Tuber maculatum Vitt., een voor Nederland nieuwe fungus hypogaeus

In the general mycological literature of the Netherlands for the past thirty years only mention is made of hypogean fungi belonging to the families Hymenogastraceae (Basidiomycetes) and Elaphomycetaceae (Ascomycetes), whereas too less attention is paid to the occurrence of typical Tuberaceae (Ascomycetes). As will be seen below Oudemans (1903) and Miss Cool (1916, 1921), however, cite some Tuberaceae. The following list comprehends all the Netherlands’ hypogean fungi collected up to this time. Basidiomycetes : Hysterangium clathroides VlTT., syn. Splanchnomyces clathroides Corda, Cool (1917, p. 28); Cool and Meulenhoff (1918b, p. 76); Flora Bat. (tab. 1974b). Gautiera graveolens Vitt., Cool (1916b, p. 59 and 1917, pp. 19, 26); Flora Bat. (tab. 1954); Cool and Meulenhoff (1918b, p. 76). Rhizopogon luteolus Fr., syn. R. virens (Alb. et Schw.) Schrot. and Hymenangium virens Klotzsch, Suringar (1870, p. 298). Rhizopogon rubescens Tul., Cool and Meulenhoff (1923, p. 49). Melanogaster variegatus (VlTT.) Tul., syn. Octaviana variegata Vitt. and Tuber moschatum Bull., De Lev. Nat. Jan. 1908; Cool (1917, p. 38); Cool and Meulenhoff (1918a, p. 55 and 1918b, p. 75). Melanogaster ambiguus (Vitt.) Tul., syn. Octaviana ambigua Vitt., Cool and Meulenhoff (1918a, p. 55). Octaviana asterosperma Vitt., Cool and Meulenhoff (1918a, P- 55)- Hydnangium carneum Wallr., Oudemans (1892, p. 483); Boedijn (N.K.A. 1926, p. 67). Ascomycetes: Elaphomyces granulatus L., Suringar (1870, p. 298). Elaphomyces muricatus Fr., syn. E. variegatus Vitt., Sprée (1870, p. 347). Hydnotria Tulasnei Berk. et Br., Cool (1921, p. 36; 1922, p. 18), Lütjeharms (1933, p. 29). Tuber puberulum Berk. et Br., Oudemans (1903, p. 212; 1904, P- 325)- Tuber excavatum Vitt., Oudemans (1903, p. 212, 1904, p. 325). Tuber dryophilum VlTT., Cool (1916a, p. 12). In October 1938 I received from Mr A. den Dulk Jr another Tuber-species, viz. Tuber Maculatum Vitt., collected in a school-garden at The Hague. This species was found ca. 10 cm below the surface of the ground, and at a distance of some 2 meters from a row of Populus nigra. In the description special reference is made to the sculpture of the reticulated spores, which contains inside the large deep meshes a light coloured circular spot, surrounded at one side by a crescentshaped figure (fig. 4 and 5). A similar drawing is given by Hesse (1891, t. 16, f. 18) for T. rapaeodorum Tul., and by Fischer (1923, f. 4) for T. excavatum ViTT. T. macrosporum Vitt. has distinct warts within the meshes of the spores, but Corda (1854, t. 17, f. 8) does not draw the half-moon. Prof. Ed. Fischer at Bern was so kind to identify this characteristic with a slide of the type-specimen. He writes me: „Beim Originalexemplar sah ich zum Teil ahnliche Warzchenbildungen in den Maschen der Skulptur wie bei Ihrer Probe, aber sie waren meist nicht so deutlich und nicht bei allen Sporen zu sehen. Der Unterschied mag aber vielleicht an der Konservierung liegen: Der Schnitt vom ViïTADiNi’schen Original liegt schon sehr lang in Glyceringelatine, wahrend ich Ihr Material untersucht habe, nachdem ich es in Milchsaure erwarmt hatte”. I cannot share Fischer’s opinion that the warts are products of the conservation, as I saw the same in a coupe put in water directly after the fresh material was received. The specimens of The Hague cannot be separated as a variety, because it is now evident that the type is provided with the same characteristic. Possibly this is a peculiarity which occurs in all Tuber-species with reticulated spores. In Tabel I the sizes of resp. ascus, pedicle, spore and mesh are to be found. The species is added to the collection of the Rijksherbarium, Leiden, under No. 938, 335 . . . 511.