B
ackhaus
:
Phormidium ingrediens sp. nova
23
preference, deduced from regional conditions,
could be a significant and further indication for
the specific properties of “Phormidium spec.”.The
related physico-chemical water conditions in riv-
ers of the Black Forest where “Phormidium spec.”
was found, were recorded as: Total hardness: 1-8
(9,5)
°dH (German degree of hardness); carbon-
ate hardness: (0,1) 1-17 °dH; ABC: 0,14-2,5 mval
(
acid binding capacity); electr. conductivity: (35)
60-200 (335)
µS/cm; pH: 6,5-7,5 (8).
The Lyngbya spec., found by K
ann
(1978,
p. 432)
in the Irdningbach in Austria, probably is the
same “Phormidium spec.” as present in the Black
Forest streams. The Irdningbach is also situated
in a region of waters with low calcium content and
holds dispatched limestones in the river bed.
3.3
Conclusions
The ability of filamentous cyanophytes to depos-
it as well as to bore into limestone, as appears
to have been demonstrated for Phormidium in-
crustatum by P
entecost
(2003),
was already
proven for Schizothrix by S
chneider
(1977)
and
S
chneider
&
L
e
C
ampion
-
A
lsumard
(1999).
This ability, however, seems to be restricted
to few taxa only. After more than 100 years of
cyanophyte research, however, more confirm-
ing observations of this phenomenon should
have occurred, but this has not been the case.
Limestone boring and calcification are two dif-
ferent processes not fully understood in the last
details; and it is not yet clear how the first or
second (contrasting) phase of activity is physi-
ologically controlled (G
eitler
1960,
S
chneider
&
L
e
C
ampion
-
A
lsumard
1999,
G
arcia
-
P
ichel
2006).
Active limestone boring by small filamen-
tous species within narrow boreholes needs the
ability for a specific intercellular Ca-transport
(
G
arcia
-
P
ichel
2006).
This condition may be
present in “Phormidium spec.”. Whether this
capacity is genetically fixed to distinct taxa and
serves as distiguishing feature remains uncer-
tain. Despite the wide distribution of “Phormid-
ium spec.” combined with high abundances, no
signs of a transition from endo- to epilithic forms
of thallus were seen. This may be a sign of evi-
dence for a clear demarcation of “Phormidium
spec.” from the species definition subsumed for
Phormidium incrustatum.
It may be possible that hormogonia of carbonate-
encrusting species are also present in streams with
low carbonate content, but in that environment they
are not able to develop at full. However, if they meet
carbonate rocks which can be bored, they take ad-
vantage of the endolithic lifestyle rather than not
being able to develop outside.This scenario can be
disproved by the ecological conditions in the head-
water system of the upper Danube river. There, the
carbonate content of the stream water increases
after it passes from the gneiss- and granite-sub-
soil into Jurassic formations (B
ackhaus
&
S
ander
1967).
The pressure for an endolithic way of life,
therefore, should decrease, but no corresponding
reactions were observed. Even in streams within
pure Jura-rock strata of the south-western Ger-
man mountain range “Schwäbische Alb” (such as
Schmiecha, Lauchert), which have a hardness of
water of 15-16 °dH, or in shell limestone streams
with even a stronger hardness of up to 22 °dH, no
epilithic thalli or travertines of “Phormidium spec.”
were observed. These facts should be estimated
as a further sign for the independence of “Phor-
midium spec.”.
By which way the hormogonia (or filaments?) do
force their entrance into the rock matrix against
lotic flow conditions needs to be clarified by a
specific examination. However, it seems to be
plausible that this process can only be success-
ful in combination with the presence of a suffi-
ciently developed biofilm just in the function as
starting support as shown by K
emmerling
et al.
(2004)
for comparable euendolithic settlements
in rock biotopes.
3.4
Species description
Based on essential points of view as morpho-
logical differences from similar phormidians, the
colonization of specific kinds of limestone, devel-
oping a typical, hitherto unknown brush-like thal-
lus within the rock matrix, and the requirements
of specific physico-chemical water conditions,
“
Phormidium spec.” is assessed to be a new spe-
cies and is described here as
Phormidium ingrediens nova species
(
Figs 20, 21)
Filamenta recta, circiter 300 µm longa, 3,5-
4,5
µm crassa, lapides calcareos verticaliter per-
forantes, multis paralleliter adjuncta, aedificantes
stratum usque ad 0,5 mm modo caespitis inversi
vel peniculi in matrice peripherica lapidis; vagi-
nae tenues, firmae, hyalinae, haud lamellosae,
chlorocincico iodurato non coerulentes; trichom-
ata (2,2) 2,9-3,7 (4,4) µm crassa, ad dissepi-
menta non constricta, non vel parum granulata,
ad finem non attenuata, cellulae isodiametricae,
(2,2) 2,9-4,7 (5)
µm longae. Cellula apicalis ro-
tunda vel conicalis; calyptra nulla; chromatoplas
