Austroblechnum bullatum J.Murillo & L.A.Triana, 2022

Murillo-A, José & Triana-Moreno, Luz A., 2022, Novelties in Austroblechnum (Blechnaceae) from Colombia, Phytotaxa 572 (3), pp. 268-274 : 269-270

Austroblechnum bullatum J.Murillo & L.A.Triana , sp. nov. (Fig. 1,2)

Type:— COLOMBIA. Risaralda: Santuario, Distrito de Manejo Integrado Planes de San Rafael , camino hacia las cascadas, cerca al río San Rafael , 2097–2489 m, 5°7´38”N, 76°1´29”W, 10 June 2022, J. Murillo et al. 4873 (holotype COL!, isotype FAUC!) .

Diagnosis: — Austroblechnum bullatum is recognized by having pendulous laminae, pinnae bullate on both surfaces, 2–3 reduced pinnae at the base of the blade, rachis covered densely with hairs up to 2.5 mm long, and rhizome scales with acuminate apex.

Rupicolous or epiphytic plants; rhizomes short, decumbent to erect, 3 cm long, 3–4 mm in diameter, stoloniferous; scales 6 × 1.2 mm, ovate-lanceolate, apex acuminate, basifixed, lustrous, light brown to dark brown, sometimes with sclerotized lines. Leaves dimorphic. Sterile leaves 29–34(–40) cm long; petioles 11–16(–19.5) cm long, 1–15 mm in diameter, sulcate, atropurpureous, generally stramineous towards the apex, sometimes stramineous in the upper 2/3, base scarcely covered with scales similar to those of the rhizome; petioles sometimes abaxially and towards the apex covered with simple hairs, scattered, straight to undulate, long and short, from 0.1 to 0.5 mm long, dark brown, 3 meristeles in cross section; laminae 20–27 × 4.5–5.5(–7.5) cm, pendulous, pinnatisect, narrowly elliptic, abruptly reduced at the base to 1–2 pairs of semicircular to triangular pinnae, 0.7–1 × 0.2–0.5(–0.7) cm; rachises adaxially sulcate and glabrous, abaxially covered with abundant simple, straight to tortuous, dark brown hairs, 1–2(–2.5) mm long, 5–12 celled, shorter towards the apex of the laminae; buds absent, aerophores absent, pinnae 23–24(–29) pairs, 2.5–3(–4) × 0.7–1 cm, falcate, bullate on both surfaces, acute apex, connate 0.5–1 mm, entire margins, glabrous or with sparse hairs similar to those on the rachis, located marginally and along the two proximal thirds of the costae on the abaxial side, abaxial epidermis with very short; terminal pinnae bases lobulate to crenate, with acute to largely acuminate apex; veins free, furcate, simple towards the pinna apex, with claviform ending and adaxial hydathodes. Fertile leaves shorter than sterile ones, (23–) 27–33 cm long; petioles 13.5–15 (–18) cm long, 1–1.5 mm in diameter, sulcate, atropurpureous to brown and with stramineous apex, base covered scarcely with scales similar to those on the rhizome; laminae (10–)14–19 × (2.5–) 4–5 cm, erect, pinnate, elliptic, abruptly reduced on its base to 2–3 pairs of semicircular pinnae, 0.3–0.6 × 0.1–0.2 cm; rachises adaxially sulcate, covered with spaced, simple, straight to tortuous hairs, 0.3–0.5(–1) mm long 3– to 4 celled, atropurpureous to stramineous; pinnae 22–27 pairs, linear, largest ones 30– 35 × 10–15 mm, with bases widened to 2.5–3.5(–4) mm. Sori and indusia following shape of pinnae, one on each side of the costa; indusia introrse, 1–2 mm wide, entire to erose when mature. Spores monolete, ellipsoid, dark brown.

Habitat and distribution: — This species is recorded only for Colombia, in the Antioquia and Risaralda departments, at elevations between 2097 and 2500 m ( Fig. 3 ). Grows within the forest, as an epiphyte or rupicolous on seepage areas.

Etymology: —The species epithet refers to the bullate aspect of the both surfaces of the pinnae.

Examined specimens: — COLOMBIA. Antioquia: Ituango, camino de Guasimal hacia Santa Lucía, límites entre los departamentos de Antioquia y Córdoba, 2500 m, 7°10´N, 75°44´W, 18 May 2003, W. Rodríguez et al. 3817 ( COL!, HUA) .

Notes:— Austroblechnum bullatum is characterized by pendulous leaves with bullate surfaces, laminae ( Fig. 2A, E ), and rachises densely covered by straight to tortuous, dark brown hairs up to 2.5 mm long ( Fig. 2D ). It resembles Cranfillia Gasper & V.A.O. Dittrich in Gasper et al. (2016: 207) in having hairs up to 2 mm long on the rachises and costae. Nevertheless, Cranfillia has black or hyaline hairs. In addition, the rachises in Cranfillia are also covered by scales ( Gasper et al. 2016), which do not occur in Austroblechnum . Rolleri & Prada (2006) characterized the species included in Austroblechnum for the presence of three meristeles in the petiole, a character that is also present in A. bullatum ( Fig 2G ).

Austroblechnum bullatum resembles A. aequatoriense in having brown rhizome scales ( Fig. 2B, C ), but differs in the apex being filiform in A. aequatoriense , whereas in A. bullatum it is acuminate. Austroblechnum aequatoriense has several (3–8) reduced pinnae pairs on the base of the laminae, whereas in A. bullatum there are only 2–3. In addition, the rachises are densely covered with hairs up to 2.5 mm long, whereas in A. aequatoriense it is either glabrous or with hairs ca. 1 mm long. It also resembles A. lherminieri in the shape of its laminae and pinnae. However, A. lherminieri is terrestrial (vs. rupicolous or epiphytic), with erect rhizomes resembling a small arborescent plant (vs. decumbent rhizome), erect (vs. pendulous) and glabrous (vs. rachises densely covered with long hairs) laminae, and flat (vs. bullate, Fig. 2E ) pinnae. It may also be confused with A. organense (Brade) Gasper & V.A.O. Dittrich due to the presence of 1–3 reduced pinnae on the base of the lamina, but differs from A. organense in being a terrestrial plant (vs. rupicolous or epiphytes) with a glabrous rachis (vs. densely covered with simple hairs), and laminae with 10–16 pairs of pinnae (vs. 22–29).

Figures

FIGURE 2. Austroblechnum bullatum. A. Habit. B. Detail of the rhizome apex. C. Rhizome scale. D. Detail of the abaxial surface, showing rachis indumentum. E. Pinna, notice the bullate lamina. F. Adaxial surface of pinna, showing claviform ending of veins and hydathodes. G. Cross section of petiole, showing three meristeles (white arrows). Photos: B–F by J. Murillo; A and G by L.A. Triana.

FIGURE 3. Distribution map of Austroblechnum bullatum (star) and Austroblechnum aequatoriense (square). Map modified from QGIS v 3.18.3-Zürich (http://qgis.org).