Enterosora Baker, Timehri

Kessler, Michael, Smith, Alan R., Øllgaard, Benjamin, Matos, Fernando B. & Moran, Robbin C., 2023, Prodromus of a fern flora of Bolivia. XLII. Update I., Phytotaxa 630 (3), pp. 183-210 : 196

Enterosora Baker, Timehri 5: 218. 1886.

Enterosora is clearly related to Zygophlebia and Ceradenia and was revised by Bishop & Smith (1992). The close relationship of all three genera has been suspected on the basis of morphological characters since the last two were described ( Bishop 1988, 1989). All three genera generally lack hydathodes on the blades adaxially, but Enterosora lacks soral paraphyses. Many, but not all, species of Enterosora have parenchyma with numerous, large intercellular air spaces in the mesophyll, and this feature results in a spongiose blade texture. However, this character is viewed by Sundue (2010) as homoplastic, occurring in various degrees throughout the grammitid clade. Soral shape is also variable, from elongate to round, and sori are often somewhat sunken in the leaf tissue, but these characters are also not unique to Enterosora . Beyond these relationships, the three genera are most closely related to several other New World grammitid genera, well removed from affinities to most Old World grammitids (e.g., Shalisko et al. 2019).

Recent molecular work by Bauret et al. (2017) and Shalisko et al. (2019) has led to a revised and broader circumscription of Enterosora , now to include the segregate genus Zygophlebia but exclude two anomalous species, Enterosora parietina and E. gilpinae . Thus redefined, Enterosora includes about 20 species in tropical America, continental Africa, and Madagascar. Previous monographic and floristic treatments of Enterosora , by Bishop & Smith (1992), Smith & Bishop (1995), Parris (2005), and Smith et al. (2018) were based entirely on morphology and included 8–10 species. The two molecular studies cited above suggest that Enterosora , as defined by Bishop & Smith (1992) and several subsequent works, is not monophyletic, and that at least three tropical American species included by Bishop (1989) in Zygophlebia – Z. sectifrons (Antilles, Costa Rica to Bolivia, and the type of the genus), Z. mathewsii ( Costa Rica to Peru), and Z. cornuta ( Costa Rica and Panama) – fall very close to species of Enterosora in phylogenetic analyses. The simplest solution is to define Enterosora more broadly, to include nearly all species of Zygophlebia (excluding Z. werffii ; see below). However, two species usually treated in Enterosora , one American and one East African-Madagascan, are discordant even with a broad definition of Enterosora . These are now included in a newly described genus, Parrisia ( Shalisko et al. 2019) , discussed below. Most of the necessary new combinations in Enterosora were made by Shalisko et al. (2019), but not for E. dudleyi , unsampled in their work.