Sponge biodiversity of South Georgia island with descriptions of fifteen new species
Author
Goodwin, Claire
National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT 18 0 EU & Shallow Marine Surveys Group, PO Box 598, Stanley, FIQQ 1 ZZ, Falkland Islands
Author
Brickle, Paul
Shallow Marine Surveys Group, PO Box 598, Stanley, FIQQ 1 ZZ, Falkland Islands & South Atlantic Environmental Research Institute, PO Box 609, Stanley, FIQQ 122, Falkland Islands
text
Zootaxa
2012
2012-11-07
3542
1
48
journal article
1175-5326
8D917062-2FC8-4EE9-83A0-FDDCB6A08F45
Clathria (Clathria) stromnessa
sp. nov.
(
Figure 6
)
Type material:
Holotype
:
BELUM
Mc
7690.
Sample
in 95% ethanol, tissue section and spicule preparation on slides;
Green Island
,
Stromness
,
Site
2,
South Georgia
(
54°09.381’S
,
36° 39.852’W
); depth
17.4m
; collected by
C. Goodwin
, J. Brown, and
S. Brown
,
28
th
November 2010
.
Paratype
:
BELUM
Mc
7674.
Sample
in 95% ethanol, tissue section and spicule preparation on slides,
Green Island
,
Stromness
,
Site
1,
South Georgia
(
54°09.448’S
,
36° 39.752’W
); depth
17.4m
; collected by
C. Goodwin
, P. Brickle and
S. Cartwright
,
27
th
November 2010
.
Etymology:
Named after the
type
locality, Stromness,
South Georgia
External morphology:
In situ appearance:
Lobed
massive (
type
specimen maximum diameter
20cm
) rust orange sponge with large oscules on top of lobes (
Fig. 6a
).
Preserved appearance:
Grey, firm, with a slightly hispid surface.
Skeleton:
The choanosomal skeleton is an irregular reticulation of bundles of 4–6 smooth styles (
Fig. 6b
), there is no differentiation between axial and extra-axial regions. The ectosome is formed of brushes of styles. Toxa and chelae microscleres are present throughout the tissue.
Spicules:
Measurements from Mc7690.
Choanosomal styles:
424(495)563 by 17(26)31µm. Fat smooth styles, the majority are gently curved (
Fig. 6c
).
Ectosomal styles:
232(292)414 by 3(6)7µm. Thin styles, the heads are microspined, bearing several short blunt spines (
Fig. 6d, e
).
Chelae:
10(12)14µm. Typical clathriid palmate isochelae (
Fig. 6f
).
Toxa:
45(150)477µm, thin smooth toxas, very wide ranging in size. Some of the smallest have a pronounced central flexion and upturned points (
Fig.
6g
).
FIGURE 6.
Clathria (Clathria) stromnessa
sp. nov.
a)
In situ
appearance
specimen Mc7690 b) Skeleton Mc7690, ectosome to top, scale bar 500µm; Spicules Mc7690 c) style, scale bar 100µm, d) ectosomal style, scale bar 100µm, e) chelae, scale bar 10µm, f) ectosomal style head, scale bar 10µm, g), h) toxa, scale bar 10µm.
Remarks:
We have assigned this species to
Clathria (Clathria)
rather than one of the other seven sub-genera on the basis of the lack of differentiation between the axial and extra-axial regions of the choanosome and the presence of a reticulate skeleton and only a single category of auxillary style (Hooper 2002). This species is unusual in not possessing any echinating acanthostyles, however these can be secondarily lost in this subgenus (Hooper 2002). The subgenus
Clathria (Isociella)
lacks echinating acanthostyles but has a regular renieroid reticulate skeleton with plumose multispicular tracts connected by paucispicular ones (Hooper 2002), whereas the skeleton of our species is irregularly reticulate. From the South Atlantic and Antarctic
C. papillosa
Thiele, 1905
and
C. paucispicula
(
Burton, 1932
)
are the only species in
Clathria (Clathria)
,
which do not possess any echinating spicules. However, the former has strongylote ectosomal spicules and bipocoelles and should probably be reassigned to
Iophon
, and the latter lacks any microscleres. The large size of the toxa is also unusual;
C. toxipraedita
Topsent, 1913
(
type
locality Burdwood Bank to the south of
Falkland Islands
and north west of
South Georgia
) has toxa up to 1750µm but possesses echinating acanthostyles.