Pycnopulvinus Toome & Aime

Toome, Merje & Aime, M. Catherine, 2014, Pycnopulvinusaurantiacus gen. et sp. nov., a new sporocarp-forming member of Pucciniomycotina, MycoKeys 8, pp. 43-50 : 46-47

Taxon classification Fungi Heterogastridiales Heterogastridiaceae

Pycnopulvinus Toome & Aime gen. nov.

Diagnosis.

Member of Heterogastridiaceae, Heterogastridiales, Microbotryomycetes, Pucciniomycotina. Pycnopulvinus is similar to Heterogastridium , but differs in possessing a distinct basal cushion, segmented spores, and pigmented sporocarps. Pycnopulvinus can also be distinguished with rDNA sequence data.

Type.

Pycnopulvinus aurantiacus Toome & Aime

Description.

Minute, pigmented stilboid sporocarps with a swollen basal region and long tubular neck bearing a mucoid droplet of spores at the tip.

Ecology and distribution.

On palm litter in South America (Ecuador); known from sequence data in Central America (Costa Rica).

Etymology.

pycno- = dense, compact, and pulvinus = cushion, for the distinctive cushion-like base of the sporocarp.

Discussion.

The genus is closely related to Heterogastridium , but has orange-colored fruiting bodies that are larger and form a distinct basal cushion. Of the other three genera currently recognized in Heterogastridiales (Kirk et al. 2008, Bauer et al. 2006), Pycnopulvinus can be readily separated from Colacogloea on the basis of DNA sequence data ( Aime et al. 2006), and the absence of stilboid fructifications or septate spores in the latter, from Krieglsteinera which does not form fruiting bodies or multicelled spores and parasitizes ascocarps, and from Atractocolax which forms smaller (140 μm diam.), gelatinous, hyaline sporocarps, produces unicellular spores and is associated with bark beetles. Currently, Pycnopulvinus is a monotypic genus. A previously undescribed isolate, CBS 176.95 (isolated from the tropical forest of Costa Rica and accessioned in the GenBank as " Pycnobasidium sp." - a generic name that has not been validly published - appears to represent a member of this genus. In the absence of morphological or other additional data, it cannot be determined whether CBS 176.95 is conspecific with Pycnopulvinus aurantiacus or represents a second species of Pycnopulvinus . Despite the rapid accumulation of environmental sequencing data, no studies thus far have published sequences referable to Pycnopulvinus , indicating that members of the genus are probably not widely dispersed in commonly sampled habitats.