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PACIFIC SCIENCE, Vol. XVIII, April 1964 
87) X 2-3.5 /x, constricta in basi; ceflulae in 
catenis ramosis dormientes, 5-23 /x diam. 
Aquatic fungus; mycelium septate, hyaline, 
branching; cells 8-65 X 1.5-4 n; aleuriophores 
50-400 X 1.5-4 fi, septate, hyaline, unbranched, 
submerged or emerging from the water; aleu- 
riospores apical, hyaline, produced singly, usually 
4- armed, main axis 57-108 (x = 84) X 9 3- 
14.5 /x, of 5-8 cells; divergent arms septate, 
arising from the second cell of the main axis, 
10-136 (x = 87) X 2-3.5 /x, constricted at the 
point of origin; resting cells in branching chains, 
5- 23 ^ diam. 
HOLOTYPE: Hawaii. On leaves in water from 
Kokee stream, Na Pali Kona Reserve, Kauai, 
August 30, 1961, Anastasiou H47. Transfers of 
this holotype have been deposited at ATCC, 
CMI, CBS, and DAOM. 
Dactylella appendiculata is characterized by 
the production of aleuriospores developing one 
to four determinate, lateral arms from the second 
cell of the main axis (Fig. 1 g-i, Fig. 2c-/). 
These arms are formed consecutively from the 
apical portion of the second cell. In other species 
of Dactylella (Drechsler, 1937:489, 493, 501) 
germ tubes usually arise from the apical portion 
of this cell. In D. appendiculata the arms are 
distinctly constricted at the base but a wall does 
not appear to be laid down at this point. How- 
ever, septation occurs distally in the arms. The 
main axis of the aleuriospore develops into a 
form (Fig. lj, Fig. 2c) characteristic of many 
species of Dactylella if the spore primordium is 
initially straight. If the spore primordium is 
curved, the main axis appears as in Fig. li and 
Fig. 2 d-f. Fig. 1 a-i and Fig. 2 a are stages in 
the development of spores of the second and 
predominant type. Fig. 2b is a stage in the de- 
velopment of a spore of the first type. 
In the original collection conidiophores were 
produced from submerged hyphae and emerged 
to about 200 /x above the water surface. At 
maturation, the spores dropped to form a dense 
mass floating on the surface tension membrane. 
Sporulation did not occur in pure culture on 
agar. However, when a portion of the colony 
on agar is submerged in water, very weak sporu- 
lation occurs after 3 to 5 weeks’ incubation at 
room temperature. Increased sporulation, though 
still sparse, occurs when a rotting leaf is sterilized 
with the water before inoculation. 
Since this species resembles certain preda- 
ceous species of Dactylella, it was cultured in 
water containing nematodes and rotifers. No 
predaceous apparatus was formed, whether or 
not these organisms were present. No improve- 
ment in sporulation occurred after addition of 
nematodes, but when water containing rotifers 
and other microorganisms was added spores 
were abundantly produced on the surface of 
leaves in the culture. Almost all spores developed 
on short aleuriophores (up to 150 /x) and were 
completely submerged at maturity. All of these 
developed from curved spore primordia. Some 
of the spores produced above the surface of the 
water developed from straight spore primordia. 
Germination of aleuriospores occurred mainly 
by germ tubes from the apical and basal cells 
of the main axis as well as from any cell of the 
divergent arms. Germ tubes arising from the 
main axis are only slightly constricted at their 
point of origin, where a distinct septum was 
usually observed. Germination from the diver- 
gent arms is normally by branching rather than 
elongation of the arms. 
The colony on Me Ye agar (Benjamin, 1959: 
322) was slimy and dull white in color, with 
very little aerial mycelium. In age, branched 
chains of yeastlike resting cells were produced 
(Fig. Ik; Fig. 2 g) . Similar resting cells devel- 
oped in the water of the original isolate and 
subsequent transfers. 
The relationship between Dactylella appen- 
diculata and other species of Dactylella is com- 
parable to that between Campylospora chaeto - 
cladia and T rip osp ermum. In spore morphology, 
C. chaeto cladia differs from Trip osp ermum by 
the production of filiform appendages at the 
apex of the arms. Some justification for placing 
C. chaetocladia in a separate genus is to be 
found in differences in conidiophores and spore 
color (Ingold and Cox, 1957:320; Hughes, 1951: 
22). Such differences between D. appendiculata 
and Dactylella do not exist. In my opinion dif- 
ferences in habitat and modification of germ 
tubes to form spore branches do not constitute 
sufficient reason for placing this organism in a 
genus which does not show its true relationship. 
Acknowledgments: The research in this proj- 
ect was supported in part by a grant from the 
Research Committee of the Faculty of Graduate 
Studies at the University of British Columbia. 
