Lenormandia spectabilis Sond.

Scientific Description

Habit and structure. Thallus dark red-brown, fading to grey, 10–40 cm high, membranous, sparsely branched with branches usually 4–25 cm long and (1–) 2–4(–6) cm broad, branches arising at or from within the margin of the parent blade, basally constricted into a short stipe, broadest half way or more along their length and tapering slightly to a rounded apex, margins entire, midrib slight. Holdfast discoid, 2–5 mm across; epilithic or epiphytic on Amphibolis and Acrocarpia paniculata. Structure. Apices cleft, apical cell conical, 50–60 µm in diameter (including very thick walls), axial cells cutting off 5 pericentral cells, the dorsal lateral cell larger than the ventral lateral cell, and the ventral pericentral cell, with the medulla 1–2 cells thick (thicker marginally) and a cortex 1–2 cells thick; surface view of blades showing rhombic areolation, cortical cells angular, irregular, 10–18 µm across and L/D 1–2. Trichoblasts present on blade surfaces associated with reproductive organs. Cortical cells uninucleate, medullary cells multinucleate; rhodoplasts discoid, chained in larger cells.

Reproduction. Gametophytes dioecious. Procarps on branches of reduced trichoblasts, with a supporting cell bearing a 4-celled carpogonial branch and a single basal cell and a lateral 2-celled sterile group, with a pre-fertilisation pericarp. Carposporophytes with a basal fusion cell and much branched gonimoblast with clavate terminal carposporangia 25–40 µm in diameter. Cystocarps single (occasionally clustered) on blade surfaces, globose to ovoid, short stalked, 0.5–1 mm in diameter; pericarp ostiolate, 5–8 cells thick. Spermatangial organs in dense clusters on blade surfaces, on branched polysiphonous shoots, with a sterile basal cell, ovoid, 35–55 µm in diameter and L/D 1.2–1.6. Tetrasporangial stichidia in scattered clusters on blade surfaces, ovoid, 300–900 µm long and 150–300 µm in diameter, slightly compressed, corticated, with tetrasporangia paired in 2–4 segments, 60–100 µm in diameter.

Distribution.Geraldton, W. Aust., to Robe, S. Aust.

Habitat. L. spectabilis is a deep-water species on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 381–383 (2003)]