Hysterium pulicare Pers., Neues Mag. Bot. 1: 85 (1794)

This is type species of genus Hysterium. Hysterium pulicare Pers. is a poorly known saprobic species. It occurs on living trees bark or dead wood of numerous species of angiosperms and gymnosperms. It produces unique ascocarps (sexual structures), called hysterothecia, which are darkly pigmented and carbonaceous. The hysterothecium is a variable boat-like structure with a pronounced lengthwise slit to release the dark, three-septate sexual spores. Due to its seemingly transitional nature, neither fully open nor closed these fungi have been interpreted as related to very different groups throughout history. (Boehm et al. 2009)

Possible synonyms:

Hysterographiumpulicare(Pers.) Corda, Icon. Fung.(Prague) 5:77(1842)

Description with measurements:

Asexual: Conidiomata pycnidial, 100-150 µm diam, depressed globose, black, the wall composed of fused interwoven hyphae.  Conidia 3-4 x 1-1.5 µm in size, cylindrical with rounded ends to narrowly ellipsoidal or allantoid, hyaline, smooth, aseptate. (Boehm et al. 2009).

Sexual: Ascostromata 500-2000 x 300-500(-700) µm, 200-300 µm tall, erumpent through bark or appearing superficial on wood where the bark is lost, elongate, narrowly elliptical to fusiform in outline, straight or irregularly curved, ovate to ± doliiform in vertical section, constricted at the base, scattered or gregarious, superficial or nearly so, dull black, with a conspicuous longitudinal cleft and often with inconspicuous parallel striations, the cleft gradually widening to expose the hymenium, which is coloured dark brown by the ascospores and encrusted paraphysoids. Peridium with lateral walls 50-90 µm thick, composed of very dark, near opaque, thick-walled brown-black cells, basal region similar, with a layer of hyaline thin-walled cells 40-50 µm thick forming the cavity floor. Interascal tissue of paraphysoids ca 1.5 µm diam, filiform with rounded ends, hyaline, smooth, sparsely septate, branched and sometimes anastomosed, exceeding the asci and plugging the ascomatal slit when dry, occasionally with slight apical encrustation where exposed. Asci (75-)100-120 x 17-24 µm, cylindrical-clavate, stalked, tapering to a rounded or irregular base, thick-walled, fissitunicate, apex rounded, I-, 8-spored, arising in parallel from the cavity floor. Ascospores 26-37 x 7-12 µm, 3-septate (very rarely 4-septate), end cells much paler (near-hyaline), narrowly ellipsoidal-ovoid to cylindrical with rounded ends, often with one side straight, reddish brown, slightly constricted at the septa, the end cells concolorous or slightly paler than median cells (Boehm et al. 2009).

Table 1: Information from Herbarium of the Swedish Museum of Natural History

Name	Country	Locality	Collector	Year	Type
Hysterium pulicare Pers. : Fr.	Sweden	Suecia, Ostrogothia, par. Qvillinge	Haglund  11	1894	Hysterographium simillimum Starbäcktype?
Hysterium pulicare Pers. : Fr.	Sweden	–			Hysterographium simillimum Starbäcktype?
Hysterium pulicare Pers. : Fr.	Sweden	Längenthal bei Kühtei (Oetz) in Tyrol, c. 6000’	Rehm	1872	Hysterium acuminatum f. alpinum Rehmtype

Sequence data:

Table 2: Sequence data of Hysterium pulicare

Culture no.	Gene Bank accession no.
	LSU	SSU	RPB2	TEF1
AFTOL-ID 1254	DQ678055	DQ678002	FJ238433	DQ677896
EB 0238	–	FJ161161	FJ161127	FJ161109

 Chemistry of Hysterium pulicare: Heagle (1973), when reviewing the world literature on SO₂ biotic plant disease interactions, reports that SO₂  decreases the incidence of fungal foliar diseases caused by Hysterium pulicare.