Cyathea diabolica Lehnert, 2016

Lehnert, Marcus, 2016, A synopsis of the exindusiate species of Cyathea (Cyatheaceae-Polypodiopsida) with bipinnate-pinnatifid or more complex fronds, with a revision of the C. lasiosora complex, Phytotaxa 243 (1), pp. 1-53 : 33-35

36. Cyathea diabolica Lehnert , sp. nov. ( Fig. 8 )

A new exindusiate species of Cyathea that differs from C. ulei in the basal veins in each segment that arise from the midveins and end above the sinuses (vs. arising from the costules or the axils with the midveins and ending below the sinuses or meeting at them in C. ulei ) besides having smaller pinnules on average.

Type: — ECUADOR. Zamora-Chinchipe: New road Loja-Zamora, trail to Podocarpus patch at Quebrada del Diablo, 2000–2400 m, 1 May 1987, H. van der Werff & W. Palacios 9252 (holotype UC-1540664!/-1540665!, isotypes MO-1609423!/-1609424!).

Trunks to 3 m tall, slender, to 6 cm diameter, erect to decumbent, without old petiole bases, the apices densely clothed with appressed dark reddish brown scales, adventitious buds lacking. Petioles to 30 cm long, inermous or verrucate, basally dark castaneous, distally green, on eah side with a line of narrow–elliptic lenticels to 20 × 2 mm, inconspicuous in dried material; without adventitious (aphlebioid) pinnae at the petiole bases; petiole scales lanceolate, 5–6 × 1.5(– 2.0) mm, their tips straight, shiny auburn to dark reddish brown, concolorous or with narrow paler to golden brown margins, colors transient, not sharply contrasted; petiole scurf ephemeral, scurf remnants in axils of leaf axes, brown to reddish trichomidia and branched multicellular hairs 0.2–0.4 mm long. Fronds to 150 cm long, ascending, distally arching. Laminae to 130 × 65 cm, lanceolate, mostly bipinnate–pinnatifid, chartaceous, apices abruptly to gradually reduced, i.e., a conform apical pinna is followed by two to three transitional pinnae; dark green adaxially, often black when dried, dark olive green abaxially. Pinnae to 35 cm long, 7–8 pairs per frond, basal pairs not greatly reduced (ca. 1/3 less than medial pinnae), articulate, long stalked to 1.5 cm, distally not or very narrowly green alate, the distal segments free. Leaf axes brown to pale castaneous adaxially and abaxially; completely glabrous abaxially except for some remnants of the scurf; hairy adaxially on costules, costae and rhachises, hairs 1.0– 1.5 mm long, brown to atropurpureous; costae inermous, 1.5–2.0 mm wide, insertions of costae into rhachises swollen, with one white pneumathode, elliptic to 1 mm long, and a black lunular spot to 3 × 1 mm. Pinnules 2.8–6.2 × 0.5–1.8 cm, the largest ones short stalked to 2.0 mm, alternate, 0.9–1.7 cm between the articulate stalks, each with a small, inconspicuous elliptic pneumathode 1.0 mm long and a dark ring at their base; pinnules linear–oblong, pinnatifid, lobed 1/2 to 3/4 towards the costules, sometimes with revolute margins, tapering from beyond the middle to acute tips, the largest ones with strongly cordate bases, otherwise cuneate to weakly cordate; basal segments/lobes opposite, the lowest pair as small auricles, not covering the costae; costules abaxially with reddish brown, flat lanceolate squamules to 2 mm long. Veins dark brown to blackish abaxially, green adaxially, weakly prominent on both sides, glabrous adaxially, abaxially with few appressed, tan to reddish brown trichomidia, white branched ot tortuous multicellural hairs, and occasional lanceolate dark reddish brown squamules, sterile veins simple, fertile veins simple forked. Sori 1.0– 1.2 mm diam., medial, sitting on the back of lateral veins, either at or below vein’s fork; receptacles globose, 0.2–0.3 mm diam., without subtending squamules, indusia absent; paraphyses relatively few, straight, dark brown, of the same length or weakly longer than sporangia (0.5–0.6 mm). Spores not examined.

Distribution and habitat: —Known only from Prov. Zamora-Chinchipe, Ecuador, where it grows at 2000–2260 m in moist montane forests.

Etymology: —The name refers to the type locality.

Additional specimens examined (paratypes): — ECUADOR. Zamora-Chinchipe: Parque Nacional Podocarpus, Reserva Arco Iris, trail into quebrada del Diablo to Prumnopytis patch, 2200–2260 m, 15 September 2010, M. Lehnert 1833 (LOJA!, QCA!, STU!), same locality, 03º58’S, 79º05’W, 2040–2250 m, 23 June 1988, B. Øllgaard 74982 (AAU!, QCA), same locality, 03º59’S, 79º06’W, 2000–2200 m, 23 November 1994, B. Øllgaard & H. Navarrete 105753 (QCA).

Remarks: —The type specimen of Cyathea diabolica was first identified as “ Cyathea sp. , aff. ulei (H. Christ) Domin ” by Alan Smith (UC!), but I saw a greater similarity to the Venezuelan species C. barringtonii A.R.Sm. ex Lellinger (1987 [1988]: 93) and C. sagittifolia ( Hooker 1866: 37) Domin (1929a: 263) because of the size and shape of the pinnules, or with Cyathea farinosa ( Karsten 1869: 163) Domin (1929a: 262) from Venezuela because of the similarities in the fine laminar indument and the strongly cordate pinnule bases. Having seen C. diabolica in field, however, I have to concede that the similarities to C. ulei concerning the trunk morphology are striking, as the trunks of both species are slender, decumbent and are densely clothed in concolorous reddish brown scales at the apices ( Lehnert 2009).

The differences are significant enough to separate Cyathea diabolica as a distinct species from C. ulei . On average, Cyathea diabolica has smaller fronds than C. ulei (to 150 cm long in C. diabolica vs. to 600 cm in C. ulei ), a higher number of pinnules per pinnae than C. ulei (15–20 pairs vs. 12–15 pairs) but a similar number of pinna pairs (mostly 10 or fewer). If both species are united, it would mean that smaller fronds have a higher degree of dissection than larger ones. Such a pattern has not been observed in Cyatheaceae so far, where it is usually the other way around. The segments of C. ulei usually have ± truncate tips, with the midveins strongly curved and ending into the acroscopic corner, while those of C. diabolica are obtuse to rounded and have straight to weakly curved midveins. The most reliable character is the basal basiscopic veins (arising from the costules or its angle with the midveins and connivent to the sinuses, often ending blindly below them in C. ulei vs. always arising from the mideveins and not connivent to the sinuses, reaching the segment margins above the sinuses in C. diabolica ).

The proximity in the distribution of both species seems negligibe, however, both species occurs in well-separated habitats. Cyathea ulei is characteristic of warm, moist lower montane forests with a tall canopy and relatively open understories as found mainly below 1500 m. Cyathea diabolica grows under cooler conditions above 2000 m in forests that have elfin-forest characteristics, with dense moss-covers, low canopies and understories with shrubs and bamboo thickets. The type locality is part of the Amotape-Hunacabamba-region ( Weigend 2002) and home of several narrowly endemics, including ferns (e.g. Kessler & Lehnert 2009, Lehnert 2006a, b, León & Moran 1996, Moran 1991, 1995), because the patchy distribution of vegetation types fosters localized speciation.

The cordate pinnule bases of Cyathea diabolica resemble those of C. barringtonii and C. sagittifolia but these species have sessile pinnae and pinnules (vs. short to long-stalked in C. diabolica ).

The type specimen of Cyathea diabolica has an overall dark aspect and the additional specimens show that this is a characteristic of the species and not simply due to the drying conditions. Another noteworthy aspect is that fertile fronds are fertile from base to tip, indicating good growth conditions, and that pinnules of shaded, sterile plants are not considerably wider, as observed in the similar C. barringtonii and C. sagittifolia from Venezuela.

The sori of Cyathea diabolica are sometimes devoured by unidentified insect larvae (Lehnert 1833).

Figures

FIGURE 8. Cyathea diabolica, sp. nov. A. Petiole scale. B. Central pinna, adaxially. C. Fertile pinnule, abaxially. D. Fertile segment, abaxially. (A, C–D from the holotype, B from van der Werff & Palacios 9252, UC)