Physematium hieronymi Ponce & Arana, 2025

Ponce, M. Mónica, Gorrer, Daniel A. & Arana, Marcelo D., 2025, Hidden and neglected taxa inside a collective taxon: taxonomic revision of Woodsiaceae in the Southern Cone of South America, Willdenowia 55 (1), pp. 29-49 : 34-38

1. Physematium hieronymi Ponce & Arana , sp. nov.

Holotype: Argentina, Jujuy, Depto. Dr. Manuel Belgrano, 9 km del desvío de la Ruta Nacional 9 camino a Tiraxi, selva con dominancia de Myrtaceae y Junglandaceae , 1600 m, 10 Dec 1998, O. Morrone & al. 3208 ( SI [accession no. 154134!]).

Diagnosis — Physematium hieronymi is similar to P. montevidense (Spreng.) Shmakov but differs by several characters: pendulous, gracile fronds (vs erect to patent); rhizomatic scales linear-triangular to narrowly lanceolate, strongly bicolorous, shiny, dark brown, totally sclerotic or with a very thin margin, blackish with castaneous to brown or reddish margin, margin entire, largely attenuate apex (vs ovate-lanceolate or triangular-lanceolate, concolorous, dull, light brown or orange becoming bicolorous, in this case with a central stripe partially to totally sclerotic, brown, margin membranous, broad (twice as wide as central stripe), fimbriate, apex ending with an apical hair); stipe scales narrowly triangular-filiform, shiny, bicolorous, dark brown at centre, sclerotic or light membranous (vs ovate-lanceolate, dull, concolorous, pale brown, orange or reddish, membranous); laminae bipinnate or bipinnate-pinnatisect, pinnules usually sharply toothed, base of pinnules broadly decurrent to rachis, rachis becoming winged (vs pinnate-pinnatifid, rarely bipinnate, pinnules slightly to strongly crenulate or bicrenulate, bases adnate to rachis); spores reticulate, without folds (vs spores reticulate-folded, with conspicuous folds).

Morphological description — Plants terrestrial, 30–50 cm tall. Rhizomes ascending, spreading, scaly, covered by persistent stipe bases; rhizomatic scales 2–3 × 0.2–0.4 mm, linear-triangular to narrowly lanceolate, strongly bicolorous, shiny, dark brown, totally sclerotic or with a very thin margin, blackish with castaneous to brown or reddish margin, margin entire, sometimes with scarce hairs, largely attenuate apex. Fronds fasciculate. Stipes very short, terete, 1.5–2 mm in diam., dark brown, often blackish proximally, scabrous, glabrescent, sometimes with paucicellular, uniseriate, glandular hairs and scaly proximally, scales narrowly triangular to filiform at apex, shiny, bicolorous, dark brown, sclerotic at centre, or sometimes light membranous. Blades linear-lanceolate to elliptic-lanceolate, bright green or light green, bipinnate or bipinnate-pinnatisect. Rachises sulcate, stramineous to pale brown, scabrous or covered by scattered, multicellular, uniseriate, glandular hairs. Pinnae numerous, remote or subremote, ascendant, nearly opposite, triangular-lanceolate to long triangular, narrow, almost 1 cm wide at base, basal pinnae reduced gradually to become auriculiform. Pinnules opposite to subopposite, obtuse to rounded at apex, basally decurrent, margin sharply toothed, teeth at bases of segments rounded to subacute, apical ones acute, margin hairy, veins visible, furcate, tips enlarged to form whitish hydathodes visible adaxially; adaxial and abaxial lamina surfaces densely covered with two types of glandular trichomes, first type tortuous, uniseriate, articulate, multicellular with acute apical cell, second type erect, capitate, apparently composed of 2 or 3 cells, uni- or bicellular stalk and an apical cell globose, pale yellow, without any apparent exudate. Sori circular, with inferior indusium, membranous, inconspicuous at maturity, divid- ed into small lobes with glandular hairs. Spores with perispore reticulate, apparently without folds, large reticles formed by thick cords or many stacked, thin cords, also micro-reticulate surface pattern formed by smaller cords. – Fig. 1A, 2, 3S –W, 4J–O, 5M–P.

Distribution — Northwestern Argentina (Catamarca, Jujuy, Salta and Tucumán), also probably in Bolivia. This rare species occurs mainly in theYungas (Montane Forest district) and Monte biogeographic provinces. – Fig. 6.

Habitat — Physematium hieronymi inhabits sunny or shady, humid rock crevices close to meadows in open habitats of the Yunguean montane forest, which develops on the upper slopes of the mountains at 1500–3500 m. These forests constitute an area of endemism dominated by Podocarpus parlatorei Pilg. ( Podocarpaceae ), Alnus acuminata Kunth ( Betulaceae ), Cedrela angustifolia DC. ( Meliaceae ) and several species of Polylepis Ruiz & Pav. ( Rosaceae ) ( Arana & al. 2021). In the Monte biogeographic province, P. hieronymi is found in shady places close to meadows in canyons and valleys, mainly in the undergrowth of woodland formations at median altitudes, intermingled with several species of Poaceae .

Etymology — The species is named in honour of the German botanist Georg Hans Hieronymus (1845–1921). Hieronymus was born in Silesia. In September 1872 he travelled to Argentina. Living in Córdoba, he dedicated himself intensely to the study of the flora, describing new species in various taxonomic groups of angiosperms and ferns. In 1883 he returned to Germany and in 1892 became a curator at the Botanic Garden and Botanical Museum Berlin-Dahlem. Hieronymus advanced the taxonomy of ferns in South America, with the description of several new taxa, especially on the genus Woodsia (= Physematium ).

Remarks — Physematium hieronymi is similar to Physematium peruvianum (Hook.) Ponce & Arana , comb. nov. ≡ Woodsia peruviana Hook., Sp. Fil. 1: 61. 1844. – Lectotype (designated by Arana & al. 2016: 16): Peru, “Shady places, Huamantanga”, 1834–1835, A. Mathews 602 (K [K000632731!]; isolectotypes: B [B 20 0094655!, B 20 0171563!], BM [BM000937848 digital image!], GH [00022287 digital image!], K [K000632730 digital image!]). However, the two species differ in several characters. In addition to the very different geographical distribution and habitats, the rhizomatic scales of P. peruvianum are lanceolate with an acute apex, castaneous, flaccid, with micro-dentate margins (vs rhizomatic scales linear-triangular, bicolorous, dark brown, with pale brown or reddish margin, entire border, sometimes with scarce hairs, and largely attenuate apex in P. hieronymi ). Also, the last segments of the fronds are fully dentate, with acute teeth with a hyaline apex, sometimes with bicuspidate teeth in P. peruvianum (vs last segments not completely toothed at bases, with obtuse to subacute teeth in P. hieronymi ). Although the type material of P. peruvianum lacks a rhizome, we were able to analyse specimens from Peru (and also high-quality digital images of specimens from Ecuador) collected in the same area from which the type material comes.

In the Southern Cone, Physematium hieronymi , owing to its habit and overall appearance, can be confused with P. jujuiense , but P. hieronymi has fronds gracile, fragile and pendulous, with laminae pinnate-pinnatifid or pinnate-pinnatisect or usually bipinnate, and pinnae more or less remote (vs fronds erect, firm and rather rigid, with laminae pinnate-pinnatisect to rarely pinnate, and pinnae more approximate in P. jujuiense ). Also, P. hieronymi grows at intermediate elevations, whereas P. jujuiense grows at higher elevations.

Additional specimens examined — ARGENTINA: CATAMARCA: Belén, Quebrada de los Potrerillos , 2700 m , 28

Jan 1952, H. Sleumer & F. Vervoorst 2460 ( LIL) ; Pomán, Saujil, quebrada del Poca Agua , camino a la Casa de Piedra , 2000 m, 22 Feb 1952, F. Vervoorst 3550 ( LIL) ; Rodeo, Quebrada de las Peñas , 27 May 1910, L. Castillón 11592 ( LIL) . — JUJUY: Dr. Manuel Belgrano, Quebrada de Lozano, Río Lozano camino a Cerro Azul, 1950 m, O. Morrone & al. 3282 ( SI) ; Tumbaya, Volcán , cantera al SE del pueblo, 2200 m, 13 Feb 1985, Kiesling & al. 5178 ( SI) . — TUCUMÁN: Anfama , 1800 m, 8 Jun 1906, L. Monetti s.n. ( LIL 40876 ) ; Tafí , San José, 2100 m, 17 Feb 1949, R. Sparre 5836 ( LIL) ; Tafí del Valle , La Ciénaga, 2567 m, 20 Apr 2013, R. Delgado 415 ( LIL) ; La Ciénaga , entre rocas, 17 Apr 1904, M. Lillo 3714 ( LIL) . Tafí , La Hoyada, 1200 m, 3 May 1922, S. Venturi 1825 ( LIL, SI) ; Cumbre del Taficillo , 1800 m, 4 Mar 1928, S. Venturi 6013 ( SI) ; Abra del Infiernillo , c. puesto vialidad, 3000 m, E. Gomez-Sosa & M. E. Múlgura 144, 146 ( SI) . — SALTA: Quebrada del Río Toro y Río Blanco , I. Vattuone 4 ( SI) .