Tetrapyrgos olivaceonigra (E. Horak) E. Horak, Sydowia 39: 102. 1987 [1986]. Fig. 4a–c

Basionym: Pterospora olivaceonigra E. Horak, Sydowia 36: 131. 1983.

Synonym: Campanella olivaceonigra (E. Horak) T.W. May & A.E. Wood, Mycotaxon 54: 149. 1995.

Holotype:— NEW ZEALAND. Mid Canterbury: Craigieburn Range, Broken River, Dracophyllum Flat, on stems of Juncus sp., 3 April 1983, E Horak ZT 2131 (PDD 27170!).

The holotype specimen consists of three basidiomes loose in the packet plus several tiny primordia attached to a stem fragment of Juncus sp., all in fair condition.

Description of dried holotype: Pileus plano-convex; lamellae narrowly adnate, intervenose, narrow; stipe eccentric, pruinose, not appreciably darkened, arising from a very small patch of buff-colored mycelium.

Macromorphological data adapted from the protologue (Horak 1983): Pileus up to 7 mm broad, conchate; surface minutely velutinous, grayish white to olivaceous. Lamellae well-developed to vein-like, anastomosing, concolorous with the pileus. Stipe –3 × – 1 mm, eccentric, cylindrical; surface tomentose, olivaceous black. Odor absent.

Micromorphological analysis of the holotype: Basidiospores 8–11 × 5.5–7 μm, triangular with a rounded lateral bulge, not distinctly tetrahedral, hyaline, inamyloid, thin-walled. Basidia 32–38 × 8–9.5 μm, 4-sterigmate, clavate, clamped. Basidioles clavate. Pleurocystidia absent. Cheilocystidia 40–55 × 3.8–6.5 μm, common, irregularly cylindrical with an apical capitulum 6.5–9.5 μm diam; central axis with a few knobby diverticula (identical to those as drawn in the protologue), hyaline, thin-walled. Pileipellis a well-developed Rameales -structure of diverticulate hyphae; terminal cells entirely diverticulate or a few with a smooth apical capitulum like the cheilocystidia. Pileus trama weakly gelatinized. Clamp connections present.

Habitat and known distribution: On stems of Juncus sp. (type) (Juncaceae) and Rubus spp. (Rosaceae) New Zealand (Horak 1983) and Australia (May & Wood, 1997).

Material examined:— AUSTRALIA. Victoria: E. Highlands, Gembrook, Mortimer Reserve, 12 May 2003, EL Lewis 880 (MEL 2231603); Victoria: Otway Range, Corner of 22 and Upper Gellibrand Rd to Stevenson Falls, 24 June 2003 SH Lewis 950 (MEL 2220682). NEW ZEALAND. Mid Canterbury: Craigieburn Range, Broken River, Dracophyllum Flat, 3 April 1983, E Horak ZT 2131 (PDD 27170, holotype; ZT, isotype); Gisborne, Urewera National Park, Ngmoko Track, 10 May 2001, G Gates and D Ratkowsky (PDD 74314).

Commentary: First described as Pterospora (Horak 1983), later transferred to Tetrapyrgos (Horak 1987), and then transferred to Campanella (May & Wood 1995), the triangular spores with a broad lateral bulge (nearly tetrahedral), capitate cheilocystidia with central diverticula, weakly gelatinized tramal tissues, and well-developed stipe (albeit small and eccentric) indicate that it is best accepted in Tetrapyrgos. The ITS sequence of a specimen of T. olivaceonigra from Australia (MEL 2220682) is sister to T. subdendrophora with 100% BS and 100% PP support, and differs from three Californian specimens of the latter by only 2.7%. Morphologically the two species are nearly indistinguishable, differing only subtly in basidiome pigmentation, but because of their geographic separation in different hemispheres, we prefer to recognize them as distinct taxa. Excellent illustrations of material from New Zealand are provided by Horak (1983) and of Australian material by May (1989).