Hymenocladia chondricola (Sond.) J.A.Lewis

Scientific Description

Habit and structure. Thallus medium to dark red, fading to yellow-red, (5–)10–50 cm high, complanately branched, foliose and often marginally proliferous in an irregular to regular manner with proliferations simple and 1–3 cm long to branched similarly to the main axes. Axes and main branches (1–)2–8(–10) cm broad, 350–1000(–1400) µm thick (margins usually thicker), small or relatively large surface proliferations occasional. Holdfast discoid, 1–4 mm across; epiphytic on Amphibolis and various robust algae (e.g. Acrocarpia) or epizoic, or epilithic. Structure multiaxial, developing a cortex 2–3 cells broad, outer cells ovoid and 4–6 µm in diameter, grading fairly sharply to a medulla mostly 300–750 µm and 4–10 cells across, larger cells ovoid and 90–170 µm in diameter, walls 5–25 µm thick, with frequent to abundant interspersed smaller ovoid cells or filaments 25–50 µm in diameter; secondary pit-connections frequent, hairs in clusters. Rhodoplasts elongate, in chains or ribbon like in inner cells.

Reproduction. Gametangial thalli dioecious. Carpogonial and auxiliary cell branches not observed. Carposporophytes with a basal, branched, fusion cell complex, with upper cells all forming ovoid carposporangia 45–75 µm in diameter, with later lobes developing. Basal nutritive tissue prominent, erect filaments disintegrating apart from thick-walled remnants near the nutritive tissue. Cystocarps scattered on the surface, protruding, hemispherical, 0.8–1.2 mm in diameter, pericarp 180–300 µm and 8–14 cells thick, inner cells ovoid (innermost stellate), ostiolate. Spermatangia in extensive sori, cut off from elongate initials (L/D 6–10) on cortical cells, ovoid, 2–3 µm in diameter. Tetrasporangia scattered, transformed from intercalary outer medullary cells, subspherical to ovoid, 70–100 µm in diameter, tetrahedrally divided.

Distribution.Port Denison, W. Aust., to Walkerville, Vic., and around Tas.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 111–113 (1996)]