Mycena citrinovirens M. Lange

Mycena citrinovirens

In Meddr. Grønland 147: 41 (1955).


Mycena citrinovirens M. Lange, rediscovered in Norway after 40 years.

by A. Aronsen in Agarica vol 13 (nr 22): 54 - 60 (1994).


Mycena citrinovirens, originally described from Greenland, appears to be regular at localities along the coast of the Oslo fjord in South Norway. In this species the appearance
of clamps seems not to have specific value. The taxonomical importance of clamps is discussed somewhat further.


Habitats dominated by scrub of Juniperus communis, near the coast of the Oslo fjord in South Norway, have proved to be very interesting for searching for Mycenas (Aronsen & Maas Geesteranus, 1989; Maas Geesteranus, 1993; Aronsen, 1994). For several years a small Mycena species has been found in these areas late in the autumn. A thorough examination shows that the species represents Mycena citrinovirens M. Lange, originally described from Greenland (Lange, 1955). Since this species until now has been known only from the type collection, it may be appropriate to give a full description of the Norwegian material.

Mycena citrinovirens M. Lange in Meddr. Grønland 147:41. 1955.

Pileus 8-12 mm across, cylindrical or more or less hemispherical when young, then conical or obtusely conical to parabolical, occasionally with a small umbo; translucent-striate, sulcate, dry, glabrous; pale yellow to greenish yellow or olivaceous with almost no yellow components, or olivaceous centre with paler, yellowish margin; drying to pale yellow all over. Lamellae 12-19 reaching the stipe, ascending, narrowly adnate, occasionally with a short decurrent tooth, becoming slightly intervenose with age; yellowish to cream coloured or pale grey to white, with the edge concolorous. Stipe up to 65 x 1.5 mm, straight to somewhat flexuous, often curved towards the base, firm, terete, equal, glabrous except for the pruinose apex; the apex whitish or pale grey, darker grey to brownish below, occasionally with a yellow component; the base densely covered with long, coarse, flexuous, whitish fibrils. Smell not distinct. Taste not recorded.

Basidia 30-36 x 6.5-8 um, clavate, with clamps or with abortive clamps or clampless, 2-spored, with sterigmata 8-9 um long. Spores (8.9-) 9.8-10.7 x (6.3-) 7.2-7.4 um (measured by Maas Geesteranus), 8.5-11.2 x 6.2-8.2 um (my measurements), smooth, broadly pip-shaped, amyloid. Cheilocystidia 15-40 x 6.5-17 um, forming a sterile band, clavate, clamped, or with an abortive clamp or clampless, covered with unevenly spaced, fairly coarse, simple, cylindrical, straight to curved excrescences 2-8 (-20) x 0.9-2 um. Pleurocystidia absent. Hyphae of the pileipellis ca 2.5 um wide, clamped or clampless, densely covered with simple to furcate, cylindrical excrescences 2-4.5 x 0.9 um, somewhat gelatinized. Hyphae of the cortical layer og the stipe 1.8-2.5 um wide, clamped or not, covered with simple, cylindrical excrescences 1.8-6.5 x 0.9-1.3 um. Lamellar trama vinescent in Melzer's reagent. Figures 1-5 and 6-9.

Scattered to gregarious among needles under Juniperus communis. Occasionally solitarily on small Juniperus twigs.

Material examined: Norway, Vestfold, Tjøme, Hvasser 13 Nov 1988 (M52/88), 26 Oct 1989 (A54/89), 4 Nov 1989 (A65/89), 5 Nov 1989 (A71/89). Vestfold, Tjøme, Moutmarka 26 Oct 1989 (A56/89), 7. Nov 1992 (A56/92), 9 Oct 1993 (A65/93).

A comparison between the type and the Norwegian material is shown in the following table (Table 1).

  M. citrinovirens,
Norwegian material
Habitat Under Juniperus, on needles Under Juniperus, on needles
Pileus 7-8 mm, clear yellow with the striae and centre greyish olive. Drying to pale yellow. 5-12 mm, pale yellow, greenish yellow, or olivaceous. Drying to pale yellow.
Lamellae Not crowded. Very pale yellow. Emarginate with a decurrent tooth. 12-19 reaching the stipe. Pale yellow to white or pale grey. Narrowly adnate, with or without decurrent tooth.
Stipe Pale greyish. Greyish-brownish.
Basidia 2-spored 2-spored
Cheilocystidia Clavate, with cylindrical excrescences. Clavate, with cylindrical excrescences.
Spores 9.0-10.7 x 6.3-8.1 um.
Broadly pip-shaped.
8.5-11.2 x 6.2-8.2 um.
Broadly pip-shaped.
Hyphae of the pileipellis Densely covered with short excrescences. Densely covered with short excrescences.
Hyphae of the cortical layer of the stipe Diverticulate. Diverticulate.
Clamp connections Absent. Absent or present or abortive.

Table 1. A comparison between Mycena citrinovirens (holotype) and the Norwegian material.

A striking character that deviates from the original material of M. citrinovirens is the presence of clamps. The clamps are, however, not present at all hyphae, and in many cases they are abortive. The general situation in Mycena is that species with 4-spored basidia have clamps at the septa of the hyphae and at the bases of basidia and cystidia, whereas clamps are absent in the 2-spored forms, but there are exceptions. Some species are known to possess clamps in both 4-spored and 2-spored forms (e.g. M. filopes and M. metata), and some consistently 4-spored species (e.g. M. strobilicola) equally consistently lack clamps. Mycena vitilis normally has 4-spored basidia and lacks clamps at all hyphae, but occasionally abortive clamps may be present at the base of some basidia (Maas Geesteranus, 1988:310), and very rarely some of the clamps are fully developed (Aronsen, coll. no A49/93). Four-spored M. leptocephala normally possesses clamp connections, but it has also been reported devoid of clamps (Maas Geesteranus, 1991: 547; Aronsen, coll. no M10/88). Mycena niveipes seems to be another example of a species with 4-spored forms either with or without clamps (Maas Geesteranus, 1988: 144).

The presence of clamp connections in species of Mycena had not been given taxonomical attention until Kühner & Valla (1972) used them to distinguish closely resembling species. Maas Geesteranus (1978) showed that the clamp connections at the cheilocystidia in Mycena invariably are correlated with their presence in other elements of the hymenium and subhymenium. Furthermore he stated that the presence of clamps is a character of specific importance. As shown by the few examples above there may be reasons not to emphasize the value of clamps in all cases. This should be taken as an argument for regarding the collections sited above as representatives of Mycena citrinovirens.

Since the possession of clamps in the Norwegian gatherings is inconstant, their function is possibly equally inconstant, namely to allow the passage of protoplasma and nuclear matter (see Kühner, 1938: 107). Perhaps even their function must be considered non-existent, explaining why the basidia have only two spores, and not four as one would expect in a species bearing clamp connections. Whether the difference between the Greenland material and the Norwegian specimens of M. citrinovirens is caused by environmental influence or genetic change must remain unanswered for the present. But it may be of a certain interest to point at the view by Kühner (1938: 121-122) who indicates that we here can see a case of a Mycena where the individuals are in a process of development. of evolution, in which they short-cut the production of spores. A process that is only hesitantly shown in lowland parts of Southern Norway, but quite finished in Greenland where climate conditions presumably are more unfavourable.

Lange (1955: 42) suggested that M. citrinovirens was related to section Adonideae (Fr.) Quèl., but Maas Geesteranus (1991: 387) placed it in section Mycena. The Norwegian collections confirm the latter opinion.


I would like to express my thanks to the authorities of the herbarium at Copenhagen for the loan of the type material of Mycena citrinovirens, and to Mrs. G. Gulden, Oslo for arranging the loan.
Sincere thanks are also due to Dr. R. A. Maas Geesteranus, Leiden for examining my material, for useful discussions, and for providing the figures following this article.
Lastly, I wish to thank Dr. K. Høiland, Oslo for reading an early draft of the manuscript.

Aronsen, A., 1994: Two new Mycenas of section Fragilipedes from Southern Norway. - Persoonia 15 (in prep).
Aronsen, A. & Maas Geesteranus, R. A., 1989: Mycena ustalis, a new species from Southern Norway. - Persoonia 14: 61.64.
Kühner, R., 1938: Le genre Mycena (Fries). Encycl. mycol. 10.
Kühner, R: & Valla, G., 1972: Contribution à la Connaissance des espèces blanches à spores non amyloides du genre Mycena (Fries) S. F. Gray (Basidiomycètes Agaricales). - Trav. Lab. "La Jaysinia" 4: 25-71.
Lange, M., 1955: Macromycetes. Part II. Greenland agaricales (Peurotaceae, hygrophoraceae, tricolomataceae, amanitaceae, agaricaceae, coprinaceae, and strophariaceae). - Medd. om Grønland: 147 (11).
Maas Geesteranus, R. A., 1978: Clamp connections at the cheilocystidia in Mycena. - Persoonia 10: 129-135.
Maas Geesteranus, R. A., 1988: Conspectus of the Mycenas of the Northern Hemisphere - ). Section Fragilipedes, species S-Z. - Proc. K. Ned. Akad. Wet. (Ser. C) 91: 283-314.
Maas Geesteranus, R. A., 1991: Studies in Mycenas. Additions and Corrections. - Proc. K. Ned. Akad. Wet. 94: 377-403.
Maas Geesteranus, R. A., 1993: New species of Mycena in section Fragilipedes. - Proc. K. Ned. Akad. Wet. 96: 335-345.