Hourangia cheoi (W.F. Chiu) Xue T. Zhu & Zhu L. Yang, in Zhu et al., Mycol. Progr. 14(no. 37): 3 (2015)
Basidioma small to medium-sized. Pileus 2–8 cm in diam., hemispherical, convex to applanate, sometimes umbonate; surface densely covered with redbrown or dull brown granular squamules when young, becoming rimose-diffract to small tuft squamulae with age, dry, sometimes staining blackish; context dirty white, bluing quickly, then changing to reddish or reddish brown in a few minutes, finally becoming brownish to blackish slowly. Hymenophore adanate, sinuate or slightly decurrent; surface flesh yellow, becoming dull yellow when mature, bluing quickly when injured, 3–5 (7) times thick of pileal context at the position halfway to the center of the pileus; pores compound, angular, 0.5–2 mm wide; tubes 5–12 mm long, concolorous with hymenophoral surface, staining blue when injured. Stipe cylindrical, 5–8×0.3–0.6 cm, solid, brown, pale red-brown to dirty pale brown, nearly smooth, sometimes finely fibrillose; context dirty white, changing bluish slowly at the upper part, then changing to reddish to reddish-brown, other parts becoming reddish to reddish-brown directly, finally all becoming brownish to blackish slowly when cut; basal mycelia dirty white. Taste and odor mild.
Basidiospores [360/21/21] (8.5) 10–12.5 (14.5)×(3.5) 4–4.5 (5.5) μm [Q=(1.81) 2.26– 2.71 (3.13), Qm=2.48±0.23], subfusiform in side view with slight suprahilar depression, narrowly oblong to subfusoid in ventral view, brownish yellow, inamyloid, with bacillate surface ornamentation under SEM. Basidia 27–34×8–11 μm, clavate, hyaline in KOH, 4- spored, sterigmata 4–5 μm long. Hymenophoral trama, phylloporoid; Pleuro- and cheilocystidia scattered, 50–90× 7–17 μm, lanceolate to clavate or ventricose, thin-walled, hyaline, sometime spale yellow-brown. Caulocystidia 60–80× 5–9 μm, clavate. Pileipellis a trichoderm, composed of cylindrical cells with terminal cells 20–55×7–13 μm in youth, of moniform hyphal elements with subglobose terminal cells 35– 70×17–30 μm with age; pileipellis elements with pale yellowbrown to pale brown vacuolar pigments. Clamp connections absent in all tissues.
Habitat: On the ground in the forests of Pinus, Castanopsis, Lithocarpus and Quercus, sometimes on the bark of the stem base of Pinus spp.
Known distribution: Currently known from southwestern China and Japan.
Index Fungorum number: IF810696
Notes: The quickly bluing context of pileus and large spores (10–12.5×4–4.5 μm) can be used to distinguish H. cheoi from other species of Hourangia. Chiu (1948) described both Boletus cheoi and B. punctilifer in the same paper. According to Chiu (1948, 1957), B. cheoi was separated from B. punctilifer by the umbonate cap, the broad adnate tubes and the glabrous stipe. Re examination of the types and newly collected materials indicated that all these characters are unstable, and there is no distinction of macromorphologica and/or micro-morphological features between B. cheoi and B. punctilifer. Chiu (1948) cited three additional collections under B. punctilifer besides the type. Two of them are H. cheoi. The third collection C.C. Cheo 7735 (HMAS 03735) has much broader basidiospores (12–15.5×5–6 μm) than those of the collections cited above, and may represent a different species. Xerocomus nigromaculatus (Hongo 1966) is similar to H. cheoi. However, X. nigromaculatus differs from H. cheoi by the blackish staining of the pileus and the stipe.
Figure 1. Phylogram resulting from the multi-gene (ITS, nrLSU, tef1- α, rpb1 and rpb2) data set using RAxML. RAxML likelihood bootstrap support values (>50 %) and Bayesian posterior probabilities (PP >0.95) are indicated above or below the branches as RAxML BS/PP. Herbarium voucher or isolate number is provided behind the species name.