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were studied using a light microscope (Nikon SE), and
photographs were taken using a Nikon P5100 camera.
Vouchers were deposited in the Department of Biology
of the Celal Bayar University, Turkey.

Codium parvulum is a procumbent (repent) species.
Thallus light green, to 13 cm long, dichotomously branched
(Fig. 10a); lower segments irregularly branched and some
parts of cylindrical branches are slightly flattened, 2-4.5
mm broad; hair distance from apical portion 140-450 µm;
mature utricules clavate, pyriform and subcylindrical, 110-
290 µm broad and 550-800 µm long (Fig. 10b); gametan-
gia cylindrical, fusiform and ovate, 40-65 µm broad and
250-440 µm long, borne at the apex of utricle; medullary
filaments 20-50 µm broad, chloroplasts discoid or fusiform
with one pyrenoid. This species was collected from Ayvalık
(39º18’47″N, 26º41’02″E), on the Aegean coast of Turkey,
at 10-15 m depth, in June 2012, from sandy and partially
stony substratum. The identification was made on the basis
of the description in Israel et al. (2010).

2.3. First report of the red alga Palisada maris-rubri
(Ceramiales, Florideophyceae) from the Eastern
Mediterranean Sea

By K. Tsiamis and V. Gerakaris

The red alga Palisada maris-rubri (K.W. Nam Fig. 11: Palisada maris-rubri. A. General herbarium habit. B.
& Saito) K.W. Nam is reported for the first time from Detail of upper thallus part. C. Cross-section of thallus, de-
Greece. Several epilithic plants were found in a rock picting large medullary colorless cells surrounded by smaller
pool, at 0.2 m depth, in the semi-enclosed bay of Ladiko, pigmented cortical cells forming a palisade-like arrangement.
Rhodes, S. Aegean Sea, in January 2006 and April 2014. Scale bars: Figure A, B = 1 cm; Figure C = 100μm.
This finding represents the first record of this species
from the Eastern Mediterranean Sea. Serio et al. (2010). P. maris-rubri probably has a wider
distribution in the Mediterranean Sea, most likely having
Plants are erect, robust, up to 15 cm high, greenish, been previously confused with Palisada perforata (Bory
hard cartilaginous in texture, attached to the substratum de Saint-Vincent) K.W. Nam.
by a discoid holdfast 2 cm in diameter (Fig. 11A); main
axes percurrent, 2-3 mm broad, irregularly and sparsely 2.4. First record of the alien sea urchin Diadema seto­
ramified; branches irregularly to alternately ramified, but sum (Echinodermata: Echinoidea: Diadematidae)
also subverticillate and unilateral to upper parts (Fig. 11B); in Hellenic waters
ultimate branches cylindrical, 3-4 mm long and 0.5-1 mm
wide, with truncate apices; in surface view epidermal cells By P. Latsoudis
without secondary pit connections, polygonal to rounded,
20 μm in diameter; in cross section, epidermal cells rect- The first record of Didema setosum (Leske, 1778)
angular, 50 x 20 μm, with a palisade-like arrangement in the Mediterranean Sea was reported in 2006 off Kaş
(Fig. 11C); medullary cells rounded, larger, up to 140 μm Peninsula, south-western coast of Turkey (Yokes & Galil,
in diameter, with thick walls, without lenticular thicken- 2006), but no other specimen was sighted in the same area
ings and intercellular spaces; two pericentral cells per axial between 2007-2009 (Yokes & Galil, 2006). This area is
cell; no reproductive structures observed. about 3 km north of Kastellorizo Island. Its occurrence
was verified later eastward, along the Lebanese coastline
Originally described from the Red Sea (Nam & in 2009 and in Antakya, south-eastern coast of Turkey
Saito, 1995), Palisada maris-rubri was reported from the in 2010, and westward, up to Gökova Bay, Aegean Sea,
Mediterranean coasts of Spain and the Eastern coast of Turkey (Yapici et al., 2014 and references therein).
Sicily (Lachea Island near Catania) (Serio et al., 2010),
and it might represent a rather recent introduction for the
Mediterranean Sea.

Despite the absence of reproductive structures, our
specimens are almost identical with those described by

Medit. Mar. Sci., 16/2, 2015, 472-488 479