Polyporales » Gelatoporiaceae » Obba

Obba valdiviana

Obba valdiviana (Rajchenb.) Miettinen & Rajchenb. 2012, in Miettinen& Rajchenberg, Mycological Progress, 11, 131-147 (2012).

Description: Description Basidiocarp annual to biennial, resupinate, snow-white, initially forming small, circular to elongated bodies up to 13×9 cm, but fusing and often covering large surfaces. Consistency hygrophanous and fleshy when fresh, hard and waxy to bony and detaching from substrate upon drying, yet easy to cut with a razor blade. Pore mouths felty and white, often resinous in cross section, 68/mm, tubes 0.55 mm long, up to 11 mm in Tasmanian material. Subiculum white when fresh and brown cartilaginous line when dry, 0.10.3(0.5) mm. Sterile margin distinct or not, up to 1 mm wide, felty, slightly separated from substrate but always well attached to it.

Hyphal system monomitic, CB, IKI, CRB+, hyphal walls swell inwards in KOH. Hyphae thin- to slightly thick-walled, (1.5)2.03.7(4.2) μm in diameter in subiculum, (1.5) 2.02.7(3.7) μm in trama, clamps present. Irregular crystal rosettes common in trama and tube mouths, typically 57 μm in diameter, in upper trama also some rhomboidal plates present, up to 20 μm long. Subiculum partly to fully agglutinated, hyphae mostly horizontally arranged and subparallel, in agglutinated parts sinuous and difficult to tell and break apart, partly covered with slime: tissue rather dense, hyphae intervowen to subparallel, thin-walled at least in lower trama. Subhymenium tightly arranged, hyphae interwoven. Small oil droplets floating around in microscopic slides. Cystidia none. Hymenium. Cells commonly with oil droplets. Basidia broad clavate to rarely constricted cylindrical, 16.522× 6.59 μm, with 4 sterigmata. Cystidioles fusiform to mammiform, common, 1320×68.2 μm. Basidiospores globose to subglobose, hyaline, CB(+), IKI, with thin to slightly thickened walls, smooth, (4.5) 4.65.3(5.6)×4.25.0(5.2) μm, L=4.99 μm, W=4.63 μm, Q'=1.01.2, Q=1.08, n=90/3 based on the Argentinian material, with a prominent hyaline, oily-like guttule in the otherwise cyanophilous cytoplasm.

Index Fungorum Number: IF519511

Notes: Remarks Obba rivulosa differs from O. valdiviana by larger pores and narrower, broadly ellipsoid basidiospores (Figures 3 and 5). Known distributions of the species do not overlap. Preliminary di×mono compatibility tests (Hallenberg 1984) performed between the polyspermic culture obtained from O. valdiviana holotype (CIEFAP culture collection 159) and 4 monosporous cultures of O. rivulosa from USA (FP 133035) gave negative results (Rajchenberg 1995). Nakasone (1981) described the strain derived from FP 133035 (USA, Oregon, Marys Peak, on Tsuga, 8. XI.1971 MJ Larsen) in her culture study of O. rivulosa, and we have studied fruiting bodies collected from the same area for this study. The Tasmanian material differs from the Argentinian material genetically (ITS distance 1.3%). No clear morphological character separates the two (Figure 5). Further sampling and closer study are needed to determine whether the two are separate species.


Figure 1. Consensus phylogram of the 22,503 trees retained in the Bayesian analysis of nrDNA ITS and LSU. Numbers represent Bayesian posterior probabilities. Branch lengths reflect expected changes per site as indicated by the scale. Clade names follow Binder et al. (2005), family names Larsson (2007), and order names Hibbett et al. (2007).


Figure 2. Cinereomyces clade consensus phylogram of the 4,503 trees retained in the Bayesian analysis of nrDNA ITS region. Numbers represent Bayesian posterior probabilities. Branch lengths reflect expected changes per site as indicated by the scale.



Figure 3. Obba valdiviana, isotype: a hymenial cells and tramal crystals, b spores. Obba rivulosa, Miettinen 8054: c spores. Cinereomyces lindbladii, Kotiranta 19911: d spores. Gelatoporia subvermispora, Kotiranta 20823: e spores, f encrusted hyphal ends in lower trama.