Melpomene flabelliformis (Poir.) A.R.Sm. & R.C.Moran

  • Authority

    Lehnert, Marcus. 2013. Grammitid ferns (Polypodiaceae). II. . Fl. Neotrop. Monogr. 112: 1--121. (Published by NYBG Press)

  • Family

    Polypodiaceae

  • Scientific Name

    Melpomene flabelliformis (Poir.) A.R.Sm. & R.C.Moran

  • Description

    Species Description - Plants growing in moss layers, mainly epiphytic in the Neotropics, also often terrestrial or epilithic in the Paleotropics. Rhizomes moderately to long-creeping, horizontal, 0.8-1.5 mm diam., regularly branching. Fronds to 30 cm long, erect to decumbent, inserted onto the rhizomes at right angles, diffusely arranged (internodes (2—)5—15 mm). Rhizome scales 3.6-4.0 x 0.8-1.5 mm, (14-)20-34(-60) cells wide across bases, dark brown to brown, strongly iridescent, broadly lanceate to ovate-lanceate, cordate to pseudopeltate at bases, acute to attenuate at tip; apical cells 1-8, linearly (if only 1-2 cells) to bifurcately arranged or in nodding clusters, never elongate. Petioles 35-95 mm long, 0.6-1.0 mm thick, terete to decurrently alate or marginate from the laminar bases, glabrous or glabrescent with few dark brown, ciliform hairs 0.8-1.2 mm long; simple and branched clavate hairs of crosiers and young fronds sometimes persistent on older fronds. Laminae firm-chartaceous, to 150-210 x 8-25 mm, linear-elliptic to narrowly elliptic (broadest in the middle), round to decurrently cuneate at bases, acute to rostrate at tips. Rachises dark brown to black, planar and slightly sunken between the segments adaxially, hemispherically protruding abaxially, glabrous or with a few ciliform hairs proximally on both sides, in fertile parts moderately hairy abaxially with ciliform and setiform, dark brown hairs 0.8—1.0(—2.0) mm long. Largest segments 7.5-11.5 x (2.8-)3.2-3.5 mm (2-3 times longer than broad), segments patent to weakly ascending (70-90°), oblong to linear-oblong, bases equilateral or weakly basiscopically decurrent, fully adnate, tips obtuse to round, rarely truncate; midveins not visible or obscurely so abaxially in dried specimens; surfaces pale green abaxially, rarely whitish but lacking wax-like layers; proximal 1-3 segment pairs markedly smaller than the following segments, but rarely auriculiform; fertile segments scantily to densely hairy abaxially, with ciliform and setiform, dark brown hairs 0.8-1.0(-2.0) mm long, margins not hairy; hydathodes present, level with the laminar tissue. Sori 2-4 pairs per segment, with 2-6 dark brown setiform hairs 0.8-1.0(-2.0) mm long.

  • Discussion

    Melpomene flabelliformis is the most widespread species of the genus, occurring in the wet mountains of the Neotropics, Africa, Madagascar, and the Mascarene Islands. The species is remarkably constant in its distinguishing characters, which nonetheless show a typical variation. Most notable is the increase of the number of laminar hairs with the fertility of the fronds. The sori usually have some long hairs with cirumsoral and receptacular insertion; additionally, hairs are scattered abaxially on the rachises and laminae of fertile frond parts. Sterile fronds may have no or only a few hairs on the distal parts of rachises and laminae. The only collection seen from Ethiopia has almost glabrous fertile fronds, with hairs only in some of the sori. The hairiness of other parts of the plant is not correlated with fertility. The petioles of sterile and fertile plants are terete to decurrently alate or marginate and glabrous or glabrescent, with single petioles of a given plant sometimes having more ciliform hairs than the others. A common feature in all these variants is the relatively long-creeping rhizome with wide internodes (small values in the absolute measurements of the internodes are from overall small plants) and strongly iridescent rhizome scales.

    Allowing for the occasional freak of nature (the small, hairy plants presenting the type material of Polypodium rigescens var. setulosum Rosenst, ex Bonap.), all Paleotropical specimens of Melpomene may be united in M. flabelliformis without rendering the morphological concept more variable than those of other species in this genus. Even with this relatively broad definition, M. flabelliformis is less variable in

    the Neotropics.

    Melpomene flabelliformis often is confused with M. moniliformis. Both species have an almost identical distribution in South America, considerable ecological overlap, and no separation in their elevational occurence. It seems probable that M. flabelliformis and M. moniliformis intergrade both morphologically and genetically. Treating both species as one, however, would require a more broadly defined, morphological concept. The application of this standard would reduce the whole genus to a small number of highly variable species. Instead, I have chosen to recognize two varieties in M. flabelliformis and four in M. moniliformis that reflect the correlations among morphological variability, geographic restrictions, and ecological adaptations. They may be useful in future studies that focus on the active speciation that is apparently going on in this complex.

    As defined here, Melpomene moniliformis differs from M. flabelliformis in lacking setiform/ciliform hairs between the sori or on the rachises abaxially. Although the laminae may have some hairs clustered in the sori or ephemeral clavate hairs in the distal parts (M. moniliformis var. subdicarpa rarely with single setiform hairs abaxially), they are generally less hairy than the laminae of M. flabelliformis on average. The rhizome scales of M. flabelliformis have thinner cell walls than those of M. moniliformis, which leads to a more obvious iridescence in the former species and a clearer lattice pattern in the latter. Additionally, the rhizome scales of M. flabelliformis often are matted near the rhizome apices, shed in the older posterior parts, and appear relatively pale brown with a plumbeous tinge en masse, whereas those of M. moniliformis are not matted, are persistent in all parts, and appear dark brown to reddish-brown en masse. In M. flabelliformis, the laminae are cuneate to attenuate at both ends (vs. laminae proximally often truncate in M. moniliformis) and the petioles are longer (1/4 of frond length or more in M. flabelliformis vs. 1/4 of frond length or less in M. moniliformis), terete to decurrently alate or weakly marginate, and glabrous or sparsely hairy and glabrescent (vs. petioles more decidedly marginate to alate and hairier). However, shaded plants of M. moniliformis var. moniliformis may have thin, weakly marginate, glabrescent petioles and basally cuneate laminae. Such plants differ from M. flabelliformis in the proportions of the proximal segments, which are broader than long and often auriculiform (vs. proximal segments longer than broad or as broad as long in M. flabelliformis).

    The segments of Melpomene moniliformis var. adnata can have the same proportions as those of M. flabelliformis, but the laminae are commonly more linear with abruptly truncate bases (vs. mainly elliptic with cuneate bases in M. flabelliformis) and lack hairs in and around the sori (vs. some to many hairs in fertile laminar portions). In M. moniliformis var. adnata fronds with segments that are only as broad as long which are typical of var. moniliformis, may be interspersed among fronds with long segments and prevail in shaded plants, which often have decrurrent laminar bases. In M. flabelliformis, the shapes of fronds and laminar bases are generally quite homogeneous in one plant. Furthermore, even though the rhizome scales of M. moniliformis var. adnata often reach the same absolute size and number of cells across the base as those of M. flabelliformis, they have the same cell structure as rhizome scales of var. moniliformis, i.e., thick, lateral cell walls of relatively dark brown color. These characters indicate a closer relationship to M. moniliformis var. moniliformis despite the overall similarity to M. flabelliformis.

    Tryon and Stolze (1993) considered Melpomene flabelliformis to include M. peruviana, an opinion not shared in other treatments (de la Sota et al., 2000; Mickel & Smith, 2004). Melpomene peruviana, as defined in the present treatment, evidently served as the basis for the description of M. flabelliformis in the Pteridophyta of Peru (Tryon & Stolze, 1993). In the same publication, Stolze described the real M. flabelliformis as the new species Grammitis andicola Stolze.

    Melpomene peruviana can be distinguished from M. flabelliformis by its small fronds (rarely more than 12 cm long) with predominantly ascending, deltate segments to 5.5 mm long; densely, persistently hairy petioles; and lanceate rhizome scales (8—)10—14(—18) cells wide across the base, whereas M. flabelliformis may have relatively large fronds (to 30 cm long) with patent, obtuse-oblong segments to 7.5-11.5 mm long, and ovate-lanceate rhizome scales (14—)20—34 cells wide across the base. Melpomene peruviana grows mainly epilithically in open areas, rarely epiphytically, in dense groups or cushions with its fronds stiffly pendent (Fig. 37); Melpomene flabelliformis usually grows in loose groups epiphytically or in moss cushions on rocks and soil within forests with its fronds held more or less erect.

    Specimens of Melpomene flabelliformis without receptacularly inserted but many circumsoral ciliform/ setiform hairs are known from Costa Rica, Prov. San José (Hennipman et al. 6992, UC; A. R. Smith & BelL 1994, UC; Stolze 1507, AAU, UC). They resemble M. pseudonutans, M. sklenarii, and M. vulcanica in t is respect but are easily distinguished by the laminar shape and scale characters.

    I have chosen to recognize some Brazilian pants formerly identified as M. flabelliformis (Labia & Prado, 2005a) as M. moniliformis var. subdicarpa. Features of M. flabelliformis and M. moniliformis var. moniliformis are mixed in this variety, but the similiarity to M. moniliformis prevails. It has the elliptic laminar outline and predominatly epiphytic life form of M. flabelliformis, but the hair distribution (setiform/ciliform hairs not on the laminae, confined to sori) and the relatively short internodes and petioles of M. moniliformis. The rhizome scales of both M. moniliformis var. moniliformis and var. subdicarpa are also smaller [(10—)14— 18(—20) cells wide across the base] and less iridescent than those of M. flabelliformis [(14—)20—34 cells wide across the base].

    Some plants from the Venezuelan tepuis have a laminar shape similar to that of Melpomene moniliformis var. subdicarpa and segments that resemble those of M. flagellata, but they agree with the sympatric populations of M. flabelliformis in the size of rhizomes, scales, and internodes. They are recognized here as a variety.

    The epithet means “fan-shaped” and undoubtedly refers to the illustration in the Plumier plate, which accompanies the diagnosis (Bishop, 1989a). However, the plant shown is likely a different species because its habit is unlike that of any specimen of Melpomene flabelliformis. Also, it is said to be from Martinique, which has no records for any species of Melpomene save this picture. Bishop (1989a) exhaustively discussed the application of this epithet to this species and its priority over Polypodium rigescens Bory.

    Distribution and Ecology: Mexico, Costa Rica, Haiti, Dominican Republic, Colombia, Venezuela, Ecuador, Peru, Brazil, and Bolivia in the New World (Figs. 3B.C; 18) and Ethiopia, Cameroon, Equatorial Guinea (Bioko, formerly Fernando Pó, fide Schelpe, 1970), Congo, Rwanda, Kenya, Tanzania, Uganda, Malawi (fide Schelpe, 1970), Mozambique (fide Schelpe, 1970), Zimbabwe (fide Schelpe, 1970), South Africa (fide Burrows, 1990), Madagascar, and the Mascarene Islands in the Old World (Fig. 3). In moist montane forests and elfin forests, at 1750-2750 m in Brazil, Mesoamerica, and the Greater Antilles; 2400-3960 m in the Andes; and (1000-)2650-3200(-4200) m in Africa.