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Background To gain insight into the branching order of the five main lineages currently recognized in the green algal class Chlorophyceae and to expand our understanding of chloroplast genome evolution, we have undertaken the sequencing of chloroplast DNA (cpDNA) from representative taxa. The complete cpDNA sequences previously reported for Chlamydomonas (Chlamydomonadales), Scenedesmus (Sphaeropleales), and Stigeoclonium (Chaetophorales) revealed tremendous variability in their architecture, the retention of only few ancestral gene clusters, and derived clusters shared by Chlamydomonas and Scenedesmus. Unexpectedly, our recent phylogenies inferred from these cpDNAs and the partial sequences of three other chlorophycean cpDNAs disclosed two major clades, one uniting the Chlamydomonadales and Sphaeropleales (CS clade) and the other uniting the Oedogoniales, Chaetophorales and Chaetopeltidales (OCC clade). Although molecular signatures provided strong support for this dichotomy and for the branching of the Oedogoniales as the earliest-diverging lineage of the OCC clade, more data are required to validate these phylogenies. We describe here the complete cpDNA sequence of Oedogonium cardiacum (Oedogoniales). Results Like its three chlorophycean homologues, the 196,547-bp Oedogonium chloroplast genome displays a distinctive architecture. This genome is one of the most compact among photosynthetic chlorophytes. It has an atypical quadripartite structure, is intron-rich (17 group I and 4 group II introns), and displays 99 different conserved genes and four long open reading frames (ORFs), three of which are clustered in the spacious inverted repeat of 35,493 bp. Intriguingly, two of these ORFs (int and dpoB) revealed high similarities to genes not usually found in cpDNA. At the gene content and gene order levels, the Oedogonium genome most closely resembles its Stigeoclonium counterpart. Characters shared by these chlorophyceans but missing in members of the CS clade include the retention of psaM, rpl32 and trnL(caa), the loss of petA, the disruption of three ancestral clusters and the presence of five derived gene clusters. Conclusion The Oedogonium chloroplast genome disclosed additional characters that bolster the evidence for a close alliance between the Oedogoniales and Chaetophorales. Our unprecedented finding of int and dpoB in this cpDNA provides a clear example that novel genes were acquired by the chloroplast genome through horizontal transfers, possibly from a mitochondrial genome donor.

Recent studies of the Chlorophyceae using 18S and 26S rDNA data in meta-analysis have demonstrated the power of combining these two sets of rDNA data. Furthermore, the 26S rDNA data complement the more conserved 18S gene for many chlorophycean lineages. Consequently, this data approach was pursued in an expanded taxon-sampling scheme for the Chlorophyta, with special reference to the classes Chlorophyceae and Trebouxiophyceae. Results of these new phylogenetic analyses identify Microspora sp. (UTEX LB 472) and Radiofilum transversale (UTEX LB 1252) as sister taxa which, in turn, form a basal clade in the Cylindrocapsa alliance (Treubaria, Trochiscia, Elakatothrix). The relative position of the “Cylindrocapsa” clade within the Chlorophyceae remains uncertain. The enhanced taxon-sampling has not resolved the relative positions of the Oedogoniales, Chaetophorales or Chaetopeltidales. Furthermore, the Sphaeropleaceae are supported as members of the Sphaeropleales in only some analyses, raising concerns about the status of the order. Although based on a limited set of taxa (currently

Pure (axenic) strains of an intercellular endophyte identified as Chlorochytrium lemnae Cohn (= Chlorosphaeropsis lemnae Moewus) were isolated from infected duckweed (Lemna spp.). Pure cultures of the host were also obtained. Both grew well in mineral media, requiring no organic growth factors. In suitably dilute media, the algae could be induced to infect dead leaves of several different Lemna clones. Since its cells divide vegetatively by the formation of common cross walls (“desmoschisis”), Chlorochytrium lemnae should be transferred from the Chlorococcales to the Chaetophorales. The taxonomic status of other algae identified as Chlorochytrium—some of them demonstrated to be stages in the life-cycle of filamentous algae—should be re-evaluated.

Five Stigeoclonium tenue and five S. aestivale strains (both species having wide ecological ranges) and five S. farctum strains (a species with relatively narrow ranges) were examined for chlorine tolerance and morphological plasticity under laboratory conditions. Hair formation, cell dimensions and thallus form were studied. Differentiation in chlorine tolerance was most pronounced in S. aestivale, next in S. tenue and less in S. farctum. For morphological differentiation the sequence was S. tenue, S. farctum and S. aestivale, and for morphological plasticity S. farctum, S. tenue and S. aestivale. It is concluded that in a widespread algal genus such as Stigeoclonium, the ecological ranges are predominantly determined by the degree of ecotypic differentiation, rather than by morphological plasticity. The present study indicates that the separation of S. farctum and S. variabile by Cox & Bold (1966) is not justified and it is suggested that S. variabile may be an ecotype of S. farctum, but to some extent ...

Comparative investigations on the morphology, life-history, and reproduction of 3 cultivated strains of the atmophytic green algaApatococcus lobatus are presented. Some ultrastructural features are added to the results of earlier investigations, and comments on the systematics and ecology are given. Morphology and cytology of each strain is variable and shows considerable overlapping. The results support the view thatApatococcus consists of a single variable species (A. lobatus) only. For the epiphytic algal associationPleurococcetum vulgaris the more significant termApatococcetum lobati is proposed.

The present communication deals with the morphology, reproduction and cytology of Stigeoclonium pascheri (formerly described as Caespitella pascheri Vischer). Effects of various concentrations of nitrate and variations in intensity and duration of light period in 24 hr LD cycles were studied on cultures of this alga in relation to the type and extent of branching and occurrence or absence of hair formation. It is concluded that these traits are not of taxonomic significance and are influenced largely by environmental conditions. The present study shows a large overlapping of morphological characters between the genera Stigeoclonium and Caespitella and supports Cox & Bold's abandonment of the latter generic name and its merger into the genus Stigeoclonium. The chromosome number determined for this alga is n = 6 which indicates that the Indian strain of this alga is a distinct cytotype from the one originally isolated by Vischer.

SUMMARY Pseudendoclonium basiliense and Trichosarcina polymorpha are essentially identical with regard to the fine structural details of cell division even though one was previously classified in the Chaetophorales and the other in the Ulvales. Cell division in the 2 genera is also shown to be like that in Ulva, as previously suggested might be the case. The combination of mitotic and cytokinetic characteristics common to the 3 genera is distinctive: (1) precocious development of a thick cleavage furrow, (2) centrioles distinctly lateral to polar fenestrae, (3) collapse of the interzonal spindle at telophase, and. (4) a cleavage furrow not associated with microtubules. It is suggested that features of vegetative cell division presently provide the best, characteristics for defining the Ulvaceae and that the use of growth habit should be abandoned. Despite the fact that a phycoplast is not present, in these algae, it is concluded that their affinities lie with genera that do possess a phycoplast.

The fine structure of the quadriflagellate zoospores of Draparnaldia glomerata (Vauch.) Agardh is described with emphasis on the flagellar root system and compared with the flagellar apparatus of related green algae. It is demonstrated that the flagellar root system in Draparnaldia is similar to that of the zoospore of Uronema belkae. Common features include presence of a cruciate root system (formula 2–5–2–5), prominent striated distal fibre connecting opposite basal bodies, a system I striated root component associated with the 2–stranded root, association of electron dense material with the 5–stranded root, mode of arrangement of the basal bodies in the absolute configuration model, and presence of four striated peripheral fibres interconnecting adjacent basal bodies. Differences exist in the shape of the striated peripheral fibres, the origin of the 2– and 5– stranded roots in the proximal part of the flagellar apparatus, and the architecture and striation pattern of the proximal part of the system I fibre that detaches from the 2–stranded root between adjacent basal bodies. Both the 2– and 5–stranded roots originate near the basal bodies and descend deeply into the zoospore. One of the 5–stranded roots passes near the eyespot of the chloroplast. The implications of these findings for the taxonomic position of the genus Draparnaldia are discussed. In addition, an evaluation is given of the present status of the order Chaetophorales. Suggestions are given to standardize some aspects of the current terminology of the cruciate flagellar root system in green algae.

Helicodictyon planctonicum (Whitford) Whitford & Schumacher (Chlorophyta) is a rare freshwater alga usually assigned to the order Chaetophorales but also reported to show features resembling members of the order Chlorococcales. In order to help clarify its phylogenetic position, an ultra-structural study was performed. The filamentous branching pattern and absence of a perinuclear envelope of endoplasmic reticulum during mitosis in H. planctonicum resemble features found among members of the Chaetophorales. However, the first and second cell divisions are perpendicular to each other as is common among chlorococcalean algae (Biebel, 1968). Additional chlorococcalean features exhibited by H. planctonicum include pyrenoids traversed by thylakoids, centrioles at the division plane following mitosis, and cytokinesis by furrowing. Therefore, it appears that H. planctonicum may be more closely allied with the Chlorococcales. However, failure to observe a phycoplast suggests Helicodictyon should be exami...

SUMMARY In vivo growth rates of Gongrosira [probably G. incrustans (Reinsch) Schmidle], a cushion-forming fresh-water green alga (Chaetophorales) are reported for the first time. The annual radial growth rate averaged 0-42 mm in a mountain stream from northern England and was positively correlated with water temperature (r = + 0-919, P < 0 05). The colonies were heavily incrusted with calcium carbonate (calcite). Photosynthetic activity probably promotes calcification between the closely packed basal filaments, but most of the precipitation appears to be abiogenic from supersaturated stream waters. Calcified Gongrosira bioherms are also described from a subtropical site in Mexico. The survival period for Gongrosira at the English site was approximately one year, and at both sites Gongrosira was a permanent and significant component of the epilithtc algal flora.

Extracts prepared from 10 bacteria-free algal cultures and 4 naturally occurring seaweeds were examined for urease and ATP-urea amidolyase (UAL-ase) activities. UAL-ase activity is confined to members of the classes Volvocales, Chlorococcales and Chaetophorales in the Chlorophyceae. Members of the Ulotrichales may possess either urease or UAL-ase. Ulva contains urease. All other algae, so far examined, which can grow with urea as nitrogen source contain urease but not UAL-ase.

Draparnaldia iyengarii sp. nov. is described from two desert localities in India. The new species has been compared with D. ravenellii Wolle, D. jaoii Cook and D. champlainesis Cook. D. iyengarii differs from all known species in having well defined and two types of short laterals composed of characteristically ellipsoidal cells. Each short lateral possesses only one multicellular, long hair.

Karyological investigations on six species of Stigeoclonium and three of Chaetophora (Chaetophorales, Chlorophyceae) are reported. While Stigeoclonium spp. were grown in BBMPTB 12 medium, the species of Chaetophora were cultivated in modified Chu-10 medium under standard culture conditions. The range of chromosome numbers was found to vary from n=5 to n= 14. Chromosome numbers of three taxa of Stigeoclonium, namely S. helveticum (n=5), S. aestivale (n = 10) and S. subsecundum (n= 14) are new records and the chromosome number obtained for Chaetophora pisiformis (n=8) is a first report.

The seta-bearing cells of Coleochaete scutata have been studied with the light and electron microscopes. These cells differentiated from vegetative cells and represent 3–5% of the cells in a typical thallus. They have the following modifications: (1) a tube-like extension of the cell wall (the seta collar); (2) the seta, which is a thin membrane-bound structure originating from the cytoplasm but exuded through the seta collar; (3) the setasome, a granular body found in the cytoplasm near the base of the seta collar; and (4) a crescent-shaped chloroplast that revolves around the base of the seta collar and extends a diverticulum of its outer membrane into the seta. Functional and evolutionary implications of seta-bearing cells are discussed.

The chlorophycean genus Schizomeris is usually considered to be a member of the Ulvales, often in the family Schizomeridaceae. However, Schizomeris differs from Ulva in several important cytological aspects. In Ulva cytokinesis is by furrowing; there are no microtubules associated with the cleavage furrow and there are no plasmodesmata. In Schizomeris cytokinesis is by cell plate formation with associated phycoplast microtubules, and plasmodesmata are present in the transverse walls. Schizomeris is similar to the investigated chaetophoralean algae in these and other respects. At present Schizomeris should be considered a distinct genus, apparently related to the Chaetophorales.

In the first paper of this series it was shown that mitosis and cytokinesis in Schizomeris are more like those events in Stigeoclonium rather than Ulva. It was concluded that Schizomeris should be included in the Chaetophorales. The present work shows that the zoospores of Schizomeris are somewhat different from those of both Stigeoclonium and Ulva. It is concluded that Schizomeris should be retained in a separate family of the Chaetophorales. Specifically, quadriflagellate zoospores of Schizomeris lack a two-stranded microtubular root, but rather have four, wide, cruciately arranged microtubular roots which probably contain an equal number of microtubules. Evolution in green algal motile cells is briefly discussed, and it is suggested that a flagellar ring such as occurs in the Oedogoniales may have evolved from quadriflagellate zoospores similar to those of Schizomeris.

Behaviour of Draparnaldiopsis indica Bharadwaja (Chlorophyta) was studied in a newly synthesized nutrient medium. The medium induced the development of normal morphological features in the alga. Branches of unlimited growth also showed differentiation into nodal and internodal cells. The typical morphology of the alga found in nature could only be obtained in this new medium.

Six different isolates of Ochlochaete Thwaites ex Harvey have been studied under identical culture conditions. All the isolates show open branching, a character previously ascribed specifically to O. hystrix Thwaites ex Harv. sensu stricto, and all form hairs on rounded cells in the central part of the thallus, a character hitherto attributed only to O. ferox Huber. Consequently, separation of these two entities on the species level is untenable. The plant described by Huber is referred to O. hystrix var. ferox (Huber) var. nov. The type material of Chaetobolus gibbus Rosenvinger is similar to one of the isolates studied and is included in O. hystrix. Quadriflagellate zoospores have been observed in all the isolates, and in one of them also biflagellate swarmers.

Quadriflagellate zoospores ofChaetophora incrassata andPseudoschizomeris caudata have similar features including an appressed membrane between the pyrenoid matrix and the starch sheath, and identical flagellar apparatuses. Components of the flagellar apparatus include: directly opposed upper basal bodies, lower basal bodies in the clockwise absolute orientation, a grooved distal fiber, peripheral and terminal fibers between adjacent basal bodies, proximal fibers connecting the lower basal bodies to the X-membered rootlets two- and X-membered rootlets associated with electron-dense components, and at least one rhizoplast. The X-membered rootlets, are comprised of five microtubules inC. incrassata and four or five inP. caudata. These features of the flagellar apparatus suggest that the two algae are closely related, and together withStigeoclonium, Uronema, Draparnaldia andFritschiella, form a natural group, the Chaetophoraceae, Chaetophorales (sensu Mattox and Stewart).

The influence of various element deficiencies was tested on 13 strains of Chaetophorales (1 Chaetophora, 2 Draparnaldia, 10 Stigeoclonium) isolated from sites in Belgium, N.E. England and Germany. Judged by the yield in batch culture, the relative response to each deficiency was quite similar in all strains: control > –P > –Fe > –Ca = –S > –Mg > –N. Judged by the extent of hair formation, the relative response was quite different: –P > –N > –Fe = –S > –Ca > –Mg > control. P- and N-limited cultures were the only ones to have typical hairs, and hair development was much greater in the former. It proved possible to maintain continued growth of a culture in a hairy condition by developing a continuous culture technique and using a medium with a high N:P ratio. Five strains were selected for more detailed study. N and P compositions, percentage hairiness and surface phosphatase activity were followed during growth in batch culture in medium leading to P-limitation. Although the maximum P composition r...

A low relief, green turf-forming alga of a heterotrichous habit was discovered in the coral reef microcosm, Museum of Natural History, Smithsonian Institution. Erect filaments bore lateral, specialized sporangia and together with basal filaments possessed septal plugs between adjacent cells, grossly similar to the "pit connections" of red algae. Data are presented which: 1) establish the identity of our plant with a plant recently described as Pilinia earleae Gallagher et Humm from the Florida Gulf coast; 2) support our establishment of the new genus Smithsoniella and our transfer of P. earleae to this new taxon. Additional data on pigmentation and cytology are related to the fine structure of other selected green algae to develop and test three hypotheses, viz. Smithsoniella earleae represents either: 1) a symbiotic association between a green and a red alga; 2) an alga which belongs to either the Ulotrichales, Chaetophorales or the Chroolepidales; or 3) an alga representing an evolutionary link between filamentous forms of the Ulvophyceae and members of the coenocytic siphonalean complex (e.g., Codiales or Caulerpales) of the Chlorophyta. Data refute hypotheses I and 2 but do lend support to the third hypothesis. RECENT FINE STRUCTURAL STUDIES of the green algae (Roberts et al., 1980; Sluiman et al., 1980; Stewart and Mattox, 1975, 1978; Stewart, Mattox and Floyd, 1973) have substantially modified our view of the relationships of members of the Chlorophyta from older systems based on vegetative and reproductive morphology. The origins of the coenocytic green algae have been especially difficult to discern (Stewart, Mattox and Floyd, 1 Received for publication 13 July 1981; revision accepted 3 November 1981. We thank individuals of the Smithsonian Institution who supported the concept of the coral reef microcosm developed by Dr. Walter Adey and colleagues and especially Dr. Adey for use of facilities in the Marine Systems Laboratory at the Smithsonian Institution. We also thank Dr. John Ogden and Nancy Ogden of the West Indies Laboratory, St. Croix, U.S.V.I. for providing space, facilities and field expertise during our visits to St. Croix, and Dr. Kenneth Towe for use of his electron microscopy facilities. Discussions with Drs. David Domozych, Ken Stewart, and Karl Mattox were especially helpful in developing our hypotheses and comments by Drs. Max Hommersand, Paul Silva, and Charles O'Kelly aided in taxonomic and nomenclatural treatments. We thank Dr. H. Humm for providing a culture of Smithsoniella from the Florida Gulf coast and Dr. Hannah Croasdale, Dartmouth College, for providing the Latin diagnosis of Smithsoniella. Support for travel to St. Croix by J. Sears was generously provided by Southeastern Massachusetts University and was greatly appreciated. 2 Present address: Department of Physiology, Health Center, University of Connecticut, Farmington, CT 06032. 1973) but recent studies (Roberts et al., 1980; Sluiman et al., 1980) suggest that they are related to the Ulvophyceae as proposed by Stewart and Mattox (1978). While surveying the green algae within the Smithsonian Institution's 6.5 kl coral reef microcosm (Brawley and Adey, 1981) in 1977, one of us discovered a most unusual heterotrichous green alga growing as a low relief, green turf on the walls and coral rock substratum of the microcosm. The fine, erect filaments bore specialized, lateral sporangia along their axes. These prominent reproductive structures were of special interest; among green algae, specialized sporangia are largely restricted to siphonous, coenocytic forms within the Caulerpales and Codiales or to multicellular forms of the Chaetophorales and Trentepohliales (Bourrelly, 1972). Even more unusual was the presence of "pit connections" between adjacent cells. Subsequent studies of these structures (Brawley and Sears, 1980, 1982) demonstrated that the apparent "pit connections" were true septal plugs occluding perforated end walls and consisted of a core and paired caps. Such structures have never been demonstrated within the Chlorophyta, although they are common in members of the Rhodophyta where they also consist of a perforated end wall occluded by a septal plug (Ramus, 1969). Stewart, Mattox and Floyd (1973) pointed out that "coe

The development and morphology of Draparnaldia mutabilis under various culture conditions is described. The germination of zoospores is strictly erect. In the first stage of development a primary rhizoid or a small prostrate system is formed, which is generally replaced in a later stage by persistent secondary rhizoids originating from basal cells of the main axis. Optimal growth occurs at about 20°C and at relatively high light intensities. The phenotypic appearance found in field material is maintained best in culture in a dilute modified Woods Hole medium at 8°C under short day conditions. In more nutrient-rich media the typical features of Draparnaldia, especially differentiation of main axes and lateral fascicles, disappear and the plants attain a Stigeoclonium-like habit. Morphological variation has been studied in herbarium material and freshly collected specimens from several localities in The Netherlands. Evidence is presented that in The Netherlands only one, rather polymorphic Draparnaldia spec...

The prostrate thallus of Stigeoclonium was studied under defined culture conditions. The development from zoospore to adult stage was followed in detail with the result that no more than three morphological groups (or species) can be discerned. The three groups are designated as Stigeoclonium helveticum, S. tenue, and S. farctum. Considerable intra- and intergenotypic variation exists, especially in the erect system of Stigeoclonium helveticum and in the prostrate system of S. tenue. The prostrate system of Stigeoclonium farctum is not always a closed pseudoparenchymatous disc, but may form an open star-like ‘variabile’ habit.

A study was made of zinc concentrations in field populations of Stigeoclonium and the aqueous chemistry of sites from which the materials were harvested; the sites included streams polluted by old mines. A significant positive relationship between zinc in the alga and that in the water was obtained when data were plotted on log10-log10 axes; its predictive ability was improved further by use of multiple stepwise regression (MSR) procedures to account for the influence of other environmental factors. The relationship between accumulation and toxicity was studied using the present and previously published data for toxicity (measured as tolerance index concentration). In both cases the environmental variables affecting Zn accumulation indicated during the first three MSR steps were (aqueous) Zn, Fe and Mg and/or Ca. Accumulation increased at a faster rate than toxicity with increasing environmental concentrations of zinc.

The unicellular, sessile and setate green alga Dicranochaete reniformis Hieronymus has been referred to the orders Tetrasporales, Chlorococcales and Chaetophorales. Ultrastructural investigation of the alga points to a pseudocilial nature of the seta and reveals the occurrence of a contractile vacuole near the base of the seta. These observations suggest a classification of this taxon within the Tetrasporales. We are, however, of opinion that this order as presently conceived, is insufficiently characterized to be considered a natural group. The pyrenoid of Dicranochaete reniformis possesses cytoplasmic invaginations of a type not previously recorded among tetrasporalean algae. The possible taxonomic significance of this character is discussed.

A study of environmental chemistry, algal morphology, algal N and P compositions and phosphatase activity was made for 32 samples of Chaetophorales (30 Stigeoclonium, one Chaetophora, one Draparnaldia) at 15 sites in NE England. Algal N ranged from 1·52–8·41% dry weight, algal P from 0·097–1·87% dry weight and the N : P ratio (by weight) from 3·65 to 35·6. Significant positive correlations (P < 0·001) were found between algal P and aqueous P and N, amount of hair formation and N : P ratio, and between phosphatase activity and hair formation. Significant negative correlations were found between algal N : P ratio and aqueous P, amount of hair formation and aqueous P, and between phosphatase activity and algal P. Algal samples with N : P ratios (by weight) of 5·58 and below lacked hairs; those with ratios of 6·46 and above had hairs. A study of the influence of pH on phosphatase activity of six populations showed three markedly different types of response. Use of the lead capture technique revealed localizat...

SUMMARY The distribution of the rare filamentous green alga Ctenocladus Borzi was examined on a world-wide basis. All the collection sites are restricted to specific inland habitats. Most of these locations are in arid regions of North America with a few scattered sites in Peru, Sicily, and Siberia. This alga has been referred to 2 genera, either Ctenocladus or Lochmiopsis Woronochin & Popova, for the past 45 years. Based on field observations, laboratory cultures, and herbarium material, Lochmiopsis is considered synonymous with Ctenocladus. The response of vegetative cell dimensions to seasonal changes (i.e., osmotic potential and temperature) in 3 saline habitats in British Columbia was also investigated. Results from the study, along with laboratory dilutions of natural saline waters, showed that cell dimensions arc not valid criteria for separating species of Ctenocladus as proposed by some authors. Consequently Ctenocladus is considered a monotypic genus with physiological variants responding to seasonal environmental conditions.

SUMMARY The results of previous research and a present survey of some of the cytological characteristics of 18 additional genera and 34 additional species are presented and discussed from the viewpoint of phylogenetic and taxonomic significance. A preliminary attempt is made to place these, algae, in 4 orders on the basis of comparative cytology, and in particular on the basis of variation in mitosis and cytokinesis and the distribution of plasmodesmata. Consideration is given to the evolution of the phragmoplast and to the hypothesis that the Chaetophorales are related to the ancestry of land plants.

Developmental features of the Characeae are reviewed with reference to speculation on affinities and interrelationships of this group. A phylogenetic scheme is offered in which the Nitelloideae are considered a line distinct from the Charoideae. Nitella, on the basis of the presence of sympodial branching in its laterals and the greater degree of sterilization of its oogonium, is considered more advanced than Chara. Within Chara, ecorticate forms are considered to be derived from corticate forms. It is probable that there is some affinity between the Chaetophorales and the Charophyta, but the distinctive features of charophytes warrant their retention in a separate phylum. In an extension of Goebel's interpretation of the antheridium, the antheridial mother cell is compared to a nodal initial.

The present paper enumerates 30 taxa of fresh water algae, in which 18 belong to the class Cyanophyceae, order Chroococcales and 12 Chlorophyceaen taxa, orders Cladophorales, Oedogoniales, Chaetophorales, Zygenmatales and Ulotrichales. Species were identified from collected samples of high altitudinal zones of Sikkim Himalayas. All taxa have been reported for the first time from the study area. Key words: Cyanophyceae; Chlorophyceaen; Sikkim Himalayas doi: 10.3126/eco.v12i0.3195 Ecoprint: An International Journal of Ecology 12: 35-42, 2005

Three taxa belonging to the genus Stigeoclonium (Chaetophorales, Chlorophyta) are described here as new records for Bangladesh, namely, Stigeoclonium amoenum var. novizelandicum , S. protensum and S. tenue var. uniforme . Key words : New records, Stigeoclonium , Chlorophyta, Chaetophoraceae, Bangladesh DOI: 10.3329/bjpt.v12i2.598 Bangladesh J. Plant Taxon. 12(2): 1-9, 2005 (December)

The order Ulotrichales is characterized by features both of the vegetative structure and of the life cycle of their members. The thalli are simple filaments in Ulothrix and Urospora, prostrate discs or monostromatic blades in Gomontia and Monostroma. Monostroma is restricted to forms that develop from saccate or filamentous primary stages, never such ones that arise as tubular growths upon a prostrate disc. In general, isomorphic generations are connected by zoospores. In addition, the new concept of the order unites the majority of examples of heteromorphic life cycles in the Chlorophyceae. Their members agree in the possession of a unicellular cyst-like generation, formerly known as Codiolum. Elsewhere in the Chlorophyceae, heteromorphic life cycles occur sporadically, as in Derbesia (Siphonales), Spongomorpha (Cladophorales), and Stigeoclonium (Chaetophorales).

Levantamento florístico dos representantes da ordem Chaetophorales na Reserva Biológica do Parque Estadual das Fontes do Ipiranga situada na cidade de São Paulo, Estado de São Paulo, sudeste do Brasil. Cinco gêneros (Chaetosphaeridium, Coleochaete, Gonatoblaste, Protoderma e Stigeoclonium), sete espécies e uma variedade taxonômica não típica de sua espécie foram identificados. Coleochaete com três espécies e uma variedade não típica foi o gênero representado pelo maior número de táxons na área, seguido pelos demais três com uma espécie cada um. Coleochaete irregularis var. curvicollis D. Bicudo & C. Bicudo é descrita pioneiramente para a Ciência. Protoderma viride é a espécie mais bem representada do ponto de vista de sua distribuição ocorrendo em três localidades, enquanto Chaetosphaeridium globosum var. globosum, Coleochaete irregularis var. irregularis e Coleochate nitellarum foram identificadas em duas localidades cada uma e Gonatoblaste rostrata, Stigeoclonium sp. e Coleochaete irregularis var. curvicollis são as menos bem distribuídas por ocorrerem em uma localidade cada uma. Taxonomic survey of the Chaetophorales in the Parque Estadual das Fontes do Ipiranga Biological Reserve, São Paulo State, southeast Brazil. Five genera (Chaetosphaeridium, Coleochaete, Gonatoblaste, Protoderma and Stigeoclonium), seven species, and one taxonomical variety, not the typical of its respective species were identified. Coleochaete with three species and one non-typical variety is the genus with the largest number of taxa in the area, followed by the other three genera with one species each. Coleochaete irregularis var. curvicollis D. Bicudo & C. Bicudo is described for the first time for science. Protoderma viride is the best distributed taxon occurring in three localities, Chaetosphaeridium globosum var. globosum, Coleochaete irregularis var. irregularis and Coleochate nitellarum are present in two localities each, whereas Gonatoblaste rostrata, Stigeoclonium sp. and Coleochaete irregularis var. curvicollis are the least distributed ones, occurring in just one locality each.