Proceedings of the Second Mediterranean Symposium on Marine

Spermatangia are grouped in superficial sori, with 1-4 mo<strong>the</strong>r cells produced by each
cortical cell (Fig. 2a). Gonimoblasts develop inwards and are 100-250 µm in size; most
cells become carposporangia, 15-20 µm in diam. (Fig. 2b). Tetrasporangial plants were
never found in our collected samples.
Fig. 2.H. ligulatum. (a) Spermatangial sorus; (b) carposporophyte.
Gelidiella sp. forms a thin dark red turf on very shaded rocks in <strong>the</strong> Grotta della Regina.
The population always stays between +80 and +50 cm above sea level, never reached
by high tide, but only by a rough sea. Plants consist <strong>of</strong> erect branches, up to 10 mm high,
arising from long terete creeping axes (Fig. 3a). Erect axes are compressed at <strong>the</strong> distal
part, max 140 µm wide. Most <strong>of</strong> <strong>the</strong>m also bear rhizoids, so <strong>the</strong> whole plant assumes a
creeping habit. The outer cortical cells are rectangular (6-7x10-12 µm) and horizontally
arranged (Fig. 3b). Apical stichidia bearing a great number <strong>of</strong> tiers, up to 24, with 4
tetrasporangia per row, were found in spring-summer (Fig. 3c).
Fig. 3.Gelidiella sp. (a) Plants collected in <strong>the</strong> Grotta della Regina; (b) outer cortical cells in surface view; (c)
tetrasporangial sorus (stichidium).
ACTES DU DEUXIEME SYMPOSIUM MEDITERRANEEN SUR LA VEGETATION MARINE (ATHENES, 12-13 DECEMBRE 2003)
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