Genus Hypoxylon
Key to Taxa of Hypoxylon
Accepted Taxa
List of Names

Yu-Ming Ju
Michael J. Adams

Subgeneric classification systems of Hypoxylon have been briefly reviewed in the INTRODUCTION. Here we only focus on our disposition of Miller's subgeneric taxa in his 1961 system.

Miller (1961) accepted four sections in the genus: Hypoxylon, Papillata, Annulata, and Applanata. Taxa in sections Hypoxylon and Annulata are largely considered in this work. Two taxa from these sections are not considered to be Hypoxylon. Hypoxylon sassafras (Schwein.: Fr.) M. A. Curtis produces a Libertella-like anamorph, and was transferred to Creosphaeria Theiss. by Ju et al. (1993). Hypoxylon subannulatum Henn. & E. Nyman sensu J. H. Miller produces a Geniculosporium anamorph, and is considered to be a Nemania taxon.

Miller's subsection Papillata of section Papillata contains 12 taxa. Its members are herein largely dispersed into either section Hypoxylon or section Annulata. Hypoxylon investiens sensu J. H. Miller, H. investiens var. epiphaeum, H. rubigineoareolatum, H. rutilum, H. croceum, and H. novemexicanum belong to section Hypoxylon, whereas H. cohaerens and H. multiforme belong to section Annulata. Other taxa should be excluded from Hypoxylon. Hypoxylon fuscellum (Rehm) J. H. Miller and H. cinereolilacinum J. H. Miller are Biscogniauxia. Hypoxylon chrysoconium Berk. & Broome, with a Geniculosporium anamorph, is probably a Nemania. Hypoxylon morgani Ellis & Everh., which has white, soft stromata, possesses traits, e.g., urn-shaped ascal apical ring, found more commonly in Xylarioideae than in Hypoxyloideae, and is unlikely a Hypoxylon.

Under subsection Primocinerea of section Papillata, Miller (1961) placed taxa with affinities to Xylaria. Some of them belong to Nemania and Ustulina. Hypoxylon laurus J. H. Miller and H. megalosporum Speg. are now considered to be members of section Hypoxylon. Hypoxylon cerebrinum (Fée) Cooke is a Neohypodiscus J. D. Rogers, Y.-M. Ju, & Laessøe (Rogers et al., 1994), a genus of Amphisphaeriaceae sensu lato. Hypoxylon grandineum (Berk. & Ravenel) J. H. Miller was proven to be a loculoascomycete, and a new genus, Loculohypoxylon Barr, was erected for it by Barr (1976). Hypoxylon culmorum Cooke produces scolecosporous conidia, and is considered to belong to Kretzschmariella Viégas (Ju and Rogers, 1994). Hypoxylon folicola J. H. Miller, a synonym of H. palmigena Berk. & M. A. Curtis, should be excluded from Xylariaceae; the latter name was recombined into Coccostroma palmigenum (Berk. & M. A. Curtis) Theiss. & Syd. by Theissen and Sydow (1915). Still, a few members of section Papillata, subsection Primocinerea have not satisfactorily been assigned to appropriate places. For example, Hypoxylon nummularioides Rehm and H. smilacicolum Howe, two monocot-inhabiting fungi, have teleomorphs similar to those of Kretzschmariella and Nemania. Because they have not been associated with their anamorphs, which are currently considered crucial for determining generic placements, their taxonomic positions are uncertain.

Taxa in Miller's section Applanata have been or will be transferred to either Biscogniauxia or Camillea, depending on whether ascospores of a taxon are dark-colored and unornamented, or light-colored and ornamented. Camillea has been monographed by Laessøe et al. (1989). A monographic treatment is urgently needed for Biscogniauxia.

A comparison between Miller's taxa that fall into Hypoxylon sensu stricto and their equivalents in this study is summarized in Table 1.

Table 1. Names of Hypoxylon sensu stricto in Miller (1961) with their equivalents in the present study. Enclosed in parentheses are abbreviations of the section and subsection names of Miller's Hypoxylon: AN: section Annulata; HY: section Hypoxylon; PA: section Papillata, subsection Papillata; and PR: section Papillata, subsection Primocinerea.

H. aeruginosum (HY) H. aeruginosum
H. archeri (AN) H. archeri
H. argillaceum (HY) H. intermedium
H. bovei (AN) H. bovei + H. discophorum
H. bovei var. microspora (AN) H. bovei var. microspora
H. cohaerens (PA) H. cohaerens
H. croceum (PA) H. croceum
H. crocopeplum (HY) H. cinnabarinum + H. crocopeplum + H. ochraceum
H. diatrypeoides (HY) H. diatrypeoides
H. fragiforme (HY) H. fragiforme
H. fuscum (HY) H. fuscum
H. haematostroma (HY) H. haematostroma + H. ochraceum
H. hians (AN) H. hians
H. howeianum (HY) H. howeianum
H. hypomiltum (HY) H. cinnabarinum + H. crocopeplum + H. fendleri + H. subgilvum
H. investiens (PA) H. dieckmannii + H. lenormandii + H. monticulosum + H. submonticulosum
H. investiens var. epiphaeum (PA) H. monticulosum
H. jecorinum (HY) H. cinnabarinum + H. erythrostroma + H. jecorinum + H. rickii
H. laurus (PR) H. laurus
H. megalosporum (PR) H. megalosporum
H. michelianum (AN) H. michelianum
H. mulleri (HY) H. placentiforme
H. multiforme (PA) H. multiforme
H. notatum (HY) H. flavoargillaceum + H. musceum + H. notatum + H. shearii
H. novemexicanum (PA) H. novemexicanum
H. oodes (HY) H. lenormandii
H. papillatum (HY) H. papillatum
H. rubigineoareolatum (PA) H. rubigineoareolatum
H. rubiginosum (HY) H. anthochroum + H. carneum + H. cercidicolum + H. dearnessii + H. fuscum + H. laschii + H. macrocarpum + H. perforatum + H. pilgerianum + H. rubiginosum + H. trugodes
H. rubiginosum var. dieckmannii (HY) H. dieckmannii + H. hypomiltum + H. investiens + H. munkii
H. rubiginosum var. ferrugineum (HY) H. ferrugineum
H. rubiginosum var. tropica (HY) H. cinnabarinum + H. sclerophaeum
H. rubrostromaticum (HY) H. subrutilum
H. rubrostromaticum var. macrospora (HY) H. subrutilum
H. rutilum (PA) H. rutilum
H. sclerophaeum (HY) H. nicaraguense + H. piceum + H. placentiforme + H. polyporum + H. sclerophaeum
H. sclerophaeum var. macrospora (HY) H. placentiforme
H. stygium (AN) H. microcarpum + H. stygium + H. stygium var. annulatum
H. thouarsianum (AN) H. thouarsianum
H. thouarsianum var. gilletianum (AN) H. thouarsianum
H. truncatum (AN) H. annulatum + H. leptascum + H. moriforme + H. nitens + H. pseudostipitatum + H. truncatum
H. truncatum var. pouceanum (AN) H. pouceanum + H. urceolatum
H. vogesiacum (HY) H. vogesiacum + H. fuscum
H. vogesiacum var. macrospora (HY) H. macrosporum
H. vogesiacum var. microspora (HY) H. fuscopurpureum