Asplenium pahli Salgado, 2021

Salgado, Arthur Edward, 2021, Taxonomic and nomenclatural notes on Philippine ferns. IV. Asplenium pahli (Polypodiales, Aspleniineae, Aspleniaceae), a new species from Leyte, Philippines, Phytotaxa 524 (2), pp. 71-84 : 73-75

Asplenium pahli Salgado , sp. nov. ( Figure 2 ).

Type:— PHILIPPINES, Leyte, 500 m, 5 February 1914. C. A. Wenzel 572 (holotype P00370339 ! designated here, isotypes P00370338 !, P00370340 !, C0364253 F ( F!), US 01516038!).

Diagnosis: — Asplenium pahli and A. anisodontum have a proliferous rachis but differ in the pinna shape and serration. A. pahli differs from A. caudatum , A. falcatum , A. gueinzianum , A. planicaule and A. polyodon in the proliferous rachis, the pinna margins being irregularly serrate, sinuses of different depth and width, fewer sori distant from the costa, not contiguous, and straight or slightly falcate.

Terrestrial. Rhizome short, erect, 0.4–0.5 cm thick, paleae and palea bases few, scattered, clathrate, black, lanceate, margin entire, <1mm long, upper part of the paleae often broken off, cells small, polygonal. Roots many, crowded at the base of fronds, brown, thin, fragile when dried. Fronds erect, pinnate, crowded at the apex of the rhizome, spirally arranged, 25–45 cm long. Stipes 10.5(13.0–17.0)21.0 cm long, adaxial side grooved, abaxial side rounded, greenish, glabrous or glabrescent, with sparse paleae, paleae bicolorous, base and margin light brown, central area black, lanceate, ≤ 1 mm long, adpressed against the surface, margin entire, irregular with an occasional acute projection formed by a clathrate cell wall, palea apex acute. Lamina oblong, 15–35 cm long, (5.5) 6.5–8 cm wide, base truncate, pinnate, chartaceous, 12–15 alternating pinna pairs, pinnae slightly reduced at near apex. Rachis proliferous, abaxial side rounded, adaxial side with a wide U-shaped groove with prominent ridges, greenish, glabrescent, with adpressed small paleae, ≤ 1 mm long, lanceate, black, margin entire, apex acute, paleae on both sides of the rachis. Pinnae 3.2–4.0 cm long, 1.0– 1.3 cm wide in the middle, noncontiguous, alternating, generally trapezoid, stalked to sessile, stalk ≤ 1 mm long, naked or with few paleae, lamina adaxial side glabrous, abaxial side glabrous or with a few reduced paleae on the costa, costa prominent of both sides, adaxial side grooved with prominent ridges gradually disappearing toward the pinna apex, abaxial side rounded, basal pinna pair sub-opposite or alternating, generally oblong, of the same length and shape as median pinnae or slightly smaller; pinna base basiscopic side cuneate, acroscopic side cuneate to broadly cuneate, pinna apex acute, pinna margins irregularly serrate, sinuses of different depth and width, acroscopic margin with 5–6 oblique widely separated teeth, larger teeth with 2–3 apical teeth, teeth blunt or acute, basiscopic margin serration similar to acroscopic margin, 3–5 oblique widely separated teeth, lamina apical segment usually missing, when present deformed with a proliferous bud at the insertion with the rachis. Venation free, costa visible with prominent ridges, 5–7 pairs of veins oblique to the costa, abaxial side veins not visible, adaxial side veins hardly visible, once forking, ending near the margin; hydathodes absent. Sori in a single row distal from pinna base, on both sides of the costa, originating about 1 mm from costa, oblique, widely separated, 3–6 sori on the acroscopic side, 2–5 on the basiscopic side, 5–7 mm long, occupying middle portion of lamina, ending before reaching the margin. Indusium thick, brown, entire, rolls back to expose mature sporangia, margin entire or slightly jagged.

Distribution and ecology:—Island of Leyte, Central-Eastern Philippines. A terrestrial species growing on the eastern slopes of the Leyte Cordillera, at 500 m elevation, in lowland tropical evergreen rainforest. Climate warm and humid; rainfall evenly distributed throughout the year ( Pagasa 2020).

Etymology:—The species epithet honors Brother George Pahl, FSC, Ph.D., an American biologist and university professor who taught, mentored, and inspired thousands of students in the United States and the Philippines during his teaching career spanning more than 50 years.

Conservation status:— A. pahli was collected in an area near the towns of Dagami and Jaro that is presently denuded of its original primary growth forest ( Lasco et al. 2001; Mongabay 2020). The only collection known is that of Wenzel in 1914. This is a possible indication that A. pahli is endangered or possibly extinct in its type locality. There might be more plants scattered in the remaining stands of old growth deep in the Leyte Cordillera.

Asplenium caudatum , A. falcatum , A. anisodontum and A. pahli represent different species as shown by the characters presented in this key.

1. Fronds non proliferous .......................................................................................................................................................................2

1. Fronds proliferous ..............................................................................................................................................................................3

2. Basal pinnae not decreasing in size, lamina base truncate; acroscopic basal pinna lobe with a prominent sharp tooth, sori single row, oblique to costa.......................................................................................................................................................... A. falcatum

2. Basal pinnae gradually decreasing in size, lamina base attenuate; acroscopic basal pinna lobe without a prominent sharp tooth, sori in two rows, one parallel to costa and one oblique to costa ............................................................................................ A. caudatum

3. Fronds up to 120 cm long. Stipe and rachis dark brown; rachis hirsute, paleae projecting away from the stipe and rachis, oblong to lanceate or reduced to long twisted biserrate filaments, margin with prominent biserrate projections up to five cells long, palea base and margin concolorous with the rest of the palea, apex a long twisted biseriate filament; median pinnae falcate, 10.0– 15.6 cm long, 0.9–1.2 cm wide; sori close and parallel to costa then curving towards the margin, 7–11mm long, contiguous ................. ..................................................................................................................................................................................... A. anisodontum

3. Fronds up to 45 cm long. Stipe and rachis greenish; rachis with a few scattered paleae, paleae adpressed against the stipe and rachis surface, deltoid to lanceate in shape, margin entire and irregular, with an occasional short, acute projection caused by a cell wall, palea base and margin bicolorous with light brown margins and black central area, apex acute; median pinna straight, 3.5–4.0 cm long and 1.0– 1.3 cm wide; sori distant from the costa, straight or slightly falcate, oblique, 5–7 mm long, not contiguous............... ................................................................................................................................................................................................. A. pahli

Figures

FIGURE 2. Asplenium pahli Salgado, Wenzel 572, holotype (P). Note the plantlets near the apex of two fronds. Muséum national d’histoire naturelle, Paris, France. Collection: Vascular plants P00370339. License CC Attribution 4.0 International.Available at: https:// science.mnhn.fr/institution/mnhn/collection/p/item/p00370339