Parablechnum roraimense V.A.O.Dittrich & Gasper, 2017

Dittrich, Vinícius Antonio De Oliveira, Smith, Alan R. & Gasper, André Luís De, 2017, Parablechnum roraimense and P. paucipinna spp. nov. (Blechnaceae: Polypodiopsida), lectotypification of P. stuebelii, and citation corrections in the family, Phytotaxa 292 (1), pp. 65-73 : 69-72

publication ID	https://doi.org/ 10.11646/phytotaxa.292.1.6
persistent identifier	https://treatment.plazi.org/id/03996552-8C20-FFAD-31F7-FF6E8042FB1B
treatment provided by	Felipe
scientific name	Parablechnum roraimense V.A.O.Dittrich & Gasper
status	sp. nov.

Treatment

Parablechnum roraimense V.A.O.Dittrich & Gasper View in CoL , sp. nov. ( Fig. 2 View FIGURE 2 )

Type:— GUYANA. Cuyuni-Mazaruni: Mt. Roraima, 2,130 m, 02 November 1973, R. Persaud 160 (holotype K, isotype BRG, not seen).

Plants terrestrial; rhizomes erect, to 10 cm long, lacking stolons; rhizome apex scales tan, concolorous, basifixed, linear-lanceolate or lanceolate, margins entire or with sparse teeth, apices acute to acuminate, 12–12.5 × 2–3.3 mm; leaves clustered at rhizome apex, 21–30 cm long, fertile leaves unknown; stipes dark-stramineous or tan to frequently almost black, proximally with sparse scales similar to those on rhizomes, distally with sparse scales similar to those on rachises (of two types), lacking hairs, compressed, deeply grooved adaxially, smooth, 8–12.5 cm, proportionally very long, 2/5–1/2 of the total frond length, 1.9–2.4 mm diam.; blades coriaceous, the sterile 10–17 × 4–10 cm, ovate or ovate-lanceolate, truncate at base and lacking vestigial pinnae, the apex conform, 1-pinnate, lateral pinnae 7–10 pairs, patent (only basalmost) or all pinnae strongly ascending, 4–7 cm × 3–8 mm, linear, falcate, revolute (sometimes strongly so), the adaxial surface wrinkled on older leaves, sessile to subsessile, the stalks to 2.2 mm long, each pinna abaxially with a tan to frequently blackish, tuberculiform aerophore at its base, bases rounded, cuneate or cordate, slightly asymmetric, with one side sometimes partially overlapping rachis, basiscopic side of distal pinnae frequently adnate to rachis, sometimes fully, apices acuminate, serrate; rachises stramineous, light or dark brown, sulcate adaxially, more or less densely clothed on both sides with somewhat appressed or spreading, ovate, lanceolate, or linear tan scales 0.1–1.1 × 2.5–5.6 mm, lacking hairs, abaxially with sparse transverse wrinkles; veins simple or once-forked, free, parallel (set 0.6–0.7 mm apart midway between costae and pinna margin), clearly visible and darkened abaxially, barely visible adaxially, deeply immersed in older leaves, with clavate tips ending before the margin, seen as a black spot adaxially; costae abaxially strongly raised, clothed with sparse tan, deltate, lanceolate or stellate, ciliate scales, 0.4–0.8 × 0.6–2.1 mm, the laminar tissue abaxially with very few, mainly stellate scales, on adaxial side with many stellate or more or less linear, strongly ciliate scales, all of them minute, less than 1 mm long, but absent on older leaves; sori, indusia, and spores not seen.

Distribution and habitat:— Plants were growing on muddy soil on an escarpment at ca. 2,130 m. Known only from the type.

Etymology:— The species name comes from the locality of the type, Mount Roraima, a mountaintop on the border of Venezuela, Guyana, and Brazil.

Notes:— Distinguished from all other species in the genus by the ascending, long rhizomes; few, strongly ascending pinna pairs (up to ten); tuberculate aerophores at pinna bases; coriaceous blades with revolute pinna margins; and costae strongly raised abaxially. We are uncertain of the closest relatives of Parablechnum roraimense ; the revolute to strongly revolute pinna margins are reminiscent of species like Parablechnum stipitellatum ( Sodiro 1883: 29) Gasper & Salino in Gasper et al. (2016b: 217) and Parablechnum loxense (Kunth in Humboldt et al. 1815: 18) Gasper & Salino in Gasper et al. (2016b: 216), but these may not be closely related.

Parablechnum stuebelii (Hieron.) Gasper & Salino in Gasper et al. (2016b: 217). ( Fig. 3 View FIGURE 3 ).— Blechnum stuebelii Hieronymus (1908: 241) . –Type: COLOMBIA. Cundinamarca: Excursion nach den Llanos de San Martín, Páramo de Guasca Gegend), M.A. Stübel 717 (lectotype B-200034236, designated here!) ( Röpert, 2000).

Plants terrestrial; rhizomes creeping to ascending or semi-erect,lacking stolons, 5–8mm thick,concealed by overlapping, appressed scales; rhizome scales concolorous or weakly bicolorous (but not discordantly so) with somewhat darker bases and centers, stramineous or light tan margins, basifixed or nearly so, and darkened (atropurpureous) at the point of attachment, obscurely bi-auriculate at bases, lanceolate to ovate-lanceolate with a caudate apex, 8–10 × 1–2.5 mm, margins entire or nearly so distally, usually minutely setose (setae to 0.1 mm) at bases; leaves 1–8 cm apart, mostly 15–45 cm long, only slightly dimorphic, the fertile slightly longer than the sterile but otherwise very similar; stipes atropurpureous, shining, flattened or slightly sulcate adaxially, with conspicuous transverse wrinkles throughout, 3–20 cm × 2–4 mm, 1/3 to about equaling or slightly exceeding the blade length, with ca. 8 elliptic to round (in cross section) vascular bundles in a ring, the two adaxial ones the largest, nearly obscured by persistent ascending scales, lacking hairs, scales of two types, the larger entire or subentire or minutely setose (setae 0.1 mm) toward the base, similar to those of rhizomes but lighter tan, the smaller scales lanceolate, tan, usually conspicuously setose on the margins, the setae 0.1–0.3 mm long, all scales, and especially the smaller ones, often pectinate or irregularly ciliate basally; blades very thick, coriaceous, the fertile leaves or fertile distal pinnae on otherwise sterile leaves not noticeably different in size or outline than sterile leaves or sterile pinnae, 10–30 × 2.5–5.5 cm, alternate to subopposite, lanceolate, 1-pinnate, ± truncate at base and lacking vestigial pinnae, blade apices gradually tapered or blades sometimes with a more discrete elongate, lanceolate terminal segment, ca. 2–4 × 0.5 cm; rachises atropurpureous, with transverse wrinkles like those of stipes, sulcate adaxially, persistently scaly but lacking hairs, the scales nearly obscuring the surface and mostly 5–10 mm with some smaller ones underlying the larger ones, scales gradually diminished in size distally; pinnae 18–25 pairs, 1.2–3 × 0.3–0.6 cm, with blackish, tuberculiform aerophores at pinna bases, sessile, lowermost 1–6 pairs somewhat deflexed, only the lowermost pair slightly shortened (if at all), bases subcordate, apices rounded, margins very strongly revolute; veins simple, free in sterile pinnae, parallel, without enlarged endings (hydathodes) adaxially, slightly raised adaxially; costae, veins, and laminar tissue scaly adaxially and abaxially, the scales mostly 2–5 mm, obviously setose on their margins; sori linear, continuous, parallel to the costae, often obscured by scales; indusia dark brown, glabrous, strongly lacerate or deeply toothed, at least at maturity, teeth often blackish; spores monolete, light tan, minor equatorial diameter ca. 0.05 mm, major equatorial diameter 0.08 mm; perispore ridged.

Notes:— Blechnum stuebelii (as “ stübelii ”) was described by Hieronymus (1908), who cited five syntypes from Colombia and one from Ecuador. In our opinion, these represent at least two (if not more) different species. The only syntype with rhizome is Stübel 717 (B). In his original description, Hieronymus described the rhizome and rhizome scales of this species, and this part of his description of the species is more or less in agreement with what we see from Peruvian and Bolivian plants—rhizomes long-creeping (fronds arising at intervals of 1–8 cm) or ascending (or scandent) and densely scaly. Because Stübel 717 is the most complete specimen, and the only one with rhizome, we choose to lectotypify the species with this syntype. The identity of the remaining five syntypes is quite unclear, and may be difficult to resolve because of the incompleteness of these specimens (without rhizome and rhizome scales). In fact, Hieronymus relied on these rhizome-less specimens heavily (and perhaps primarily) in casting his description of the fronds of Blechnum stuebelii . What is clear is that these five syntypes all represent one or more than one species of Parablechnum other than Stübel 717.

Because Hieronymus’ description of B. stuebelii was based on multiple taxa, we redescribe and illustrate it, based largely on the excellent specimens seen from Peru and Bolivia cited below.

The remaining five syntypes of Blechnum stuebelii (see Röpert (ed.) 2000+), species uncertain and pending further monographic study of Parablechnum , are as follows: Stübel 841 (B), barcode B200034232, from Ecuador, Pontos; Stübel 435 (B), barcode B200034231, from Colombia, Umbegung von Bogotá; Stübel 415 (B), barcode B200034235, from Colombia, Bogotá Excurs.; Stübel 683 (B), barcode B200034234, from Colombia, Excursion nach den Llanos de San Martín, Salto del Diablo; and Stübel 59, pt. (B), barcode B200034233, from Colombia, Tolima, Pandano. One additional specimen identified as this species by Hieronymus is Ule 8509 (B, 2 sheets), barcodes B200034237 and B200034238, from Brazil, Roraima. The five syntypes cited, but not the lectotype, are all dimorphic or subdimorphic, with sterile pinnae considerably wider than pinnae of fertile fronds; all of them seem much less scaly on the blades than the lectotype and specimens cited herein from Ecuador and Peru.

Distribution and habitat:— This species grows on steep rocky slopes (type), in open paramo vegetation ( Ecuador), in primary montane forests and scrub vegetation, and on low-forested (to 4 m) ridge lines, at 2400–2850 m. The rhizomes often appear to be semi-erect, and scrambling or scandent.

Additional specimens examined:— ECUADOR. Zamora-Chinchipe: Nangaritza, Cordillera de Nanguipa, Cerro Colorado , ridge 8 km SSE of Nambija, 20 km ESE of Zamora, 04°07’51”S, 78°46’36”W, 2,630 m, 20 Feb 2002, C. J. Cole et al. 275 (MO, UC) GoogleMaps . PERU. Depto. Pasco: Pcia. Oxapampa, Chacos , 10°38’59”S, 75°17’34”W, scrub on sandstone and cloud forest on richer soil, 2700 m, 6 Nov 2009, H. van der Werff, A. Peña & C. Rojas 23230 (MO, UC). Pcia. Oxapampa, Dist. Huancabamba, Parque Nacional Yanachaga-Chemillén, parte alta de la trocha Yanachaga- Palcazú, 10°22’51”S, 75°27’21”W, 2,840 m, 30 Nov 2007, A. Monteagudo et al. 16043 (MO, UC) GoogleMaps ; Pcia. Oxapampa, road to Chacos , 10°35’S, 75°06’W, 2,400–2,700 m, 17 Jul 2003, H. van der Werff et al. 18523 (MO, UC) GoogleMaps .

Notes:— Judging from pinna size and shape, vestiture (scaliness), and very coriaceous blade texture with strongly revolute pinnae, P. stuebelii appears to be most closely related to P. loxense (Kunth) Gasper & Salino in Gasper et al. (2016b: 216), widespread in paramo vegetation from Costa Rica to Bolivia. Hieronymus (1908) also considered Blechnum loxense the closest ally to his B. stuebelii . The lectotype indicated above is, in fact, the only one of the six syntypes to be clearly indicated as growing in paramo vegetation. Parablechnum stuebelii is the most scaly species known thus far in the genus. Parablechnum loxense , although more scaly than most other species, is decidedly less scaly than P. stuebelii , and also differs in having thick trunks to 1 m tall, larger fronds, and generally stronger dimorphism (even though described as sometimes monomorphic by Moran 1995), with sterile pinnae often being noticeably more expanded than fertile pinnae. The two species are vastly different in rhizome habit, however, with P. stuebelii having conspicuously creeping, scrambling rhizomes. Although P. stuebelii fronds seem to be usually either entirely sterile or entirely fertile, it is difficult to tell that they are different without careful inspection and removal of scales, i.e., the fertile and sterile pinnae are very similar in size and shape. One frond has been noted (van der Werff et al. 18523, UC) that has sterile proximal pinnae and fertile distal pinnae. Whether this is an aberration or a frequent occurrence in the species is unknown. The spores and sporangia of P. stuebelii seem unusually large, approaching 0.1 mm, suggesting that the species is polyploid. Unusually large spores were illustrated for the presumed relative, P. loxense , by Tryon & Lugardon 1991: 531). The number of annular cells is also large, 30+. A more distant relative may be P. stipitellatum , which ranges from Colombia to Bolivia. It agrees with P. stuebelii in have very coriaceous blades with revolute pinnae, and setose scales on the rachises and costae. It differs from P. stuebelii in having much larger fronds (to 1.5 m + long), much more strongly dimorphic fertile and sterile fronds, attenuate and serrulate pinna tips, and generally darker colored rhizome and stipe base scales.