Cyathea pycnocarpa (Kunze) Domin, 1929

Lehnert, Marcus, Tejedor, Adrian, Kessler, Michael, Rodríguez Duque, Wilson D. & Gallego, Luis Fernando Giraldo, 2025, A reassessment of the Neotropical Cyathea pungens complex (Cyatheaceae), European Journal of Taxonomy 988, pp. 1-57 : 36-39

Cyathea pycnocarpa (Kunze) Domin

Figs 11 , 12A

Cyathea pycnocarpa (Kunze) Domin ( Domin 1929a: 263) . – Alsophila pycnocarpa Kunze ( Kunze 1834: 97) .

– Type: PERU • Huánuco, Pampayacu ; Jul. 1829; E.F. Poeppig s.n.; holotype: LZ [destroyed]; lectotype: B [ B 20 0000124 , labelled “ Poeppig 201 ”]!, designated by Lehnert 2016.

Alsophila pterorachis Baker (Hooker & Baker 1874: 456) . – Cyathea pterorachis (Baker) Domin ( Domin 1929a: 263) .

– Type: PERU • San Martin, Tarapoto , “by rocky streams”; 1855–56; R. Spruce 4717; lectotype: K [ K000227601 ]!, first step designated by Lehnert 2016, second step designated here; isolecotypes: B [ B 20 0000362 , fragment]!, NY [ 00148759 , fragment of B] image!, US [ 00066280 ] image!.

Etymology

The specific epithet refers to the small size of the sori.

Selected material studied

PERU – San Martín • San Martin, path up to the telephone antenna above Tarapoto, ( Alto Ahuashiyacu ), along Tarapoto; 6.45° S, 76.30° W; 1333 m a.s.l.; 10 Aug. 2002; M.J.M. Christenhusz 2081; GOET, TUR • “ In m. Pingullu-Urku ” [ Cerro Pingulla ?]; [ca 06.356° S, 76.689° W]; [ca 800–1500 m a.s.l.]; Aug. 1856; R. Spruce 4715 forma pygmea [excluded syntypes of Alsophila floribunda ]; P [ P00642347 , P00642348 ]. – Cuzco • Quispicanchi, Marcapata-Quinze Mil road, quebrada of tributary of Río Azara ; 13°27.2′ S, 70°54.5′ W; 1570 m a.s.l.; 23 Oct. 2002; M. Lehnert 458; GOET, NY, UC, USM. – Madre de Dios • Prov.Manu, Parque Nacional Manu Rio Manu , Rio Sotileja ; 11.67° S, 71.92° W; 400–500 m, 1 Oct. 1986; R.B. Foster & B. dʼAchille 11548; US.

BOLIVIA – La Paz • Nor Yungas , PN Cotapata , a 600 m de la Estación Tunquini ; 16.191° S, 67.869° W; 1690 m a.s.l.; 22 Aug. 1998; A. Portugal, I. Jiménez & C. Rojas 221; GOET, LPB, UC .

Description

Trunks absent or to 1.5(–3.0) m tall, slender, 6–7(–10) cm diam., straight to decumbent, with persistent old petiole bases, inermous to muricate; apices hidden between petioles; adventitious buds absent. Leaves to 150 cm long; weakly arching to strongly arching. Petioles to 55 cm long, inermous to sparsely muricate, prickles 1–2 mm long, dark yellowish brown to stramineous, sometimes basally darker brown; aerophores to 10 × 1 mm, inconspicuously brown in dried material, whitish in fresh material; without adventitious (aphlebioid) pinnae at the petiole bases; petiole scales lanceolate, to 16 × 1.5–2.5(–3.0) mm, their tips straight, weakly twisted, concordantly to discordantly bicolorous, shiny medium to dark brown with whitish margins, scales in distal half of the petiole almost concolorous white except for brown spots near the base; colors only sharply contrasted in scales near petiole base and on crosiers; petiole scurf sparse tomentum of small branched hairs and dissected squamules 0.2–0.4 mm long, yellowish white with brown parts, grayish white in general aspect, easily abraded. Blades 80–95 × 45 cm, mostly bipinnate, chartaceous; shiny dark green adaxially, often blackish when dried, olive-green abaxially; apices abruptly reduced to non-conform apical sections, sometimes very broad and almost gradually reduced. Rachises stramineous to yellowish brown on both sides, in basal half often with some scattered prickles less than 2 mm long; adaxially with antrorsely curved uniseriate hairs 0.5–1.0 mm long, abaxially glabrous except for scurf remnants, containing a mix of appressed, white trichomoidia, dissected squamules (0.2–0.5 mm) and larger filiform scales to 20 mm long. Largest pinnae 23–39 cm long, pinnae 5–7 pairs per leaf, sessile or stalked to 1.5–2.5 cm, ascending, distally narrowly to broadly green alate, the distal segments sessile, adnate, the pinnatifid terminal section long decurrent into the costae. Costae inermous, to 1.5–2.0 mm wide, adaxially with antrorsely curved uniseriate hairs 0.5–1.0 mm long, abaxially glabrescent with scurf like on the rachises, insertions into rachises retaining larger, filiform scales from crozier, insertions abaxially weakly swollen, each with an inconspicuous planar pneumathodes, dark brown, elliptic, to 2.0 × 1.0 mm, area around it often black in dried specimens. Largest pinnules (3.5–)5.2–7.8 × (1.0–) 1.2 cm, sessile, articulate, alternate, 1.5 cm between the stalks, oblong-lanceolate to triangular-ovate, subentire to strongly crenate, incised to ⅕ of their width, bases truncate to weakly cuneate, tapering from beyond the middle to short acute to short attenuate tips; basal lobes pronounced to auricles; costules adaxially glabrous or with few hairs like on the costae, abaxially with ephemeral tan to light brown trichomidia and mostly concolorous, tan to yellowish brown, flat and bullate squamules 0.5–1.0 mm long, with short subulate tips; costules basally with a black ring going all around their bases (abscission layer); segments not differentiated, outlined only by pinnate venation and short marginal lobes; veins weakly prominent abaxially and adaxially, lateral veins ending at lobe margins; midveins yellowish brown abaxially and adaxially, lateral veins yellowish to greenish brown or blackish; adaxially glabrous except for occasional single hairs on the midveins, abaxially without hairs, with squamules and trichomidia like on the costules; sterile and fertile veins simple. Sori 0.6–0.8(–1.0) mm diam., medial to subcostal, parallel to the miveins or in tight triangular lines, indusia absent; receptacles globose to ellipsoid, 0.2–0.3 mm diam.; paraphyses few, hyaline, white, shorter than sporangia (0.2–0.3 mm). Spores not examined.

Distribution and ecology

Peru and western Bolivia at elevations of (400–) 500–1690 m a.s.l., mostly in montane forests, observed along rocky creeks in shaded gullies (quebradas).

Remarks

A relatively complete leaf of this species was included in the type material of A. floribunda (Spruce 4715 “forma pygmea ”; isotypes P00642347, P00642348). The type of Alsophila pterorachis (Spruce 4717) has serrate pinnule margins, which is atypical for C. pycnocarpa . It is placed here because of the matching overall appearance, pinnule shape and petiole scale morphology. Nevertheless, it may just represent a precociously fertile plant of a different, larger bipinnate-pinnatifid species.

With its overhanging leaves and subentire pinnules, Cyathea pycnocarpa is a relatively distinct species in the Andes, but not well understood until now. It had been subsumed under either Cyathea pungens (because of the small sori and the general resemblance) or C. dombeyi (because of the presence of small brown teeth in the pale scale margins). The material was long interpreted as precociously fertile plants of C. pungens s. lat.

As fragmentary specimen, Cyathea pycnocarpa bears a strong resemblance to the Brazilian C. dichromatolepis , where the pinnae are similarly coarsely dissected with entire pinnules and a large pinnatifid apical section. This Brazilian endemic has larger, wider petiole scales with broader white margins. It also reaches larger sizes than C. pycnocarpa , which can already be deduced from the thickness of the petioles and leaf axes. In the field, both species are easily distinguished because C. pycnocarpa has only 5–7 pinna pairs and blades with truncate bases whereas C. dichromatolepis can have twice the number of pinnae and blades with tapering bases.

Foster & dʼAchille 11548 (F, US) from Madre de Dios, Peru, is a very large specimen with most of the laminar indument relatively dark. Because of the dark squamules, it could be mistaken for C. tortuosa , but that species has white tortuous hairs on the blade abaxially and a dense villous hairs cover on the axes abaxially, which are both absent in this specimen.

Figures

Fig. 11. Cyathea pycnocarpa (Kunze) Domin. A. Petiole with scurf and scales. B. Petiole scale from petiole base. C. Pinna, silhouette. D. Fertile pinnule, abaxially. (all from Lehnert 458, BONN)

Fig. 12. A. Original illustration of Alsophila pycnocarpa Kunze (Kunze 1846: tab. LXXXVI; CC0 1.0 Deed; https://www.biodiversitylibrary.org/item/137895#page/429/mode/1up), showing a whole leaf with characteristic pale indument on the leaf axes. B. Herbarium specimen of Cyathea squamata (Klotzsch) Domin, showing typical pinnule shape with distinct petiolule and cordate bases; whitish laminar squamules also discernable in digitized image (Cuatrecasas et al. 12585, F; © Field Museum of Natural History. CC BY-NC 4.0. https://fm-digital-assets.fieldmuseum.org/1088/090/C0645972F.jpg (accessed 27 Feb. 2025)).