Danaea atlantica Christenh., E.M.Almeida & L.P.Felix, 2018

Christenhusz, Maarten J. M., Almeida, Erton M. & Felix, Leonardo P., 2018, A new species Danaea (Marattiaceae) from the Atlantic forests of Brazil, Phytotaxa 356 (3), pp. 226-232 : 227-230

Danaea atlantica Christenh., E.M.Almeida & L.P.Felix , sp. nov. ( Figs. 1–4 )

Type:— BRAZIL. São Paulo: Ubatuba , between Picinguaba and Ubatumirim, Quilombo da Fazenda, Casa de Farinha, 15 November 2017, L. P. Felix 16961 (holotype: K!; isotype: EAN!) .

This species belongs to subgenus Arthrodanaea , having erect rhizomes, nodose petioles and entire pinna margins. It is similar to D. geniculata and D. bipinnata , but differs from these species in its upright leaves with dark purple petioles ( Fig. 4 ). It has narrower pinnae (see key for comparison) and occasionally makes additional pinnules ( Fig. 3 ), unknown from any other Brazilian species (but present in D. bipinnata of western Amazonia); differences are subtle in herbarium specimens, but clearly discrete in fresh material.

Terrestrial ferns with erect rhizomes, along which leaves and roots are radially arranged. The rhizome stout, up to 6 cm, 2 cm wide at apex, stipules 0.3–0.5 cm wide. Leaves imparipinnate, sterile leaves 50–75 cm, petioles dark purple, 30–46 cm, with (one or) two or three nodes; rachises sparsely scaly below, with wings up to 0.8 mm in upper part of internode; blades 20–34 × 13–24 cm, elliptic, widest in the middle, with (4–)5–7(–8) pinna pairs; largest lateral pinnae elliptic to oblanceolate, ca. 4 times longer than wide, 10.2–15.1 × 2.7–3.8 cm, widest at or above the middle, apices acuminate, bases acute, margins entire, slightly sinuate at apex; a small pinnule (1.2–3.4 × 0.5–1.2 cm) sometimes present at base of one or two of lateral pinnae; terminal pinnae similar in size as largest lateral pinna of same leaf, ovate-lanceolate, 9–13 × 2.6–3.7 cm, widest below the middle, margins entire, slightly sinuate at apex. Veins mostly simple and paired at base or occasionally forked, 11–13 veins per cm; fertile leaves 51–70 cm long, petioles 40–50 cm, dark purple, with two or three nodes, blades 20–25 × 18–22 cm with 5–6 pinna pairs; lateral pinnae rather narrowly lanceolate, largest lateral pinnae 6–9 × 2–3 cm, widest at the middle, apices acute, bases acute-truncate, margins entire, sinuate-dentate at apex; terminal similar in size and shape; juveniles with simple leaves up to 9 cm, the first pinnae appearing at a length of 8 cm. ( Figs. 2 , 3 , 4 )

Etymology:— This species is endemic to the Mata Atlântica, one of the biodiversity hotspots in the world, hence this epithet was chosen.

Distribution:— The new species is so far only known from the Serra do Mar in São Paulo State, between Ubatuba and Caraguatatuba. It may possibly also occur in adjacent Rio de Janeiro State, where the vegetation and geology is similar, but collections have yet to confirm its presence there.

Ecology:— Danaea atlantica grows in thick humus covering loam or clay in moist shade under closed canopy forest, often in deep shade under boulders ( Fig. 1 ).

Specimens examined (paratypes):— BRAZIL. São Paulo: Ubatuba, Ubatumirim, Parque Estadual da Serra do Mar, Núcleo Picinguaba, along Rio da Fazenda , Casa da Farinha , 6 March 2008, Christenhusz et al. 4911 ( SP!, SPSF!, TUR!) ; Near the headwaters of Rio da Fazenda , 23°20’S 044°50’W, 172 m, 6 March 2008, Christenhusz et al. 4937 ( MO!, SP!, SPSF!, TUR!) ; Caraguatatuba, Trilha do Poção , 2008, Christenhusz et al. 4952 ( SP!, SPSF!, TUR!) .

Figures

FIGURE 1. Habitat of Danaea atlantica at the type locality near Picinguaba, São Paulo, Brazil. Photograph by Maarten Christenhusz.

FIGURE 2. Habit of Danaea atlantica with fertile leaf. Photograph Maarten Christenhusz.

FIGURE 3. Leaf of Danaea atlantica, showing the occasional additional leaflet. Photograph by Maarten Christenhusz.

FIGURE 4. Detail of a node on the petiole of Danaea atlantica. Photograph by Maarten Christenhusz.