ON THE EVOLUTION AND CIRCUMSCRIPTION OF THE NECKERACEAE (MUSCI)

Abstract

  The family Neckeraceae (Musci) contains the traditional subfamilies Neckeroideae and Thamnobryoideae (“Thamnioideae”). The family must be defined mainly on gametophyte characters, since the sporophytes display great plasticity. A few gametophyte characters critical in the definition of the Neckeraceae are pointed out. A list of the 23 genera provisionally accepted in the family is provided. The key word in understanding the evolution of the Neckeraceae is reduction, implying anatomical and morphological reduction in both generations. For example, the evolution of the peristome shows a reduction series from the generalized perfect hypnoid type (e.g., Thamnobryum Nieuwl.) to various reduced “neckeroid” types (e.g., Neckera Hedw. and Neckeropsis Reichardt). Several primitive versus advanced character states in the gametophytes and sporophytes of neckeraceous mosses are briefly discussed. Hypnodendron (C. Müll.) Lindb. ex. Mitt. and Climacium Web. & Mohr. are provisionally recognized as outgroups. It is emphasized that the evolution of the two generations have not always progressed at same “rate”, since there exist genera with a primitive gametophyte and an advanced sporophyte, and vice versa.