Janssen, Janssen & Rakotondrainibe, 2008

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 : 332-334

35. Cyathea concava Bonap.

( Figs 35 ; 44I; 51D )

Notes ptéridologiques 5: 43 (1917); l. c. 9: 49 (1920). — Cyathea boivinii Mett. ex Kuhn var. concava (Bonap.) Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 32 (1951). — Type: Madagascar, forêt d’Analamazaotra, 800 m, Perrier de la Bâthie 6120 (holo-, P! [2 sheets: P00422553, -54]; iso-, P! [2 sheets]).

Cyathea ballardii Tardieu, Naturaliste malgache 3: 75 (1951); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 25 (1951). — Alsophila ballardii (Tardieu) R.M.Tryon, Contributions from the Gray Herbarium 200: 29 (1970). — Type: Madagascar, Analamazaotra, Jardin Botanique de Tananarive 3768 (lecto-, P! [P00422556], here designated; isolecto-, P!).

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Forêt d’Analamazaotra, 18°56’S, 48°26’E, Académie Malgache s.n. (P). — Toamasina, Ambatovy, Berano village, 18°50’11’’S, 48°19’17’’E, 1125 m, 17.I.2005, Antilahimena et al. 3192 (P). — Andasibe, station forestière Mitsinjo, 18°56’S, 48°26’E, 930-950 m, 11.XI.2004, Janssen et al. 2564 (MO, P, TAN), 2565 (MO, P, TAN), 2566 (MO, P, TAN), 2573 (MO, P). — RS d’Analamazaotra, 18°56’S, 48°26’E, 900-950 m, 13.XI.2004, Janssen et al. 2579 (MO, P, TAN). — Andasibe, Analamazaotra, 18°56’S, 48°26’E, 9.VI.1938, Jardin Botanique deTananarive 3768 (P). — Idem, 1000 m, Lam & Meeuse 5311 (K). — Perinet, 18°56’S, 48°26’E, 1930, Olsoufieff s.n. (B). — Toamasina, Ambatovy, 18°49’13’’S, 48°20’06’’E, 2.II.2005, Razafindraibe et al. 30 (P). — Forêt d’Analamazaotra, 18°56’S, 48°26’E, 900 m, 19.X.1912, Viguier et al. 800 (B, P). — Toamasina, Andasibe, forest of Mantadia, 18°55’S, 48°25’E, 1000-1200 m, 10.XI.1994, van der Werff et al. 13788 (MO, P). — Perinet, 18°56’S, 48°26’E, s. coll. M525 (K).

FIELD OBSERVATIONS. — Trunk: HT up to 5(-10) m, DT 5.5-7 cm, dead petiole bases persistent in the upper part of the trunk, i.e. about 1 m below the apex, caducous below and the leaf scars exposed, at most a rudiment remaining on the scar rim; trunk surface blackish brown, finely muricate; formation of adventitious buds after damage to the trunk is most likely possible; occasionally 2 or 3 trunks seem to arise from the same stock in young plants.

Petiole: with 1 row of light brown aerophores on either side, usually with a dark margin, 0.2-0.5 cm long; petiole bases recurved to sigmoid, in young plants long sigmoid forming a short fascicle above the trunk apex.

Leaf scars: 1.5 × 1.5-4 cm, rounded or elliptic to rhombic, flat or their lower half somewhat raised, some orifices below the scar; spirally arranged.

Crown: comparatively small, more or less horizontal, rarely umbrella-shaped.

Trunk apex: covered with very dense, brown scales, usually concealed by the more or less spaced petioles.

Lamina: elliptic to rounded; LL 95-150 cm, WL 85- 110 cm, FW 35-60 cm, NP 8-10.

DESCRIPTION

Petiole: 25-40(-55) cm long, 1-1.7 cm in diameter; green to stramineous, reddish brown abaxially and adaxially, finely and distantly muricate, the tubercles rather blunt and never stinging; without or with a very thin and caducous tomentum of brown, intricate squamules; never with reduced pinnae in the lower half of the petiole.

Lamina: bipinnate-pinnatisect to tripinnate, coriaceous, exhibiting a slight fertile-sterile dimorphism; shiny green to shiny dark green above, below pale green to shiny light green, but never glaucous; lamina base truncate, lamina apex abruptly attenuate, basal pinnae patent to slightly reflexed and slightly conduplicate, leaves usually completely fertile including lamina and pinnule apices; rachis of the same colour as the petiole.

Largest pinnae: 45-60 cm long, distant by 10- 14 cm, adjacent pinnae contiguous to overlapping; costae and costulae green to stramineous.

Largest pinnules: 7-12 × 1.4-2.5(-3) cm, adjacent pinnules spaced by less than their width, triangular, acute to shortly caudate, divided to the costula into segments, the 1-3 proximal segment pairs distinctly petiolulate, segments sessile in the lower third of the pinnule and progressively adnate further up, adjacent segments confluent only in the upper third of the pinnule; fertile pinnule segments distinctly concave, 0.4-0.5 cm wide, spaced by less than to about their width, rarely contiguous, straight, their margin crenate-serrate to biserrate and not revolute, their apex rounded to obtuse, somewhat asymmetric; sterile pinnule segments slightly wider, 0.5-0.6 cm, with subentire to crenulate margins, less strongly concave and adjacent segments more or less contiguous, confluent already from the middle of the pinnule; lateral veins in the segments once furcate.

Scales and hairs: scales present from the petiole base upwards to 15 cm on the petiole, very dense and overlapping, persistent at the petiole base, rapidly caducous further up on the petiole with a sudden transition from densely covered to naked, very narrowly triangular to filiform, 2.5-3.5 × <0.1- 0.1(-0.2) cm, straight, their apices twisted, crispate and somewhat intricate, shiny brown, concolourous, sometimes with a dark centre, with a narrow and finely dentate margin, appressed to the petiole or not and then antrorse, not indurated; adaxial face of the rachis, costae and costulae moderately densely tomentose with short, patent, contorted, dark brown, stiff, multicellular hairs; leaf otherwise glabrous.

Sori: very close to the midvein, contiguous to spaced by less than their width, about 0.1 cm in diameter, covering the entire segment or its lower three quarters; indusia globular, light to dark brown, coriaceous to membranous, at maturity dehiscing in 2-3(-4) persistent lobes, occasionally not dehiscing down to the base of the receptacle; receptacle capitate to rarely disciform, shorter than the rim of mature indusia, with inconspicuous filiform paraphyses shorter than the sporangia.

DISTRIBUTION

Central Madagascar: Analamazaotra and Mantadia forests; endemic.

ECOLOGY

800-1100 m. Dense evergreen rainforests and forest margins.

REMARKS

Cyathea concava is well characterized by its habit with slender and usually naked trunks in combination with a more or less horizontal crown composed of comparatively short leaves and therefore much smaller than the large umbrella-shaped crowns of C. boivinii , C. hildebrandtii , and C. similis . It has been cited as a synonym of C. humblotii (= C. boivinii, Christensen 1932: 34 ) from which it is easily distinguished by its thin petioles, very narrow scales restricted to the base of the petiole, concave, serrate pinnule segments, which are petiolulate or sessile in the lower third of the pinnule, globular indusia and a complete lack of a lamina indument of loose, crispate hairs.

Young leaves may have a caducous indument of loosely attached, light brown, crispate, branched hairs and scales (cf. van der Werff et al. 13712, Janssen et al. 2573) that completely disappears in mature leaves.

TYPIFICATION AND SYNONYMY

Two sheets of Perrier de la Bâthie 6120, containing a leaf apex and a longitudinally halved petiole base respectively, are marked “Original” by Bonaparte and are considered together to represent the holotype.Two further sheets, comprising the other half of the petiole base and a middle pinna, constitute independent isotypes, but should be kept associated as they provide complementary morphological information.

Both sheets of Jardin Botanique deTananarive 3768 carry the name C. ballardii in Tardieu’s writing, but none is distinguished as the holotype of the species. We choose P00422556 as the lectotype.

Figures

FIG. 35. — Cyathea concava Bonap.: A, pinnule segments abaxially with a fragment of the costula (at the junction with the costa); B, fertile pinnules abaxially with a fragment of the costa, sori only partly indicated; C, sterile pinnule abaxially with a fragment of the costa; D, habit; E, scale from the base of the petiole;F, basal part of the leaf (from the petiole base up to the first pinna pair, one pinna pruned), lateral view; G, leaf scars and trunk surface. A, B, D, F, G, Janssen et al. 2565 (P); C, Janssen et al. 2564 (P); E, Janssen et al. 2579 (P). Scale bars: A, E, 0.5 cm; B, C, G, 1 cm; D, 1 m; F, 5 cm.

FIG. 51. — Photographic documentation of field characters in Cyathea: A-E, habit; A’-E’, trunk apex; A”-E”, trunk surface at breast height; A-A”, Cyathea madagascarica Bonap.; B-B”, C. melanocaula Desv.; C-C”, C. remotifolia Bonap.; D-D”, C. concava Bonap.; E-E”, C. dregei Kunze; A”, persistent dead petiole bases removed from the trunk in the upper half of the picture; E, erect habit (above), creeping habit (below); E”, branched creeping trunks. A-A”, Janssen et al. 2829; B, E, uncollected; B’, B”, Janssen et al. 2608; C, C’, Janssen et al. 2582; C”, Janssen et al. 2432; D, D”, Janssen et al. 2565; D’, Janssen et al. 2579; E’, Janssen et al. 2967; E”, Janssen et al. 2779. Vouchers at P. Photos B’, B”, C’, D’ by G. Rouhan (MNHN); all other photos by T. Janssen. Scale bars: A-E, 1 m; A’-E’, A”-E”, 10 cm.