Cercopemyces crocodilinus T.J. Baroni, Kropp & V.S. Evenson, in Baroni et al., Mycologia 106(4): 786 (2014)
Etymology: The specific epithet, crocodilinus, refers to the erect, thick pyramidal scales on the pileus surface, resembling the dorsal surface of a crocodile (Latin crocodillus).
Diagnosis: Distinctive from the other species in the genus by the white pileus and stipe, the thick pyramidal scales or conical warts covering the pileus, the pale cream sinuate or adnexed, close, narrow lamellae, the short equal stipe with bulbous-napiform base with an ephemeral ring of conical-shaped floccose warts adhering to the top of the bulb and larger basidispores (4.8–6.4 (3.5–5.5 µm) than found in Cercopemyces ponderosus (3.6–4(–5) x 2.7–3 µm.
Pileus white but with pale buff brown or pale earthen brown especially over the disk (10YR9/4–8/6 Munsell), 40–100 mm broad, convex, becoming broadly and shallowly depressed with expansion; surface dry, becoming subareolate, densely covered with fleshy conical firmly attached pyramidal scales that are 1–4 mm across and white or concolorous with earthen or with pale yellow hues mixed in; near the margin small floccose scales form an appendiculate veil along the margin; margin inrolled, remaining incurved with expansion. Flesh features not recorded when fresh, but as dried uniformly white, thick (10 mm). Lamellae white when fresh, becoming pale cream yellow or cream olive buff when dried, sinuate or finely adnexed, not free, close or almost crowded, with numerous short lamellulae, narrow (5 mm in dried state), edges more or less even, concolorous. Stipe white with pale buff earthen brown as in the pileus, 42–62 mm long, 15–27 mm broad at the apex, 35–50 mm broad at the base, more or less equal with a bulbous and napiform base on some, bulbous portion similar in length to upper equal portion making the stipe seem short; surface dry, glabrous but with a ring of ephemeral, white conical floccose rounded scales adhering to the top of the basal bulb in a collar-like ring; this tissue similar to that of the appendiculate margin of the pileus indicating a universal or peronate veil was present in button stages; flesh white, solid as in pileus, unchanging when exposed; basal mycelium white, tightly binding soil and humus. Odor fungoid. Taste not determined.
Basidiospores hyaline under compound light microscope, 4.8–6.4 × 3.5–5.5 µm (n = 40/2, x = 5.44 ± 0.40 × 4.0 6 0.40 µm, Q = 1.02–1.6, Qm = 1.37 6 0.13), ellipsoid, broadly ellipsoid or some globose (Q = 1.02), round in polar view; walls inamyloid, cyanophilic with a delicately punctate roughened ornamentation that can be observed in Melzer’s reagent or cotton blue in lactic acid with the aid of DIC optics, but best observed with SEM. Basidia (1–) 4-sterigmate, long, narrowly clavate, 27–36 × 6.4– 8(–9) µm, with long, tapered sterigmata, 4–5.6 µm long and 1.6 µm wide at the base, lacking cyanophilic bodies in the basidia. Hymenial cystidia absent. Lamella trama hyaline, parallel, cylindrical or slightly inflated hyphae, 4–12 µm diam; cells often short (20– 60 µm long). Pileipellis a hyaline or a sordid, yellowish tan layer of loosely interwoven cylindrical hyphae, 4– 8(–10) µm diam, not well differentiated from the context, not encrusted; the pyramidal scales composed of two layers, an upper yellowish brown compact layer, 160–240 µm deep, often with abundant cystidiate inflated end cells present, overlying a deeper (800–1000 µm) hyaline, loosely entangled layer of cylindrical or slightly inflated hyphae, 5 – 10 µm diam, this hyaline layer also with some scattered inflated cystidiate end cells in the upper regions near the yellowish brown compact layer; cystidiate end cells, 28–62 × 12–18(–24) µm, variable in shape: clavate, capitate, fusiform, sphaeropedunculate, broadly lageniform, utriform, occasionally septate. Pileus context hardly differentiated from the pellis, composed of hyaline, loosely or densely interwoven, hyphae that are mostly cylindrical, some slightly inflated, 4–16 µm diam. Stipitipellis a hyaline layer of repent, interwoven, narrowly cylindrical hyphae, 3.2–5.6 µm diam, not encrusted; the conical floccose warts making up the ring on the surface of basal bulb composed of hyaline, interwoven, cylindrical hyphae, 4–16 µm diam, with many swollen inflated cystidiate end cells similar in construction and size to the cystidiate end cells found on the pileus margin and in the upper layers of the pyramidal warts on the pileus surface. Stipe context a hyaline compact layer of parallel or somewhat interwoven, cylindrical or slightly inflated hyphae, 6–15 µm diam., thin-walled, mostly filled with refractive bodies of various dimensions. Clamp connections present in all tissues.
Habit and habitat: Solitary, gregarious, caespitose, or scattered, on the ground, under Cercocarpus ledifolius with Pinus monophylla present (Raft River Mountains, Utah) or associated with Cercocarpus montanus (east slope of the Colorado Rocky Mountains). June.
Index Fungorum number: IF805635
Figure 1. Phylogram resulting from a Bayesian analysis of a combined nLSU-rpb1 dataset shows placement of Cercopemyces crocodilinus. Support measures shown for nodes with 79 percent or greater posterior probability support. GenBank numbers represent nLSU sequences.
Figure 2. Phylogram resulting from a Bayesian analysis of a combined nLSU-ITS dataset showing placement of Cercopemyces crocodilinus. Support measures are shown for nodes with 80 percent or greater posterior probability support. GenBank numbers are for nLSU sequences.
Figure 3. Phylogram resulting from a Bayesian analysis of ITS sequences including species of Cercopemyces. GenBank numbers are for the ITS sequences.