Ctenitis (C.Chr.) C.Chr., Man. Pteridol.

Kessler, Michael, Moran, Robbin C., Mickel, John T., Matos, Fernando B. & Smith, Alan R., 2018, Prodromus of a fern flora for Bolivia. XXXV. Dryopteridaceae, Phytotaxa 353 (1), pp. 448-450 : 448-450

Ctenitis (C.Chr.) C.Chr., Man. Pteridol. 544. 1938.

Ctenitis is characterized by the costae and costules with reddish, blunt ctenitoid hairs (2–4 short cylindrical cells separated by reddish brown walls); ungrooved adaxial rachises and costae; free veins; lower blade surfaces often with minute glands; lanceolate to ovate scales on the blade axes abaxially; pinnate-pinnatifid or often decompound blades; and often clathrate scales on the abaxial surfaces of the rachises and costae. In the field, Ctenitis is often readily recognized by very dense long, hairlike rhizome and stipe-base scales, which contrast with the much broader scales of otherwise superficially similar genera such as Megalastrum .

Ctenitis is most closely related to the polystichoid ferns, including Polystichum , Arachniodes , and Dryopteris ( Schuettpelz & Pryer 2007, Lehtonen 2011). It is a pantropical genus of about 125 species (PPG I 2016). The number of species in the Neotropics is estimated to be about 50 ( Viveros & Salino 2015). There is also considerable diversity in Ctenitis on islands in the Indian Ocean, with ca. 40 known species ( Duan et al. 2017, Henniquin et al. 2017). Phylogenetic studies by Hennequin et al. (2017) suggest that the Afro-Madagascan diversity, including also the Mascarene Islands and the Comoros, is monophyletic and probably the result of a single transoceanic dispersal from the Neotropics, in Oligocene-early Miocene. Additional diversity in Ctenitis is in eastern Asia, where 28 species were treated by Holttum (1991) for Flora Malesiana.

Following Christensen’s (1913, 1920) monographs, the American species were not studied comprehensively until very recently ( Viveros et al. 2018). Regional treatments are available for Mexico (21 sp.; Mickel & Smith, 2004), Mesoamerica (20 sp., mostly the same as in Mexico; Moran 1995), and the islands of the Antilles ( Proctor 1977, 1985, 1989). Greatest diversity in the genus in the New World is in southern Mexico, the Antilles, and southeastern Brazil.

In Bolivia, most species of Ctenitis (six species known) are apparently uncommon and rarely collected.Also, they appear to grow mostly along streams in semihumid forest habitats, rather than in very wet forests where Megalastrum is common. For this reason, in Bolivia Ctenitis is most diverse in La Paz and Santa Cruz departments, rather than in Cochabamba, which otherwise has a highly diverse fern flora but which has little semihumid forest ( Kessler et al. 2001, Soria & Kessler 2008).