The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide
Author
Gravili, Cinzia
Author
Vito, Doris De
Author
Camillo, Cristina Gioia Di
Author
Martell, Luis
Author
Piraino, Stefano
Author
Boero, Ferdinando
text
Zootaxa
2015
3908
1
1
187
journal article
42365
10.11646/zootaxa.3908.1.1
6f1d1977-6b97-4789-828c-76ed250cf1ae
1175-5326
242729
D6AD2B49-170B-4D9C-84AA-DBE0FEEAD8BE
Eutima gracilis
(Forbes & Goodsir, 1851)
Fig. 60
A, B
See
Kramp (1961)
and
Russell (1953
,
1970a
) for a complete synonymy.
FIGURE 60.
Eutima gracilis
:
A
, hydranth with gonangium;
B
, adult medusa (redrawn and modified: A after Russell 1970, B after Russell 1953 by A. Gennari). Scale bars: A, magnification unknown; B, 6.0 mm.
Material examined.
HCUS-S 0 67 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.
Description
(after
Russell 1953
;
Cornelius 1995
):
Hydroid.
Hydranths of
Campanulina
type
, cylindrical, long, with blue pigment granules just below tentacle whorl; about 28 tentacles in a single whorl united by a large membranous basal web; hydrothecae lacking or strongly reduced; gonothecae cylindrical, with truncate end, long, containing up to 8 developing medusae.
Habitat
type
and substrate.
Sedimentary environment (depth range
0–15 m
), on
Chaetomorpha linum
(alga), sediment/
Ruppia
(Barangé & Gili 1987)
.
Seasonality.
February, April–December in the Mediterranean Sea (Bouillon
et al.
2004;
Moscatello
et al
. 2004
; De Vito 2006).
Reproductive period.
Unknow in the Mediterranean Sea.
Medusa.
Adult. Umbrella almost hemispherical when fully grown, up to
13 mm
wide (exceptionally to
30 mm
), mesoglea thick, watchglass-like; manubrium cross-shaped in transverse section, short, mounted on extremely long, narrow gastric peduncle extending far beyond bell margin and with small conical base; mouth with 4 small, simple lips; 4 straight radial canals and circular canal narrow; 4 gonads, same in colour as manubrium, restricted to portion of gastric peduncle, extending almost from base of peduncle to manubrium; velum fairly narrow; marginal bulbs not distinct; 2–4 (sometimes more) long perradial marginal tentacles; 40–80 or more marginal warts with fine black pigment granules; usually one lateral cirrus on each side of every tentacle and wart; 8 statocysts. Colours: mesoglea usually highly transparent, but colouration possibly due to local diet; manubrium pale pink or greenish.
Developmental stages. Umbrella high and bell-shaped when young, expanding laterally to become just flatter than hemispherical when fully grown, the smallest described stage is only 0.5 mm in height; manubrium short and no peduncle; mouth with 4 small lips; 4 radial canals and ring canal narrow; no signs of gonads; 2 opposite perradial marginal bulbs or swellings, one of which with a short lateral cirrus; 4 interradial and 8 adradial bulbs or swellings without lateral cirri; 8 marginal vesicles situated adradially, each with a single concretion (for more details about developmental stages of this species see
Russell 1953
).
Cnidome.
Atrichous, basitrichous, and merotrichous isorhizas; sometimes microbasic mastigophores.
Distribution.
Atlantic, Indo-Pacific?, Mediterranean (
Russell 1953
, 1963; Fraser 1972;
Cornelius 1995
;
Medel & López-González 1996
; Bouillon
et al.
2004;
Moscatello
et al
. 2004
;
Gravili
et al.
2008a
;
Touzri
et al.
2010
).
Records in Salento.
Rare in the Salento Peninsula (
Moscatello
et al
. 2004
; De Vito (2006).
Remarks.
Only the medusa stage was seen in the present study. The hydroid is not known from nature, it was reared by Werner and illustrated by
Russell (1970a)
. During swimming, the few long tentacles and the long gastric peduncle of the medusa wave together (
Russell 1953
).
References.
Babnik (1948)
, Russell (1949, 1953, 1970a),
Kramp (1961)
,
Benović (1973)
,
Schmidt & Benović (1979)
, Benović & Bender (1987),
Goy
et al.
(1988
,
1990
,
1991
),
Gili
et al.
(1991)
,
Cornelius (1995)
,
Benović & Lučić (1996)
,
Medel & López-González (1996)
, Bouillon
et al.
(2004),
Moscatello
et al
. (2004)
, De Vito (2006),
Gravili
et al.
(2008a)
,
Touzri
et al.
(2010)
.