Phrix J.G.Stewart, 1974

Holotype species: Phrix gregaria (E.Y.Dawson) J.G.Stewart

Currently accepted name for the type species: Phrix spatulata (E.Y.Dawson) M.J.Wynne, M.Kamiya & J.A.West

Original publication and holotype designation: Stewart, J.G. (1974). Phrix: a new genus in Delesseriaceae (Rhodophyta). Phycologia 13: 139-147.

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Description: Small thalli consisting of prostrate cylindrical axes and tufts of simple laminae, rarely branched from the median rib, spatulate, erect (up to 7 mm high and 1-3.5 mm wide), provided with a short stipe (250-600 µm high and 95-120 µm wide) and an evident midrib. This is devoid of cortication except for a slight rhizoidal cortication present in the basal part of the adult laminae which increases slightly on the jamb and on the prostrate axes. The laminae are ridged or densely wavy from the margin to the midrib; only the smaller plates are flat or slightly wavy. The laminae have a single more or less lenticular apical cell that separates the axial cells; these, early (close to the apex), each separate 4 periaxial cells: first the 2 lateral periaxial cells (or basal of the second order cell filaments) are separated and, subsequently, the 2 dorsal ventral periaxial ones (on the plane perpendicular to the lateral ones). The axial and periaxial cells, due to their size and elongated shape, make the median rib particularly evident. The periaxials (75-110 µm long and 20-30 µm wide) very rarely present intercalary divisions. The cells of the 2nd order rows elongate more than the other cells of the lamina, thus marking microscopic, pinnate veins which however disappear near the margin; 3rd order and higher order cell rows are produced abaxially from the cells of 2nd order rows; not all 3rd order rows reach the edge of the lamina; the frequent intercalary divisions in the cells of the 2nd order and higher order rows, in addition to making the cells of the lamina small and irregular, make it difficult to follow the individual rows towards the margin and establish their degree of branching. Spermatocysts grouped in numerous small ellipsoidal soria scattered throughout the lamina (on both sides of the midrib) and delimited by the sterile cells of the 2nd and 3rd order filaments which at maturity appear as microscopic veins. The cystocarps, one or more on the rib of the lamina, sometimes fused together, are prominent, ostiolated with a neck slightly turned towards the apex; the carposporocysts are single, terminal and slightly elongated. The tetrasporocysts are grouped in the middle-upper part of the lamina to form an elliptical sorus divided into two mirror-image halves by the median rib and protruding on the two faces of the lamina. The tetrasporocysts are initially produced by the lateral periaxial cells, subsequently also by the adjacent cells of the 2nd order rows.

Information contributed by: Cormaci & al. (2023: 553).. The most recent alteration to this page was made on 2023-12-11 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Muñoz, L.A., Wynne, M.J., Kamiya, M., West, J.A., Küpper, F.C., Ramirez, M.E. & Peters, A.F. (2018). Reinstatement of Phrix (Delesseriaceae, Rhodophyta) based on DNA sequence analyses and morpho-anatomical evidence. Phytotaxa 334(3): 215-224, 14 figs.

Comments: This genus currently includes only the following species: P. spatulata, reported in the Mediterranean as Apoglossum gregarium.

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 11 December 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 19 July 2024

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