Hexagona marcucciana Bagl. & De Not., Hedwigia 7: 121. 1868.
Type. Holotype collected by C. Montague in 1829, deposited at PC; paratype collected by Guyon and Durieu de Maisonneuve in 1844, in Algeria.
Type Locality, "in Alboeris" (? Alberes Mts.), Pyrennaeus, France.
Hexagona nitida seems not to be congeneric with typical Hexagona but additional data are required in order to prove this idea. One African (BPI) and all European (BPI, FH, PC, SP, UPS) collections that I have seen of H. nitida show fruiting bodies with corky consistency, broadly attached to the substrate, and with a shiny, black, glabrous pilear surface; the pilear cover is, under the microscope, a hyaline cuticle, 15-40 µ thick, composed by hyaline generative hyphae, mostly with periclinal orientation, immersed in a colorless matter not soluble in KOH. Although no trace of a trichoderm was found on the collections, I did see an African collection (NY) with the growing margin showing an undetermined kind of derm, formed mostly by anticlinal, slender generative hyphae; in older parts of the pilear cover of this collection the generative hyphae became gradually agglutinated, appearing as if held by a colorless substance, probably an exudate, and a periclinal orientation was then observed. I do not know if this undetermined derm is a constant character of this species when young or only an anomaly; I believe that only growing and fresh collections will offer an answer to this question. The hyphal system of H. nitida is trimitic, the skeletal hyphae with yellowish-brown walls similar to those observed in Hexagona but the hyphae of the upper part of the context do not show a clear, predominant, periclinal orientation as is seen in the typical Hexagonae. The hymenium of H. nitida is formed by long basidia, (15-) 20-38 X (5-) 6-9 µ, and narrow basidioles, 15-30 X 3-5 µ; the whole hymenium appears as if immersed in a colorless substance, which is not soluble in KOH and does not stain in phloxine solution or lactophenol cotton blue. Most of the collections are abundantly fertile showing cylindric, flattened at one side, hyaline, smooth, nonamyloid basidiospores, (9-)10.5-13.5(-15) X 4-5 µ.
Lloyd (1910: 14) placed H. nitida in his He.ragona sect Ungulacformis and included also H. sulcata Berk., H. durissima Berk, & Br., H. resinosa (Murr.) Lloyd and H. gunnii Berk.; all these latter species differ from typical Hexagona by many important, structural characters and definitely they cannot be maintained in Hexagona; H. nitida has the same hyphal system as typical Hexagona while the other species of sect Ungulaeformis Lloyd have a different structure; H. sulcata and its allies have a trimitic hyphal system with hyaline skeletal hyphae and have true cystidia in the hymenium; H. gunnii is dimitic and lacks skeletal hyphae.
H. nitida seems to be a rare species that grows on living and dead trees of genus Quercus. If it is proved that the real affinities of this species are actually with Hexagona Fr. then this will be the only species of Hexagona with a temperate geographical distribution; H. nitida has been reported in Europe from France (Montagne, 1856: 170), Sardegna I. (Fries, 1874: 590, as H. mori), continental Italy, Marche (Curzi, 1925: 64), Switzerland, Ticino (Benzoni, 1934; Blumer, 1936: 307), Yugoslavia, Servia (Pilat. 1939: 282) and Portugal, Extremadura (Pinto-Lopes, 1949: 213); it has been reported also in northern Africa from Algeria (Montague, 1856: 170) and from Morocco (R. ]Maire A: Werner, 1937: 84), There is also a report from Cyprus I. by Georghiou and Papadopoulos (1957: 30).