Fig. 3.8 (a–y) Morphology of Leptomitales s. lat.(a–c)
Drawings of Atkinsiellaceae. Atkinsiella dubia,
showing irregularly lobate thallus (a) within which pri-
mary zoospores and cysts form in situ (b). Typical
reniformsecondary zoosporebeing released from a
primary cyst (c). From Karling ( 1981 ), after Sparrow
( 1973 ). (d–i) Drawings ofLeptomitaceae. Constricted
hyphae ofLeptomitus lacteus,(d) and mature oogo-
nium showing single large lipid droplet (shaded) and
adjacent ooplast (e). Constricted hyphae ofApodachlya
pyriferawith an empty terminal sporangium and with
primary cysts nearby (f). From Dick (1973a) with per-
mission. (g–i) Constricted hyphae ofApodachlyella
showing a lateral sporangium (g) and young (h) and
mature (i) oogonia illustrating the characteristic elon-
gate antheridium, divided into cyst-like compartments
from which fertilization tubes develop. From Longcore
et al. ( 1987 ) with permission. (j, k) Drawings ofCornu-
myces pygmaeum (syn. Lagenidium pygameum)
showing typical irregular lobate thallus (j) that forms
within pollen grains and detail of adjacent oogonial and
antheridial thallus showing developing oospore (k).
From Karling ( 1981 ), after Zopf. (l, m) Drawings of
Aphanomycopsis spp.Suririellainfected withA. bacil-
larearumshowing both elongate segmented thallus and
aphanomycoid discharge of primary aplanospores (l).
From Karling ( 1942 ), after Tokunaga ( 1934 ). Midge
eggs infected withA. sexualisshowing two developing
oospores, associated with an elongate segmented
antheridium (m). From Karling ( 1981 ) after Martin
( 1975 ). (n–q) Drawings showing development ofChla-
mydomyzium anomalum(syn.Myzocytium anoma-
lum) within an infected nematode. Newly infected
nematode showing elongate compartmentalized thalli
(n). Each compartment swells to form an ovoid sporan-
gium with a dome-shaped discharge papillum (o). Dis-
charged aplanospores releasing secondary-type
zoospores (p). Thick-walled resting spores that arise
parthenogenetically (q). From Karling ( 1981 )after
Barron ( 1976 ). (r–x)DrawingsofPythiella vernalis
infectinghyphaeofPythium, which, although unse-
quenced, probably belongs in this order. Thallus with
elongate discharge tube (r) from which a cluster of apha-
nomycoid primary cysts are released (u). These release
secondary-type zoospores (u). Series of drawings sum-
marizing sexual reproduction showing transfer to the
oogonium of cytoplasm from an adjacent antheridia (v,
w,x). From Karling ( 1981 ) after Couch ( 1935 )60 G.W. Beakes et al.