Halichrysis (J.Agardh) F.Schmitz, 1889

Lectotype species: Halichrysis depressa (J.Agardh) F.Schmitz

Original publication: Schmitz, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora oder Allgemeine botanische Zeitung 72: 435-456, pl. XXI.

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Type designated in: Agardh, J.G. (1876). Species genera et ordines algarum, seu descriptiones succinctae specierum, generum et ordinum, quibus algarum regnum constituitur. Volumen tertium: De Florideis curae posteriores. Epicrisis systematis Floridearum. pp. [ii*-iii*], [i]-[viï], [1]-724. Lipsiae [Leipzig]: apud T.O. Weigel.

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Precise date of publication: 20 Dec 1889

Description: Thallus peltate or imbricate, sometimes iridescent, blades arising from a branched or unbranched, cylindrical stipe, frequently anastomosing, spreading and imbricate when mature, margins often recurving towards the substratum. Construction multiaxial, cortex of 1-2 layers of small cells, medulla of several layers of thick-walled, colourless cells. Gametangial plants dioecious; spermatangial sori superficial on one or both surfaces. Spermatangia formed on terminal cortical cells. Procarpic, carpogonial branches in cortex, 3-celled, borne in pairs on a large supporting cell bearing a single, 2-celled auxiliary cell branch. Gonimoblast developing outwards. Cystocarps ostiolate, scattered, on one or both surfaces of the thallus, never coronate, strongly protruding outwards, tela arachnoidea absent, columnar gonimoblast persisting. Tetrasporangia formed in an terminal position from cortical cells, forming on the upper or lower surfaces, or both, occasionally in nemathecioid sori. Spores regularly cruciately arranged. Although nothing is known of the growth in culture or of the life history, it is likely that species of the genus have a ‘Polysiphonia-type’ life history.

Information contributed by: M.D. Guiry. The most recent alteration to this page was made on 2017-01-24 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: Schneider, C.W. & Wynne, M.J. (2007). A synoptic review of the classification of red algal genera a half a century after Kylin's "Die Gattungen der Rhodophyceen". Botanica Marina 50: 197-249.

Comments: The genus Halichrysis is named for the iridescence apparent in live specimens of the type species; such iridescence is a feature of many peltate or prostrately groing algae, including some belonging to other families of red algae, such as Drachiella (Delesseriaceae, Maggs and Hommersand, 1993). The phenomenon is poorly understood. Two other genera of Rhodymeniales form peltate blades: Maripelta and Sciadophycus (q.v.); in both of these genera a medulla composed of a single layer of large cells is formed. In Maripelta (q.v.), the blades are not imbricate and reattachment does not take place, and the tetrasporangia are formed in an intercalary position. In Sciadaophycus, although the tetrasporangia are formed in a terminal position similar to those of Halichrysis, a tela arachnoidea is formed in the cystocarp. Details of the development of the procarp and of the cystocarp are known only for H. concrescens; the formation of two carpogonial branches on the same supporting cell is unique amongst the Rhodymeniaceae and is otherwise only found in species of Gastroclonium and Chylocladia. Huvé and Huvé (1976) have shown that early reports of a tela arachnoidea in H. concrescens are incorrect and a cellular network does not persist in the cystocarp. In recent years, inclusion of the genera Weberella (Huvé and Huvé 1977) and Drouetia (Norris 1991) in Halichrysis has been proposed on the basis of the peltate or imbricate habit of species of these genera, the presence of a polystromatic medulla and the absence of a tela arachnoidea. However, full details of the reproduction of the type species of these genera are unknown, particularly with regard to the structure of the procarp, and this requires further study, given the structure of the procarp in H. concrescens. Halichrysis depressa is known only from the area around the Straits of Gibraltar (Tangier, Algeria and Ceuta, Spain) where it grows at depths of 4-10 m; other reports are doubtfully correct (Huvé and Huvé 1976). H. peltata (W.R. Taylor) Huvé et Huvéhas been referred to Asteromenia (q.v.). H. coalescens (Farlow) R.E. Norris et A.J.K. Millar in R.E. Norris is found in eastern Australia (Millar 1990), South Africa, Indonesia, and the Galápagos Is. where it grows in the lower intertidal and at depths of up to 20 m. H. japonica Segawa is known only from Japan. H. micans (Hauptfleisch in Engler et Prantl) Huvé et Huvé is known from Borneo, Indonesia, Vietnam and Japan. Chrysymenia concrescens J. G. Agardh, described from Australia, is known only from the type material, and was transferred to Halichrysis by De Toni (1900). Millar (1990) re-examined the type material and suggested that the species was best placed in Halichrysis.

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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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Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 24 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 16 July 2024

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