Diversity of sessile rotifers (Gnesiotrocha, Monogononta, Rotifera) in Thale Noi Lake, Thailand
Author
Meksuwan, Phuripong
Author
Pholpunthin, Pornsilp
Author
Segers, Hendrik
text
Zootaxa
2011
2997
1
18
journal article
47028
10.5281/zenodo.207999
b2e49ad5-de16-41c0-ad9d-1fa53dc0addf
1175-5326
207999
Collotheca algicola
(Hudson)
(
Figs 2
d–2f) and
Collotheca ambigua
(Hudson)
(
Figs
2
g–
2i
)
We tentatively consider these two taxa as separate species, even though the most recent checklist of the group considers
C
.
algicola
(Hudson)
a synonym of
C
.
ambigua
(Hudson) (Segers 2007)
. Our material matches well the original description of both species (
Hudson & Gosse 1886
). We found three morphological characters that distinguish the two (
Table 3
):
● the dorso-lateral corona lobes are more prominent in
C
.
algicola
than in
C
.
ambigua
● the separation between foot and trunk is more pronounced in
C
.
ambigua
than in
C
.
algicola
; ● they differ significantly in size, with
C
.
ambigua
being the larger of the two.
TABLE 3.
Comparison of diagnostic features of four species of
Collotheca
(after Koste, 1978)
Species Characters
C
.
algicola
(Hudson)
C
.
ambigua
(Hudson)
C
.
campanulata
C.
trilobata
(Collins)
(Dobie)
Corona lobes Five Five Five Three
Dorsal corona lobe |
Gradually narrow onto Gradually narrow the tip end onto the tip end |
Rather parallel with rounded tip |
Rather parallel with rounded tip |
Dorso-lateral corona lobes |
Prominent Small |
Rather prominent |
Completely lacking |
Corona ventral lobe sinus |
Rather deep Rather deep |
Rather shallow |
Very deep |
Separation between foot and Less distinct Distinct Distinct Distinct
trunk
That the relatively small
C. algicola
is not a young, immature and therefore not fully grown specimen is indicated by the accumulation of excretophores (
Fig. 2
e), a phenomenon which is commonly observed in old specimens of many species of
Collotheca
, but not in young ones (
Koste 1978
). We nevertheless refrain from concluding on the matter as we observed only low numbers of both of the taxa concerned. In particular, we found only a single specimen of what we identify as
C
.
algicola
.
FIGURES 3A–3F.
Collotheca
spp. 3a–c:
Collotheca campanulata
(Dobie, 1849)
; 3d–3f:
Collotheca trilobata
(Collins, 1872)
. Scale bars: 3a–3f = 100 µm.
Collotheca ambigua
could also be confused with
C
.
campanulata
(Dobie)
(
Figs 3a–3
c) or
C
.
trilobata
(Collins)
(
Figs 3
d–3f). However, they can be distinguished from
C
.
campanulata
by having a deeper and wider sinus separating the ventral corona lobes (compare
Fig.
2
i and 3c), and by shape of its relatively narrower dorsal corona (compare
Figs 2
h–
2i
and 3b–3c).
C
.
ambigua
can further be separated from
C
.
trilobata
by having small dorso-lateral corona lobes (absent in
C
.
trilobata
) and relatively small ventro-lateral corona lobes when compared to
C. trilobata
(compare
Figs 2
h–
2i
and 3e–3f; see also
Table 3
).