Cyathea aemula Lehnert, 2009

Lehnert, Marcus, 2009, Three new species of scaly tree ferns (Cyathea-Cyatheaceae) from the northern Andes, Phytotaxa 1, pp. 43-56 : 45-47

publication ID	https://doi.org/ 10.11646/phytotaxa.1.1.5
persistent identifier	https://treatment.plazi.org/id/03C9DA28-FFD8-FFEE-FD81-ACDFFBE1267A
treatment provided by	Felipe
scientific name	Cyathea aemula Lehnert
status	sp. nov.

Treatment

Cyathea aemula Lehnert View in CoL , sp. nov. ( Figs. 1A View FIGURE 1 , 2 View FIGURE 2 )

Species generis Cyatheae exindusiata apicibus frondorum abrupte vel gradualiter terminantibus, squamis discordanter bicoloratis, paraphysibusque longis; a Cyathea ulei paraphysibus longioribus, furfure petiolorum albicante densiore plusque persitentiore (vs. Cyathea ulei furfure brunneo, fugaci vel absente), pinnulis fertilibus incisis plusquam medio spatio usque ad costulis (vs. non plusquam medio spatio) praestans; in pinnulis longe petiolatis similis Cyatheam kalbreyeri vel Cyatheam divergentem, sed ab hac in paraphyibus longis squamisque petiolorum bicoloratis (vs. paraphysibus brevibus squamisque concoloratis Cyatheae kalbreyeri ), ab illa in absentia indusiorum (vs. Cyathea divergens cum indusiis sphaeropteroideis instructa) differt.

Type:— ECUADOR: Pastaza: Mera Cantón, 2 km NW of Mera, Campamento Vacacional Evangelico Mangayacu , up the ridge behind the Campamento , 01°26'00"S, 78°07'30"W, 1350–1500 m, 29 Jul 1992, Fay & Fay 3781 (holotype UC, isotype MO) GoogleMaps .

Trunks slender, to 7 m tall (but commonly smaller), straight or only basally ascending, without adventitious buds or old petioles, fronds shed cleanly; trunk apices hidden in fascicles of petioles of green fronds, consisting of two to four pseudowhorls so that the fascicles appear stretched ( Fig. 1A View FIGURE 1 ). Fronds to 235 cm long, arching to drooping, appearing spirally arranged along the trunk ( Fig. 1A View FIGURE 1 ). Petioles to 95 cm long, inermous to weakly muricate, stramineous to pale brown, with a line of distant, narrow whitish pneumathodes on each side, hardly seen in dried material, without adventitious pinnae at the bases; petiole scurf long persistent, a matted tomentum of small branched hairs and dissected squamules 0.2–0.4 mm long ( Fig. 2C View FIGURE 2 ), yellowish white with brown parts, greyish white in general aspect. Petiole scales broadly lanceolate to longovate ( Fig. 2A View FIGURE 2 ), 14.0–20.0 × 4.5–5.0 mm, with round to weakly cordate bases, pseudopeltately attached, tips straight, shiny auburn to dark brown, concordantly bicolorous with broad, pale brown to golden-brown, fringed margins ( Fig. 2B View FIGURE 2 ). Laminae 90–140 × 80–90 cm, bipinnate-pinnatifid, chartaceous, lustrous dark olive-green adaxially, not blackish when dried, olive green abaxially; apices abruptly reduced and conform or gradually reduced. Pinnae to 45 cm long, 4–5 pairs per frond, stalked to 6 cm ( Fig. 2D View FIGURE 2 ), distally very narrowly green-alate, the distal segments decurrently adnate. Leaf axes brown on both sides, completely glabrous abaxially except for scurf remnants, hairy only adaxially on costules, costae and distal parts of rachises, hairs 1.0– 1.5 mm long, tan to brown; costae smooth, 2–3 mm wide, insertions of costae into rachises swollen, each abaxially with one inconspicuous pneumathode acroscopically, orange-brown, elliptic, to 2 × 1 mm, and with a diffuse black spot basiscopically, at least when dried. Largest pinnules 12.0–14.0 × 2.8–3.2 cm, stalked to 14 mm, alternate, (0.6–) 1.5–2.6 cm between adjacent stalks, pinnules linear-oblong to lanceolate, incised 1/2 or more towards the costules, sterile pinnules basally truncate to cuneate ( Fig. 2E View FIGURE 2 ), fertile ones truncate to weakly cordate, tapering from beyond the middle to long-acuminate to short-attenuate tips ( Fig. 2F View FIGURE 2 ); the brown stalks inarticulate, their bases with an orange-brown to blackish, elliptic pneumathode to 1.0 × 0.4 mm ( Fig. 2G View FIGURE 2 ); segments to 25 × 8 mm, long-deltate to linear deltate, patent to ascending, with entire margins, tips falcate, obtuse to acute ( Fig. 2G View FIGURE 2 ); basal segments usually opposite, the lowest ones not remote from each other, sinuses acute and narrow (1.0– 1.5 mm) in sterile pinnules ( Fig. 2E View FIGURE 2 ), wide (2.0–3.0 mm) and obtuse to acute in fertile pinnules ( Fig. 2F View FIGURE 2 ). Veins prominent abaxially ( Fig. 2G View FIGURE 2 ) and adaxially, ending in segment margins, basal veins connivent to sinuses; veins glabrous adaxially, abaxially glabrous except for scurfy greybrown to brown trichomoidia and catenate hairs, these on and between the veins, also along the segment margins; sterile and fertile veins simple or forked. Sori 1.2–1.6 mm diam., inframedial to subproximal, forming a triangle pattern on each segment ( Fig. 2F View FIGURE 2 ), on the back of simple veins or at vein forks, indusia absent, receptacles globose to ellipsoid, 0.4–0.5 mm diam.; paraphyses numerous, hyaline, white, longer than sporangia (0.8–1.0 mm) ( Fig. 2G View FIGURE 2 ). Spores pale yellow to whitish, exospore smooth, finely porate, perispore absent.

Distribution and habitat: —Moist tropical montane forests at 1000–1560 m on the eastern Andean slopes of southern Colombia and northern Ecuador.

Etymology:—Refers to the strong similarity to several other Cyathea species (Latin, aemulus = mimicker).

Additional specimens examined (paratypes):— COLOMBIA: Putumayo: Mocoa, Corregimiento de San Antonio, Vereda Alto Campucana , finca La Mariposa, 1400 m, Mocoa Fernandéz et al. 11120 (COL). ECUADOR: Napo: Hakuna-Matata private lodge, ca. 5 km W of Archidona, 1000 m, 05 Oct 2007, Homeier et al. 2693 (QCA); Parque Nacional Sumaco-Galeras, Cordillera Galeras, 00°49.7'S, 77°32.2'W, 1560 m, 03 Apr 2008, Homeier et al. 3653 (GOET, MO, QCA, QCNE).

Cyathea aemula has a tendency towards leaf dimorphism, which is characteristic of Gymnosphaera ( Holttum 1963) but exceptional in Cyathea . The pinnule shape and the petiole indument (i.e. scurf, scales) of Cyathea aemula are similar to Cyathea divergens Kunze (1834: 100) , which can be distinguished by the presence of indusia ( C. aemula is exindusiate) and the short paraphyses (vs. long paraphyses).

The whitish to greyish scurf on leaf axes and lamina and the long paraphyses of Cyathea aemula are shared by C. gibbosa ( Klotzsch 1844: 542) Domin (1929: 262) from Venezuela and Colombia. That species has more shortly stalked and generally narrower pinnules than C. aemula as well as concolorous shiny auburn petiole scales and laminar squamules (vs. petiole scales bicolorous and laminar squamules absent in C. aemula ).

Cyathea kalbreyeri ( Baker 1894: 129) Domin (1929: 262) View in CoL has similarly strongly incised pinnules but differs from C. aemula View in CoL in having almost concolorous auburn to orange-brown petiole scales (vs. bicolorous auburn to dark brown with broad, paler margins in C. aemula View in CoL ), none or very little scurf (vs. relatively dense and long lasting), and scandent fronds to 7 m long with 12–16 pinna pairs on average (vs. fronds to 2.35 m long with 4–5 pinna pairs).

Cyathea aemula View in CoL was previously mistaken for C. ulei ( Christ 1905: 367) Domin (1930: 108) View in CoL , to which it bears a striking resemblance in its habit ( Figs. 1A, B View FIGURE 1 ). Both species grow in the understory of humid forests, and as it is often observed in Cyathea species growing under such conditions, they have relatively slender trunks and fronds arranged more spirally than in pseudowhorls. This leads to a stretched appearance of the fascicle of petioles around the trunk apex compared to this condition observed in tree ferns with thicker trunks. Both species have also veins that are connivent to the sinuses between adjacent segments, relatively few, widely spaced pinnae, and a laminar dissection that appears rather coarse. Cyathea aemula View in CoL differs from C. ulei View in CoL in having longer paraphyses (to almost twice the length of the sporangia in C. aemula View in CoL vs. of the same length as or weakly longer than the sporangia in C. ulei View in CoL ), more persistent and abundant, whitish petiole scurf (vs. brownish and ephemeral, usually absent), smaller, inconspicuous pneumathodes on the side of the petioles (vs. conspicuously white pneumathodes at least in fresh material) and more strongly incised fertile pinnules with obtuse to acute segments (incised more than half towards the costules vs. up to half to the costules with rounded to truncate segments). Furthermore, the veins in C. ulei View in CoL are always simple while they may be forked in C. aemula View in CoL . Despite the morphological similarity, preliminary analyses of chloroplast DNA sequences do not support a close affinity of both species (unpublished data).