Pteris sotae O.Martínez, 2016

Martínez, Olga G., 2016, Pteris sotae (Pteridaceae), a new endemic species for the Argentinean flora, Phytotaxa 267 (4), pp. 291-295 : 291-294

Pteris sotae O.Martínez , sp. nov. ( Figs. 1 , 2 )

Pteris sotae is similar to P. boliviensis but differs by the presence of translucent hairs on the laminae, costae and costules.

Type:— ARGENTINA. Salta: Depto. Orán, Río Blanquito , a 200 m del pueblo, 950 m, 20 September 2014, Martínez, Jarsún, Chambi, & Suárez 3876 (holotype MCNS!; isotypes MO!, NY!, SI!) .

Terrestrial; rhizomes short–creeping, 0.7–1.5 cm diam., apex with brown ovate–lanceolate scales 0.5–2.0 (–3.0) mm long, with sparsely ciliate margins. Fronds clustered, subdimorphic, 60–80 cm long. Stipe dark brown at base, apex and rachis straw–colored, with vascular bundle shaped like “ U ” with ends largely elongated and bent over the main shaft, open end oriented adaxially, grooved adaxially, the grooves continuous to the rachis; scaly at base, the scales similar to those from the rhizome, to 3.0–4.0 × 0.3–0.5 mm. Rachis glabrous to sparsely pubescent, hairs to 0.2–0.5 mm, with 2–4 cells. Laminae ovate–lanceolate, 2–pinnate–pinnatifid at base and 1–pinnate–pinnatifid above the basal pinnae pair, herbaceous, hairy on both surfaces, hairs 3–5 cells, apex obtuse or rounded, translucent, 0.2–0.5 mm on surfaces between veins, to 0.5–1.0 mm on costae and costules. Proximal pair of pinnae 20–27 cm long, stalked to 1.0 cm, opposite; median pinnae 2–5 pairs, 15–25 cm long, sessile, subopposite, sometimes dimidiate; apical pinnae 20–30 cm long, pinnate to pinnate–pinnatifid, slightly decurrent on the rachis. Segments alternate or subopposite, oblong, to 3.0–5.0 × 0.5–1.0 cm, the margins entire at the middle to serrate at the apex, sinuses between segments roundish; the terminal segment narrowly deltate, to 6.0–8.0 × 0.5–1.0 cm. Venation copiously areolate, with 2–3(–4) series of areoles along costules, slightly prominent especially on abaxial surfaces. Sori linear, along segment margins except for base/sinus and apex, without paraphyses; indusia entire, ca. 0.8 mm wide, inserted on segment margin, membranous, with hairs on surface and the base. Spores trilete, tetrahedral, 42–57 × 25–40 μm, surfaces verrucose with continuous equatorial cingulum.

Distribution and habitat: — Pteris sotae is an endemic species of the Tucuman –Bolivian Forest, and grows in wet forests at 900–1400 m ( Fig. 3) together with P. brasiliensis Raddi (1819: 293) , P. cretica Linnaeus (1767:130) , P. deflexa Link (1833: 30) , P. denticulata Swartz (1788: 129) , P. exigua O.G.Martínez & J. Prado (2011: 295) , P. inermis (Rosenst.) de la Sota (1972: 99) , and P. quadriaurita Retz. (1791: 38–39) .

Etymology: —The specific epithet is dedicated to the late Elías Ramón de la Sota, the most prestigious Argentinian pteridologist to whom the author of this paper wishes to pay tribute.

Specimens examined (Paratypes): — ARGENTINA. Salta: Orán, Río Blanquito de Santa Cruz , bosque de Myrcianthes , 1000 m, 18 September 2006, Martínez 1099 ( MCNS) ; 950 m, 20 September 2014, Martínez et al. 3879 ( MCNS) ; 900 m, Martínez et al. 3882; cerca El Angosto de Paraní , 1074 m, 21 September 2014, Martínez et al. 3948 ( MCNS) .

Additional specimens examined: — Pteris boliviensis J.Prado & A.R.Sm. : BOLIVIA. Cochabamba: Prov. Chapare, 1700 m, 22 February 1929, Steinbach 9327 (BA 30/2296, isotype).

Discussion: — Pteris sotae can be easily distinguished by the areolate venation of the pubescent laminae, which bear translucent hairs with obtuse or rounded apices. The main difference to P. lechleri is the hair type found on the laminae (hairs blunt in P.sotae vs. hairs acute in P. lechleri ). Pteris sotae is also superficially similar to P. boliviensis Prado & A.R.Sm. but that species differs in having glabrous laminae ( Prado & Smith 2002) and smaller fronds (to ca. 52 cm long vs. to 80 cm long in P. sotae ).

Pteris denticulata ( Martínez & Vilte 2012) , another species with areolate venation, differs from P.sotae in the type of stele found in the petioles (U-shaped with shorts ends in P. denticulata vs. U-shaped with ends largely elongated and bent over the main shaft in P. sotae ). Regarding petiole stele anatomy, P. sotae resembles more P. quadriaurita , a species with free veins.

The spores of Pteris sotae were well-formed trilete with cell contents in all studied material. Atypically formed, partially aborted or collapsed spores without cell contents have not been documented so far, which would be indicative of hybrids or apogamic species, like P. brasiliensis and P. denticulata ( Martínez & Morbelli 2009) . Thus P. sotae is here considered to be a sexually regularly reproducing species.

Pteris species with anastomosing veins are distributed pantropically ( Chao et al. 2014); five species of this group are found among the fifteen Pteris species present in Argentina.

Figures

FIGURE 1. Pteris sotae A. Frond, pinnate–pinnatifid lamina. B. Rhizomatic scales. C. Cross section of the petiole. D. Pinnatifid pinna. E. Abaxial pinnule surface. F. Indusium with hairs. (Drawn from the holotype).

FIGURE 2. A. Individual of Pteris sotae. B. Abaxial surface with translucent hairs. C. Spores of Pteris sotae, distal face.