Page 7 - BALSAMO_etalii_1996

MARINE GASTROTRICHA FROM SICILY
scales o n the head with thick and curved spine which distally forms
a peculiar three-keeled webben expansion; 2-3 trilobated and keeled
scales o n the neck with a spine with two accessory points; hemiellip-
tical scales o n the trunk with prominent keel and thick and straight
spine. Five small scales at the dorsal posterior end. Two ventral
longitudinal rows of spined scales per side. Ventrolaterally
hemielliptical scales with curved spines bearing two accessory po-
ints, ventrally trilobate small scales with short spines. Interciliary area sides. The body is wholly covered with 11-13 lon-
is bare. A pair of narrow keeled scales with spines and other four
similar scales in a transversal series at the ventral posterior end.
Pharynx 30-70 pm long.
Emended description to that of Valbonesiand Luporini,
1987
Medium size species, 100-236 pm in total length. The
body is slender, with a slightly trilobate head, 30-40 pm
wide, a faint neck constriction, 29-37 pm, a trunk of
37-55 pm maximum width, decreasing posteriorly to
Fig. 2 - Chaetonotus luporinii n. sp. A, dorsal view: B. head scale; C, neck scale; D, dorsal scale of the trunk: E, ventrolateral scale of the trunk;
F, ventral view. Dotting mimics the locomotory ciliature.
179
18-21 pm, and a 14-34 pm long caudal furca, correspond-
ing to about 117 of body length (Fig. 2A).
The head is covered with a frontal cephalion, two pairs
of small pleuria and a small subrectangular hypostomion
on the ventral side. Two tufts composed of numerous
cephalic cilia, 5-30 pm long, arise from the cephalion
gitudinal rows (7 dorsal) each of 16-18 spined scales.
Both the scales and the spines have a different shape
depending on the body region: the first five-six scales of
each dorsal row, 6.2-6.5 pm long, are trilobate and bear a
very thick and curved spine which becomes so wider
distally to form a peculiar three-keeled, webbed expan-
sion, 8-9 pm long. These expansions touch each other
creating a continuous dorsal envelope on the head (Figs
2B-3). The next two-three scales of the dorsal rows are
6.5-6.8 ym long, trilobated and keeled; each of them has