Marasmius dichromopus Speg., Bol. Acad. Nac. Cienc.

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 : 128-129

Marasmius dichromopus Speg., Bol. Acad. Nac. Cienc. Córdoba 28: 293. 1926. Fig. 11a–d

Accepted as a synonym of Tetrapyrgos nigripes by Singer (1973) and Horak (1983).

Holotype:— ARGENTINA. Buenos Aires Prov.: La Plata, on decayed debris of Eucalyptus globulus ( Myrtaceae ), 16 May 1919, C Spegazzini 2690 ( LPS!).

The holotype specimen consists of one intact basidiome and one fragmented basidiome. Description of dried holotype: Pileus <5 mm diam, convex, striate, dull, pale brown. Lamellae adnate, subdistant (about 14), narrow, pale brown. Stipe about 10 × 1 mm, central, pruinose, darker brown. Material badly infected by mold. Basidiospores (few observed) 8–9 × 6–7.8 μm, triangular with a distinct lateral bulge to tetrahedral, hyaline, inamyloid, thin-walled. Basidia 19–25 × 5–6.5 μm, 4-sterigmate, clavate, clamped. Basidioles subfusoid to clavate. Pleurocystidia absent. Lamellar edges badly eroded; cheilocystidia few observed, clavate, diverticulate. Pileipellis a well-developed Rameales -structure; hyphae irregularly knobby and diverticulate, inamyloid. Pileus trama weakly gelatinous. Clamp connections present.

Status: The central stipe, weakly gelatinized tramal tissues, and tetrahedral spores indicate placement in Tetrapyrgos . While we accept this as a species of Tetrapyrgos , whether it represents the more northern T. nigripes or the more southern T. longicystidiata is unclear. The material was collected on Eucalyptus , a tree introduced into Argentina from Australia, which may suggest that this Tetrapyrgos species represents an introduced Australasian taxon.

Figures

FIGURE 11. Anatomical features for: Marasmius dichromopus (Spegazzini 2690—Holotype a–d). a. Basidiospores. b. Basidiole. c. Cheilocystidia apices. d. Pileipellis terminal cells. Marasmius nigripes var. albus (Corner E192522—Holotype e–g). e. Basidiospores. f. Cheilocystidia. g. Pileipellis terminal cells. Scale bar = 10 μm. Illustrated by D.E. Desjardin.