Cyathea ivohibensis (C.Chr.)

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 : 254-256

7. Cyathea ivohibensis (C.Chr.)

Janssen & Rakotondr., comb. et stat. nov. ( Figs 8 ; 45D ; 47E )

Cyathea quadrata Baker var. ivohibensis C.Chr. in Perrier, Catalogue des Plantes de Madagascar, Ptéridophytes: 22 (1931), nom. nud.; Dansk Botanisk Arkiv 7: 28 (1932); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 21 (1951). — Type:Pic d’Ivohibe (Bara), 1500-2000 m, XI.1924, Humbert 3200 (holo-, BM, not found; iso-, P! [3 sheets], G!). — Fianarantsoa, village d’Ivohibe, corridor forestier reliant la RS d’Ivohibe au PN d’Andringitra, forêt d’Angodongodona, lieu-dit Amparambatopitsinjova, 22°25’07’’S, 46°55’31’’E, 1100-1150 m, 21.IV.2005, Janssen et al. 2795 (epi-, P! [4 sheets: P00589591-94], here designated; isoepi-, P! [3 sheets], TAN!; one trunk surface mould at P!).

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Prov. de Fianarantsoa, Ivohibe, corridor forestier reliant la RS d’Ivohibe au PN Andringitra, forêt d’Angodongodona, lieu-dit Amparambatopitsinjova, 22°25’07’’S 46°55’31’’E, 1100 m, 20.IV.2005, Janssen et al. 2790 (MO, P,TAN).— Idem, 1100-1150 m, 21.IV.2005, Janssen et al. 2791 (MO, P, TAN). — Idem, Janssen et al. 2792 (P), 2794 (MO, P, TAN). — RS d’Ivohibe, à 8 km à l’est du village d’Ivohibe, 22°29’S 46°59’E, 1100-1250 m, 14.X.1997, Rakotondrainibe et al. 4131 (MO, P,TAN). — Corridor reliant les réserves d’Andringitra et d’Ivohibe, à 8 km au NE du village d’Ivohibe et 5,5 km à l’ESE du village d’Angodongodona, 22°25’18’’S, 46°53’54’’E, 1150-1300 m, 3.XI.1997, Rakotondrainibe et al. 4277 (P, TAN). — Idem, 9.XI.1997, Rakotondrainibe et al. 4342 (P).

FIELD OBSERVATIONS. — Trunk: HT up to 4 m, DT 4-5 cm, dead petioles caducous and leaf scars exposed; sometimes with adventitious buds; trunk surface brown, densely muricate, bearing persistent brown scales.

Petiole: with 1 or 2 rows of brown, distant aerophores on either side; petiole bases distinctly sigmoid.

Leaf scars: 1 × 2.5 cm, rounded to ovate, slightly raised, with about 5 thin rather caducous spines, up to 0.7 cm long, on their lower rim, spirally arranged.

Crown: spreading more or less horizontally.

Trunk apex: densely scaly, concealed by the close standing petiole bases.

Lamina: elliptical to oblanceolate; LL 90-130 cm, WL 30-40 cm, FW 50-70 cm, NP 40-55.

DESCRIPTION

Petiole: 8-15 cm long, 0.8-1.3 cm in diameter; green to stramineous, abaxial face sometimes reddish to dark brown; aphlebia absent.

Lamina: pinnate-pinnatisect, herbaceous (not coriaceous), dull green below, shiny dark green above, lamina base cuneate with pinnae gradually reduced in size, basal pinnae reflexed; rachis of the same colour as the petiole.

Largest pinnae: 14-(-22) cm long, distant by 2.5-3 cm, adjacent pinnae not overlapping, their apex caudate, pinnatifid; costae and costulae of the same colour as the petiole.

Largest pinnules: (0.8-)1-1.5(-2.5) × (0.2-) 0.3- 0.4 cm, spaced by less than their width, broadly adnate to the costa to subsessile with a narrowed base in the lower half of the pinna, oblong, slightly falciform, margin entire to crenate, apex rounded to obtuse; veins once furcate.

Scales and hairs:scales present from the petiole base upwards to 10 cm on the petiole, densely imbricate,

H

persistent, narrowly triangular, 0.8-2(-2.5) × 0.1- 0.15 cm, straight, their apex rarely somewhat twisted or crispate, shiny brown with a dark brown to black centre, appressed to the petiole or not and then antrorse, not indurated; dense, patent, multicellular, hyaline, hairs present on the abaxial face of all axes and veins as well as on indusia and, less dense and mixed with many smaller antrorse, brown, more or less straight and appressed hairs, on the adaxial face of the rachis and costae.

Sori: subcostular, contiguous to distant, about 0.1 cm in diameter, covering the pinnules in their lower one to three quarters; indusia globular, light brown, membranous, at maturity dehiscing in 2 or 3 lobes or irregularly; receptacle capitate, shorter than the rim of mature indusia, with inconspicuous filiform paraphyses shorter than the sporangia.

DISTRIBUTION

Southern Central Madagascar: Ivohibe-Andringitra region; endemic.

ECOLOGY

(800-)1100-1500(-2000) m. Dense evergreen rainforests.

REMARKS

This species is easily distinguished from Cyathea decrescens and its varieties, including C. decrescens var. quadrata , by its brownish, narrowly lanceolate scales that are not indurated, nor arched, nor spiny. Furthermore, the trunk surface is muricate and not covered with squaminate spines. Considerable variation with respect to segment shape ( Fig. 8A, B ) and density of the hairy indument occurs. Th e type specimen has large, strongly serrate and subsessile pinnules in the basal half of the pinnae ( Fig. 8D ). Juvenile plants exhibit wider segments with rounded apices and subentire margins. Rakotondrainibe 4131 has abundant multicellular hairs with a dark thick-walled basal cell, leaving a black scar when fallen.

TYPIFICATION AND SYNONYMY

The holotype of this species has not been found at BM, but should be in Christensen’s herbarium. As the specimen is referenced in the catalogue of BM we

currently refrain from choosing a lectotype among the duplicates of the original collection.

The petiole scales are of prime importance in distinguishing this species from C. decrescens , but only a few rudimentary scales are left in the currently available original material. We therefore consider it useful to designate an epitype.

Figures

FIG. 8. — Cyathea ivohibensis (C.Chr.) Janssen & Rakotondr.: A, pinnules abaxially with a fragment of the costa,large form with crenate margins; B, pinnules abaxially with a fragment of the costa, small form with subentire margins; C, habit; D, pinnae abaxially with a fragment of the rachis, sori only partly indicated, large form with crenate margins; E, leaf scars and trunk surface; F, pinnae abaxially with a fragment of the rachis, sori only partly indicated, small form with subentire margins; G, basal part of the leaf (from the petiole base up to the first eight pinna pairs), lateral view; H, scale from the base of the petiole. A, D, Janssen et al. 2795 (P); B, C, E-H, Janssen et al. 2790 (P). Scale bars: A, B, H, 0.5 cm; C, 1 m; D-F, 1 cm; G, 5 cm.

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

FIG. 47. — Photographic documentation of field characters in Cyathea: A-E, habit; A’-E’, trunk apex; A”-E”, trunk surface at breast height. A-A”, Cyathea marattioides Willd. ex Kaulf.; B-B”, C. perrieriana C.Chr.; C-C”, C. auriculata Tardieu; D-D”, C. decrescens Mett. ex Kuhn; E-E”, C. ivohibensis (C.Chr.) Janssen & Rakotondr. A, Janssen et al. 2488; A’, B’, uncollected; A”, Janssen et al. 2484; B, Janssen et al. 2504; B”, Janssen et al. 2505; C-C”, Janssen et al. 2508; D, Janssen et al. 2521; D’, Janssen et al. 2562; D”, Janssen et al. 2406; E, E’, Janssen et al. 2790; E”, Janssen et al. 2794. Vouchers at P. Photos B-D, A’-D’, A”-D” by G. Rouhan (MNHN); all other photos by T.Janssen. Scale bars: A-E, 1 m; A’-E’, A”, B”, D”, E”, 10 cm; C”, 5 cm.