Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 68. (Budapest 1976)

Bohus, G.: Agaricus studies, VI.

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS Tomus 68. Budapest HUNGARIC1 1976. Agaricus Studies, YI. by G. BOHUS, Budapest Abstract — Data are given to 8 Agaricus species. With 2 figures. Data on the form circle of Agaricus arvensis Sehff. ex Fr. According to the statement of PILÂT : " Ag. arvensis... is very variable, or rather a series of weak species belongs here, whose systematic value is in many respects not yet elucidated". True enough, quite often materials come forward which do not correspond to the typical A. arvensis. Mycologists have to set aside these collections without precisely determining them. PILÂT (1951a) separated A. osecanus, A. arvensis var. macrolepis and var. cretaceus from A. arvensis, and BOHUS did the same for A. maerosporoides and A. arvensis var. umbrelloideus. Without separating it, one can state on the basis of the Hungarian material that there exists a form with small spores and another with bigger spores. A large material has been collected in the Hortobágy (Com. Hajdú—Bihar) from the form having small spores (6.3-7 X 4.5-5 pun) : Nagyiván, 23 May 1974, leg. E. BEGITTER. Óhat, meadow, 27 May 1974, leg. M. BABOS, grassy locust-tree wood, 24 June 1974, leg. M. BABOS, Kónya, pasture, 22 Sept 1967, leg. MRS. TÓTH. Spore dimensions of form with bigger spores: 7.4-8.2 X 5.2-5.8 [xm: Mts. Pilis, Leányfalu, grassy place, 15 October 1958, leg. G. BOHÜS and M. BABOS. — 7.2-9 X

4.9-5.9 pun: Hortobágy, prope Debrecen, pasture, 5 May 1960, leg. MRS. SZABÓ. — 7.5-8.8 x5-6 pom: Hortobágy, prope Debrecen, pasture, 9 November 1960, leg. F. DENCSI. Key to the group Arvenses s. str. 1 Under trees 1 — In grassy places without trees 5 2 Under locust trees. Stem-shape intermedier between A. abruptibulbus and arvensis. Fruit-body slender, umberelloid A. arvensis var. umbrelloideus BOHUS — Under other trees 3 3 Stem hardly or not bulbous 4 — Stem sharply bulbous. Pileus cracked already in youth into imbricate to subeoneentric and adpressed scales A. arvensis var. macrolepis PILÂT & Pouz. 4 Fruit-body medium-sized. Pileus up to 10 cm. Stem relatively short, 5-6 cm. Spores globose-ellipsoid, much more globose than generally in A. arvensis A. osecauus PILÂT — Fruit-body large. Pileus 9-27 cm. Spores ellipsoid A. arvensis var. cretaceus (PILÂT) (1951b) 5 Lamellae rosy. Pileus broad: 17-25 cm, may break up into scales, centre may be areolate. Stem thick and relatively short. Spores 8-9.5 X5-6 pun A. maerosporoides BOHUS — With other characters 6 6 Spores smaller: 6.3-7x4.4-5 pun A. arvensis SCHFF. ex FR. small-spored form — Spores larger: 7.2-9 X

4.9-6 [im. A. arvensis SCHFF. ex FR Further data on Agaricus deylii Pilât (Fig. 1) This species has been scarcely reported up to now. Earlier it has been mentioned when the degree of reddening has been discussed. Now on the basis of four occurrences in 1974 it is necessary to refer to the different sizes of the fruitbodies. The specimen collected in 1960 and 1968 approached though did not reach the size of PILÂT'S material from Karlátejn, where the thickness of the stem was about 20 mm. The rather rich collections of 1974 and 1975 show a transition to the small specimens of the Ann. Hist.-nat. Mus. Nat. Hung., 1976, 68.