THE SYSTEMATICS OF<i>STAURONEIS</i>(BACILLARIOPHYTA) II. THE LIFE HISTORY OF<i>S. PHOENICENTERON</i>AND RELATED SPECIES

Mann, David G.; Stickle, Alan J.

doi:10.1080/0269249x.1995.9705350

Cited by 13 publications

(3 citation statements)

References 23 publications

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“…Potentially, one of the richest sources of nonmolecular characters is the sexual phase, which is an obligate part of the life cycle in most diatoms (as yet, no diatoms have been proven to have a strictly asexual life cycle, although this is probable in a very few pennate diatoms: see Mann 1989c, 1999. Details of pairing, gamete formation, plasmogamy, and auxospore development have proved useful taxonomically in several raphid pennate genera, including Sellaphora (Mann 1989b), Navicula (Mann and Stickle 1989), Craticula (Mann and Stickle 1991), Dickieia (Mann 1994b), Amphora (Mann 1994a), Placoneis (Mann and Stickle 1995a), and Stauroneis (Mann 1996a, Mann and Stickle 1995b). However, there is no account of sexual reproduction in Seminavis , apart from very brief observations of S. macilenta (Gregory) Danielidis et D. G. Mann (Danielidis and Mann 2002).…”

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SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

Chepurnov

Mann

Vyverman

et al. 2002

Journal of Phycology

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Cell division, the mating system, and auxosporulation were studied in the marine epipelic diatom Seminavis cf. robusta Danielidis & D. G. Mann. The interphase protoplast contains two girdle‐appressed chloroplasts, each with an elongate bar‐like pyrenoid, and also a central nucleus, located in a bridge between two vacuoles. Before cell division, the chloroplasts divide transversely and translocate onto the valves. The nucleus relocates to the ventral side for mitosis. After cytokinesis and valve formation, the chloroplasts move back to the girdle, showing a constant clockwise movement relative to the epitheca of the daughter cell. Seminavis cf. robusta is dioecious, and sexual reproduction is possible once cells are less than 50 μm. In crosses of compatible clones, gametangia pair laterally, without the formation of a copulation envelope, and produce two gametes apiece. The intensity of sexualization increases as cells reduce further in size below the 50‐μm threshold. At plasmogamy, the gametangia dehisce fully and the gametes, which were morphologically and behaviorally isogamous, fuse in the space between the gametangial thecae. The auxospore forms a transverse and longitudinal perizonium. After expansion is complete, there is an unequal contraction of the protoplast within the perizonium, creating the asymmetrical shape of the vegetative cell. Apart from this last feature, almost all characteristics exhibited by the live cell and auxospores of Seminavis agree with what is found in Navicula sensu stricto, supporting the classification of both in the Naviculaceae. Haploid parthenogenesis and polyploid auxospores were found, lending support to the view that change in ploidy may be a significant mechanism in diatom evolution.

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SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

Chepurnov

Mann

Vyverman

et al. 2002

Journal of Phycology

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“…Elsewhere, the gametangia can become separated by the secretion of mucilage between them during meiosis, e.g. in Stauroneis (Mann and Stickle 1996). Previous observations of Navicula species (Geitler 1952a, b, Mann and Stickle 1989) have shown that if a copulation envelope is present around the gametangia, it is extremely diffuse and watery, and we could detect none in our N. cryptocephala populations.…”

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SEXUAL REPRODUCTION IN NAVICULA CRYPTOCEPHALA (BACILLARIOPHYCEAE)¹

Poulíčková

Mann

2006

Journal of Phycology

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Homothallic sexual reproduction and auxosporulation were studied in monoclonal cultures and seminatural populations of the freshwater epipelic diatom Navicula cryptocephala Kütz. Gametangia paired via the girdle, one gamete was formed per gametangium (and hence one zygote per pair of gametangia), and gamete fusion took place without the formation of any copulation envelope or copulation canal. Superfluous nuclei from meiosis survived unusually long, so that gametes and young zygotes were probably functionally polyploid; later, all but two haploid nuclei degenerated. Expanded auxospores had a swollen center, but during formation of the initial valves, the auxospore contracted away from the perizonium to produce linear‐lanceolate valves. The pattern of reproductive behavior found in N. cryptocephala can be classified as type IIA2a auxosporulation in Geitler's system. The same type of zygote and auxospore formation seen in clonal cultures was observed in seminatural material from four lakes in Scotland and the Czech Republic. Variation in nuclear structure and auxosporulation in the N. cryptocephala species complex is discussed, as is the evolution of type II auxosporulation (one zygote per pair of gametangia) from type I auxosporulation (two zygotes per pair). The penalty of smaller numbers of zygote produced in type II may be outweighed by formation of larger auxospores (prolonging the vegetative phase) or more vigorous auxospores. The variation present among members of the N. cryptocephala complex indicates that biogeographical analyses based on use of the name N. cryptocephala, as performed recently to support the ubiquity hypothesis of protist distributions, are almost meaningless.

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“…However, to reach this conclusion, it is necessary to observe early stages in auxosporulation, because space constraints within the copulation envelope lead subsequently to reorientation of the auxospores and gametangia, so that they often become parallel to each other (e.g. contrast Type IC is not particularly common among the raphid diatoms surveyed by Geitler (1973), who listed it in Caloneis, Rhoicosphenia Stauroneis Ehrenberg, Neidium Pfitzer, Brachysira Ku¨tzing (formerly included within Anomoeoneis Pfitzer) and Nitzschia angustata (W. Smith) Grunow (for independent reports for some of these genera, see Mann, 1982Mann, , 1989aMann, , 1996aMann & Stickle 1996). Geitler's tentative categorization of Neidium has since been shown to be incorrect (Mann, 1984;, but his other examples seem to be valid and type IC behaviour has also been found in Achnanthes Bory (Idei 1991, Roshchin & Chepurnov 1999, Campylopyxis Medlin (Mann, 1990), Craticula Grun.…”

Section: Sexual Reproduction In a Systematic Contextmentioning

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Heterothallic auxosporulation, incunabula and perizonium inPinnularia(Bacillariophyceae)

Poulíčková

Mayama

Chepurnov

et al. 2007

European Journal of Phycology

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The cytology and life cycle of Pinnularia cf. gibba was examined in nine clones from three Scottish localities. This freshwater epipelic diatom is heterothallic and produces two isogametes per gametangium in type IC auxosporulation (Geitler's classification [1973]). The zygote undergoes a highly unusual metamorphosis before beginning expansion, becoming shortly linear-lanceolate; this is accompanied by formation of a complete covering of thin, oxidation-resistant strips and scale-like structures (at the poles), which are quite separate from the perizonium formed during auxospore expansion. Observations of similar incunabular structures in P. acidojaponica show that these elements are siliceous. The P. cf. gibba perizonium also has unusual features, including a remarkably wide primary band. Trikaryotic and haploid auxospores are sometimes formed and haploid 'zygotes' mature and expand like diploids, but do not develop into mature initial cells. Several phases of mucilage secretion take place, from the gametangia, zygotes and auxospores. Triplets of gametangia and polyspermy occurred with high frequency; this and the systematic significance of variation in auxospore, incunabula and perizonium structure, are discussed. Aspects of the taxonomy of the P. gibba group are treated in supplementary material provided on the European Journal of Phycology website.

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THE SYSTEMATICS OFSTAURONEIS(BACILLARIOPHYTA) II. THE LIFE HISTORY OFS. PHOENICENTERONAND RELATED SPECIES

Cited by 13 publications

References 23 publications

SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

SEXUAL REPRODUCTION IN NAVICULA CRYPTOCEPHALA (BACILLARIOPHYCEAE)¹

Heterothallic auxosporulation, incunabula and perizonium inPinnularia(Bacillariophyceae)

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THE SYSTEMATICS OFSTAURONEIS(BACILLARIOPHYTA) II. THE LIFE HISTORY OFS. PHOENICENTERONAND RELATED SPECIES

Cited by 13 publications

References 23 publications

SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)1

SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)1

SEXUAL REPRODUCTION IN NAVICULA CRYPTOCEPHALA (BACILLARIOPHYCEAE)1

Heterothallic auxosporulation, incunabula and perizonium inPinnularia(Bacillariophyceae)

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SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)¹

SEXUAL REPRODUCTION IN NAVICULA CRYPTOCEPHALA (BACILLARIOPHYCEAE)¹