Diphasiastrum thyoides (Willd.) Holub (1975: 108)

Øllgaard, Benjamin & Testo, Weston, 2021, The Lycopodiaceae of Panamá, Phytotaxa 526 (1), pp. 1-66 : 46-48

Diphasiastrum thyoides (Willd.) Holub (1975: 108) . Fig. 21C

Lycopodium thyoides Willd. (1810: 18) .— Lycopodium complanatum L. var. tropicum Spring , in Martius (1840: 116).— Lycopodium complanatum L. var. adpressifolium Spring (1842: 102) .— Lycopodium complanatum L. var. thyoides (Willd.) Christ (1900: 42) . Type:— VENEZUELA: Silla de Caracas, Humboldt s. n. (B-Willd. 19352, holotype).

Lycopodium comptonioides Desv. (1827: 185) excl. synonyms. Type:— BRAZIL: Locis montosis Brasilii, Herbier de A. N. Desvaux, Donnée par Mme Vve Lavallée en 1896. With Desvaux’s label and annotation (P holotype).

Lycopodium complanatum L. var. validum Weatherby (1910: 414) . Syntypes (Fide Mickel & Beitel 1988):— MEXICO: Chiapas, Between Cristóbal Las Casas and Huitzlan. Seler 2273 (GH, K); Ghiesbrecht 600 (GH); Oaxaca, Cerro San Felipe, González & Conzatti 889 (GH); Veracruz, Region d’Orizaba, Bourgeau 3159 p. p. (GH, M, US); Hidalgo, Trinidad, Pringle 11856 (GH, L, MO).

Plants with creeping, trailing to scandent rhizomes, usually above ground, or hanging over banks. Rhizomes terete, 1.2–2.5 mm in diam. excl. leaves. Rhizome leaves relatively distant, borne in irregular spirals, or subverticillate, subulate, appressed to ascending. Aerial shoots arising from the rhizomes in a dorso-lateral position, ascending to erect, 10–50 cm tall, with vegetative portions to ca. 30 cm tall. Main upright axis terete to somewhat flattened, bearing lateral, flattened, fan-shaped branchlet systems. Ultimate branchlets flattened, dorsiventral, anisophyllous, 1.5–3 mm wide incl. leaves, with trimorphic, decussate leaves in 4 ranks. Upper, median branchlet leaves with pointed, subulate to acicular, appressed, 1–2 mm long, free blades, and a conspicuous, ca. 0.4–0.6 mm wide, prominently decurrent base. Lateral branclet leaves bilaterally compressed, long-decurrent, 2.5–7 mm long incl. bases, the free blades 1–3 mm long, appressed to spreading, acuminate to long-pointed, the leaf bases 0.6–1.5 mm wide, with almost parallel to distinctly diverging margins, often curved down. Ventral leaves inconspicuous, acicular, without decurrent base, 1–2 mm long. Peduncles terminating main erect axis or major axes of upper branchlet systems, 10–25 cm long, terete, with rather distant, subulate, appressed leaves, each bearing 4–9 pedicellate strobili. Strobili 1.5–5 cm long, 2–4 mm in diam. incl. sporophylls, often with protracted sterile tips. Sporophylls usually borne in alternating whorls of 3, forming 6 longitudinal ranks, subpeltate, with a basiscopic, median wing on the stalk, with broadly deltoid-ovate, longcuspidate, ca. 2–3 mm long, 1.5–2 mm wide exterior face, with almost entire, broadly membranous margins. Sporangia 1.5–2 mm in diam., with side walls of epidermis cells evenly sinuate. Spores densely reticulate on all faces.

Distribution: Throughout moist mountainous regions of Tropical America, south to northern Argentina.

­­­ Habitats: Clearings, road banks, open habitats, and secondary scrub in upper montane forest, and in the lowest páramos, alt. 1700–3700 m elev.

­­­ Notes: The present application of the name Diphasiastrum thyoides follows the “ L. thyoides -complex” of Wilce (1965: 155–158). We have not attempted to treat the infraspecific variation. There are few collections of D. thyoides from Panamá, and the species appears to be less common there than in most other parts of its range. Christian López (pers. comm.) reports this species from Volcán Barú, above 3000 m elev.

­­­ Specimens­­­studied:—Bocas­­­del­­­Toro: Valle de Silencio, 2500 m, Antonio 1554 ( MO) . Chiriquí: Boquete, road to Volcán Barú , 2255 m, Florpan 6885 ( AAU, HB, PMA). Sendero El Salto del Parque Nacional Volcán Barú , elev. 2260 m, R. Ríos 205 ( PMA) .