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Species Information
Summary: This species in the strict sense of Ju(2) remains to be established for the Pacific Northwest. Features include 1) fruitbodies mainly on hardwood that are cushion-shaped to spread out flat, 2) color that is rusty to infrequently vinaceous, the surface flat or with conspicuous to inconspicuous perithecial prominences, 3) yellowish brown or brown granules immediately beneath the surface and between perithecia, with KOH-extractable pigments colored orange or rust, and 4) spores that are (8-) 9-12 x 4-5.5 microns, elliptic-inequilateral, with dehiscent perispore. |The species concept of Miller, J.H.(1) is wider than that of Ju(2): "Miller (1961) extended the definition of H. rubiginosum to cover those specimens with the ascospore size range 9-12.8 x 4-6 [microns], with stromata less than 3 mm thick, and with dark brown granules" [Latin name italicized bold], but Ju(2) restricted H. rubiginosum to "those specimens with yellowish brown to brown granules containing orange-series KOH-extractable pigments, with a rusty to infrequently vinaceous stromatal surface, with ellipsoid-inequilateral ascospores (8-) 9-12 x 4-5.5 microns, with dehiscent perispore, and without massive basal tissue", (Ju). |The synonyms given here are those given by Ju(2).
According to Miller, J.H.(1), Hypoxylon rubiginosum is found all over the world, not limited by thermal zones, and is the most common Hypoxylon species in the world and the most variable. Ju(2), who use the narrower concept, mention collections only from AZ, FL, GA, IL, MO, NJ, OH, SC, WI, France, Finland, Germany, Switzerland, and the United Kingdom. It has been reported at least from BC (Redhead(5), 1997, and Callan(1), 1998), but it is not certain whether these reports refer to collections fitting the narrower concept of Ju(2) or merely the wider concept of Miller, J.H.(1).
Fruiting body: stromata [fruitbodies] 0.3-10cm x 0.3-5cm broad and 0.05-0.12(0.15)cm thick, effused-pulvinate, sometimes pulvinate or even hemispheric; surface dark brick, sepia, brown-vinaceous, or grayish sepia; plane [flat] "or with inconspicuous to conspicuous perithecial mounds", ostioles lower than the stromatal surface; "yellowish brown or brown granules immediately beneath surface and between perithecia", with KOH-extractable pigments orange or rust; tissue below the perithecial layer usually inconspicuous, (Ju), stromata "variable in form depending on characters of substrate", indefinitely effused [spread out] and plane [flat], 1-20cm x 0.5-10cm, and 0.05-0.3cm thick on large logs, or irregularly pulvinate [cushion-shaped] to hemispheric, 0.1-0.5cm x 0.2-0.7cm and 0.1-0.3cm thick on small branches with bark, erumpent, superficial, texture coriaceous-fleshy or slightly carbonous when old; rusty red to bright red to dark purple-red; surface pulverulent [powdery], "smooth with no perithecial elevations or with elevations very pronounced with almost free perithecia"; interior dark brown up to vertices of perithecia; perithecia hemispheric to oblong and angular from compression, "with ostiola umbilicate and not extruded", (Miller, J.H.), spread-out thin crust with black perithecia 0.03-0.08cm across, embedded; brick-red to wine-red or ocher-brown to rust-brown, depending on stage of development; "when old blackish, tuberculate and uneven, often furrowed and dotted with the craterlike or papilliform perithecial ostioles, stroma ochre to brown", (Breitenbach)
Microscopic: SPORES (8)9-12 x 4-5.5 microns, elliptic-inequilateral, with narrowly rounded ends, "brown to dark brown, unicellular", "with straight germ slit spore-length", "perispore dehiscent in 10% KOH, smooth or with inconspicuous coil-like ornamentation", epispore smooth; ASCUS 100-170 x 5.5-8 microns, the spore-bearing part 63-83 microns long, the stem 35-90 microns long, with apical ring lightly blueing to blueing in Melzer''s reagent, discoid, 0.8-1.5 microns high and 2-3 microns broad; PERITHECIUM 200-500 microns in diameter and 300-600 microns high, spherical to obovoid, (Ju), SPORES 9-12.8 x 4-6 microns, inequilaterally elliptic, light to dark brown, obliquely uniseriate; ASCUS 60-80 x 8-9 microns in spore-bearing part, cylindric, with stem 40-50 microns long; PARAPHYSES copious, filiform; PERITHECIUM 200-500 microns in diameter and 300-700 microns high, hemispheric to oblong and angular from compression, (Miller, J.H.), SPORES 10-12 x 4.5-5.5 microns, broadly elliptic to bean-shaped, "rather flattened on one side, smooth, dark brown", with 1 droplet, germination cleft barely visible, spores uniseriate; ASCUS 8-spored, 120-130 x 5.5-8 microns, amyloid; PARAPHYSES barely visible, filiform, (Breitenbach)
Habitat / Range
including Acer, Fagus, Fraxinus, Populus, Quercus, (Ju), on almost all woody dicotyledonous plants, especially Acer and Fraxinus, also on the monocotyledonous Bambusae and occasionally found on gymnosperm wood, (Miller, J.H.), on dead, often barkless wood of various hardwoods, all year, (Breitenbach)
Similar Species
Hypoxylon fuscum is sometimes similar externally but has larger spores, (Breitenbach).
