Hypoxylon salicicola Granmo.
Stromata effused, with
inconspicuous to conspicuous perithecial mounds, 35-65 mm long x 5-20
mm broad x 0.4-0.5 mm thick; surface dark rust (39) to sepia (63), brown vinaceous (84), finely
cracked between perithecial mounds when mature, with dark brick (60) effused
margins when immature; dark orange granules
beneath surface and between perithecia, with KOH-extractable pigments
fulvous (43) to rust (39); the tissue below the perithecial layer
usually inconspicuous, dark brown.
Perithecia spherical to obovoid, 250-350 µm diam.
Ostioles black, lower than the stromatal surface, frequently at
the centre of slight circular depression.
Asci 110-125 µm total length x 6-6.5 µm broad, the spore
bearing-parts 42-70 µm long, the stipes 55-65 µm long, with apical ring
weakly amyloid, obsolete, discoid, 0.6 µm high x 2-2.4 µm broad.
Ascospores brown, ellipsoid nearly equilateral, 7.2-9.6 x 3-4.2 µm ( M = 8.4
x 3.8µm), with straight germ slit spore-length;
perispore dehiscent in 10% KOH, smooth.
Anamorph in nature: reported as Nodulisporium-like by Ju & Rogers
(1996) from cultures..
Habitat: According to Granmo (1999), H. salicicola is
found on dry branches and trunks of Salix sp., once on Prunus padus,
either on wood or on bark.
Known distribution: northern Europe (North Norway, Sweden, Granmo
1999) and USA (Arizona, Ju & Rogers 1996).
Specimens examined: NORWAY. Troms: Bardu: Sørdalen,
0.5 km S of Sørmo, 11 Jun. 1999, AG 50/99, leg. det. A. Granmo, on decaying branch of Salix sp
(wood and cortex).Troms: Bardu: Setermoen, Moegga, 29 Jul. 2000, AG
det. A. Granmo,on
Hypoxylon salicicola is still unknown in France,
and we are very grateful to Dr. Granmo for the two specimens we received from
him. Its is likely to have a distribution restricted to arctic alpine
regions in Europe, therefore it should be searched for in Alps and Pyrénées. For
a more complete description, the reader is referred to Granmo
This species is clearly morphologically related to H. rubiginosum,
from which it differs in smaller perithecia, asci and ascospores. Moreover
the nearly equilateral ascospores of H. salicicola differ from those
of H. rubiginosum which are inequilateral. Ju & Rogers (1996) reported
two collections from Sweden and USA (Arizona) on Salix with similar morphological
features, which have a Nodulisporium-like anamorph in culture with a
slow growth rate compared with that of H. ruboginosum.
HPLC data are not yet available for H. salicicola and the Arizona
specimen. Hypoxylon rubiginosum (Pers.: Fr.) Fr. var. microsporum
Whalley (Whalley, 1981) is another taxon known
from Australia and Sierra Leone, similar to H. rubiginosum but with
smaller ascospores 7.5-8.5 x 4-4.5 µm, for which further studies are needed to
assess its relationships with H. rubiginosum and H. salicicola.