Hymenophyllum jimenezii A.R.Sm. & M.Kessler, 2017

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 214

Hymenophyllum jimenezii A.R.Sm. & M.Kessler , sp. nov. ( Fig. 1 A–C ).

Distinguished from Hymenophyllum fragile in the rachises being unwinged, the narrow, more gradually tapering, seemingly indeterminate blades, and less divided, smaller pinnae. From H. angustum , it also differs in the unwinged rachises, generally shorter and sparser hairs, and thinner petioles and rhizomes.

Type: — BOLIVIA. La Paz: Prov. Nor Yungas, PN-ANMI Cotapata, sendero Chojilapata , laguna arriba del 2nd campamento, 16º13’S, 67º52’W, 2430 m, I. Jimenez 3908 with F. Miranda, J. Bermejo, R. Ubidia (holotype: UC; isotype LPB not seen) .

Paratype: — BOLIVIA. La Paz: Prov. Franz Tamayo, PN-ANMI Madidi, senda Keara-Mojos, desde Tokuaqe, antes de llegar a Chunkani, 14º38’S, 68º57’W, 2830 m, sterile and probably juvenile, I. Jimenez 1006 ( UC).

Plants epiphytic; rhizomes long-creeping, filiform, ca. 0.2 mm diam., beset with numerous mostly simple, contorted, pluricellular hairs to ca. 1 mm long. Fronds 10–20 cm long, seemingly of ± indeterminate apical grown, spaced 1–4 cm apart along the rhizomes; petioles 1–4 cm long, 0.15–0.2 mm wide, brown, sparsely to moderately pubescent, hairs to 0.5 mm long, a mixture of simple, forked, and stalked-stellate; rachises non-alate, moderately pubescent, hairs light reddish, simple, forked, and stalked-stellate; blades 1-pinnate-pinnatifid, narrowly triangular, apically gradually tapering and seemingly indeterminate, proximal pinnae about the same size as next pairs or slightly reduced; pinnae 15–25+ pairs, mostly 8–12 × 5–7 mm, pinnatifid into about 5 segments on each side of a pinna, ultimate segments ca. 1 mm wide, rounded at tips, with hairs on the costae, veins, and margins, the hairs light reddish, a mixture of simple, forked at the base, and short- to long-stalked and bearing 2 or 3 branches; abaxial laminar surface between veins sparingly pubescent, not obscured by hairs, hairs light reddish, sessile-stellate or with a very short stalk; involucres to 1.2 mm wide, slightly wider than long, terminal on pinna lobes, with numerous light reddish marginal hairs to 0.6 mm long.

Etymology: —We name this species for Bolivian botanist Iván Jimenez, who not only made the two collections of this species, but also of many other interesting ferns ( Kessler & Smith 2007).

Range: —Thus far, endemic to Bolivia (LP).

Ecology: —Rare, known from only two collections; epiphytic in humid montane forests; 2400–2850 m.

Notes: —This delicate, medium-sized species of subg. Sphaerocionium is perhaps most closely related to Hymenophyllum fragile and H. angustum . Hymenophyllum jimenezii is found at higher elevations (2400–2850 m) than H. angustum (<1500 m).

Figures

FIGURE 1. Hymenophyllum jimenezii. A. Holotype. B. Detail of holotype. C. Pinna. (All from the holotype: I. Jimenez 3908).