Molecular phylogenetic analyses and micromorphology reveal placement of the enigmatic tropical discomycete Polydiscidium in Sclerococcum (Sclerococcales, Eurotiomycetes).

Polydiscidium is an enigmatic, monotypic, and rarely reported genus of Ascomycota of uncertain placement. The morphologically unique Polydiscidium martynii grows on dead wood and forms compound ascomata composed of thick, black, gelatinous somatic tissue that branches out from a common base. Multiple apothecia are located on the branches, mostly toward the tips, and are composed of 8-spored asci and paraphyses embedded in a gelatinous matrix that turns blue in Melzer's reagent. The species was previously known from only three collections from Guyana (holotype), Trinidad, and the Democratic Republic of the Congo and no sequences exist. Due to its peculiar morphology, taxonomic affinities of Polydiscidium have been debated, with different authors having placed it in Helotiaceae, Leotiaceae, or Leotiomycetes incertae sedis. Recent collections of this species resulting from long-term field work in Guyana and Cameroon led us to revisit the morphology and phylogenetic position of this fungus. Newly generated sequences of P. martynii were added to an Ascomycota-wide six-locus data set. The resulting phylogeny showed Polydiscidium to be a member of order Sclerococcales (Eurotiomycetes). Next, a four-locus (18S, ITS, 28S, mtSSU) phylogenetic reconstruction revealed that Polydiscidium is congeneric with Sclerococcum. A new combination is proposed for this species, Sclerococcum martynii. Micromorphological features, including the gelatinous hymenium composed of asci with amyloid gel cap and septate brown ascospores, are in agreement with Sclerococcum. New combinations are proposed for two additional species: Sclerococcum chiangraiensis and S. fusiformis. Finally, Dactylosporales is considered a later synonym of Sclerococcales.

Importance of Seasonal Variation in Hawaiian Mushroom (Agaricomycetes) Basidiomata Production for Biodiversity Discovery and Conservation.

The Hawaiian Islands have a relatively well-known funga for a tropical location, yet there are over 400 species of mushrooms (Agaricomycetes) in the archipelago that remain to be documented. Importantly, the International Union for Conservation of Nature (IUCN) recently evaluated six mushrooms endemic to the islands as threatened with extinction. To improve detection of mushrooms for biodiversity discovery and better monitor threatened species in the archipelago-where many localities lack strong annual precipitation patterns associated with an obvious season for increased mushroom basidiomata production-we examined the phenology of Hawaiian mushrooms. Monthly richness was determined from a literature review and abundance from online data repositories. Phenological patterns were separately explored for native species and differing elevation and annual precipitation categories. Despite relatively consistent monthly temperatures and areas with regular monthly rainfall, we found Hawaiian mushrooms generally exhibit uneven temporal patterns in basidiomata production: richness and abundance are generally highest in January and lowest from February to April, then usually increase from May to July and remain at elevated levels through December. This pattern does not occur when considering native species richness only, nor when examining abundance data stratified by elevation and annual rainfall categories. Increased monthly basidiomata abundance in low elevation (<1,000 m), dry (<1,000 mm rainfall/year) locations on O'ahu and low, mesic (1,000-2,500 mm rainfall/year) locations on O'ahu and Kaua'i are positively correlated with increased monthly rainfall. Phenology of macrofungal sporocarp production should potentially be included in species threat assessments by the IUCN to increase detection via traditional surveying methods.