Pleosporales - CBS - KNAW

Fungal Diversity
lectotype species (de Greuter et al. 1988; Holm1975;
Shearer et al. 1990). Leptosphaeria was originally
defined based mainly on the characters of ascospores
being ellipsoid or fusoid, one to many septa, hyaline to
dark brown. These few common characters meant that
Leptosphaeria comprised many species, and some of
them should be assigned to either Euascomycetes or
Loculoascomycetes (Crane and Shearer 1991). Leptosphaeria
had been divided based on host and habitat
(Saccardo 1878b, 1891, 1895) as well as the pseudothecium
(glabrous, hairy, setose) and ascospore septation
(see comments by Crane and Shearer 1991). von Höhnel
(1907) used centrum structure in the classification of
Leptosphaeria, and divided Leptosphaeria into three
genera, viz. Leptosphaeria, Scleropleella and Nodulosphaeria.
Müller (1950) subdivided Leptosphaeria into
four sections based on pseudothecial and centrum
structure as well as ascospore characters. This classification
was modified by Munk (1957), who named these
four sections as section I (Eu-Leptosphaeria), section II
(Para-Leptosphaeria), section III (Scleropleella) and
section IV (Nodulosphaeria). Holm (1957) used a
relatively narrow concept for Leptosphaeria, which
included species closely related to the generic type, L.
doliolum. This viewpoint was accepted by some workers
(Eriksson 1967a; Hedjaroude 1969; Shoemaker 1984a).
Nevertheless, it still seems a heterogeneous group of
fungi (see comments by Crane and Shearer 1991). Its position
among the Loculoascomycetes is also debated. It has been
placed in the Pleosporaceae (von Arx and Müller 1975;
Luttrell 1973; Sivanesan 1984) orLeptosphaeriaceae (Barr
1987a, b; Eriksson and Hawksworth 1991) orPhaeosphaeriaceae
(Eriksson and Hawksworth 1986).
Phylogenetic study
Molecular phylogenetic analysis based on multigenes
indicated that species of Leptosphaeria (including the
generic type L. doliolum) and Neophaeosphaeria form a
paraphyletic clade with moderate bootstrap support (Dong
et al. 1998; Schoch et al. 2009; Zhang et al. 2009a), which
is sister to other families of Pleosporales (Zhang et al.
2009a). Thus the familial rank of the Leptosphaeriaceae
could be temporarily verified, but further molecular
phylogenetic study is needed in which more related taxa
should be included.
Concluding remarks
Morphologically, Leptosphaeria is mostly comparable
with Amarenomyces, Bricookea, Diapleella, Entodesmium,
Melanomma, Nodulosphaeria, Paraphaeosphaeria, Passeriniella,
Phaeosphaeria and Trematosphaeria. While it
prefers non-woody parts of dicotyledonous hosts, its
cylindrical ascus with short pedicel and smooth, fusoid
Fig. 43 Lentithecium fluviatile (from IFRD 2039). a Erumpent b
ascomata scattering on the host surface. b Habitat section of the
immersed ascomata. c, d Section of an ascoma and a partical peridium.
Note the peridium cells of textura angularis. e Clavate 8-spored ascus
with a short pedicel. f, g Hyaline, 1-septate broadly fusoid ascospores.
Scale bars: a, b=0.5 mm, c=100 μm, d=50 μm, e–g=20 μm
and multi-septate ascospores make it readily distinguishable
from all other genera (Shoemaker 1984a).
Leptosphaerulina McAlpine, Fungus diseases of stonefruit
trees in Australia and their treatment: 103 (1902).
(Didymellaceae)
Generic description
Habitat terrestrial, parasitic or saprobic. Ascomata small,
scattered, immersed, globose to subglobose, with a small,
slightly protruding papilla, ostiolate. Peridium thin. Hamathecium
of rare or decomposing cellular pseudoparaphyses.
Asci bitunicate, obpyriform. Ascospores broadly clavate or
cylindrical, hyaline, turning pale brown when old, asymmetrical,
multi-septate, smooth-walled.
Anamorphs reported for genus: Pithoascus and Pithomyces
(Hyde et al. 2011).
Literature: Barr 1972; Chlebicki 2002; Crivelli 1983;
Kodsueb et al. 2006a; Zhang et al. 2009a.
Type species
Leptosphaerulina australis McAlpine, Fungus diseases of
stone-fruit trees in Australia and their treatment: 103 (1902).
(Fig. 45)
Ascomata 140–170 μm diam., scattered, immersed,
globose to subglobose, with a small slightly protruding
papilla, ostiolate (Fig. 45a). Peridium thin, composed of
one or two layers of large cells of textura angularis, pale
brown (Fig. 45a). Hamathecium of rare or decomposing
cellular pseudoparaphyses, up to 5 μm broad, filling
the gaps between the asci. Asci 38–53×55–75 μm
(x ¼ 67:5 43:3mm, n=10), 8-spored, without pedicel, bitunicate,
fissitunicate dehiscence not observed, obpyriform, with a
large ocular chamber and apical ring (Fig. 45b and c).
Ascospores 30–40(-47)×11–14 μm (x ¼ 36:5 13mm, n=
10), broadly clavate, hyaline, turning pale brown when old,
asymmetrical, upper hemisphere usually with one transverse
septum and with a somewhat narrowly rounded
end, lower hemisphere usually with two transverse septa
and with broadly rounded ends, slighted constricted at
the primary septum, mostly with one vertical septum in
each central cell, smooth, with thin gelatinous sheath
when young, 2–3 μm thick (Fig. 45d and e).
Anamorph: none reported.