Proceedings of the Second Mediterranean Symposium on Marine

PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION (ATHENS, 12-13 DECEMBER 2003)
78
MATERIALS AND METHODS
Thalli were collected in <strong>the</strong> following sites: <strong>the</strong> sou<strong>the</strong>rn littoral <strong>of</strong> Bari (Adriatic Sea,
41°6’58”N, 16°53’38”E) for H. ligulatum; a small marine cave, <strong>the</strong> Grotta della Regina
at Torre a Mare, in <strong>the</strong> district <strong>of</strong> Bari (Adriatic Sea, 41°5’21”N, 16°59’38”E) for Gelidiella
sp.; Torre Borraco (Taranto, Ionian Sea, 40°18’25”N, 17°40’3”E) for Batophora sp.
Specimens are kept at <strong>the</strong> herbarium <strong>of</strong> <strong>the</strong> Department <strong>of</strong> Biology and Plant Pathology.
Observations were made on freshly collected, formalin-preserved, lab-cultured material
and on herbarium specimens.
Vegetative characteristics reliable for <strong>the</strong> diagnosis <strong>of</strong> <strong>the</strong> genus Batophora were
observed on 50 thalli randomly collected in <strong>the</strong> field and compared with those <strong>of</strong>
specimens <strong>of</strong> B. oerstedii and B. occidentalis obtained from Chetumal Bay (Mexico). Labcultures
were performed in order to observe thallus morphogenesis and possibly to
induce gametophore production. Substrates colonised by Batophora sp., collected in <strong>the</strong>
field, were <strong>the</strong> culture material. Erd-Schreiber medium, changed weekly, was used.
Germanium dioxide (6 ppm) was added to <strong>the</strong> medium in order to reduce diatom
contamination. Tests were carried out in growth chambers under <strong>the</strong> following
conditions: 90 µmol m -2 s -1 PFD, 18° and 26°±1°C, 12:12 or 16:8 light/dark regimes.
Some Apulian thalli <strong>of</strong> Batophora sp. resembled Dasycladus vermicularis (Scopoli)
Krasser so that a comparative study with <strong>the</strong> latter species was performed.
RESULTS
Thalli <strong>of</strong> H. ligulatum were collected for <strong>the</strong> first time in June 1998 (Fig. 1a) in shaded
crevices, at 1-3 m depth. Apulian gametophytes have a small attachment disc, about 1 mm
in diam., from which one to several flattened fronds arise. Plants are brownish red, up to
200 mm long and 5-20 mm broad. The stipe expands into irregularly branched blades,
tapering at <strong>the</strong> ends, proliferating from both margins and surfaces. The cortex consists <strong>of</strong> 2-
3 layers; <strong>the</strong> outer cortical cells are small and polygonal in surface view. The medulla ranges
from ra<strong>the</strong>r compact to very loose and lacunose; it is obliquely crossed by few cylindrical
filaments, about 8 µm in diameter, and by long arms <strong>of</strong> pseudostellate cells (Fig. 1b).
Fig. 1. H. ligulatum. (a) Habit <strong>of</strong> <strong>the</strong> herbarium specimen collected at Bari, Adriatic Sea; (b) cross section <strong>of</strong> a blade.