Electronic Flora of South Australia Genus Fact Sheet

Genus HERPOSIPHONIA Nägeli 1846: 238

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Herposiphonieae

Thallus prostrate or with erect, free, lateral indeterminate axes bearing determinate laterals, from a few mm to several cm high. Branching pattern of 3 determinate laterals on consecutive segments, separated from the next group of 3 by one indeterminate lateral, occasionally developed as a long lateral axis; determinate laterals usually more-or-less erect from alternate sides of successive segments of axes, in some species pectinately or distichously arranged. Indeterminate axes terete to slightly compressed, determinate laterals terete. Pericentral cells 6–16, ecorticate. Trichoblasts absent on indeterminate axes but usually present subterminally on determinate laterals. Attachment by rhizoids cut off from ventral pericentral cells, with digitate haptera; usually epiphytic.

Reproduction: Cystocarps lateral on determinate laterals, ovoid. Spermatangial organs on branches of trichoblasts.

Tetrasporangia in determinate laterals, single per segment, with 2–3 cover cells.

Lectotype species: H. tenella (C. Agardh) Ambronn 1880: 197.

Taxonomic notes: A genus of 20–30 species found on most coasts, with 6 species recorded below from southern Australia. Several other species probably occur there but descriptions await collection of more adequate material. Species of Herposiphonia are not easy to categorise or separate and the degree of variation in many is uncertain. The account below deals only with recognised and previously named species. Comparisons with species from other regions (e.g. the tropical Pacific - Hollenberg 1968b; Abbott 1999, pp. 368–378) are needed in a more extensive monographic study.

References:

ABBOTT, I.A. (1999). Marine Red Algae of the Hawaiian Islands. (Bishop Museum Press: Honolulu, Hawai'i.)

AMBRONN, H. (1880). Lieber einige Hite von bilateralität bei den Florideen. Bot. Zeit. 38, 161–174, 177–185, 193–200, 209–216, 225–233, pls III, IV.

HOLLENBERG, G.J. (1968b). An account of the species of the red algae Herposiphonia occurring in the central and western Tropical Pacific Ocean. Pacif. Sci. 22, 536–559.

NÄGELI, C. (1846). Herposiphonia. Zeitschr. für. wissensch. Botanik. 3, 4, 238–256.

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO SPECIES OF HERPOSIPHONIA

1. Prostrate axes extensive, attached for most of their length, with simple, erect, determinate laterals 1–3 mm high	H. calothrix
1. Prostrate axes of limited extent, with extensive erect indeterminate branches 1–12 cm long, bearing shorter determinate laterals	2
2. Thallus relatively robust, axes usually over 200 µm in diameter and determinate laterals over 100 µm in diameter	3
2. Thallus slender, axes usually less than 200 µm in diameter and determinate laterals less than 100 µm in diameter	4
3. Branching of indeterminate axes irregular, with determinate laterals variously orientated; axes 200–600 µm in diameter, determinate laterals 100–200 µm in diameter; colour often orange-brown	H. versicolor
3. Branching of indeterminate axes usually pectinate with determinate laterals mostly abaxial; axes usually 300–450 µm in diameter, determinate laterals 100–150 µm in diameter; colour red	H. rostrata
4. Erect branches 1–2 cm high, branching dense, determinate laterals not pectinate; axial segments 90–140 µm in diameter, L/D 1–2 (–3), determinate lateral segments, L/D 1–2 (–3)	H. fill pendula
4. Erect branches usually 3–6 cm high, branching open with pectinate determinate laterals; axes 160–260 or 80–110 µm in diameter, determinate lateral segments L/D 1–1.6 or 3–4	5
5. Axes 160–260 µm in diameter, segments L/D 0.8–1.2, determinate laterals 50–90 µm in diameter, segments L/D 1–1.6; tetrasporangia markedly swelling segments	H. monilifera
5. Axes 80–110 µm in diameter, segments L/D 2–4, determinate laterals 45–60 µm in diameter, segments L/D 3–4; tetrasporangia unknown	H. pectinella

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