Derbesia Solier, 1846
Lectotype species: Derbesia marina (Lyngbye) Solier
Original publication: Solier, A.J.J. (1846). Sur deux algues zoosporées formant le nouveau genre Derbesia. Revue Botanique, Duchartre 1: 452-454.
Type designated in: Solier, A.-J.-J. (1847). Sur deux algues zoosporées devant former un genre distinct, le genre Derbesia. Annales des Sciences Naturelles, Botanique, Troisième Série 7: 157-166, pl. 9.
Request PDFDescription: Thallus of two different forms, branched siphonous phase (diploid sporophyte) of sparse to dense erect siphons, the latter sometimes appearing brush like, to about 3 (-5) cm. tall, arising from rhizoidal siphons which are perennating in at least one species; and vesicular phase (gametophyte), previously assigned to the genus Halicystis, consisting of a spherical to pyriform vesicle to over 3 cm diam., with very short and slender anchoring stalk. Main component of siphon wall, at least for some species, appears to be mannan in the branched form, and xylan in vesicular form. Sexual cycle has been considered to involve alternation of the 2 heteromorphic phases the diploid filamentous form producing stephanokontan zoospores (i.e. with ring of apical flagella) in lateral specialized sporangia separated from vegetative portions by plugs or a "double septum" near their bases. and haploid vesicular form developing biflagellate anisogametes from gametangia appearing as a transverse band within the vesicle. Gametes released forcibly through papillae which appear as white dots on vesicle wall. However, cytological examinations have shown that at least in some species, e.g. D. tenuissima, there is a haplo-heterokaryotic life cycle, with haploid gametophyte alternating with heterokaryotic sporophyte, the latter characterized by the presence of haploid nuclei from the two parents. Under these circumstances, nuclear fusion occurs in young sporangia shortly before meiosis and cleavage of zoospores. Variations include macrogametes producing new sporophytes by parthenogenesis, development of vesicular phase directly from sporangia without production of zoospores, and growth of new sporophyte from zoospores. Asexual reproduction occurs by fragmentation, and subsequent proliferation of extruded protoplasts.
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: Geographical distribution is global; latitudinal range extends from tropics into arctic waters. Filamentous phase is known to grow on protected stones or walls near low-tide line, and on coarse algae, shells or sponges to at least -22 m.; vesicular phase grows to at least -18 m. and may be found singly or in clusters on shaded underwater rock cliffs, in caves, under ledges, and on lithothamnioid algae.
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Contributors
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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=32846
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 29 August 2011. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 21 November 2024
