Cyathea kirkii Hook.

Janssen, Thomas & Rakotondrainibe, France, 2008, A revision of the indusiate scaly tree ferns (Cyatheaceae, Cyathea subgen. Alsophila sect. Alsophila) in Madagascar, the Comoros and the Seychelles, Adansonia (3) 30 (2), pp. 221-376 : 341-342

37. Cyathea kirkii Hook.

( Figs 1B ; 37 ; 45D ; 52D )

Synopsis Filicum: 22 (1865); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 26, fig. 2 (9-10) (1951). — Alsophila kirkii (Hook.) R.M.Tryon, Contributions from the Gray Herbarium 200: 30 (1970). — Type: Comoros, Johanna, 2000 ft. [Anjouan, 600 m], VIII.1862, Kirk s.n. (holo-, K! [K000009946]; iso-, K!).

ADDITIONAL MATERIAL EXAMINED. — Comoros. Limminghe 60 (P).

Anjouan, 12°15’S, 44°25’E, III.1877, Bewsher s.n. (K). — Idem, V.1850, Boivin s.n. (P[2]). — Idem, 1859, Grey 1845 (BM). — Idem, 800-1200 m, Hildebrandt 1748 (B, BM, K, P, W). — Sunley s.n. (K). — S. coll. s.n. (P).

Grande Comore, Nioumbadjou, Karthala Volcano , 11°47’57’’S, 43°17’50’’E, 450 m, 9.VIII.1958, Benson 28 (BM). — Idem, de Boboni à Convalescence, 11°45’S, 43°17’E, 600-700 m, 19.XI.2002, Rakotondrainibe et al. 6729 (P). — Idem, 800-1000 m, 19.XI.2002, Rakotondrainibe et al. 6734 (P). — Idem, E de Singani, 11°51’S, 43°19’E, 400-450 m, 21.XI.2002, Rakotondrainibe et al. 6751 (P) .

Moheli, Miringoni, Voundrouvou, 12°17’17’’S, 43°39’50’’E, 660 m, 24.XI.1999, Labat et al. 3208 (K, MO, P). — Miringoni, Mdawnyombe, chalet St. Antoine , 12°17’18”S, 43°39’51”E, 688 m, Labat 3738 (P). — St. Antoine , 12°17’48’’S, 43°38’07’’E, 700 m, Schlieben 11198 (B, K) .

FIELD OBSERVATIONS. — Trunk: HT up to 3(-7) m, DT 7-10 cm, dead petiole bases caducous and the leaf scars exposed.

Leaf scars: 2.5 × 6 cm, elliptic.

Lamina: LL 160-180 cm, NP 13-26.

DESCRIPTION

Petiole: 15-75 cm long, about 2 cm in diameter and light brown to stramineous when dry, finely muricate to smooth; without reduced pinnae in the lower half of the petiole.

Lamina: pinnate-pinnatisect to tripinnate, herbaceous to subcoriaceous (not coriaceous), fertilesterile dimorphism absent; dark green above, light green below; rachis of the same colour as the petiole, smooth.

Largest pinnae: 50-65 cm long, adjacent pinnae overlapping; costae and costulae of the same colour as the rachis.

Largest pinnules: 8-12 × 1.5-2.5 cm, adjacent pinnules spaced by less than their width, linearoblong, their apex caudate, divided to the costula into broadly adnate segments, the 0-2 proximal segment pairs sessile to shortly petiolulate, segments proximally more or less decurrent, the bases of adjacent segments confluent from about the middle of the pinna or only in its upper third; pinnule segments 0.3-0.4 cm wide, spaced by less than to about their width, straight and with an asymmetric apex to slightly falciform, their margin crenulate, flat, their apex rounded to obtuse; lateral veins in the segments once furcate.

Scales and hairs: scales present from the petiole base upwards to 30 cm on the petiole and rachis, at its base densely imbricate to contiguous, sometimes only slightly overlapping, gradually thinner and smaller further up on the petiole, persistent, narrowly triangular, 1.2-2 × 0.1-0.2 cm, straight to falciform, not twisted, at most their apex slightly crispate, more or less contorted further up on the petiole, shiny brown to dark brown, with a narrow, light brown, erose margin, more or less appressed, coriaceous, not indurated; scattered dull to shiny dark brown to black, narrowly triangular, appressed scales on the abaxial face of the costae, where they are up to 0.5 cm long and sparse, and of the costulae where they are up to 0.2 cm long and more abundant; scattered shiny brown, acaroid squamules on the abaxial face of the segment midveins and in the upper part of the costulae; adaxial face of the costae and costulae densely tomentose with antrorse, brown, more or less contorted, multicellular hairs, these hairs less dense on the rachis; scattered brown, filiform scales on the adaxial face of the rachis and costae.

Sori:very close to the midvein, contiguous to spaced by less than their width, about 0.1 cm in diameter, covering up to three quarters of the segment; indusia globular, subcoriaceous,brown, at maturity dehiscing into irregular lobes, but usually not down to the base of the receptacle; receptacle capitate, shorter than the rim of mature indusia, with inconspicuous filiform paraphyses shorter than the sporangia.

DISTRIBUTION

Comoros: Anjouan, Grande Comore and Moheli; endemic .

ECOLOGY

450-1000 m. Dense evergreen rainforests.

REMARKS

Cyathea kirkii might be confounded with C. boivinii var. hildebrandtii in the Comoros, from which it is most easily distinguished by its smooth petiole, shorter and narrower petiole scales, globular indusia and dark brown, lanceolate scales on the abaxial face of the rachis and costae. Its short, appressed petiole scales distinguish the species from all Madagascan tripinnate taxa. Labat et al. 3208 has a reduced pinna, 11 cm long, about halfway on the petiole.

The species is phylogenetically closely related to the bipinnate Madagascan taxa ( Janssen et al. 2008). It is included together with the tripinnate species in group III in the present treatment in order to facilitate usage of the keys.

TYPIFICATION AND SYNONYMY

The specimens on the two sheets of Kirk s.n. (K!) are fertile, but only one of them, carrying a fertile pinna with a rachis fragment, includes the name “ Cyathea kirkii Hk. ” in Hooker’s handwriting and is considered to represent the holotype specimen.

Figures

FIG. 1. — Spores of Cyathea sect. Alsophila in Madagascar and on the Comoros: A-C, spores of taxa belonging to the bipinnate clade (Janssen et al. 2008) have a perispore formed by dense slender rodlets; D-F, spores of taxa belonging to the tripinnate clade (Janssen et al. 2008) have a perispore with prominent crests; A, C. approximata Bonap.; B, C. kirkii Hook.; C, C. serratifolia Baker; D, C. boivinii Mett.ex Kuhn var.boivinii; E, C. melleri (Baker) Domin;F, C. similis C.Chr.,a young spore with a distantly verrucose perispore (Janssen & Rakotondrainibe 2006; Gastony & Tryon 1976). A, Janssen et al. 2449 (P); B, Rakotondrainibe et al. 6751 (P); C, Rakotondrainibe et al. 6230 (P); D, Janssen et al. 2481 (P); E, Janssen et al. 2536 (P); F, Janssen et al. 2576 (P). Scale bars: 10 μm.

FIG. 37.— Cyathea kirkii Hook.: A, pinnules abaxially with a fragment of the costa, sori omitted from one pinnule; B, pinnule segments abaxially from the basal part of a pinnule (at the junction of the costula with the costa), form with smaller segments; C, habit; D, pinnule segments abaxially from the basal part of a pinnule (at the junction of the costula with the costa), common form; E, basal part of the leaf (from the petiole base up to the first pinna pair), dorso-lateral view, ventral view in upper third, one half of the petiole pruned away by longitudinal section; F, scale from the base of the petiole (left: dorsal view; right: lateral view). A, D-F, Rakotondrainibe et al. 6729 (P); B, C, Labat et al. 3208 (P). Scale bars: A, E, 5 cm; B, D, F, 0.5 cm; C, 1 m.

FIG. 45. — Distribution maps for Cyatheaceae (genus Cyathea) of Madagascar and the Comoros. Species are arranged in alphabetical order.

FIG. 52. — Photographic documentation of field characters in Cyathea: A-D, F, habit; A’-D’, F’, trunk apex; A”-D”, F”, trunk surface at breast height; A-A”, Cyathea boivinii Mett. ex Kuhn var. boivinii; B-B”, C. boivinii var.hildebrandtii (Kuhn) Janssen & Rakotondr.; C-C”, C. boivinii var. andringitrensis Janssen & Rakotondr.; D, D’, C. kirkii Hook.; F-F”, C. lastii Baker; A”, the petiole bases are sometimes completely decayed on older trunks (left), but persistent in most trunks observed (right); E, C. boivinii var. andringitrensis Janssen & Rakotondr., dense tomentum of intricate squamules on the petiole; A, A’, A” (left), C, C’, uncollected; A” (right), Janssen et al. 2604; B, Janssen et al. 2433; B’, Janssen et al. 2442; B”, Janssen et al. 2464; C”, Janssen et al. 2594; D, D’, Labat et al. 3208; E, Janssen et al. 2591; F-F”, Janssen et al. 2431. Vouchers at P. Photos A’, A” (left), B’, B”, C-C”, E by G. Rouhan (MNHN); D, D’ by J.-N. Labat (MNHN); all other photos by T. Janssen. Scale bars: A-D, F, 1 m; A’-D’, F’, A”-C”, F”, 10 cm; E, 1 cm.