Pleosporales - CBS - KNAW

Fungal Diversity
n=10), 8-spored, bitunicate, fissitunicate dehiscence not
observed, cylindrical but narrowing towards the base, with a
short, furcate pedicel which is 10–25 μm long, ocular
chamber not observed (Fig. 70d and e). Ascospores 110–
160×2.5–4 μm (x ¼ 135:3 3mm, n=10), filamentous,
narrower toward the lower end, pale brown, 22–30-
septate, separating into two partspores from the middle
septum, from the breaking point the second cell of each
partspore enlarged.
Anamorph: none reported.
Material examined: GERMANY, near Kassel, on dead
stem of Cirsium arvense (L.) Scop., Spring 1853 (BPI-
629021, type).
Notes
Morphology
Ophiobolus was established by Reiss (1854) as a
monotypic genus represented by O. disseminans based on
its “Perithecia discreta, ostiolis prominentibus: sporae ascis
inclusae, binatae, filliformes, multiseptatae”.
A broad generic concept was adopted for the genus by
Holm (1948) and Müller (1952). Shoemaker (1976)surveyed
Canadian species of Ophiobolus using the broad concept of
Holm (1948) and Müller (1952). A narrower generic concept
was used by Holm (1957), which only included species with
ascospores separating into two halves. Holm (1957) assigned
species with enlarged ascospore cells to Nodulosphaeria,and
those with long spirally coiled ascospores to Leptospora
(Shoemaker 1976). This left only three species accepted
under Ophiobolus (Holm 1957), although this concept has
rarely been followed with new species recently being
described (Raja and Shearer 2008).
Walker (1980) provided a detailed description from the
type material and dealt with many species of scolecospored
fungi that had been placed in Ophiobolus by Saccardo
(1883). Thus, currently several Ophiobolus sensu lato
species are separated into Acanthophiobolus, Entodesmium,
Leptosphaeria and Leptospora. Ophiobolus sensu lato
contains about 300 species names (Sivanesan 1984; http://
www.mycobank.org/, 04/02/2009).
Phylogenetic study
Ophiobolus fulgidus (Cooke & Peck) Sacc. (as Leptosphaeria
fulgida (Cooke & Peck) M. E. Barr in Dong et al.
1998) lacks support in the clade of Leptosphaeriaceae
(Dong et al. 1998). We expect it may closely related to
Phaeosphaeriaceae.
Concluding remarks
We agree from morphological data that Ophiobolus
should comprise species that have filamentous spores that
break easily into two halves at the central septum, with the
second cell on either side being swollen (Walker 1980) and
that the genus presently comprises three species (i.e. O.
anthrisci (L. Holm) L. Holm, O. ophioboloides (Sacc.) L.
Holm and O. acuminatus). All other Ophiobolus species
need to be re-examined and should be placed in other
genera such as Nodulosphaeria and Leptospora. The genus
is in need of revision and molecular phylogenetic study.
Ophiosphaerella Speg., Anal. Mus. nac. Hist. nat. B. Aires
19: 401–402 (1909). (Phaeosphaeriaceae)
Generic description
Habitat terrestrial, saprobic or hemibiotrophic. Ascomata
small- to medium-sized, solitary or scattered, immersed,
globose or subglobose, papillate, ostiolate. Peridium thin.
Hamathecium of dense, filliform, septate pseudoparaphyses.
Asci bitunicate, fissitunicate dehiscence not observed, cylindrical
often narrower near the base, with a short furcate
pedicel. Ascospores filamentous, pale brown, multi-septate.
Anamorphs reported for genus: Scolecosporiella (Farr et
al. 1989).
Literature: von Arx and Müller 1975; Schoch et al. 2006,
2009; Spegazzini 1909; Walker 1980; Wetzel et al. 1999;
Zhang et al. 2009a.
Type species
Ophiosphaerella graminicola Speg., Anal. Mus. nac. Hist.
nat. B. Aires 19: 401 (1909). (Fig. 71)
Ascomata 280–325 μm high×250–300 μm diam., solitary
or scattered, immersed with a short papilla protruding out of
the substrate, globose or subglobose, often laterally flattened,
dark brown to black, papillate, papilla ca. 100μm high, 140–
180 μm broad, disk-like in appearance from above, periphysate
(Fig. 71a and b). Peridium 11–25 μm wide, thicker near
the apex, comprising two cell types of small cells, outer wall
composed 6–10 layers of lightly brown flattened cells of
textura angularis, inner layer composed of paler and thinwalled
cells, both layers thicker near the apex (Fig. 71b).
Hamathecium of dense, long pseudoparaphyses 0.8–1.5 μm
broad near the apex, septate, 2–3 μm broad between the asci.
Asci 105–135×5.5–10 μm (x ¼ 118:5 7mm, n=10), 8-
spored, bitunicate, cylindrical and narrower near the
base, with a short, furcate pedicel, up to 30 μm long,
small inconspicuous ocular chamber (to 1.5 μm wide×
1 μm high) (Fig. 71c, d, e and f). Ascospores 100–125×
1.8–2.2 μm (x ¼ 118 2mm, n=10), filamentous, pale
brown, 12–20 septa, smooth-walled.
Anamorph: none reported.
Material examined: ARGENTINA, Tucumán, on leaf
sheath of Leptochloa virgata (L.) P. Beauv., 14 Apr. 1906,
C. Spegazzini (LPS 858, holotype).