Mucura, Triana-Moreno & Yañez & Kuo & Rothfels & Pena & Schwartsburd & Sundue, 2023

Triana-Moreno, Luz A., Yañez, Agustina, Kuo, Li-Yaung, Rothfels, Carl J., Pena, Nelson Túlio L., Schwartsburd, Pedro B. & Sundue, Michael, 2023, Phylogenetic revision of Dennstaedtioideae (Dennstaedtiaceae: Polypodiales) with description of Mucura, gen. nov., TAXON 72 (1), pp. 20-46 : 40

IV. Mucura L. A. Triana & Sundue, gen. nov. – Type: Mucura

bipinnata (Cav.) L.A.Triana & Sundue (≡ Dicksonia bi-

pinnata Cav.).

Diagnosis. – Differing from all other Dennstaedtiaceae by having dichotomously branching rhizomes, petioles that lack epipetiolar buds, marginal sori with both abaxial and adaxial indusia forming a cylindrical or cup-shaped involucre, and trilete spores with a verrucate and broadly ridged perispore, and sometimes irregular reticles.

Description. – Plants terrestrial; rhizomes long creeping, dichotomously branching, pubescent; petioles subterete, without an adaxial sulcus, with an omega-shaped vascular bundle, lacking epipetiolar buds; leaves large, erect, decompound, laminar axes alate, the wings decurrent onto the next order, lacking proliferous leaf buds; veins free, with slender apices; sori marginal, provided with abaxial and adaxial indusia that together form a cylindrical cup-shaped involucre; spores trilete, broadly ridged and verrucate, and sometimes irregular reticles. ( Fig. 8 )

Distribution and habitat. – Distributed from Mexico and the West Indies to the southern cone of South America, in humid forests, from sea level to 3500 m. Largely absent from Amazonia.

Etymology. – This name is a Spanish feminine noun [mú·ku·ɾa] derived from the Caribbean and Chibcha linguistic families ( Flórez, 1955) that refers to a fired clay pot, commonly made by indigenous people living within the geographic distribution of the genus. These clay pots are characterized by having a globose base, like the indusium of Mucura globulifera , and a long narrow neck, reminiscent of the cylindrical indusium of M. bipinnata .

Discussion. – Mucura comprises two Neotropical species that may be sister to the clade of Microlepia and Sitobolium . It is distributed from Mexico and the West Indies to the southern cone of South America but not distributed in Amazonia. Previously treated in Dennstaedtia, Navarrete & Øllgaard (2000) emphasized the morphological disparity between species treated here as Mucura and other Neotropical species of Dennstaedtia . We agree, and our ancestral character state reconstruction recovers several autapomorphic states. It has a rachis-costa architecture found in no other lineage where the axes are provided with adaxial wings that are continuous between orders (from the rachis to the pinna costae, and pinna costae to pinnule costules). Mucura has a unique perispore ornamentation consisting of verrucae, broad ridges, and irregular reticles on the distal face ( Fig. 4A ). Also unique to Mucura are the subterete petiole bases; as far as we have seen, all other Dennstaedtioideae have petioles that are adaxially sulcate. Notably, Mucura lacks epipetiolar buds which are present in nearly all other Dennstaedtiaceae . They can further be distinguished from Dennstaedtia by their elongate, and branched rhizomes. These distinct morphological features, along with its phylogenetic position, warrant recognition of this clade at the rank of genus.

Figures

Fig. 8. Characters of Mucura. A, Habit; B, Upper leaf surface and alate rachis-costa axes; C, Lower leaf surface and marginal sori with cylindrical indusia; D, Unbranched rhizome and petiole lacking epipetiolar buds. — All photos by M. Sundue.

Fig. 4. Examples of perispore morphology of spores in distal view. A, Verrucae and irregular reticles with prominent ridges covering the corners, Mucura globulifera (Yañez & Márquez 86, LP); B, Tubercles, Sitobolium wilfordii (Unknown coll. s.n., UVMVT192145, VT); C, Verrucae and prominent ridges to the spore sides, Sitobolium hirsutum (Rothfels & al. 5282, VT); D, Network of rodlets, Microlepia speluncae (Rojas 4878, MO); E, Regular reticle, Dennstaedtia glabrata (James & Sundue 1593, VT); F, Prominent ridges, Dennstaedtia distenta (Mickel 4163, LP); G, Verrucae and ridges, Dennstaedtia dissecta (Palacios 1296, LP). — Scale bars = 10 μm.