Premise of research. The polybotryoid fern clade is completely Neotropical and consists of Cyclodium, Maxonia, Olfersia, Polybotrya, and Polystichopsis. It has never received a detailed phylogenetic analysis. We performed such an analysis to examine the relationships among species and genera and to map the evolution of their morphological and anatomical characters.Methodology. Our study included 46 (77%) of the 60 species in the clade. It also included 37 outgroup species from 19 genera. We sequenced four plastid DNA markers (rbcL, rps4-trnS, trnG-trnR, and trnL-trnF) and analyzed the data with maximum likelihood and Bayesian inference. One anatomical and 11 morphological characters were mapped on the resulting phylogenetic trees using the criterion of maximum parsimony.Pivotal results. The polybotryoid clade was strongly supported as monophyletic, as were its component genera. Nearly all its species have long-creeping rhizomes. Polystichopsis was resolved sister to the other polybotryoid genera. Its monophyly is supported by the morphological synapomorphies of distichous phyllotaxy, long straightish white hairs on the leaves, and tuberculate perines. Two species currently classified in Arachniodes (Arachniodes macrostegia and Arachniodes ochropteroides) form a clade with Olfersia. No known morphological characters support this clade. Olfersia, however, is highly distinct from all other polybotryoids by the combination of its imparipinnate laminae, submarginal connecting vein, strong sterile-fertile leaf dimorphy, loss of indusia, and evolution of acrostichoid sori. Maxonia is defined by its terrestrial root-climbing habit and dimorphic sterile and fertile leaves. Cyclodium and Polybotrya were resolved as sister. The presence of peltate indusia is synapomorphic for Cyclodium. Polybotrya is defined by several morphological synapomorphies: a rhizome anatomy unique among dryopteroid ferns (each individual meristele is surrounded by a dark sclerenchymatous sheath), strong sterile-fertile dimorphy, and loss of indusia. A possible synapomorphy for Polybotrya is the terrestrial root-climbing habit. Within Polybotrya, anastomosing veins and round discrete sori have evolved more than once.Conclusions. This is the first phylogenetic analysis of the polybotryoid ferns. The clade was resolved as monophyletic, as were its genera. An unexpected result was that two species currently classified in Arachniodes (A. macrostegia and A. ochropteroides) were resolved sister to Olfersia. Most of the main clades of polybotryoids were supported by morphological and/or anatomical characters.
Polystichopsis chaerophylloides
SEM spore photo of Polystichopsis chaerophylloides. Fig. 5A in published article, showing spore from Puerto Rico, Britton & Marble 1082, NY; scale bar = 10 micrometers.
polystichopsis_chaerophylloides_232b_Britton & Marble 1082 ( NY)_Puerto rico.jpg
Arachniodes ochropteroides
SEM spore photo of Arachniodes ochropteroides. Fig. 5B in published article. voucher: Suriname, T. Hawkins 1906 ( NY). Scale bar = 10 micrometers.
arachnoides_ochropteroides_112_T. Hawkins 1906 ( NY)_Suriname.jpg
Olfersia alata
SEM spore photo of Olfersia alata. Fig. 5C in published article. voucher: Cuba, Wright 784 (NY). Scale bar = 10 micrometers.
olfersia_alata_118b_Wright 784 ( NY).jpg
Maxonia apiifolia
SEM spore photo of Maxonia apiifolia. Fig. 5D in published article. Voucher: Jamaica, Maxon 2822 (NY). Scale bar = 10 micrometers.
Maxonia6_Jamaica_Maxon 2822 ( NY).jpg
Cyclodium inerme
SEM photo of Cyclodium inerme. Fig. 5E in published article. Voucher: Guyana, Tillett et al. 44942 (NY). Scale bar = 10 micrometers.
cyclodium_inerme_79a_Guyana_ Tillett et al. 44942 ( NY).jpg
Polybotrya aequatoriana
SEM spore photo of Polybotrya aequatoriana. Fig. 5F in published article. Voucher: Bolivia, S. Beck 3060 (NY). Scale bar = 10 micrometers.
Polybotrya_aequatoriana_128b_S. Beck 3060 ( NY), Bolivia.jpg
Polybotrya aequatoriana2
SEM spore image of Polybotrya aequatoriana. Voucher: Bolivia, S. Beck 3060 (NY). Scale bar = 10 micrometers.
Polybotrya_aequatoriana_Bolivia, S. Beck 3060 ( NY).jpg
Polystichopsis chaerophylloides2
SEM spore image of Polystichopsis chaerophylloides. Voucher: Puerto Rico, Britton & Marble 1082 (NY). Scale bar = 10 micrometers.
Polystichopsis chaerophylloides, PR, Britton & Marble 1082 ( NY).jpg
Arachniodes ochropteroides2
SEM spore image of Arachniodes ochropteroides. Voucher: Colombia, Sanin 5088 (NY). Scale bar = 10 micrometers.
Arachniodes ochropteroides, Colombia, Sanin 5088 (NY).jpg
Arachniodes ochropteroides3
SEM spore photo of Arachniodes ochropteroides. Voucher: Colombia, Sanin 5088 (NY). Scale bar = 10 micrometers.
Arachniodes ochropteroides, Colombia_Sanin 5088 ( NY).jpg
Arachnoides ochropteroides4
SEM photo of Arachnoides ochropteroides. Voucher: Surinam, T. Hawkins 1906 (NY). Scale bar = 10 micrometers.
Arachnoides ochropteroides, 112c_Surinam, T. Hawkins 1906 (NY).jpg
Arachniodes ochropteroides5
SEM spore photo of Arachnoides_ochropteroides. Voucher: Suriname, T. Hawkins 1906 (NY). Scale bar = 10 micrometers.
arachnoides_ochropteroides_Suriname, T. Hawkins 1906 (NY).jpg
Cyclodium inerme2
SEM spore photo of Cyclodium inerme. Voucher: Guyana, Tillett et al. 44942 (NY). Scale bar = 10 micrometers.
Cyclodium inerme, Guyana, Tillett et al. 44942 (NY).jpg
Maxonia apiifolia2
SEM spore photo of Maxonia apiifolia. Voucher: Jamaica, Maxon 2822 (NY). Scale bar = 10 micrometers.
Maxonia apiifolia, Jamaica, Maxon 2822 (NY).jpg
Maxonia apiifolia3
SEM spore photo of Maxonia apiifolia. Voucher: Panama, Croat 17202 (NY). Scale bar = 10 micrometers.
Maxonia apiifolia, Panama, Croat 17202 ( NY).jpg
Maxonia apiifolia4
SEM spore photo of Maxonia_apiifolia. Voucher: Jamaica Maxon 2284 (NY). Scale bar = 10 micrometers.
Maxonia_apiifolia, Jamaica Maxon 2284 (NY).jpg
Maxonia apiifolia5
SEM spore photo of Maxonia_apiifolia. Voucher: Jamaica Maxon 2284 (NY). Scale bar = 10 micrometers.
Maxonia_apiifolia, Jamaica Maxon 2284 (NY).jpg
Maxonia apiifolia6
SEM spore photo of Maxonia_apiifolia. Voucher: Jamaica Maxon 2822 (NY). Scale bar = 10 micrometers.
Maxonia_apiifolia, Jamaica Maxon 2822 (NY).jpg
Olfersia alata2
SEM spore photo of Olfersia_alata. Voucher: Cuba, Wright 784 (NY). Scale bar = 10 micrometers.
Olfersia_alata, Cuba, Wright 784 (NY).jpg
Olfersia alata3
SEM spore image of Olfersia alata. Voucher:_Cuba, Wright 784 (NY). Scale bar = 10 micrometers.
Olfersia_alata_Cuba, Wright 784 (NY).jpg