A REVISION OF THE GENERA PILOTRICHIDIUM AND DIPLONEURON (MUSCI: HOOKERIACEAE)

Abstract

  Pilotrichidium is a genus of two species (P. callicostatum and P. antillarum) with strictly neotropical, primarily geographically distinct, distributions: P. callicostatum north to Mexico, southwest to Ecuador, southeast to Venezuela, and in the Caribbean on the islands of Trinidad and Jamaica; P. antillarum throughout the islands of the Caribbean (except Trindiad and Jamaica) and in Honduras. The affinities of Pilotrichidium lie with the Hookeriopsoid group of the Hookeriaceae, specifically with Diploneuron, Schizomitrium, Thamniopsis, and Hookeriopsis. Pilotrichidium brunnescens and P. antillarum var. complanatum are syn. nov. of P. antillarum, and P. diatomophilum is transferred to the genus Schizomitrium as S. diatomophilum (C. Müll.) Allen & Crosby comb. nov.

  Diploneuron, a monotypic genus (D. connivens) known only from Jamaica and Cuba is distinguished by its unique double costae. The costae become marginal approximately one-half the distance from the leaf base and coalesce at the apex into a thickened subulate point. The genus is best positioned in the hookeriopsoid group of the Hookeriaceae, and is closely allied to Pilotrichidium.