Monographs Details: Melpomene pilosissima var. tsatchelae (Labiak) Lehnert
Authority: Lehnert, Marcus. 2013. Grammitid ferns (Polypodiaceae). II. . Fl. Neotrop. Monogr. 112: 1--121. (Published by NYBG Press)
Family:Polypodiaceae
Synonyms:Melpomene tsatchelae Labiak
Description:Species Description - Plants predominantly epiphytic, frequently epilithic. Rhizomes short- to very short-creeping, ascending to erect, 0.8-1.2 mm diam. Fronds to 22.5 cm long, patent to stiffly pendent, inserted onto the rhizomes at acute angles, closely arranged (internodes 1-3 mm), caespitose. Rhizome scales to 4.0-4.2 x 0.6 mm, (9—)12—14(—16) cells wide across bases, clathrate, dark brown to brown, strongly iridescent, lanceate, narrowly cordate basally, acute to attenuate at tips; apical cells 3-8 cells, linearly or furcately arranged. Petioles to 50-80(-100) mm long, 0.5-0.8 mm diam., terete to weakly marginate or decurrently alate from the laminar bases, with many dark brown to castaneous hairs 0.8-3.0 mm long, simple and branched clavate hairs of crosiers and young fronds sometimes persistent on older fronds. Laminae to 125 x 10-22 mm (ca. 2/3 of frond length), firm-herbaceous to chartaceous, narrowly elliptic to lanceate (broadest at and/or below the middle), round to cuneate at bases, short-acute at tips; 1-3 proximal segment pairs markedly smaller than the subsequent segments, sometimes remote, but not auriculiform. Rachises dark brown to ack, planar adaxially, hemispherically protruding a axially, sparsely to densely hairy abaxially and in the proximal half adaxially. Largest segments 5.0-9.0 x 1.0-2.0 mm (ca. 4-5 times longer than broad), segments oblong to linear deltate, weakly ascending (60-80°), bases inequilateral, fully adnate, tips obtuse to acute; midveins usually partially visible as black lines abaxially; margins sometimes undulate; setiform/ciliforms hairs few to many, evenly distributed on the abaxial laminar surface, always some to many hairs along the margins, at least one at the tips, sometimes few on adaxial laminar surface; hairs not clustered in sori; hydathodes well developed. Sori 1—6 pairs per segment, with setiform hairs 1.5-2.0 mm long scattered in and around them.

Discussion:The holotype of Melpomene pilosissima var. tsatchelae is a dense clump of plants that apparently grew in a thick moss cushion, and some aspects of its divergent morphology may be related to these growing conditions. The relatively long petioles and widely spaced proximal segments may be due to shading. Similar aspects are known from other species, like M. moniliformis, which produce fronds with stretched, wide-sinused bases but regular-formed distal parts, if they grow in dense cushions or out of deep crevices. The frond morphology of the isotypes of var. tstachelae is more similar to that of var. pilosissima (i.e., proximal segments less remote and less decreasing in size), and the midveins in many fronds are only obscurely visible (not as illustrated in Labiak, 2000), indicating a certain variability of this character.

The visibility of the midveins characterizes many species of Melpomene, but it is not an absolute character. Instead, it ranges within two classes: the first varying from clearly to obscurely visible, and the second varying from obscurely visible to hidden. The studied material implies that both var. pilosissima and var. tsatchelae belong to the second class. The var. tsatchelae evidently represents one extreme of the morphological variability in M. pilosissima.

Melpomene pilosissima var. tsatchelae replaces var. pilosissima in most areas of the northern Andes. The var. pilosissima differs in the predominant shape of the segment tips (mainly obtuse vs. mainly acute in var. tsatchelae) and the visibility of the midveins (not or obscurely visible vs. mostly partially visible). The var. tsatchelae also tends to have longer petioles (50-80(-100) mm vs. 26-55 mm long in var. pilosissima) and more apical cells on the rhizome scales (on average 3-8 vs. 1-6).

The name refers to the people of the Tsatchela tribe, who live near the type locality.
Distribution:Chiapas Mexico North America| Guerrero Mexico North America| Alajuela Costa Rica Central America| Bolívar Ecuador South America| El Oro Ecuador South America| Imbabura Ecuador South America| Loja Ecuador South America| Cajamarca Peru South America| Piura Peru South America| Lara Venezuela South America| Mérida Venezuela South America| Boyacá Colombia South America| Cauca Colombia South America| César Colombia South America| Cundinamarca Colombia South America|