Meniscium triangularis R.S.Fernandes & Salino, 2014

Fernandes, Rozijane Santos, Yesilyurt, Jovita Cislinski & Salino, Alexandre, 2014, New species and combinations in Meniscium (Thelypteridaceae), Phytotaxa 184 (1), pp. 1-11 : 4-7

Meniscium triangularis R.S.Fernandes & Salino sp. nov. (Figures 2A–D; 3B; 5C–D)

Meniscium triangularis is similar to M. cocleanum , M. reticulatum ( Linnaeus 1759: 1325) Swartz (1803: 274) and M. membranaceum ( Mettenius 1859: 22) Pichi Sermolli (1968: 180) by the presence of buds in axils of pinnae and having triangular-lanceolate pinnae. It differs from these species mainly by the presence of the dense indument of scales and trichomes on the abaxial surface of the lamina, appressed trichomes on the main veins and costae, asymmetric pinna bases, round sori, and glands on the sporangia.

Type:— COLOMBIA. Antioquia: Anorí, Vereda Santa Gertrudis, finca La Estrella , entre las quebradas Santa Gertrudis y Rivas. 07°07’46.3”N, 75°09’31.4”W, 1315 m, 2 October 2003. W . D. Rodríguez et al. 4115, (holotype HUA142183 [basal portion] + HUA 142184 [a distal portion], isotypes COL, NY) .

Plants terrestrial. Rhizomes unknown. Fronds probably monomorphic (sterile specimen not seen). Fertile fronds 124– 158 cm long; petioles 63–88 cm long, 4.7 mm in diameter at base, brown at the base and stramineous to greenish further up, pubescent with slightly appressed, tortuous trichomes, 0.2 mm long; laminae 61–70 cm long, 1-pinnate, elliptic to oblong, chartaceous. Rachises sinuate, pubescent, abaxial side glabrous or spreading trichomes, adaxial surface with acicular, curved trichomes 0.2–0.3 mm long and spreading scales mostly 0.4–1.4 × 0.05–0.10 mm with two or more lateral cell ranks, irregular, filiform to lanceolate, basifix and appressed, caducous. Buds present in axils of distal pinnae. Aerophores present at pinna bases. Pinnae 10–11 pairs, 14–15 × 2.0– 2.3 cm, lateral pinnae lanceolate to narrow-triangular, usually sessile or stalked to 5 mm in proximal pair, bases asymmetric with acroscopic sides excavate to truncate and parallel to rachis and basiscopic sides rounded to short-lobed, proximal pinnae with cuneate base, margins entire to undulate, slightly crenate near the apex, with appressed trichomes, apex acute to acuminate; adaxial surface pubescent only at costae with scattered acicular, curved to appressed trichomes (0.1 mm long), abaxial surface of costae and veins tomentose with a white appearance, trichomes dense, acicular, ciliform, appressed 0.3– 0.5 mm long, scales appressed, caducous, 0.4–1.4 × 0.05–0.1 mm, filiform to lanceolate, or with irregular forms, sometimes with long ciliate margins; laminar surface between the veins glabrous or with sparse, small, appressed, capitate trichomes (0.08–0.10 mm long with two cells); venation regularly anastomosing, forming 6–9 of areoles between costa and pinna margin, ca. 7–10 veins arising from costae of fertile pinnae per 3 cm; cross-veins straight to slightly arcuate, uniting at an obtuse angle (145°), giving rise to a free excurrent veinlet, these veinlets occasionally bisecting the areole. Sori round, on the cross-veins, not confluent at maturity, trichomes present on the receptacle between sporangia; sporangia with globose caducous glands on the capsule. Spores monolete, ellipsoidal, perispore echinulate with sparse stelae.

FIGURE. Scanning electron micrograph ( SEM) of sporangia. A. Meniscium divergens sporangium with acicular trichomes ( T. W. Henkel et al. 4368, NY). B. Meniscium triangularis sporangium with globose gland ( W. D. Rodríguez et al. 4115, NY). Scale bars: A, B = 100 μm.

Distribution and habitat:— Meniscium triangularis is known only from the type locality in Colombia where it grows in secondary forest at 1315 m.

Etymology:— The epithet refers to the shape of lateral pinnae.

Notes:— Meniscium triangularis is well characterized by features that have not been commonly mentioned in the past, such as the presence of scales on the abaxial surface of the lamina (Fig. 2D). The species is also distinguished by the presence of the buds on axils of distal pinnae (Fig. 2A), a character that is also found in M. cocleanum . However, M. cocleanum has a glabrous abaxial laminar surface, oblong sori, and glabrous sporangia, while M. triangularis has scales and appressed trichomes on the main veins and costae, round sori and glandular sporangia (Fig. 3B).

Meniscium triangularis and M. reticulatum have the same triangular–lanceolate pinna outline. However, Meniscium triangularis can be distinguished by having buds in the axils of distal pinnae, abaxial surface of costae and veins tomentose with trichomes and scales, trichomes 0.3–0.5 mm long, acicular, ciliform, dense, appressed, which gives a white aspect to the costae; conspicuous scales 0.4–1.4 × 0.05–0.10 mm, appressed, caducous, with irregular forms, with long-ciliate margin, sori rounded (Fig. 2A–D), and sporangia capsule with globose, caducous glands (Fig. 3B). Conversely, M. reticulatum lacks buds on the axils of basal pinnae or buds, has the abaxial surface of costae and veins with curved, acicular trichomes, 0.1–0.2 mm long, slightly to moderately dense, scales usually lacking or rare, filiform or shapeless and margin not ciliate, sori oblong, and sporangia glabrous.

Meniscium membranaceum has an indument of trichomes and scales on costae and veins similar to that of M. triangularis , from which it differs by having only 2–4 pinnae pairs, with 19–20 areole rows between costa and pinna margin, buds in the axils of basal pinnae and straight secondary veins forming a 180° angle.

FIGURE. Scanning electron micrograph (SEM) of spores. A, B: Meniscium cocleanum spores with winged surface. C, D: M. divergens with echinulate surface with low, dense echinulae. E, F: M. nesioticum with cristate-reticulate surface. (A–B from Salino et al. 15361, BHCB; C–D from T.W. Henkel et al. 4368, NY; E–F from G.C. Aymard 5331, UC). Scale bars: A, C, E = 10 µm; B, D, F = 5 µm.

Meniscium membranaceum and M. triangularis have echinulate spores, however, M. triangularis has sparse stelae forming clumps (Fig. 5C–D), while M. membranaceum has stelae with perforations (Fig. 5A–B). Meniscium reticulatum has cristate–reticulate spores, confirming the statements of Wood (1973) and Tryon & Tryon (1982).

FIGURE. Scanning electron micrograph (SEM) of spores. A, B: Meniscium membranaceum spores with echinulate surface with stelae with perforations; C, D: M. triangularis spores with echinulate surface with sparse stelae forming clumps; E, F: M. reticulantum spores with cristate-reticulate surface. (A, B from A. Salino 15015, BHCB; C, D from W. D. Rodríguez et al. 4115 NY; E, F from Ranker & Lamieux 1665, UC). Scale bars: A, C =10 µm; B, D = 5 µm; E, F =100 µm.