Pedobesia MacRaild & Womersley, 1974

Holotype species: Pedobesia clavaeformis (J.Agardh) MacRaild & Womersley

Original publication and holotype designation: MacRaild, G.N. & Womersley, H.B.S. (1974). The morphology and reproduction of Derbesia clavaeformis (J. Agardh) DeToni (Chlorophyta). Phycologia 13: 83-93, 15 figs, 1 table.

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Description: Thallus consists of 1) small calcified disk at least sometimes showing concentric rings, 2) uncalcified, branched, sprawling siphons and 3) clusters of uncalcified erect, clavate siphons which may appear as dense tufts. The two essentially prostrate states are interconvertible under certain conditions, and appear relatively persistent. The small disc form, which can measure to at least 1400 ┬Ám diam., has a surface ornamented with rows of numerous circular to obovate pores, and walls containing aragonitic calcium carbonate; secondary discs may overgrow older parts of thallus, forming a multi-layered encrusting structure. Fine siphons may develop from the margin of the disc. Both disc form, but more especially prostrate siphonous form produce dense clusters of erect siphons to about 6 cm. tall. The calcified phase distinguishes this genus from genera such as Derbesia and Bryopsis. Pedobesia is homoplastic; pyrenoids are absent. Reproduction by fragmentation, or by numerous stephanokontic zoospores produced in spherical to ovoid sporangia borne laterally on erect siphons, and separated from siphons by a thick refringent plug or gelatinous septum. Non-motile spores or other variations sometimes occur. Spores develop into one of the prostrate stages. Sexual reproduction is presently undiscovered; it has been suggested that the discs represent a gametophytic phase which has lost the capacity to form gametes.

Information contributed by: L. Hillis. The most recent alteration to this page was made on 2011-08-29 by M.D. Guiry.

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

Comments: Pedobesia has been reported with certainty from Australia, New Zealand, Japan, Galapagos Islands, Brazil, and the Mediterranean. Within habitat sites include shallow rocks, heavily shaded rock pools. Vertical range extends to at least -3 m on steeply sloping rock faces on exposed coasts. Distribution undoubtedly is much broader

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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. 29 August 2011. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 01 April 2023

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