morphological and molecular data, including sequence data of the plastid encoded large subunit ribulose 1,5-bisphosphate carboxylase gene ( rbc L) and the nuclear encoded rDNA internal transcribed spacer (ITS) region. The bloom-forming alga falls within the morphological limits of the green seaweed Ulva prolifera O.F. Müller (' Enteromorpha prolifera (O.F. Müller) J. Agardh') but our phylogenetic analyses show that it forms a clade with representatives of the Ulva linza-procera-prolifera (LPP) complex. The Chinese rbc L sequences are identical to those of specimens collected from Japan, New Zealand, Finland and Portugal, suggesting that the taxon is widely distributed. rDNA ITS sequences showed a close affinity with Japanese isolates of the species complex. The Qingdao bloom is a typical illustration of a green tide, which occurs increasingly along several coasts worldwide.     

Axes of differentiation in the bower-building cichlids of Lake Malawi

The 500-1000 cichlid species endemic to Lake Malawi constitute one of the most rapid and extensive radiations of vertebrates known. There is a growing debate over the role natural and sexual selection have played in creating this remarkable assemblage of species. Phylogenetic analysis of the Lake Malawi species flock has been confounded by the lack of appropriate morphological characters and an exceptional rate of speciation, which has allowed ancestral molecular polymorphisms to persist within species. To overcome this problem we used amplified fragment length polymorphism (AFLP) to reconstruct the evolution of species within three genera of Lake Malawi sand-dwelling cichlids that construct elaborate male display platforms, or bowers. Sister taxa with distinct bower morphologies, and that exist in discrete leks separated by only 1-2 m of depth, are divergent in both sexually selected and ecological traits. Our phylogeny suggests that the forces of sexual and ecological selection are intertwined during the speciation of this group and that specific bower characteristics and trophic morphologies have evolved repeatedly. These results suggest that trophic morphology and bower form may be inappropriate characters for delineating taxonomic lineages. Specifically the morphological characters used to describe the genera Lethrinops and Tramitichromis do not define monophyletic clades. Using a combination of behavioural and genetic characters, we were able to identify several cryptic cichlid species on a single beach, which suggests that sand dweller species richness has been severely underestimated.     

Cryptic diversity of Ulva (Ulvales,Chlorophyta) in the Great Bay Estuarine System (Atlantic USA): introduced and indigenous distromatic species

Distromatic foliose blades of the algal genus Ulva are notoriously difficult to identify due to their simple morphologies and few diagnostic characteristics that often exhibit intraspecific variation and interspecific overlap. Hence, species differentiation is difficult and diversity estimates are often inaccurate. Two major goals of this study were to assess the diversity of distromatic Ulva spp. in the Great Bay Estuarine System (GBES) of New Hampshire and Maine, USA, and to compare historical and present day records of these species. Molecular analysis (using ITS sequences) of field-collected specimens revealed four distinct taxa: Ulva lactuca, U. rigida, U. compressa, and U. pertusa. Prior to molecular screening, Ulva lactuca was the only distromatic Ulva species reported for the GBES. Ulva pertusa and the foliose form of U. compressa are newly recorded for the Northwest Atlantic, and the range of U. rigida has been extended. Molecular analysis of historical herbarium voucher specimens indicates that U. rigida, U. pertusa, and the foliose form of U. compressa have been present in the GBES since at least 1966, 1967, and 1972, respectively. The distromatic morphotype of U. compressa is found only in low salinity areas, which suggests that salinity may influence its morphological development. Molecular and morphological evaluations are critical if we are to distinguish between cryptic taxa, accurately assess biodiversity, and effectively monitor the spread of non-indigenous macroalgae.     

Identification by SDS PAGE of green seaweeds ( Ulva and Enteromorpha) used in the food industry

SDS PAGE was tested as an analytical tool for the identification of fourgreen algae (Ulva rigida, U. rotundata, Enteromorphaintestinalis, E. compressa) used as food ingredients. A referencepattern composed of the bands present all year long was performed foreach species. The pattern for Ulva rotundata consists of 7 bandslocated between 69.9 and 15.5 kDa with the presence of triplicate bandsat 29.5, 26.3 and 22.9 kDa. The pattern for Ulva rigida is consistsof three bands with apparent molecular weights of 68.5, 56.4 and 44.7kDa. The Enteromorpha compressa pattern is characterised by sixbands located between 65.8 and 19.8 kDa. A double band withmolecular weights of 23.1 and 23.9 distinguished this pattern from theothers. Six bands situated between 66.4 and 19.4 kDa with a specifictriplicate band of 25.9, 23.9 and 22.5 kDa constituted the specific patternof Enteromorpha intestinalis. SDS PAGE appears to be suitable forthe identification of green seaweed foods.     

A phylogeny of planorbid snails,with implications for the evolution of Schistosoma parasites

The Planorbidae represent one of the most important families of freshwater snails. They have a wide distribution and are significant both medically and economically as intermediate hosts for trematode worms. Digenetic trematodes of the genus Schistosoma cause schistosomiasis, a disease that infects 200 million people, and domestic animals throughout the tropics. Three of the four recognized species groups of Schistosoma rely on snails of the family Planorbidae to complete their life cycles. Each species group requires a specific planorbid genus-Bulinus, Biomphalaria, or Indoplanorbis. Our understanding of the relationships among the genera within the Planorbidae is rudimentary and based solely on internal anatomy and shell morphology. Two molecular markers, ribosomal 28S and actin exon 2, were sequenced and a phylogeny constructed for 38 taxa representing 16 planorbid genera. The phylogeny supports the division of the Planorbidae into two subfamilies, the Bulininae and Planorbinae. Interestingly, two representatives of the family Ancylidae fall within the Planorbidae highlighting the need for further analysis and possible reclassification of this group. A molecular based phylogeny of the genus Schistosoma was then mapped against the snail tree. The trees indicate that planorbid-transmitted Schistosoma appear not to be co-speciating with their current snail host lineages. Rather, host switching was prominent, including a switch involving two distantly related planorbid genera, Biomphalaria and Bulinus. Our study of the Planorbidae poses fundamental questions regarding how and when Schistosoma acquired new snail hosts, including how switches to relatively distant hosts are accomplished and why some available planorbids were not colonized.     

ULTRAVIOLET ABSORBING SUBSTANCES FROM AGARUM FIMBRIATUM (PHAEOPHYCEAE) PROTECT GRIFFITHSIA PACIFICA FROM UV RADIATION

Patterns of recruitment and abundance of Ulva pertusa and Enteromorpha linza in the three locations on the south coast of Korea where green tide frequently occurred were investigated with respect to the substrate profile, temporal and spatial variations, and their persistence. Artificial substrates (10 to 20 cm) were made of a mixture of a piece of granite rock and cement on ceramic tiles. These setting plates, representing different surface texture, were placed horizontally and vertically along the rocky shoreline, and replaced every 1 to 2 months. Both populations showed highly seasonal blooms, with peaks in October, 1998 to February, 1999 and another slight peak was observed in the fall of 1999 only for Ulva. However, the winter peak of 1998 did not appeared in the following year, indicating that a significant year-to-year variation existed. Regarding their settlement onto artificial plates with different roughness, Ulva preferred to settle on the rough surface both in the upper and lower intertidal zone; however, this pattern only appeared in the upper zone for Enteromorpha. Vertical distribution of the two populations was well separated; Enteromorpha was more abundant in the upper zone and Ulva in the lower zone. Their seasonal blooms were concomitant with ammonia levels, but occurrence was not well correlated with nitrate and phosphate. The ability of the populations to persist, once blooms occurred, was also distinct; Ulva persisted ca. twice as long as Enteromorpha , having a greater impact in the presence of green tide in this geographical area.     

火丝菌科(盘菌目)部分属的系统学研究

本文以核糖体小亚基(SSUrDNA)为分子标记,对28个属60个种的71个序列片段进行序列分析,探讨火丝菌科的属间亲缘关系。研究结果支持广义的火丝菌科概念,表明该科是单起源的,显示5个主要分支。腐生或与植物共生形成菌根、囊盘被表面具有毛状物的15个属构成A分支,该分支中仅部分属之间的关系比较明确;与苔藓植物生长在一起的4个属构成B分支;C分支包括Otidea和Otideopsis两属,后者与Otidea的成员混杂在一起;D分支仅包括Acervus的成员;E分支由Geopyxis,Tarzetta,Paurocotylis等5个属组成。分子系统学的研究结果与形态学分类系统之间存在一定差异,依据形态特征和超微结构建立的亚科和族均未获得支持。     

Taxonomic significance of pollen types in the Guyana Highland-centred composite genera of Mutisioideae (Asteraceae)

The Guyana Highland-centred genera, or Stenopadus group, are a complex of species that belong to the tribes Mutisieae and Stifftieae of Asteraceae. The pollen morphologies of 29 species, from 12 of 13 genera of this complex, are described and illustrated using light and scanning electron microscopy. The exine sculpture and structure are highly significant. Four exine types, previously characterized, were distinguished: Gongylolepis , Wunderlichia , Mutisia , and Stenopadus . The characterization of the Stenopadus exine type is enlarged here. These exine types led to the recognition of four well-defined pollen types, whereas the spine length and exine thickness characterized six subtypes. Pollen types circumscribe genera or groups of genera, and some subtypes distinguish species. The pollen morphology within the complex is discussed in relation to the rest of Mutisioideae and other palynologically allied tribes of Cichorioideae. There is little correlation between pollen types and tribes; only the Stenopadus exine type is exclusive to the Stifftieae tribe. The remaining types are shared by the two tribes of the complex. Pollen morphology supports the hypothesis that this group of genera is close to the Gochnatia complex and the Cardueae tribe.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 327–340.     

Cryptic species in the Pyropia yezoensis complex (Bangiales,Rhodophyta): Sympatric occurrence of two cryptic species even on same rocks

In a previous study on wild populations of Pyropia, the occurrence of two possible new species (Pyropia sp. 2 and Pyropia sp. 3) which are closely related to the two commercially important Pyropia species, P. yezoensis and P. tenera, was confirmed as the result of molecular phylogenetic analyses. To characterize the morphological features of the two wild Pyropia species, we collected Pyropia blades in a natural population in which Pyropia sp. 3 was known to occur, and carried out molecular identification before detailed morphological observations. Through the molecular identification we found, unexpectedly, that Pyropia sp. 2 blades grew sympatrically in the same site. Therefore, after molecular identification, we examined in detail the external morphology and anatomy of the two wild Pyropia species using more than 10 blades each. As a result, it is concluded that all of the blades of the two species are morphologically identical to P. yezoensis, but distinct from P. tenera. It is therefore considered that both of the two wild Pyropia species are cryptic species within the P. yezoensis complex. Furthermore, this study revealed that the two cryptic species grew sympatrically, even on the same rocks within the natural habitat.     

MOLECULAR AND MORPHOLOGICAL ANALYSIS OF ENTEROMORPHA INTESTINALIS AND E. COMPRESSA (CHLOROPHYTA) IN THE BRITISH ISLES

The very common green seaweeds Enteromorpha intestinalis (L.) Nees and E. compressa (L.) Nees are important fouling organisms and have commonly been used as indicators of eutrophication, but their taxonomic status is problematic. The genus presents extreme difficulties because there is wide intraspecific variation in morphology, but morphological differences between species are small and difficult to detect. In this study, molecular data were used in parallel with morphological characters to resolve the taxonomic problems. Phylogenetic analysis of sequences of the internal transcribed spacers ITS1 and ITS2 and the 5.8S gene distinguished two groups of samples, which were identified by morphological characters as E. compressa (branched) and E. intestinalis (normally unbranched). There was a low level of sequence divergence within each group of samples, but divergence between groups was as great as that between either of the two species and the outgroup E. prolifera. Clades representing E. compressa and E. intestinalis were also found in analyses of an independent molecular data set, chloroplast DNA restriction fragment length polymorphisms (RFLPs). Enteromorpha intestinalis and E. compressa represent two distinct, genetically divergent species. Reinterpretation of published studies shows that these species are reproductively isolated. However, E. compressa and E. intestinalis are sometimes very difficult to distinguish from each other and could be regarded as cryptic species. The presence or absence of branching was the most useful character distinguishing these two species, but there was an element of ambiguity because low salinity or salinity shock can induce branching in E. intestinalis. If environmental factors such as salinity are taken into account, branching can be used to identify the great majority of thalli correctly. This study therefore provides a basis for identifying the two most important marine fouling macroalgae and for their use in environmental monitoring and experimentation. Typification of these two Linnaean species showed that current usage of the names accords with the lectotype and protologue of both species. Samples that resembled E. usneoides did not form a clade in any of the trees, and constraining the data to support the monophyly of this group incurred a penalty. Enteromorpha usneoides appears to be an ecotype of E. compressa.     

A phylogeny of four mitochondrial gene regions suggests a revised taxonomy for Asian pitvipers (Trimeresurus and Ovophis)

We present a phylogeny of the Asian pitvipers, based on 2403 bp of four mitochondrial gene regions. All but six known species of Trimeresurus sensu stricto (s.s.) as currently defined, as well as multiple populations of widespread species, which may yet be described as full species, and representatives of all other Asian pitviper genera, are included. Both the greater sampling and larger dataset provide improved resolution over previous studies and support the existence of distinct species groups within Trimeresurus s.s. Although all but two species currently referred to this genus form a monophyletic group, morphological and molecular analyses identify four subgroups that warrant recognition at the generic level. We propose a new generic arrangement to reflect these findings. We also highlight the non-monophyly of Ovophis, and propose a new genus to accommodate a species formerly assigned to Ovophis.     

Phylogenetic relationships of the carabid subfamily Harpalinae (Coleoptera) based on molecular sequence data

The carabid subfamily Harpalinae contains most of the species of carabid beetles. This subfamily, with over 19,000 species, radiated in the Cretaceous to yield a large clade that is diverse in morphological form and ecological habit. While there are several morphological, cytological, and chemical characters that unite most harpalines, the placement of some tribes within the subfamily remains controversial, as does the sister group relationships to this large group. In this study, DNA sequences from the 28S rDNA gene and the wingless nuclear protein-coding gene were collected from 52 carabid genera representing 31 harpaline tribes in addition to more than 21 carabid outgroup taxa to reconstruct the phylogeny of this group. Molecular sequence data from these genes, along with additional data from the 18S rDNA gene, were analyzed with a variety of phylogenetic analysis methods, separately for each gene and in a combined data approach. Results indicated that the subfamily Harpalinae is monophyletic with the enigmatic tribes of Morionini, Peleciini, and Pseudomorphini included within it. Brachinine bombardier beetles are closely related to Harpalinae as they form the sister group to harpalines or, in some analyses, are included within it or with austral psydrines. The austral psydrines are the sister group to Harpalinae+Brachinini clade in most analyses and austral psydrines+Brachinini+Harpalinae clade is strongly supported.     

Molecular phylogeny of naidid worms (Annelida: Clitellata) based on cytochrome oxidase I

Naidids are tiny, primarily freshwater oligochaete annelids which reproduce asexually by fission. We investigated the phylogenetic relationships within this group by sequencing 1224 bp of the mitochondrial gene cytochrome oxidase I (COI) from 26 species of naidids (representing 13 of the 23 genera currently recognized), as well as from four tubificids, their closest allies. Although not completely concordant, maximum parsimony and Bayesian inference analyses agreed in several important respects, with no well-supported conflicts. Our study, the first detailed molecular investigation of naidid relationships, suggests that naidids fall into two groups, one comprised of the genus Pristina, and another comprised of all other genera sampled. The clear division of naidids into these two groups best matches an early, simple classification of the group by Lastockin (1924); the more recent classifications proposed by Sperber (1948) and Nemec and Brinkhurst (1987) are not as consistent with our results. We note that our study suggests the genus Stylaria is comprised of two distinct species, Stylaria lacustris and Stylaria fossularis, rather than merely two morphotypes of a single species. Based on our phylogenetic results, we suggest that pigmented eyes evolved only once among naidids but must have been lost multiple times, and that the elongation of the prostomium into a proboscis evolved at least twice independently. The simplest form of fission, architomy (fragmentation), occurs in two of the most basally branching naidid genera, and may represent the plesiomorphic condition for naidids.