The following text is from the original introductory material. No attempt has been made to update the nomenclature to current status as found on the remainder of this site. For example, Gymnopus dryophilus is called Collybia dryophila below. Likewise, Rhodocollybia butyracea is still referred to as Collybia butyracea. Other examples will be apparent.
The first use of the name "Collybia" was by Fries (1821) who placed small, white-spored mushrooms with a fleshy-membranous pileus and a hollow stipe in Agaricus tribe Collybia. The species that he included were arranged in two subdivisions of the tribe, the Genuinae and the Omphalariae. The Genuinae contained 16 species with slightly fleshy pilei and hollow stipes, and the Omphalariae had nine species that possessed membranous, plicate-rugose pilei and slender stipes with a horn-like texture.
In the "Epicrisis Systematis Mycologici," Fries (1838) placed 75 species in Agaricus tribe Collybia. These species were characterized by white spores, an incurved pileus margin, central cartilaginous stipes, and putrescent basidiocarps (i.e., they did not revive when moistened). The Genuinae and Omphalariae were abandoned as taxonomic units, and four new sections of tribe Collybia were introduced: Striipedes, Levipedes, Vestipedes, and Tephrophanae. With the incorporation of many different species in these new sections, Agaricus tribe Collybia of the "Epicrisis" clearly represented a change in Fries’s concept of the tribe from that previously outlined in the "Systema." In fact, nearly all of the species in Agaricus tribe Collybia of the "Systema" were included in Marasmius tribe Collybia of the "Epicrisis." Even though Staude (1857) intially recognized Collybia as a genus, and Kummer (1871) subsequently provided the first valid combinations in Collybia, they did not group species by infrageneric categories. Nevertheless, Fries’s four sections of Agaricus tribe Collybia established the primary groups around which the more comprehensive subgeneric classifications of Collybia were constructed (e.g., Quélet 1872, Peck 1897, Patouillard 1900, Ricken 1915, Kauffman 1918).
The modern history of Collybia involves the discovery of more species in a number of regions as well as the segregation of other fundamentally different species. An emphasis on microscopic characters in particular has helped to bring the limits of Collybia into sharper relief. For example, observations by Singer (1936, 1938, 1939a, 1943a) have contributed to substantiate earlier segregates such as Oudemansiella Spegazzini (1881), Crinipellis Patouillard (1889), and Flammulina Karsten (1891). In addition, Kühner’s (1938) investigations with acetocarmine provided the data for recognition of Calocybe Kühner ex Donk (1962), and gave taxonomic validity to Lyophyllum Karsten (1881) (including Tephrocybe Donk, 1962). The latter genera now incorporate nearly all of the species originally classified in Collybia section Tephrophanae.
Additional studies of other genera and species have contributed substantially to a better understanding of the limits of Collybia by the removal of obvious disparate elements. Such works include the recognition of Caulorhiza by Lennox (1979), and Baeospora, Callistosporium, and Strobilurus by Singer (1938, 1944, 1962b). Monographic treatments of Clitocybula (Métrod 1952, Bigelow 1973), Marasmiellus (Singer 1973), Marasmius (Singer 1976, Gilliam 1976), and supplements to Strobilurus Wells & Kempton 1971, Redhead 1980), and Cyptotrama (Redhead & Ginns 1980) have assisted indirectly in the circumscription of Collybia.
Traditionally, Collybia and Marasmius have been difficult to separate. The problem stems from the distinction between them conceived by Fries (1838); Marasmius revives when moistened and Collybia does not. Unfortunately, Fries included reviving (marcescent) and non-reviving (putrescent) species in both Collybia and Marasmius. His inconsistency has been a primary source of ambiguity for agaricologists (Peck 1897, Kauffman 1918, Smith 1949, Kühner & Romagnesi 1953). As Gilliam (1976) has pointed out, the major objection to use of reliability as a generic character is the subjectivity of determining its presence or absence. Clearly, microscopic features provide the most practical, accurate, and objective way of distinguishing between Collybia and Marasmius, and offer a means for recognizing a natural hiatus. Thus, revivability should be discarded as a character for differentiating Marasmius from Collybia.
In general, Tricholoma has been distinguished from Collybia on the basis of sinuate-emarginate lamellar attachment and basidiocarp stature and texture. Although these macroscopic characteristics are perhaps not as accurate or objective as microscopic features, they usually provide a practical method for generic identification. However, certain cases arise where the distinction is not readily apparent. For example, Tricholoma section Adusta contains species that might be confused with Collybia, but the former are not marcescent and lack clamp connections. Furthermore, evidence presented by Tyler et al. (1965) suggests a hiatus between Tricholoma and Collybia because Tricholoma species do not accumulate urea while species of Collybia do (except C. maculata and C. acervata).
Likewise, the classic distinction between Clitocybe and Collybia has been a difference in lamellar attachment and basidiocarp stature. An infundibuliform, umbilicate, or depressed pileus and decurrent lamellae have been used to differentiate Clitocybe. In contrast, Collybia typically possesses convex pilei and adnate lamellae. However, these macroscopic features are unreliable in a few instances (e.g., Clitocybe fellea and similar taxa), because the latter sometimes do not have depressed pilei or the lamellae may be somewhat adnate. Yet, it has been my experience that these species exhibit a combination of features that are generally foreign to Collybia: gray-brown colors, hygrophanous pilei, farinaceous odors and tastes, and putrescent basidiocarps.
As a consequence of the revisionary and comparative studies on individual species and segregate genera, a circumscription of Collybia seems now based on a more homogeneous group of species. This homogeneity is best represented by Singer’s (1975) synopsis of the genus, and with some modifications, his delimitation of Collybia is employed here.
Inasmuch as species of Collybia show considerable variation in stature, size, and consistency of basidiocarps, the taxonomy has come to rely on other features, especially microscopic ones. Many taxonomic criteria are commonly applied and well understood throughout agaric systematics, therefore the following discussion is limited to those characteristics judged to be particularly important in Collybia.
Spore deposit color and chemical reactivity. The color of the spores (basidiospores herein out) in a freshly deposited mass ranges from white to cream or pinkish buff to pinkish cream. The majority of species in subgenus Collybia produces white to cream colored spores (pinkish only in Collybia fusipes) that are unreactive to Melzer's reagent and cotton blue. Subgenus Rhodocollybia consists of species that yield a pink tinted deposit from which some spores are dextrinoid and cyanophilous. In the isolated case of C. fusipes, the pink, unreactive spores are associated with a "dryophila-type" orientation of the hyphae of the pileipellis (cf. Clemençon 1981, Fig. 2). Because of the unreactive spores and the hyphal orientation, C. fusipes (the type species of section Striipedes) is best accommodated in subgenus Collybia. In that subgenus, C. fusipes occupies an intermediate position, and re-inforces the contiguity of subgenus Collybia and subgenus Rhodocollybia.
Hyphal orientation in the pileipellis. There are two basic types of hyphal arrangement in the pileus surface: radial and interwoven. In addition, the hyphae are, by and large, repent and cylindric. Occasionally, though, some species have hyphal end cells that recurve from the repent layer (e.g., C. putilla, Fig. 84) or intercalary branches may form pileocystidia (C. cookei, Fig. 23). In C. acervata (Fig. 27) the hyphae form a trichodermium at first, but soon become repent.
Four of the six sections in subgenus Collybia recognized here can be characterized in accordance with consistent features in the hyphal arrangement and by specific configurations or elements. For instance, species in sections Levipedes and Striipedes have the pileipellis hyphae organized in an interwoven manner which has been termed a "dryophila-type cutis" or a "dryophila structure" by Singer (1975). The hyphae are frequently branched, often bifurcate and short-celled, and are best observed in a paradermal section (C. alkalivirens, Fig. 33; C. dryophila, Fig. 37). In section Vestipedes, the hyphae of the pileipellis are long and cylindric, more or less parallel with one another, rarely branched, radially oriented from the disc toward the margin, and lack short, lateral proliferations or knobs (C. subnuda, Fig. 59). Singer (1975) calls this type of hyphal orientation a "confluens-type cutis." Short lateral branchlets and knobs are known as diverticula and are diagnostic for section Subfumosae. These excrescencies are sometimes highly developed and appear as distinct elements (C. dysodes, Fig. 72) or they may be quite simple and inconspicuous (C. pinastris, Fig. 77).
Substrate. Species of Collybia are typically saprobic and will decompose lignin and cellulose (Lindeberg 1944). Additional evidence extrapolated from data on occurrence of oxidative enzymes in agarics support these contentions (e.g., Matsubara & Iwasuki 1972, Lamaison 1976, Marr 1979). In only one instance has a mycorrhizal association been reported for Collybia (C. butyracea with white pine, McArdle 1932). In some species, substrate preference is rather narrow and is useful for differentiating between related taxa. For example, Collybia agricola and C. earleae occur on soil, whereas C. dryophila fruits among leaf litter and sometimes on well-rotted wood. Collybia pinastris and C. contraria are apparently restricted to conifer needle litter. On the other hand, blackened fungous remains are usually a diagnostic substrate for section Collybia.
F. S. Earle (1909) was the first to designate a type species for Collybia. He selected a type on the basis of it being the first species mentioned by Quélet (1872). This was Agaricus radicatus Rehl.:Quélet. The next workers to deal with typification were Clements and Shear (1931), and they chose Agaricus dryophilus Bull.:Fries. This selection was accepted by Singer (1936, 1951), and Singer and Smith (1946). Donk (1949a) disagreed with previous workers and proposed that Agaricus tuberosus Bull.:Fries should be the type. He defended this proposal by pointing out that A. tuberosus was among the original species of the Genuinae in tribe Collybia in the "Systema" (Fries 1821) whereas A. dryophilus was not. He considered A. radicatus to be a poor choice as it is referable to Oudemansiella rather than Collybia. Furthermore, A. tuberosus was one of the species not transferred to Marasmius by Fries in 1838. Kummer (1871) included it when he made valid combinations in Collybia. The proposal of A. tuberosus has been accepted as lectotype by Singer (1962a, 1975), Rogers (1950), Dennis (1951), Horak (1968), Pegler (1977), and Kühner (1980).
Until Donk (1949a) rediscovered Kummer’s book, Quélet (1872) was considered the first to recognize Collybia at generic rank. Later that same year, Donk (1949b) pointed out that Staude (1857) had used the generic name 14 years earlier than Kummer. Even though Staude did not combine species in Collybia, Donk insisted that Staude had validly published the genus and that Collybia (Fr.) Staude (with A. tuberosus as type) should be conserved against Gymnopus Pers. ex S.F. Gray [Gymnopus (Pers.) Roussel]. Donk typified Gymnopus with Agaricus fusipes Bull.:Fries.
Both Rogers (1950) and Singer (1955) disagreed with Donk in regard to Staude’s generic names, suggesting that these names were invalid. Also, Rogers (1949, 1950) thought conservation of Collybia unnecessary in light of the typification of Gymnopus presented by Singer and Smith (1946). Nevertheless, Donk (1962) persisted in his proposal for conservation of Collybia against Gymnopus. This proposal has been accepted by the General Committee at the Twelfth International Botanical Congress (Stafleu, et al. 1978).
Descriptions of macroscopic features are based on fresh material except where otherwise noted. Color terms cited as plate, column, line (e.g., 5B4) are from Kornerup and Wanscher (1967). More complex notations from the latter such as 4,5B4; 4,5B4,3; 5B4,3; 5B-C4; 5B-C-D4; 4,5B-C4,3; indicated all possible plate, column, line combinations for that designation. Color names within parentheses (ochraceous buff) are those of Ridgway (1912). Designations given as a number and abbreviated color name (e.g., 80. gy.y Br) are taken from the ISCC-NBS Color Name Charts illustrated with Centroid Colors (Kelly & Judd 1955).
Examinations of cortical layers of the pileus were made by viewing three types of sections: radial, tangential, and paradermal. These were usually taken from an area of the pileus midway between the disc and margin. An initial comparative survey of different regions of the pileus seemed to indicate that the three types of sections from this mid-region gave the clearest picture of the number and thicknesses of layers present. Moreover, the orientation of the hyphae and types of hyphal elements could be determined easily. To study the cortical layers of stipes, tangential or radial sections or both were cut from a point approximately halfway between the apex and base. Again, a preliminary survey showed that these sections provided the best depiction of the layers and revealed any surface ornamentation. The presence or absence of cheilocystidia was best determined by viewing intact lamellar edges.
The reaction of spore walls to Melzer’s reagent is described as inamyloid (no reaction), dextrinoid, (reddish-brown reaction), or amyloid (blue to black reaction).
Line drawings were made either with the aid of a camera lucida attached to an American Optical Microstar compound microscope, or a drawing tube affixed to a Wild M20 compound microscope. The structures are depicted as they appear in sections or squash mounts in 3% KOH, or NH4OH-Congo Red (except Figs. 2,6,11,12,33,35,51 which were in Melzer’s reagent). Reagents employed for macrochemical reactions are listed in Table I. Reactions were performed in white porcelain spot plates for a minimum of 10 minutes. The locations of specimens examined are in accordance with Holmgren and Keuken (1974).
Formulae for Chemical Reagents Cited
Ammonium Hydroxide (NH4OH): undiluted household solution.
Congo red: dissolve Congo red dye in undiluted household NH4OH to saturation, then filter.
Cotton blue (Poirrier's blue): dissolve 0.05 g of Cotton blue C4B (NAO499; Matheson, Coleman, and Bell) in 30 g of lactic acid.
Ferrous sulfate (FeSO4): 10% aqueous solution (w:v).
Melzer's reagent: 1.5 g KI, 0.5 g iodine, 22 g chloral hydrate, 22 g water.
PDAB (p-dimethylaminobenzaldehyde): dissolve 6 g PDAB in 229 ml of 95% ethanol, then add 71 ml of concentrated HCl.
Potassium hydroxide (KOH): 3% aqueous solution (w:v).
Tincture of Guaiac: dissolve finely powdered gum guaiac in 95% ethanol to saturation, then filter.