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Antrocentrum nigrescens (Havey in Hooker & Harvey)Kraft & Min-Thein 1983: 177, figs 17–35.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Acrotylaceae

Selected citations: Millar & Kraft 1993: 15.


Rhabdonia nigrescens Harvey in Hooker & Harvey 1847: 409. J. Agardh 1852: 354; 1876: 590. Kützing 1866: 26, pl. 74. Kylin 1932: 36.

Rhabdonia mollis Harvey 1863, synop.: xli. J. Agardh 1876: 593.

Solieria mollis (Harvey) Kylin 1932: 20, fig. 12.

Rhabdonia patens Harvey 1863, synop.: xli. J. Agardh 1876: 593.

Thallus (Fig. 122F) medium to dark red-brown, 5–20 cm high, much branched irregularly with percurrent axes or main branches and terete, slender, laterals, 0.7–1.5 mm in diameter, tapering to a point gradually or abruptly, often proliferous when damaged, occasionally with recurved branch ends. Holdfast (Fig. 124A) densely fibrous, branched, 0.5–2 cm across, bearing one to several fronds; epilithic or epiphytic. Structure. Apices uniaxial with a prominent apical cell, cells of axial filament each with two adjacent periaxial cells (Fig. 123G), rotated on successive cells, forming a lax filamentous medulla (central filament soon inconspicuous), becoming densely filamentous below, and a cortex of large, isodiametric to slightly radially elongate inner cells 20–30 µm across and a small-celled outer cortex 1–2 cells thick (Fig. 123H), outer cells ovoid to pointed, 4–6 µm in diameter, L/D 1–2, forming distinct to indistinct rosettes in surface view. Rhodoplasts discoid, becoming ribbon shaped, many per cell.

Reproduction: Sexual thalli monoecious; probably procarpic. Carpogonial branches (Fig. 123I) borne singly on inner cortical cells, 3-celled, directed inwards with reflexed trichogynes. Supporting cell apparently acting as auxiliary cell, with adjacent vegetative filaments developing centripetally to form a broad enveloping tissue. Gonimoblast initials cut off thallus inwardly, then growing over the inside of the enveloping tissue as the auxiliary cell disintegrates, forming centripetal tufts of filaments with terminal ovoid carposporangia 20–30 µm in diameter. Cystocarps (Fig. 124B) embedded, 0.7–1 mm in diameter, with prominent enveloping tissue and thickened cortex, ostiolate. Spermatangial clusters (Fig. 123J) scattered, with outer cortical cells producing several initials each forming 2–3 ovoid spermatangia.

Tetrasporangia (Fig. 123K) scattered, developed from mid cortical cells, laterally pit-connected, ovoid, 30–50 µm long and 20–35 µm in diameter, zonately divided.

Type from Georgetown, Tas. (Gunn 1318); lectotype in Herb. Hooker, BM.

Selected specimens: Yanchep, W. Aust., drift (G. & L. Kraft, 1.ix.1990; MELU, K8420). Garden I., W. Aust. (Clifton, type of R. patens in TCD). Eyre, W. Aust., drift (Woelkerling, 22.xi.1968; AD, A34250). Point Sinclair, S. Aust., drift (Womersley, 25.i.1951; AD, A13694). Troubridge Light, Gulf St Vincent, S. Aust., 17 m deep (Shepherd, 4.ii.1969; AD, A33437). Aldinga, S. Aust., on Amphibolis and Posidonia, just below lowest tide (Kraft, 27.ii.1972; MELU, K4485). Victor Harbor, S. Aust., drift (Womersley, 17.x.1948; AD, A9257). Seal Beach, Kangaroo I., S. Aust., drift (Womersley, 21.i.1965; AD, A28638). Rocky Point, Kangaroo I., S. Aust., drift (Womersley, 21.viii.1948; AD, A8586). Pennington Bay, Kangaroo I., S. Aust., sublittoral fringe (Womersley, 6.i.1949; AD, A10785). Robe, S. Aust.,, shaded pool (Womersley, 7.xi.1965; AD, A29649). Portland, Vic., 5–7 m deep on Ecklonia holdfast (Kraft, 27.iv.1990; MELU, K8271). Aireys Inlet, Vic., drift (Kraft & Wetherbee, 21.ii.1976; MELU, K5803). San Remo, Vic., drift on Back Beach (Sinkora A2031, 27.xi.1974; AD, A54211). Crawfish Rock, Westernport Bay, Vic., 6 m deep (Gabrielson & Scott, 10.ix.1981; MELU, PG027). Walkerville, Vic., drift (Sinkora A2093, 26.ii.1975; AD, A48318). Gabo I., Vic., 18 m deep (Shepherd, 17.ii.1973; AD, A43511). Eddystone Point, NE Tas. (Perrin, Nov. 1949; AD, A16431). Collaroy, N.S.W., drift (May, 15.x.1944; NSW 10095).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Yanchep, W. Aust., to Collaroy, N.S.W., and the N coast of Tasmania.

Taxonomic notes: Antrocentrum nigrescens has a distinctive fibrous holdfast and varies in thickness of the branches, especially as seen in herbarium sheets, depending on state of the plant and drying pressure. It is common in the drift and is probably confined to southern and south-eastern Australia; Japanese records (as Solieria mollis) have been referred to S. tenuis Zhang & Xia in Xia & Zhang (1984, p. 119).


AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 - Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

HOOKER, J.D. & HARVEY, W.H. (1847). Algae Tasmanicae. Lond. J. Bot. 6, 397–417.

KÜTZING, F.T. (1866). Tabulae Phycologicae. Vol. 16. (Nordhausen.)

KRAFT, G.T. & MIN-THEIN, U. (1983). Claviclonium and Antrocentrum, two new genera of Acrotylaceae (Gigartinales, Rhodophyta) from southern Australia. Phycologia 22, 171–183.

KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.

MILLAR, A.J.K. & KRAFT, G.T. (1993). Catalogue of Marine and Freshwater Red Algae (Rhodophyta) of New South Wales, including Lord Howe Island, South-western Pacific. Aust. Syst. Bot. 6, 1–90.

XIA, E.Z. & ZHANG, J.F. (1984). A new species of Solieria from China. Chin. J. Oceanol. Limnol. 2, 119–124.

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

Author: G.T. Kraft & H.B.S. Womersley

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.

Illustrations in Womersley Part IIIA, 1994: FIGS 122F, 123 G–K, 124A, B.

Figure 122 image

Figure 122   enlarge

Fig. 122. A–C. Amphiplexia hymenocladioides (AD, A44750). A. Habit. B. Longitudinal section of a branch apex. C. Cross section of mature cystocarp. D, E. Amphiplexia racemosa (AD, A35852). D. Habit. E. Cross section of cystocarp, with ostiole. F. Antrocentrum nigrescens (AD, A48318). Habit. [B–E as in Kraft 1977a.]

Figure 123 image

Figure 123   enlarge

Fig. 123. A–F. Amphiplexia hymenocladioides (AD, A44750). A. Surface pattern with rosettes of outer cortical cells. B. Section of cortex with hairs and a carpogonial branch. C. Auxiliary cell with a carpogonial branch (carpogonium connected to auxiliary cell) and producing gonimoblast filaments. D. Carposporangia produced centripetally from cells lining the cystocarp cavity. E. Section of cortex with sunken clusters of spermatangia. F. Section of cortex with immature and mature tetrasporangia. G–K. Antrocentrum nigrescens (G, MELU, PG027; H, MELU, K5803; I, J, AD, A33437; K, AD, A28638). G. Branch apex showing paired periaxial filaments. H. Transverse section of a branch. I. Section of cortex with a 3-celled carpogonial branch. J. Section of cortex with spermatangia) clusters. K. Section of cortex with immature and mature tetrasporangia. L, M. Claviclonium ovatum (L, MELU, K6570; M, AD, A33615). L. Transverse section of a clavate lateral branch. M. Section of cortex with 3-celled carpogonial branches. [A–F after Kraft 1977a; G–M after Kraft & Min-Thein 1983.]

Figure 124 image

Figure 124   enlarge

Fig. 124. A, B. Antrocentrum nigrescens (A, MELU, K5803; B, MELU, K4485). A. Habit of liquid-preserved cystocarpic plant, with fibrous holdfast. B. Cross section of cystocarp, with ostiole. C–F. Claviclonium ovatum (C, AD, A51275; D–F, MELU, K7077). C. Habit. D. Habit of a branch with cystocarps (arrows). E. Section of branch apex with several carpogonial branches. F. Section of a cystocarp with centripetal sporogenous filaments, and ostiole. [A, D, E, F as in Kraft & Min-Thein 1983.]

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