Gloiocladia halymenioides (Harv.) R.E.Norris
Phycologia 592 (1991)
Conservation Code:
Not threatened
Naturalised Status: Native to Western Australia
Name Status:
Current
Scientific Description
John Huisman & Cheryl Parker,
Monday 20 June 2011
Habit and structure. Thallus medium to dark red-brown, (2–)5–15(–20) cm high, complanately branched with main branches subdichotomous to alternate, flat, 3–10 mm broad, decreasing to 1–2 mm broad near apices; branches pinnate with marginal laterals 2–10(–20) mm long, often subpinnate; some plants with small surface proliferations. Holdfast discoid, 2–3 mm across; epilithic or on jetty piles. Structure multiaxial, developing a cortex 50–95 µm thick, of branched filaments 2–4 µm in diameter and 5–8 cells long, inner cells L/D 4–8, outer cells ovoid, arising from a layer 1–4 cells thick of tangentially ovoid cells 8–15 µm in diameter on the outer side of the medulla; transition from cortex to medulla sudden. Medulla 2–4 cells thick, cells ovoid, 50–200(–350) µm in diameter, with frequent secondary pit-connections. Rhodoplasts discoid.
Reproduction. Gametangial thalli dioecious. Carpogonial branches very small, 4-celled, borne on mid cortical cells; supporting cells enlarging post-fertilization with numerous thickened arms to cells of the erect filaments and bearing a 2-celled auxiliary cell branch, auxiliary cell ovoid, with a proteinaceous inclusion. Carposporophyte dendroid, 250–360 µm across, with a basal fusion cell producing several erect arms bearing lobes of ovoid carposporangia 12–22 µm in diameter. Basal nutritive tissue prominent, erect filaments well-developed and relatively persistent. Cystocarps external, mostly marginal or on short branchlets, 0.7–1.2 mm across with a rim of 2–6 prominent, acute, horns, ostiolate. Spermatangia cut off from initials on outer cortical cells, ovoid, 1–2 µm in diameter. Tetrasporangia in scattered groups or in nemathecia on the central region of lesser branches, pit-connected to mid cortical cells, ovoid, 10–18 µm in diameter, decussately divided.
Distribution. Fremantle, W. Aust., to Walkerville, Vic., and around Tas.
Habitat. G. halymenioides is found on relatively sheltered coasts, but especially where there is strong current flow, usually in depths of 2–20 m.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 101–103 (1996)]
