The North American Species of Crepidotus
63. Crepidotus nephrodes (B. & C.) Sacc., Syll. Fung. 5: 882. 1887.
Agaricus (Crepidotus) nephrodes B. & C., Ann. & Mag. Nat. Hist. II: 12: 422. 1853.
Crepidotus fulvifibrillosus Murr., North Amer. Flora 10: 153. 1917.
Crepidotus applanatus var. fulvifibrillosus (Murr.) Pilát, Monogr. des especès europ. du genre Crepidotus, p. 35. 1948.
Pileus 2-9 cm broad, sessile, convex to conchate, becoming flabelliform to subreniform, white or whitish, yellowish-white, grayish-white, or grayish-olive buff, brownish-fibrillose to squamulose, at times villose-tomentose, margin at first incurved, in age obscurely striatulate when wet. Context whitish, moderately thick; odor and taste mild, or taste at times disagreeable (astringent, nauseous, or bitter).
Lamellae radiating from the villose basal tubercle, rounded-adnate, white, pallid, or grayish, at first, finally brownish, close, narrow to medium broad, edges entire.
Spores in deposit: "Sayal brown," "Dresden brown," "Saccardo's umber," or "buffy brown," (4.5) 5-7 (7.5) µ in diameter, globose to subovoid, punctate, pale cinnamon in 2% KOH. Basidia (20) 30-36 x 5.5-7 µ, 4 -spored. Pleurocystidia none; cheilocystidia 28-53 x 5-9 (12) µ, clavate or ventricose, at times with a neck, or subcapitate. Gill trama subparallel, hyphae 6-15 µ broad. Pileus trama loosely interwoven. Cuticle of repent hyphae, bearing scattered to dense fuscous or brownish fibrils, at times aggregated to form squamules, some hyphae incrusted. Clamp connections present.
Habit, Habitat, and Distribution: On hardwoods, logs, stumps, and fallen branches, eastern United States, June-Sept.
Material Studied: MAINE: Bigelow 10766 (MASS); MASSACHUSETTS: Bigelow 7259, 8326 (MASS); MICHIGAN: Imshaug 3653 (MICH): Potter 3087, 3105, 3408 (MICH); Shaffer 681, 2828 (MICH); Smith 9553, 57183, 57861, 66266, 66385, 66863; Thiers 694, 3952, 3967; NEW HAMPSHIRE: Bigelow 11785,11786 (MASS); Miller 569 (MICH); NEW YORK: Deegan 45, H84 (MICH); C. V. Smith (CUP 5528); NORTH CAROLINA: Hesler 5118; Smith 10842; SOUTH CAROLINA: Ravenel, type (K); TENNESSEE: Hesler 25059, 25675; VIRGINIA: Murrill 104, type (NY) of C. fulvifibrillosus, from Falls Church, July 2-6, 1904; WISCONSIN: Shaffer 681 (MICH).
Observations: Berkeley and Curtis (1853) originally described Agaricus (Crepidotus) nephrodes, on material sent to them from South Carolina by Ravenel. Subsequently, Murrill (1917) described a Virginia collection as C.fulvifibrillosis. Although Murrill knew of C. nephrodes, he distinguished his Virginia collection from it, chiefly on the macroscopic character of the fibrils on the pileus surface. Neither Murrill nor Berkeley and Curtis studied critically the microscopic features of these fibrils nor of other structures. In 1947, Singer recognized the two as distinct species, separating them on gill width and pileus fibril-ornamentation, and adding that C. nephrodes is not really different from what is commonly called C. malachius in North America. Pilát (1948), in his studies of European Crepidotus, including some North American species, obviously looks upon C. applanatus as a very broadly-conceived species, for he places a number of species-names in synonymy. For example, he places C. nephrodes as a synonym under C. applanatus and proposes that Murrill's C. fulvifibrillosus be attached to applanatus as a variety. He bases his proposal on the squamulose-tomentose character of the pileus of Murrill's species. Singer (1947) says that C.fulvifibrillosus is identical with C. applanatus, except for the scales on the former; and further, that the specific value of these scales must be established. Finally, Singer (1962) recognizes as valid distinct species, applanatus, fulvifibrillosus, and nephrodes, listing several synonyms of nephrodes, including malachius, hygrophanus, leucochrysos, and possibly putrigenus and others (see Singer, 1962: 662). Our studies of the types of C. nephrodes and C. leucochrysos indicate some relationship, but the latter species is without brown, incrusted hyphae on the pileus and lacks clamp connections.
We have studied numerous North American collections, and also the available types, and are now convinced that fulvifibrillosus is the same as nephrodes; that malachius, hygrophanus, putrigenus, and applanatus are distinct species (see our proposed keys and descriptions herein).
The types of C. nephrodes and C.fulvifibrillosus show some variations but no difference in their fundamental structure. The lamellae vary, in collections studied, from moderately narrow to moderately broad; and, in spacing, from crowded to close or moderately close. The color of the young gills seems to vary from whitish to pallid or grayish. The pileus in both types (and in other collections) bears brown, incrusted hyphae. These hyphae, however, vary in distribution and density, and thus may be either scattered or dense, or they may stand more or less separately, or aggregated to form fibrillose scales.
In our effort to separate nephrodes and fulvifibrillosus, we have found no character, nor a combination of characters, which we regard as valid for such a separation.