Polyphysaceae

Abstract: In this paper, we summarize the diversity of Polyphysaceae species in Todos os Santos Bay, in the state of Bahia, Brazil. On the basis of ten years of collections and the analysis of herbarium material, six species have been recorded for the area: Acetabularia caliculus J.V.Lamour. in Quoy & Gaimard; A. crenulata J.V.Lamour.; A. schenckii Mobius; Parvocaulis myriosporus (Joly & Cord.-Mar.) C.W.N.Moura & J.C.De Andrade comb. nov.; P. pusillus (M.Howe) Berger et al.; and P. parvulus (Solms) S. Berger et al. The last has a distribution extending to the southern Atlantic Ocean. Acetabularia myriospora was transferred to Parvocaulis (as P. myriosporus) on the basis of its short corrugated peduncles and lack of a lower corona in the gametangial ray discs, which are diagnostic characters of this genus. In Todos os Santos Bay, Acetabularia species are more widely distributed than are Parvocaulis species, which are currently restricted to Itaparica Island. The most common taxa were A. caliculus and A. schenckii, which were collected from the majority of the study sites. This paper provides detailed descriptions of the morphology, reproductive aspects and geographic distributions of the algae, as well as discussing the taxa studied.

Abstract: The genus Falsolikanella, introduced by Granier (1987), was based on the basal Cretaceous species Likanella campanensis Azema and Jaffrezo (1972) and assigned to the tribe Diploporeae (Pia, 1920) emend. Guvenc, 1979 within the green alga order Dasycladales. Later, other species were assigned to Falsolikanella. Sections of the type specimens of Likanella campanensis are reviewed. They show that in this species, the arrangement of the laterals is not metaspondyl, but typical of the genus Actinoporella (Gumbel in Alth, 1882) emend Conrad, Praturlon, and Radoicic, 1974, with coronae arising from a single primary lateral. Therefore, the species is assigned to the genus Actinoporella within the tribe Acetabularieae Decaisne, 1842, family Polyphysaceae Kutzing, 1843, and the generic attribution of other species previously assigned to Falsolikanella is discussed.

Abstract: Ecology and Evolution Group, Department of Biology, P.O. Box 60, Middle Tennessee State University, Murfreesboro, TN 37132 USA With 1 figure and 1 table Abstract: The genus Acetabularia represents a group of historically important, macroscopic, single-celled green algae initially used by Joachim Hammerling to demonstrate localization of genetic material within the nucleus of a cell (by grafting one species onto another and allowing it to regenerate its original form). Acetabularia, and the related genus Acicularia, are considered to be “living fossils” within the family Polyphysaceae because of their long and uninterrupted fossil record, and, as such, are important taxa in the evolutionary progression of green algae (and plants). To date, there is just a single published study on the sterols of Acetabularia mediterranea. Sterols, tetracyclic lipids which act to reinforce eukaryotic plasma membranes, are often used as chemotaxonomic indicators to assess relationships between eukaryotes. Examination of sterols within Acetabularia and Acicularia may help further identify an ancestral set of sterols that has since radiated throughout many green algae. Two C28 and three C29 sterols commonly found in green algae, all with Δ5 unsaturations and with the dominant one being 24-ethylcholest-5-en-3β-ol, were observed in four species of Acetabularia and one of Acicularia. The chemotaxonomic and evolutionary aspects of this finding are discussed herein.

Abstract: Abstract Cells of the members of the Dasycladales have a unique body plan well known from fossils. They persist today in 38 recognized species. This study investigates in detail the development of reproductive structures in 17 Polyphysaceae (= Acetabulariaceae) species and provides a molecular phylogenetic analysis of 18S ribosomal DNA sequence data of 23 species of the order Dasycladales, including 17 of the 19 extant members of the family Polyphysaceae. Reproductive cap development is documented by scanning electron microscopy in 17 species, by histological sections in five species, and by growth measurements. Other morphometric data are also provided for most species. Bayesian analysis of DNA data reveals three well-supported clades for which morphological synapomorphies exist, but which are not completely in accordance with previous generic concepts. An early-branching clade comprising the monotypic Chalmasia and two species of Halicoryne is characterized by the formation of buds by the pointed cap rays. The second clade, comprising five species of Polyphysa (except P. peniculus), is characterized by corrugation of the cell stalk. It forms a sister group to the third clade, which comprises all eight Acetabularia species, plus P. peniculus and Acicularia schenckii. This clade is united by the lack of a velum covering the developing caps and by the relative timing of cap ray initiation. The extended Acetabularia clade is also characterized by the presence of a corona inferior, a structure that apparently was secondarily reduced in P. peniculus. Acetabularia acetabulum, a model species for cell biology, is sister to all other species of this clade. Its unique, congenitally fused cap rays may have evolved by a simple shift of growth zones during cap initiation. We propose to include both the monotypic Acicularia (as Acetabularia schenckii) and Polyphysa peniculus (as Acetabularia peniculus) in the genus Acetabularia. For the remaining Polyphysa species of clade 2, a new genus name, Parvocaulis S. Berger et al., is proposed.