Hydroids of the family Halopterididae (Cnidaria, Hydrozoa) collected in the western Pacific by various French expeditions
Author
Agís, José Ansín
Facultade de Ciencias do Mar, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Campus Lagoas-Marcosende, E- 36310 Vigo (Spain) agis @ uvigo. es
agis@uvigo.es
Author
Vervoort, Willem
Nationaal Natuurhistorisch Museum, P. O. Box 9517, NL- 2300 RA Leiden (The Netherlands) vervoort @ naturalis. nnm. nl
Author
Ramil, Fran
Facultade de Ciencias do Mar, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Campus Lagoas-Marcosende, E- 36310 Vigo (Spain) framil @ uvigo. es
framil@uvigo.es
text
Zoosystema
2009
2009-03-31
31
1
33
61
http://www.bioone.org/doi/abs/10.5252/z2009n1a3
journal article
10.5252/z2009n1a3
1638-9387
5398547
Corhiza pauciarmata
n. sp.
(
Fig. 11
;
Table 11
)
TYPE MATERIAL
. —
Norfolk Ridge.
SMIB
4, stn DW 55, 23°21.4’-
23°21.4’S
, 168°04.5’-
168°04.8’E
,
215-260 m
,
9.III.1989
, 1 colony with 3 damaged gonothecae,
holotype
(
MNHN
Hy 1296).
SMIB
5, stn DW 101,
23°21.2’S
,
168°04.9’E
,
270 m
,
14.IX.1989
, 1 colony with 4 hydrocladia, no gonothecae,
paratype
(RMNH-Coel. 31459).
ETYMOLOGY. — The species name is derived from Latin:
pauci
: poor and
armata
: armed. It indicates that the species has only three nematothecae around the hydrotheca; in the majority of
Corhiza
species
the number of nematothecae on hydrothecate internodes is higher.
DISTRIBUTION. — The material originates from two stations on the Norfolk Ridge and was collected between 215 and
270 m
.
DESCRIPTION (
HOLOTYPE
)
Colonies with a polysiphonic stem, unbranched, which hydrocladia arising at irregular distances on all sides of the stem.
Hydrocladia unbranched, inserted on well-developed apophyses. Basal part of hydrocladia with the first internode separated by transverse nodes and without nematothecae, followed by a long internode with two or three nematothecae and distal oblique node. Remainder of stem formed by a succession of hydrothecate and ahydrothecate internodes,alternately separated by oblique and straight nodes; hydrothecate internodes with basal oblique node and distal straight node; ahydrothecate internodes reverse.
FIG. 10. —
Monostaechas
sp.
, SMIB 4, stn DW 55:
A
, internodes, lateral view;
B
, internode, frontal view;
C
,
D
, internodes from same hydrocladium with differently developed lateral nematothecae, frontal views. Scale bar: 0.1 mm.
Hydrothecate internodes with one hydrotheca and three nematothecae: one mesial inferior and two laterals. Hydrotheca cup-shaped; abcauline wall straight; adcauline wall adnate for nearly half its length; hydrothecal rim circular, smooth and slightly everted. Mesial inferior nematothecae not
TABLE 11. — Measurements of
Corhiza pauciarmata
n. sp.
in μm.
SMIB 4 stn DW 55
Hydrocladial internode:
Length ahydrothecate 450-700
Length hydrothecate 370-420
Diameter at node 60-90
Hydrotheca:
Length abcauline wall 310-370
Length free portion adcauline wall 240-270
Diameter at rim 260-310
Mesial infracalycine nematotheca:
Length 70-80
Diameter at rim 35-40
Lateral nematotheca:
Length 110-130
Diameter at rim 60-70
Nematotheca of ahydrothecate internode:
Length 60-90
Diameter at rim 30-35
reaching hydrothecal base and with adcauline wall of upper chamber deeply scooped. Lateral nematothecae placed on well-developed apophyses, one on each side of hydrotheca, not reaching hydrothecal margin; upper chamber with the rim deeply scooped on both sides (spanner-like shape).
Ahydrothecate internodes with two frontal nematothecae, one placed in lower third, one in upper third; nematothecae with adcauline wall of upper chamber scooped.
All nematothecae bithalamic and movable.
The gonosome is damaged; a detailed description cannot be given. Gonothecae elongate, narrowing basally, inserted laterally at the hydrothecal base by means of a two-segmented pedicel. Apex truncate, with circular aperture closed by a lid; two nematothecae on basal third.
VARIABILITY
In several ahydrothecate internodes there was only one nematotheca on basal part of internode.
REMARKS
Schuchert (1997)
in his review of the family
Halopterididae
agrees with the diagnosis of the genus
Corhiza
given by
Millard (1975)
. Nevertheless he indicated that several species of
Antennella
and
Halopteris
can have a
Corhiza
-like mode of growth as an alternative colony form; therefore in his opinion the scope of the genus must be revised.
Our material shows the typical colony form of
Corhiza
, with an erect, unbranched, polysiphonic stem, giving rise to hydrocladia; in consequence we include it in this genus.
The genus
Corhiza
comprises nine species. The main distinguishing features of eight species,
C. bellicosa
Millard, 1962
,
C. complexa
(Nutting, 1905)
,
C. fascicularis
(
Allman, 1883
)
,
C. pannosa
Millard, 1962
,
C. scotiae
(Ritchie, 1907)
,
C. sociabilis
Millard, 1980
,
C. suensoni
(
Jäderholm, 1896
)
and
C. valdiviae
(Stechow, 1923)
, were summarised by
Schuchert (1997)
. The ninth species,
C. splendens
Vervoort& Watson, 2003
, was described later.
The presence of only one pair of lateral nematothecae and the absence of axillar nematothecae behind the adcauline wall of the hydrotheca distinguishes
C. pauciarmata
n. sp.
from the majority of
Corhiza
species.
Corhiza bellicosa
has three pairs of lateral nemathotecae and
C. pannosa
,
C. scotiae
,
C. sociabilis
and
C. splendens
two pairs;
C. complexa
and
C. valdiviae
have only one pair but carry axillar nematothecae.
Only
C. fascicularis
and
C. suensoni
show the same number and the same disposition of nematothecae around the hydrotheca as is also found in
C. pauciarmata
n. sp.
Corhiza fascicularis
has not been recorded since its original description, the
type
material is lost and, in consequence, it is a poorly known species (
Schuchert 1997
). This species differs from
C. pauciarmata
n. sp.
because its stem is dichotomously branched, all nematothecae are conical and long, the lateral nematothecae surpassing the hydrothecal rim and the upper chamber is not scooped, there are three nematothecae on ahydrothecate internodes and the transverse node between hydrothecate and ahydrothecate internodes lies at the level of the hydrothecal rim.
Corhiza suensoni
, according to the original description given by
Jäderholm (1896)
, has hydrocladia composed only of hydrothecate internodes, there are two or three unpaired nematothecae per internode (one mesial inferior and one or two distal), the lateral nematothecae surpass the hydrothecal rim and the margin of the upper chamber is not scooped.Moreover,
Schuchert (1997)
indicates that
C. suensoni
is similar to
C. complexa
, but the former has no axillar nematotheca. In his opinion the
type
material of
C. suensoni
should be re-examined to confirm the absence of the axillar nematotheca.