Diphasium jussiaei (Desv. ex Poiret) Presl ex Rothm. (1944: 65)

Øllgaard, Benjamin & Testo, Weston, 2021, The Lycopodiaceae of Panamá, Phytotaxa 526 (1), pp. 1-66 : 48-49

Diphasium jussiaei (Desv. ex Poiret) Presl ex Rothm. (1944: 65) [as jussieui]. Fig. 21D

Lycopodium jussiaei Desv. ex Poiret (1814: 543) .— Lycopodium scariosum Forst. var. jussieui (Desv. ex Poiret) Baker (1887: 29) . Type :— PERU: Perou, Herb. Jussieu 658 (P holotype).

Lycopodium jussiaei Poiret var. microphyllum Poiret (1814: 543) . Type:—Amérique meridionale, Herb. Bonpland (P holotype).

Lycopodium haenkei Presl (1825: 78) . Type :— PERU: In montosis Peruviae ad Huanocco, Haenke s. n. (PRC holotype; K possible isotype).

Lycopodium heterophyllum Sprengel (1827: 13) .— Lycopodium lindseaceum Spring (1838: 180) . Type:— PERU: Peruvia, Humboldt s. n. (B, Herb. Willd. 19425 holotype).

Lycopodium holtonii Underw. & Lloyd (1906: 123) . Type :— COLOMBIA: In montibus juxta Bogotam, Holton 79 (NY holotype; K isotype).

Lycopodium scariosum Forst. var. ramosissimum Nessel (1940: 172) .— Lycopodium canceris Herter (1949a: 8) . Type:— JAMAICA: Bancroft 2420 c (BONN Herb. Nessel holotype).

Plants creeping, trailing or hanging over banks. Main stems usually above ground, rooting at intervals, rigid, 2–4 mm thick excl. leaves, usually above ground. Leaves of main stems radially arranged, uniform, 3–5 mm long, ca 1 mm wide, linear-lanceolate, with broadly membranous upper part and apex (sometimes scarious), irregularly obtuse to acute, erose apex. Aerial shoot systems 5–75 cm tall, branched almost from the base, in large individuals with a main axis almost conform to the main stem, upward gradually changing to anisophyllous, bearing alternating, fan shaped branchlet systems. Branchlets dorsiventral, anisophyllous, flattened, 4–6 (–8) mm wide incl. leaves, with 2 dorso-lateral ranks of broad leaves and 2–3 indistinct ventral ranks of narrow leaves. Dorsolateral leaves flattened in the plane of the branchlet system, or inclinate to it, obliquely elliptic, acroscopic margin 2–3.5 × 1–1.5 mm (middle), upward and ventrally curved, subacute to mucronate to short hair-tipped, basiscopic margin short to long decurrent. Ventral leaves appressed, lanceolate-subulate, with membranous apices. Strobili terminating main aerial axes, or stronger branches, pedunculate or rarely sessile. Peduncles to 12 cm long, simple or to twice forked, bearing 1–3 strobili, radially symmetrical, with distant, narrow membranous-tipped, appressed leaves. Strobili (1–) 3–10 cm long, 4–6 mm in diam. incl. leaves. Sporophylls borne in alternating whorls of 4, forming 8 longitudinal ranks, subpeltate, with a basiscopic, median membranaceous wing on the stalk, with ovate, more or less acuminate exterior face, 4–6 mm long, ca 2 mm wide, with narrowly membranous, shallowly erose denticulate margins. Sporangia 1.5–2 mm in diam. Spores reticulate, with large, regular meshes on distal faces, and unornamented proximal faces.

Distribution: Jamaica, the Cordillera Central of the Dominican Republic, Costa Rica, Panamá, Venezuela, the Andes south to Bolivia, Brazil (Itatiaia). Rio de Janeiro) and in Serra do Mar (São Paulo) (see Øllgaard & Windisch 2014, Rodriguesia 65(2): 293–309).

Habitats: In Panamá, rather uncommon and in disturbed sites in upper montane forest, 1900–2500m elev.

Notes: Diphasium jussiaei is related to D. scariosum (G.Forster) Rothmaler ( Indonesia to New Zealand), and to plants from Chile and Juan Fernandez recognized as D. gayanum (Remy) Holub. The plants referred to Diphasium jussiaei are generally larger and coarser than those species. A modern revision of the group is desirable.

Specimens­­­ studied:— Chiriquí: Distr. Renacimiento, alrededores de Cerro Pando, Fca. Los Quetzales —hito fronterizo PMA/CR (Monumento), elev. 1940–2385 m, Araúz et al. 527 ( PMA) . Panamá: Bocas del Toro, Cord. Talamanca, Headwaters of Río Colubre , 6 airline km NW of the peak of Cerro Echandi on the Costa Rica / Panamá border, Davidse et al. 25228 ( MO) . Headwaters of Río Colubre, 2400–2550 m, Gómez et al. 22380 ( AAU) .