Electronic Flora of South Australia Genus Fact Sheet

Genus POLYOPES J. Agardh 1849: 85

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Halymeniaceae

Thallus cartilaginous, densely tufted, with numerous narrow, subdichotomous, fronds from a discoid holdfast, branches slightly to moderately compressed. Structure multiaxial with rounded apices, developing a cortex several cells thick with outer anticlinal filaments, surface cells small, innermost cells slightly stellate, and a medulla of mostly longitudinal and anastomosing filaments; refractive ganglionic cells absent.

Reproduction: Sexual thalli dioecious. Carpogonial branch ampullae relatively simple, with short secondary filaments and occasional tertiary filaments. Auxiliary cell ampullae considerably larger, with numerous secondary and up to five orders of filaments, composed of small ovoid cells; auxiliary cell prominent, remaining distinct at base of carposporophyte, without a fusion cell. Involucre prominent, derived from ampullary filaments; ostiole slight. Spermatangia forming a surface layer near branch apices.

Tetrasporangia in nemathecia near branch ends, amongst numerous multicellular paraphyses, cruciately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Lectotype species: P. constrictus (Turner) J. Agardh 1849: 86.

Taxonomic notes: A genus of about 5 species (Kajimura 1990, p. 130) characterised by the densely branched habit, subdichotomous branching, and slightly raised tetrasporangial nemathecia near branch ends. Polyopes differs from the superficially similar Prionitis in having much branched auxiliary cell ampullae, in contrast to sparingly branched ones in the latter genus (Kawaguchi 1989, p. 251), and from Carpopeltis in having bushier ampullae and cystocarps scattered rather than clustered in thickened branch ends.

References:

AGARDH, J.G. (1849). Algologiska bidrag. Öfvers. K. Svenska Vetensk. Akad. Rh-h. 6(3), 79–89.

KAJIMURA, M. (1990). A new species of Polyopes (Halymeniaceae, Rhodophyta) from Hawaii. Bot. Mar. 33, 127–131.

KAWAGUCHI, S. (1989). The genus Prionitis (Halymeniaceae, Rhodophyta) in Japan. J. Fac. Sci. Hokkaido Univ., Ser. V, 14, 193–257.

The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.

Author: H.B.S. Womersley & J.A. Lewis

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO SPECIES OF POLYOPES

1. Thallus usually 4–16 cm high, branches 0.5–2 (–2.5) mm broad; medulla dense

P. constrictus

1. Thallus 1–3.5 cm high, branches less than 0.5 mm broad; medulla lax

P. tenuis


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