Tetrapyrgos atrocyanea (Métrod) E. Horak, Sydowia

Honan, Amy H., Desjardin, Dennis E., Perry, Brian A., Horak, Egon & Baroni, Timothy J., 2015, Towards a better understanding of Tetrapyrgos (Basidiomycota, Agaricales): new species, type studies, and phylogenetic inferences, Phytotaxa 231 (2), pp. 101-132 : 107-108

Tetrapyrgos atrocyanea (Métrod) E. Horak, Sydowia 39: 102. 1987 [1986]

Basionym: Pterospora atrocyanea Métrod, Prodr. Fl. Mycol. Madag. 3: 140. 1949.

Holotype:— MADAGASCAR. Tananarive , 16 December 1934, leg. R. Decary 1642 (PC!).

Description is adapted from protologue ( Métrod 1949) and from type study by Horak (1968).

Pileus 25 mm diam., convex, striate; disc bluish black; margin bluish violet; context thin, tough, gelatinous. Lamellae arcuate-decurrent, close to crowded, narrow, white; edges obtuse, flocculose. Stipe 30–35 × 1–1.5 mm, hollow, pruinose, curved and thickened at the base; apex white; base bluish violet to greyish violet.

Basidiospores 7–8 × 2.5–3.5 μm, ovoid with two lateral wings 2–2.5 μm long ( Métrod 1949), 7–9 μm broad and long, tetrahedral ( Horak 1968), hyaline. Basidia 30–40 × 6–7 μm, 4-spored. Pleurocystidia absent. Cheilocystidia 45–55 × 3.5–5 μm, cylindrical, apex cylindrical or slightly swollen, irregularly diverticulate, hyaline. Pileipellis and stipitipellis of versiform cells, diverticulate, ramose, hyaline. Pileus and lamellar tramal hyphae 1.5 μm diam, thin-walled, gelatinous. Subhymenium tightly packed, non-gelatinous.

Habitat and known distribution: On soil in pasture. Madagascar.

Material examined: Holotype.

Commentary: This species is known from the holotype specimen that is stored in alcohol (Herb. PC), and represents the type species of the genus Tetrapyrgos . Horak (1968) has studied the holotype and published an analysis and figures of micromorphological features. The documentation of “ovoid spores with wings,” Rameales -type cells on the pileus, stipe, and lamellar edges, and a stipe with a white apex and bluish black base, provide enough data to help circumscribe the genus Tetrapyrgos . More material is required to determine whether this taxon from Madagascar is distinct from T. subcinerea (described from Sri Lanka and reported herein from throughout southern Asia and parts of Africa), or whether it represents a later synonym of T. subcinerea . Until additional material becomes available for analysis, we recognize the holotype as representing a distinct species.