Page 8 - BALSAMO_etalii_1996

M. BALSAMO, E. FREGNI, P. TONGIORGI

a very thick and short spine, 4.5-5.7 pm, showing two Fig. 3 - Chaetonotus luporinii n . sp. (Giardini Naxos, Sicily). Dorsal
small accessory points close to the apex (Fig. 2C). Dorsal view of the head. Nomarski optics, ~ 1 2 0 0 .
scales of the trunk are large, 13.2-17.7 x 7.2-11.2 pm,
hemielliptical and have a prominent median keel which described in the Somalian gastrotrichs. The complex
extends into a very thick and straight spine (Fig. 2D). morphology of the dorsal and ventral posterior ends, un-
This one is provided with two evident accessory points described in Chaetonotus sp. 3, was absolutely constant
at its half length and has an apex obliquely cut and shar- in al1 the animals from Sicily, as well as in the specimens
ply tapering. The length of the dorsal spines ranges from of the same species which have been collected from
8.1 to 12.4 p m The last two spines of the median row are Italian (Punta Ala, Tuscany), Ciprian (Larnaka Bay) and
curved: the last one protrudes into the intrafurcal space, Egyptian sites (Sharm E1 Sheik, Red Sea). It is worth
14-15 pm. The two spines just adjacent to the last one noting that the specimens from Red Sea had the dorsal
only have very short spiny processes. At the dorsal spines of the trunk considerably longer than those of
posterior end three pairs of keeled scales are arranged as animals collected at al1 the other sites, 22 pm vs 12 pm
represented in Figure 2A. One of them, with double keel, (Fig. 4).
bears the posterior pair of tactile bristles. Another pair of
dorsal bristles is present on the neck. Five small scales Within the subgenus Schizochaetonotus this species is
conclude the dorsal covering, the lateral ones elliptical especially close to C. nepturzi, with which shares the
and the median o n e subtriangular, al1 with a keel main metric parameters, the shape of the dorsal scales
prolonged in a spiny process. and also the three long parafurcal spines. The peculiar
morphology of the dorsal spines of the trunk, as well as
Lateral spines are slightly longer than the dorsal ones, that of the cephalic spines are certain diagnostic features
8.4-17.2 p m The last two dorsolateral spines and the last for this species. Moreover, the shorter length of the dor-
lateral ones are characteristic of this species because sal spines, 8.1-8.4 vs 11-20 pm in C. neptuni, and the
especially strong and long. The next to last dorsolateral great variety of the scales and spines shape on different
spine is particularly long, 37.5-39.6 pm, whereas the body regions in C. luporinii are further characters help-
other two are similar in length, 21.7-22.5 pm and fu1 for a distinction between the two species.
21.7-27.5 pm respectively; and are inserted just at the
base of the furcal appendages. The furca, about 117 of the Usually found in medium to coarse sediment from lit-
body length, shows very long adhesive tubes, 25 pm. toral zone, at 2-3 m water depth.

Ventrally, two longitudinal rows of spined scales run Distribution
on each body side. The ventrolateral rows are composed
of hemielliptical scales bearing long, thick and curved Type locality: Giardini Naxos (Taormina, Sicily), the
spines, 9-17 pm, with two hardly visible accessory points public beach south of the town. Other localities: Punta
and apex tapering into a thin and long process (Fig. 2E). Ala (Tuscany, Italy), Sharm E1 Sheik (Red Sea, Egypt), Lar-
The rows adjacent the ciliary bands are made up of naka Bay (Island of Cyprus).
trilobate small scales with thin, curved and shorter
spines. The two ciliary bands are separated by the small The species is named after Piero Luporini, one of the
hypostomion and limit a bare area. At the ventral Italian researchers on this phylum, who found this
posterior end a pair of narrow and long scales, with keel species for the first time.
and simple spine, is followed by four other similar scales,
15.6-19.0 pm long, which are arranged in a transversal
series on the intrafurcal edge (Fig. 2F). The two centra1
spines are thicker, slightly longer and clearly visible in
the intrafurcal space, 16 pm.

The mouth is subterminal and wide, 7 . 5 pm in
diameter. The cylindrical pharynx is 30-70 pm long,
namely about one third of the total body length. Most of
the specimens observed were in parthenogenetic phase.
Spermatozoa were not seen.

Remarks

The identification of the Italian specimens with
Chaetonotus sp. 3 Valbonesi & Luporini (1987) is based
on the peculiar morphology both of the dorsal spines
and of the long lateral posterior spines, which appeared
consistent in al1 the individuals collected. The Sicilian
animals showed only one dorsal termina1 spine
protruding into the intrafurcal space instead of the two