First person to use this name on MO: Image Sharer
Etymology: Latin convexa, referring to the convex pileus.
Pileus 1.0–3.6 cm diam, convex, surface orange-buff at first, then light, sudan brown at center, fibrillose. Lamellae white, up to 0.3 cm broad, crowded, adnate, without lamel- lulae. Stipe 2.0–6.0 cm long × 0.2–0.9 cm diam, central, cylindrical, expanded at base, fibrous, solid at first, fistulose when mature, surface white or pale brown at the apex, striate, sometimes tortuous. Pileus context up to 0.2– 0.3 cm thick near stipe attachment, thin at margin, white to cream-colored. Smell slightly farinaceous. Spore deposit white.
Basidiospores 2.0–3.0 × 1.8–2.5 μm, Q = 1.13, sub- globose, hyaline, inamyloid, surface smooth under scan- ning electron microscope. Basidia 12–18 × 2.5–4.3 μm, clavate, four sterigmate, subhyaline, siderophilous granules present in acetocarmine and FeSO4. Hymenial cystidia 12–16 × 2.0–4.0 μm, fusiform, thin-walled. Hymenophoral trama 200–220 μm broad, regular with thin-walled hyphae 2.0–5.0 μm diam, hyphae not pigmen- ted, subhymenial layer 35–47 μm broad. Pileipellis an epicutis of dense, radially parallel, repent hyphae, hyphae 3.0–6.5 μm diam, smooth, thin-walled, pigmented. Stipitipellis hyphae 2.4–8.5 μm diam, smooth, thin-walled, not pigmented. Clamp connections present.
Habit, habitat, and distribution: Saprophytic in small groups on soil in coniferous forests. Known from northeastern China.
Additional specimen examined: CHINA. LIAONING PROVINCE: Shenyang City, Mountain Hui, on soil, 6 Jul 2013, YXD no. 254 (SYAU-FUNGI-007).
Comments: The main characters of C. convexa are the orange-buff pileus, very small basidiospores, and tortuous stipe. All the characters indicate that C. convexa belongs to Sect. Carneoviolaceae (Singer 1986). Within this section, C. convexa is similar to C. alpestris in having a yellow pileus. However, the basidiospores are smaller than in C. convexa (2.0– 3.0 × 1.8–2.5 μm) than in C. alpestris (6.2–6.8 × 2.7–3.0 μm) (Singer 1978). Furthermore, C. convexa has a tortuous stipe, which is absent in the other species in this section. In the molecular analyses, C. convexa grouped in Clade II. In this clade, the pileus of C. ionides and that of C. obscurissima have a violet tone (Pearson 1946; Bon 1987), which differs from C. convexa, which has a yellow-colored pileus. Based on the color of pileus, C. convexa also differs from C. gambosa, which has a white pileus (Bon 1987). The gills of C. carnea and C. persicolor are white (Fries 1874; Singer 1978), and the pileipellis features a cellular epicutis (Singer 1986), both of which characters differ from C. convexa.
- Mycologia: 10.1080/00275514.2017.1286570, 7 (2017)