Amauropelta subacrostichoides A.R.Sm., 2017

Smith, Alan R. & Kessler, Michael, 2017, Prodromus of a fern flora for Bolivia. XXX. Thelypteridaceae, Phytotaxa 331 (1), pp. 1-34 : 17-18

Amauropelta subacrostichoides A.R.Sm. , sp. nov. ( Fig. 4 )

Distinguished from congeners by having the fertile fronds (only one seen; sterile fronds not seen), at maturity, with sporangia suffused over the entire abaxial laminar surface, or nearly so; indusia not seen in the mature fronds, but possibly early-caducous; non-clathrate scales on the costae abaxially, otherwise, the costae essentially glabrous or with sparse, often appressed hairs 0.1–0.2 mm long; small peglike or tuberculiform aerophores at pinna bases.

Type:— BOLIVIA. Cochabamba: Tiraque, El Limbo, 17º08.10S, 65º37.35W, 2000 m, S. Altamirano et al. 1192 (holotype UC!; isotype BOLV) .

Plants terrestrial; stems unknown, most likely erect or suberect; petioles stramineous, darkened at bases, to ca. 25 cm × 3–4 mm, proximally with numerous scattered scales, proximally the scales shiny-brown, lanceolate, to ca. 5 × 1.5 mm, setulose on surface and margins, scales becoming fewer and scattered distally, but some seen nearly to blade bases; leaves to ca. 80 cm long; blades thick-chartaceous, pinnate-pinnatifid, proximal ca. 8 pinna pairs deflexed and gradually reduced, the shortest ca. 8 mm long, blade apex confluent, pinnatifid, gradually tapering; rachises stramineous, pubescent with hyaline single-celled hairs, especially adaxially and laterally, hairs mostly 0.2–0.5 mm long; pinnae sessile, alternate throughout blade, tapering from the base, to 5 × 0.8 cm, shallowly pinnatifid about half their width, segments relatively small, 1.5–2 mm wide; aerophores present at pinna bases, tuberculiform or small and peglike to 0.6 mm; laminar buds lacking; veins 4–6 pairs per segment, lowermost pair from adjacent segments meeting margins just above sinuses; costal scales present, these non-clathrate, ± adpressed, to 2+ mm; costae, veins, and margins glabrous abaxially, or with scattered (sparse) hairs along costae, laminar surfaces between veins glabrous, glands apparently lacking, indument adaxially on costae, costules, and laminar tissue between veins of numerous spreading or ascending, acicular hairs mostly 0.2–0.6 mm; sori medial, round, at maturity seemingly confluent and the laminae subacrostichoid (sporangia completely covering the surface); indusia seemingly absent, none seen, not even indusial fragments.

Range:— Known only from Bolivia ( CO).

Ecology:— Rare, known only from the type; terrestrial in humid forests; 2000 m.

Notes:— Affinities of this peculiar species are uncertain, but it may be related to Amauropelta opposita (Vahl) Pic. Serm. ; however, that species has laminar glands, generally lacks costal scales, and has prominent indusia. The rhizome is unknown, but likely erect.

Figures

FIGURE 4. Amauropelta subacrostichoides. A. Habit. B. Pinna. C. Pinna segments, adaxial surface detail. D. Stipe base scale. (All from the holotype: S. Altamirano et al. 1192)