Lundiella indica gen. et sp. nov., a new member of colonial Volvocales (Chlorophyceae) from India

A new alga designated as Lundiella indica gen. et sp. nov. is described from India. It is at present known only in vegetative condition. It clearly belongs in the colonial Volvocales but its features of vegetative morphology do not agree with those of any known genus of this order.     

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.     

Dissection of conjugants and mating type plus and minus cells in selfing clones of the isogamous green alga Closterium ehrenbergii

In the sexual reproduction of the green alga Closterium ehrenbergii, two sexually competent cells that are morphologically indistinguishable from the vegetative cells first come close to each other to form a sexually interacting pair. Each then divides into two gametangial cells. Isogamous conjugation occurs between nonsister gametangial cells of the two resulting pairs. With unusual selfing clones derived from a certain cross of heterothallic strains, we dissected apart a pair of gametangial cells that had already been united together by a delicate transparent tube, into which each gametangial cell was going to develop its conjugation papilla. In spite of such a degree of differentiation, when each was cultured in fresh medium, individual gametangial cells could dedifferentiate into vegetative cells and form subclones. By crossing such subclones with standard stable heterothallic mating-type strains, we show that each selfing clone of this alga actually produces both stable mt ⁺ and stable mt ^- cells, in addition to unstable mt ^- cells with selfing potency, during its mitotic vegetative growth. Although the selfing in C. ehrenbergii studied here differs in certain points from true homothallism, the results of the present study provide insight into how homothallism might have evolved from heterothallism.     

A Light Microscope Study of Carposporophyte Development in Gracilaria verrucosa (Hudson) Papenfuss

Gracilaria verrucosa is a very common marine red alga of Greekcoasts. The diploid carposporophyte which develops attachedto the female gametophyte of Gracilaria is described. The immaturecystocarps are very small while the mature ones are globose,ostiolate and are borne profusely all over the surface of thethallus. The earliest observed fusion cell is small and fusesprogressively with adjacent vegetative cells to form a largemultinucleate cell. From this fusion cell gonimoblast initialsoriginate, dividing further and giving rise to a large numberof gonimoblast cells. The resultant carposporophyte consistsof a basal-central, multinucleate cell surrounded by a conicalor hemispherical mass of gonimoblast cells. Chains or clustersof successively maturing carpospores are borne from the terminalgonimoblast cells. The liberation of mature carpospores takesplace through the ostiole of the cystocarp. The liberated carposporeslack cell walls and are naked in a mucilage mass. Gracilaria verrucosa (Hudson) Papenfuss, Gigartinales, Gracilariaceae, Rhodophyta, carposporophyte, development     

GLOEOCOCCUS MINUTISSIMUS SP. NOV. ISOLATED FROM SOIL1

A new species of Gloeococcns, G. minutissimus, is described from unialgal culture; the organism was isolated from soil collected near Bastrop, Bastrop Co., Texas. This alga consistently produced Chlamydomonas-like vegetative cells that were motile within nonmotile colonies of definite shape. Its taxonomic position is also discussed.     

THE OCCURRENCE AND PHYLOGENETIC SIGNIFICANCE OF PUTATIVE PLACENTAL TRANSFER CELLS IN THE GREEN ALGA COLEOCHAETE

Following fertilization, zygotes of the green alga Coleochaete orbicularis, which are retained on the haploid thallus, first enlarge, then become covered with a layer of vegetative cells. Light microscopy and high-voltage electron microscopy revealed the presence of localized wall ingrowths in vegetative cells adjacent to zygotes. These covering cells resemble the gametophytic placental transfer cells of embryophytes in their morphology, location, and time of development. If Coleochaete cells with wall protuberances function as do placental transfer cells of embryophytes, their presence is evidence that photosynthates may be transported between haploid thallus cells and zygotes. Thus, a nutritional relationship between different phases of the life cycle, similar to that which occurs in embryophytes, may also have evolved in green algae. This first report of putative placental transfer cells in a green alga supports Bower's (1908) ideas concerning the origin of land plant sporophytes and alternation of generations. The presence or absence of cells with wall ingrowths in several species of Coleochaete was correlated with estimates of zygote-plant area ratios.     

Research note: Amorphochlora amoebiformis gen. et comb. nov. (Chlorarachniophyceae)

A chlorarachniophycean alga, Lotharella amoebiformis, which has been classified in the genus Lotharella is placed into a new genus Amorphochlora gen. nov., based on its phylogenetic position, which has been clarified by the recently accumulated molecular phylogenetic information, and the morphological difference between the vegetative cells of the Lotharella species. Following this taxonomic treatment, a new combination Amorphochlora amoebiformis comb. nov., is proposed.     

CHLAINOMONAS KOLII(HARDY ET CURL) COMB. NOV. (CHLOROPHYTA,VOLVOCALES), A REVISION OF THE SNOW ALGA,TRACHELOMONAS KOLII HARDY ET CURL (EUGLENOPHYTA,EUGLENALES)1,2

The snow alga Trachelomonas kolii is transferred from the Euglenophyta (Euglenales) to the Chlorophyta (Volvocales) as Chlainomonas kolii comb. nov. As a result of critical examination of both living and type material, this species was found to have 4 flagella per vegetative cell, true starch, and 1 axial plastid per cell with several peripheral lobes. Vegetative cells of Trachelomonas kolii were described originally as having 1 flagellum, lacking true starch but having paramylum, and as having several parietal plastids per cell. The reticulate markings on the outer envelope of vegetative cells were found to be different from those in the original illustrations. Vegetative cells and resting spores of Chlainomonas kolii and Chlainomonas rubra are compared. The similarities of resting spores of Chlainomonas kolii and Chlamydomonas nivalis are discussed. These are the first records of Chlainomonas kolii from snow in Washington State.     

THE FINE STRUCTURE OF SPOROGENESIS IN THE XANTHOPHYCEAN ALGA PSEUDOBUMILLERIOPSIS PYRENOIDOSA1,2

The fine structure of vegetative cells, sporogenesis, and zoospores of the xanthophycean alga Pseudo-bumilleriopsis pyrenoidosa is described. Cleavage in sporogenesis closely resembles that of certain aquatic fungi.     

Amorphophallus nicolsonianus (Araceae), a new species from India

Amorphophallus nicolsonianus species nova, with cylindrical or napiform corms, is the only representative of the sect.Rapyogkos in India. All the other hitherto known species of this region have globose or depressed globose corms. The new species is related to some Indochinese species and toA. hildebrandtii ( Engl.)Engl. & Gehrm. from Madagascar.     

SINGLE-CELL PIGMENTATION OF PORPHYRA LINEARIS ANALYZED BY FOURIER TRANSFORM MULTI-PIXEL SPECTROSCOPY AND IMAGE ANALYSIS1

The novel method of Fourier transform multi-pixel spectroscopy was used for the nondestructive analysis of and comparison of pigmentation in different regions of live thalli of the red alga Porphyra linearis. Because the thallus in this alga consists of a monolayer of nonoverlapping cells, we were able to analyze the pigmentation of single cells by combining light absorbance with natural fluorescence data. From the image of each cell in the vegetative male and female reproductive and holdfast regions, more than 4 ± 10⁴ fluorescence and absorbance spectra were obtained. Specific pigments in the different regions were localized by the use of a software program of similarity mapping followed by image construction. The reconstructed images revealed subcellular localization of each pigment according to specific spectroscopic fingerprints. The results showed that the vegetative and female reproductive cell types had a significantly higher content of phycoerythrin than of phycocyanin, and quite similar chlorophyll a levels. Most of the holdfast cells were poorly pigmented, but had more chlorophyll a than phycoerythrin or phycocyanin. The male reproductive cells contained only traces of pigments. Thus, by using Fourier transform multipixel spectroscopy, we were able to characterize the pigmentation of different regions of the thallus and follow the distribution patterns of the different pigments on the subcellular level along the differentiation gradient of the alga.     

Ecology of Zygnema stellinum Vauch. during desiccation of a shallow body of water

the effect of desiccation on the green alga Zygnema, a typical aquatic form of the order Conjugatae, family Zygnemaceae, is investigated. The vegetative reproduction of Zygnema occurs with the separation of the filaments in two different ways. It is shown that changes take place in cell morphology during desiccation. After division most of the cells acquire the shape of a square. These are usually half as large as the vegetative cells prior to division. Also, the form and color of the chromatophores change; they become green-brown, i.e., Zygnema falls into a state of rest, since no cell division is observed. During this state of rest the filaments suffer the unfavorable conditions of summer drought. In the fall, at the end of August, with the shortening of the day and reduction of temperature, the alga develops parthenospores for overwintering.     

LONG-TERM MAINTENANCE OF FERTILE ALGAL CLONES: EXPERIENCE WITH PANDORINA (CHLOROPHYCEAE)1,2

There is a need for simple, inexpensive methods to maintain algal clones of constant genotype over long periods of time. Pandorina zygospores survive many environmental rigors which destroy the vegetative cells. The zygospores are the preferable from for storage of the alga and remain viable for at least 15 yr. storage procedures and germination techniques are described for zygospores of 2 species. These are compared with reports in the literature concerning other algal genera. General procedures for storage and maintenance of both vegetative cells and spores are proposed.     

A study of the red alga,Calonitophyllum medium (Hoyt) comb. Nov. [= Hymenena media (Hoyt) Taylor]

Ontogeny of the vegetative system and reproductive structures found in Hymenena media (Hoyt) Taylor (Delesseriaceae, Nitophylleae) indicates that the alga is similar to the Phycodrys group in its vegetative development, and to the Nitophyllum group in its female reproductive system. The vegetative system bears striking resemblance to the type species of a European genus, Radicilingua [R. thysanorhizans (Holm.) Papenf.]. Reproductive structures of two other species of this genus, R. adriatica (Kylin) Papenf. and R. reptans (Zanard.) Papenf. and the type species are inadequately known. On the basis of several vegetative characters and the location and superficial organisation of the tetrasporangial sori, a new genus, Calonitophyllum, is proposed to contain our Western Atlantic plants. The new combination, Calonitophyllum medium (Hoyt) Aregood, thus replaces Hymenena media (Hoyt) Taylor.     

Snow algae of the Windmill Islands, continental Antarctica 3. Chloromonas polyptera (Volvocales, Chlorophyta)

A new name, Chloromonas hohamii, is proposed to accommodate a common North American snow alga previously incorrectly referred to as Chloromonas polyptera. Chloromonas hohamii differs in having the motile vegetative cells with a cup-shaped chloroplast opening in the anterior end of the cell, shorter, narrower, ellipsoidal to elongate to somewhat fusiform, sexual spores with non-spiralled wall flanges, shorter and narrower daughter cells derived from the spores, and it grows in snow of significantly lower pH and conductivity. Received: 29 August 1997 / Accepted: 24 April 1998     

OCTOSPORIELLA COLORADOENSIS GEN. ET SP. NOV., A NEW TETRASPORALEAN GREEN ALGA FROM TWO COLORADO MOUNTAIN LAKES1

A new green alga, Octosporiella coloradoensis, belonging to the order Tetrasporales, family Tetrasporaceae, is described from Colorado mountain lakes. Colonies are planktonic or attached, the latter often forming loosely aggregated colonial complexes, thus creating an irregularly shaped complex. Individual colonies are spherical and consist of eight subcolonies, with each subcolony having spherically arranged octads of cells. Each vegetative cell bears two pseudoflagella that extend well beyond the colonial sheaths. Cell division is by eleutheroschisis and may be synchronous or asynchronous. Daughter colony formation is apparently coenobic, with each cell in the octad forming new subcolonies of eight cells each. Zoospore formation may precede daughter colony formation but the flagella remain rigid and non-motile. Large akinetes form in response to nutrient depletion. These germinate to produce eight aplanospores which divide to reconstitute a typical colony of Octosporiella. Sexual reproduction was not observed.     

EVIDENCE FOR SEXUAL REPRODUCTION IN THE PRIMITIVE GREEN ALGA NEPHROSELMIS OLIVACEA (PRASINOPHYCEAE)1

Evidence for a specialized sexual process in Nephroselmis olivacea Stein is presented. This alga is a member of the Prasinophyceae, which is regarded by some as the most primitive Class of green plants. N. olivacea has a heterothallic type of mating system. Plus and minus gametes were morphologically similar but showed different behaviors during the mating process. The minus gamete settled to the substratum, attaching by its ventral side. The plus gamete attached to the dorsal side of the minus gamete by the region near the flagellar bases of the plus gamete. The mature zygotes were spherical and strongly adhered to the substratum. After zygote germination, two biflagellate daughter cells, each with two pyrenoids were liberated. These cells divided, resulting in four vegetative cells, each with a single pyrenoid.     

ULTRASTRUCTURE OF TETRASPOROGENESIS IN THE MARINE RED ALGA PTILOTA HYPNOIDES1

Both tetrasporangia and dormant apical cells of short vegetative filaments of the marine red alga Ptilota hypnoides have been examined by electron microscopy. Various cytoplasmic inclusions readily distinguish the vegetative apical cells from the reproductive apical cells which become tetrasporangial mother cells. The transformation of tetrasporangial mother cells into mature tetrasporangia involves a series of cytoplasmic changes which can be correlated with specific changes in the investing wall layers. The extracellular changes provide the basic criteria for the division of tetrasporogenesis into 3 successive stages. The ultrastructure of each stage is described and discussed in relation to the current knowledge of red algal cytology. In addition, a possible mechanism for the liberation of spores and gametes of red algae is proposed.     

PARASITIC INTERACTIONS AND VEGETATIVE ULTRASTRUCTURE OF CHOREOAEMA THURETII (CORALLINALES,RHODOPHYTA)1

The monotypic coralline red alga, Choreonema thuretii (Bornet) Schmitz (Choreonematoideae), grows endophytically within three geniculate genera of the Corallinoideae. Although the thallus of Choreonema is reduced, lacks differentiated plastids, and is endophytic except for its conceptacles, its status as a parasite has been questioned because cellular connections to the host had not been ob served. Transmission electron microscopy, however, disclosed a previously undescribed type of parasitic interaction in which Choreonema interacts with its host through specialized cells known as lenticular cells. These small, lens-shaped cells are produced from the single file of host-penetrating vegetative cells. Pit plug morphology between vegetative and lenticular cells is polarized. Plug caps facing the vegetative cell have normal coralline morphology, while those facing the lenticular cell are composed of three layers. Regions of lenticular cells near host cells protrude toward the host cell; upon encountering the host cell wall, the prolrusion produces numerous finger-like fimbriate processes that make cellular connections with the host cell. Lenticular cells may extend several protrusions toward a host cell or penetrate more than one host cell; two or more lenticular cells may also penetrate the same host cell. The lack of secondary pit connections, cell fusions, and passage of parasitic nuclei suggest that this parasitic relationship may be evolutionarily older than previously reported cases of parasitism in red algae.