Hypnum schweinfurthii C. Müll., Linnaea 39:462.1875; Taxithelium schweinfurthii (C. Müll.) Jaeg., Ber. Tatigk. St. Gallischen Naturwiss. Ges. 1876-77: 423. 1878. Type: NIAM-NIAM [Sudan-Zaire border]. Adrivulum ad pedem coUis Baginse in faucibus, 27 May 1870, Schweinfurth s.n. (isotype, NY!).
Hypnum octodiceroides C. Müll., Linnaea 39:463.1875; Taxithelium octodiceroides (C. Müll.) Jaeg., Ber. Tatigk. St. Gallischen Naturwiss. Ges. 1876-77: 423. 1878, syn. nov. Type: NIAM-NIAM [Sudan-Zaire border]. Ad rivulum Boddo in Mbanga, in radicibus arborum, 21 Feb 1870, Schweinfurth s.n. (isotype, NY!).
Although two of the three taxa originally included in Hypnum subsect. Limnobiella C. Müll. were described in the same publication by Müller himself, I choose Hypnum acuminulatum as the lectotype. Since none of the taxa is currently in Glossadelphus, and since Limnobiella has never been affiliated with Taxiphyllum but rather has a traditional association with Taxithelium (Renauld & Cardot, 1901; Brothems, 1908), lectotypification reinforcing that alignment instead of introducing a new one seems most appropriate. The genus Glossadelphus was lectotypified by Robinson (1974) with Hypnum truncatulum C. Müll. Although this would not have been my choice, it is not in serious conflict with the protologue and thus should stand. Such a lectotypification implies that section Collophyllum Fleisch. is illegitimate and should be sect. Glossadelphus by modern nomenclatural standards. We now return to Phyllodon, m y incentive for involvement with this group. Phyllodon was described by Schimper in the Bryologia europaea (1851) and established for Hookeria retusa Wils., nom. nud. The genus has gone unused and mostly unnoticed, and no species has ever been transferred into it. In an attempt to account for this generic name in a rearrangement of the Hookeriales (Buck, 1987), I searched the British Museum where both Wilson's and Schimper's herbaria are deposited. Fortunately, a specimen was located that was labeled as Hookeria retusa, and matches the protologue of Phyllodon. Its data are as follows: Peru. Casapi, Matthews 821 (BM!). It unquestionably conforms to our modern concept of Glossadelphus truncatulus (C. Müll.) Fleisch., also described from Peru (Poppigs.n.—Bul). Indeed, even Mitten (1869) cited the Matthews specimen (without collection number) under Ectropothecium truncatulum (C. Müll.) Mitt. Therefore, Glossadelphus is a synonym of Phyllodon. Although Glossadelphus could be conserved, it has been heterogeneous since its inception and is probably best dislodged from usage.
The use of Phyllodon for G. truncatulus and its allies is followed here. However, defining generic boundaries presents problems. Glossadelphus truncatulus has truncate leaves with prominent bifid teeth on the upper margins. The leaf cells are papillose from both projecting upper cell ends and serially arranged papillae over the cell lumina. Glossadelphus truncatus (Welw. & Duby) Fleisch. likewise has truncate leaves with both types of papillae. However, the upper margin is only roughened from the projecting papillae and does not have bifid teeth. Glossadelphus lingulatus (Card.) Fleisch., the type of G. sect. Anastigma, has truncate leaves with bifid marginal teeth, but only projecting cell ends forming papillae. Glossadelphus scutellifolius (Besch.) Fleisch. has truncate leaves with serially arranged papillae over the cell lumina but neither bifid marginal teeth nor prorulae. It might be placed in Taxithelium, but the alar region is less developed than is typically displayed in the genus. More significantly, its leaf cells are bluntended, as in the other, above-mentioned species, not narrowly pointed as in Taxithelium. I therefore include these four species in Phyllodon and make the appropriate combinations. I have not seen either Glossadelphus oophyllus (C. Müll.) Heisch. or G. natans (C. Müll.) Fleisch., but they may also belong in Phyllodon.