Megalastrum

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

Key to the Bolivian species of Megalastrum

1 Blades pinnate-pinnatifid or barely 2-pinnate with proximal pinnules on lower pinnae adnate to costae; basiscopic pinnules of proximal pinnae sometimes pinnatifid ............................................................................................................................................. 2

– Blades 2-pinnate or more divided, larger and lower pinnules stalked, at least not all broadly adnate ............................................. 5

2 Costules and veins abaxially with whitish hairs 0.5–1 mm long .............................................................................. M. bolivianum

– Costules and veins abaxially glabrous or with sparse hairs 0.1–0.3 mm long ................................................................................. 3

3 Rachises densely puberulent; rhizome scales brown en masse, orange to medium brown under strong light and magnification ..... ......................................................................................................................................................................................... M. biseriale

– Rachises glabrous or sparsely puberulent; rhizome scales dark brown ........................................................................................... 4

4 Basal basiscopic pinnules enlarged and more deeply lobed than suprabasal ones, often overlapping the rachis ...... M. fibrillosum

– Basal basiscopic pinnules the same size and shape as the suprabasal ones, not overlapping the rachis ........................ M. biseriale

5 Indusia present, sometimes small and appearing only as a tuft of whitish hairs in the center of the sori ........................................ 6

– Indusia absent ................................................................................................................................................................................... 7

6 Indusia 0.1–0.3 mm in diameter, appearing as a tuft of whitish hairs in the center of the sori; blades abaxially with short hairs between the veins ...................................................................................................................................................... M. adenopteris

– Indusia 0.8–1 mm in diameter; blades abaxially glabrous or nearly so between the veins ............................................ M. andicola

7 Scales of costae and costules pale at the bases and darker at the tips, conspicuously dentate; spores echinulate ........................... 8

– Scales of costae and costules uniformly colored or slightly darker at bases, subentire to moderately serrate; spores cristate ....... 9

8 Blades 1–3 m long, medially 3-pinnate-pinnatisect ..................................................................................................... M. fugaceum

– Blades 0.3–0.4 m long, medially 2-pinnate-pinnatisect ................................................................................................... M. nanum

9 Blades adaxially pubescent on and between veins, hairs to ca. 1 mm long ................................................................................... 10

– Blades adaxially glabrous or with sparse hairs <0.5 mm long on veins and/or surfaces between veins ....................................... 14

10 Costal and costular hairs abaxially dense, uniformly short, thin, 0.1–0.3 mm long ...................................................................... 11

– Costae and costules abaxially glabrous or with some stout hairs of variable length mostly 0.3–1 mm long ................................ 13

11 Laminar tissue between veins adaxially with numerous hairs, these ca. 0.1–0.3 mm long; costal scales filiform to linear-lanceolate, mostly 3–5 cells wide, dull brown .................................................................................................................................... M. vastum

– Laminar tissue between veins adaxially with sparse to numerous hairs; costal scales broadly lanceolate, 10–15 cells wide ....... 12

12 Costal scales ovate-lanceolate, light tan or orange-tan; sori supramedial to inframarginal; laminae between veins with acicular hairs on both sides, hairs mostly uniformly short, <0.5 mm ..................................................................................... M. adenopteris

– Costal scales broadly lanceolate, shiny, castaneous; sori medial; laminae between veins glabrous to hairy on both sides, some hairs to 0.5 mm .................................................................................................................................................................. M. peruvianum

13 Abaxial surfaces between veins sparsely to moderately or densely pubescent with short, erect hairs .......................................... 14

– Abaxial surfaces between veins lacking hairs ................................................................................................................................ 15

14 Abaxial blade surfaces between veins moderately to densely pubescent, hairs often> 0.5–1 mm; rhizome and stipe base scales linear-lanceolate, <10 × 1 mm; proximal pinnae stalked to 1 cm ................................................................................... M. ciliatum

– Abaxial blade surfaces between veins sparsely pubescent, hairs mostly or entirely <0.5 mm; rhizome and stipe base scales lanceolate,>10 × 1 mm; proximal pinnae stalked 3–5+ cm ................................................................................ M. praetermissum

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