Russula cf. crustose

Russula cf. crustose

Pileus 38.2 – 70 mm diam., convex when young, then plane with a depressed centre to infundibuliform when mature, surface viscid when moist, pale yellow (161D), yellowish white (N155D) gradually to white (N155D) at the margin, margin incurved when young and becoming upturned when mature, striate. Lamellae 63 mm wide, adnexed, crowded, white (NN155D), unchanging when bruised, with lamellulae in 3–4 series, edge entire. Stipe 25–32 × 10–15 mm, central, cylindrical, surface finely longitudinally venose, white (NN155D). Context solid to stuffed or hollow stipe when mature, white, unchanging after treating with KOH. Odour indistinct. Spore print absent. Basidiospores 4.88–7.56 × 4.80–6.39 μm (Q= 1.02 –1.18 – 1.30), sub globose to broadly ellipsoid, ornamentation composed of warty amyloid with connecting lines forming slightly reticulate, up to 1 μm high. Basidia 17.79–35.10 × 4.28–8.40 μm, subclavate to clavate, with 4 spores, sterigmata 1.11 – 3.87 μm long. Pleurocystidia 51.9 – 64.68 × 7.09 – 13.23 μm, abundant, capitulate, thin-walled. Cheilocystidia not found. Lamellar trama composed of numerous sphaerocytes surrounded by connective hyphae; sphaerocytes globose to elliptical. Pileocystidia not observed.

Note: Russula cf. crustosa and R. crustosa macroscopic and microscopic features were indistinguishable, except pileus colour, pileus surface and basidiospore size. R. crustosa can be recognized by brownish-yellow, greenish, or subolivaceous pileus, and the cuticle cracking and forming small spot-like areolae on pileus surface. On the other hand, Russula cf. crustosa had yellowish white pileus, surface smooth. Moreover, Russula cf. crustosa differs from R. crustosa by having smaller basidiospores.

Fig. 1 Phylogenetic tree of eight Russula specimens, one Lactarius specimen (indicated in bold), and some reliable best-hit sequences from GenBank database using Maximum Likelihood method. Number at the node indicates bootstrap values. Termitomyces microcarpus was used as an outgroup.