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 : 306-308

27. Cyathea melanocaula Desv.

( Figs 28 A-F; 45K; 51B)

Prodrome de la famille des fougères : 322 (1827); Christensen, Dansk Botanisk Arkiv 7: 23, pl. 4 figs 12-15 (1932); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 8 (1951). — Alsophila melanocaula (Desv.) R.M.Tryon, Contributions from the Gray Herbarium 200: 30 (1970). — Type: habitat in Madagascaria, Desvaux s.n. (holo-, P! [P00418680]). — Madagascar, Toliara, Tolanaro, forêt de Manantantely, Domaine de la Cascade, aux bords de la rivière au-dessus de la cascade, 24°59’19’’S, 46°55’25’’E, 150 m, 25.XI.2004, Janssen et al. 2608 (epi-, P! [4 sheets: P00589616-19], here designated; isoepi-, P! [3 sheets], TAN!; one trunk surface mould at P!).

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Bernard s.n. (P). — Toliara, Ebakika, 24°44’S, 47°09’E, 17.XI.1932, Decary 11055 (P). — Toamasina, Andovoranto , 18°08’30’’S, 49°23’E, Higginson s.n. (K). — Fort Dauphin , forêt de Manantantely, 24°59’S, 46°55’E, 60- 300 m, 22.IX.1928, Humbert 5837 (BM, P). — Bassin de la Manampanihy , mont Vohimavo N d’Ampasimena, 24°20’S, 47°08’E, 100 m, III.1947, Humbert 20642 (P).— Toliara, Tolanaro , forêt de Manantantely, 24°59’19’’S, 46°55’25’’E, 150 m, 25.XI.2004, Janssen et al. 2609 ( MO, P), 2610 ( MO, P, TAN), 2614 (P). — Bas Matitana, 22°26’S, 47°55’E, X.1911, Perrier de la Bâthie 11554 (P). — Fianarantsoa, corridor reliant les PN de Ranomafana et d’Andringitra, Ambatofotsy, 21°44’S, 47°24’E, 680-700 m, 4.XI.2000, Rabarimanarivo et al.114 (P). — Fianarantsoa, Farafangana, 2 km S d’Analamena, 24°10’41’’S, 47°44’11’’E, 27 m, 15.VIII.2006, Razafitsalma et al. 977 (P). — Prov. d’Andovoranto, rive gauche de la Vohitra, près de Brickaville, 18°50’S, 49°04’E, 4.X.1912, Viguier et al. 474 (B, P). — Without locality, s. coll. s.n. (K) .

FIELD OBSERVATIONS. — Trunk: HT up to 2(-5) m, DT (4-)5-7(-10) cm, the appressed bases of dead petioles persist in the upper part of the trunk, caducous below and leaf scars exposed; trunk surface black, muricate with short and distant excrescences carrying a caducous scale on their tip; trunk more or less thickened at its base.

Petiole: with 1 or 2 rows of light brown to blackish, much spaced aerophores on either side and on its entire abaxial surface near the petiole base; petiole bases long, appressed to the trunk and gradually recurved.

Leaf scars: 1.5-2.7 × 3.5-4 cm, elliptic, with relatively short and blunt spines on their lower rim, big and shallow, brown orifices below the scar; spirally arranged.

Crown: many-leaved, more or less infundibuliform, petioles and rachis erect.

Trunk apex: densely scaly, dark brown, concealed by the petiole bases.

Lamina: narrowly elliptic to oblanceolate; LL (60-) 100-180 cm, WL 38-60 cm, FW 57-100 cm, NP 19-25(-40).

DESCRIPTION

Petiole: 10-25 cm long, 1-1.7 cm in diameter; completely black to dark violaceous brown.

Lamina:pinnate-pinnatifid to pinnate-pinnatisect, subcoriaceous, shiny light green below, shiny green above, lamina base attenuate to acute, the basal pinnae patent and not conduplicate; basal pinnae less deeply dissected than the middle pinnae, spaced by several times their width, the basalmost much reduced and oblong with an entire to sinuate margin and more or less caducous; rachis of the same colour as the petiole.

Largest pinnae: 24-32 cm long, distant by 5-8 cm, adjacent pinnae slightly spaced to slightly overlapping, their apex pinnatifid and long attenuate-caudate and only shallowly lobed; costa black at least in its lower half, its upper part and the costulae light brown to stramineous (dry).

Largest pinnules: 2.7-4 × 0.7-1.0 cm, spaced by less than their width, broadly adnate to the costa, slightly decurrent, adjacent pinnules confluent from the base of the pinna or only in its upper half, sinus rounded, pinnules oblong, straight, their margin entire, crenulate near the rounded apex; veins once to three times furcate.

Scales and hairs: scales present from the petiole base upwards to about 30-40 cm on the petiole and rachis, moderately dense and overlapping, persistent, narrowly triangular, 1.5-2 × 0.2 cm, straight, at most their apex slightly twisted, shiny light to dark brown, with a narrow light brown erose margin, coriaceous, slightly to conspicuously indurated at their base and more or less arching, adaxial scales not appressed to the petiole; very sparse antrorse hairs on the adaxial face of the costae; leaf otherwise completely glabrous.

Sori: subcostular, spaced by less than to about their width, 0.1-0.2 cm in diameter, covering up to three quarters of the pinnule; indusia globular, dark brown, coriaceous, at maturity dehiscing in 2-4 lobes; receptacle capitate, shorter than the rim of mature indusia, paraphyses inconspicuous.

DISTRIBUTION

Central and Southern Madagascar: south of 18°S; endemic .

ECOLOGY

50-300(-700) m.Dense evergreen rainforests, usually in very wet places, i.e. near or in small streams.

REMARKS

Young plants have less strongly dissected, i.e. pinnatifid to lobate, narrowly lanceolate pinnae, spaced by about their width. Very young plants have simply pinnate leaves and the pinnules have a sinuate margin (cf. Janssen et al. 2609, 2614).

Only few specimens of this taxon exist and most have been collected, in lowland forests. As a rare species depending on a rare habitat it is probably highly threatened.

TYPIFICATION AND SYNONYMY

Even though the fragmentary holotype is characteristic of the species with respect to lamina dissection and its black axes, the specimen has been confounded with C. borbonica Desv. ( Christensen, 1906: 193) and epitypification with specimens including the petiole base with scales seems to be useful.

28. Cyathea obtecta Rakotondr. & Janssen , sp. nov. ( Figs 28 G-K; 46B)

Filix arborescens valde characteristica, foliis ornatis duobus paribus aphlebiis, 3-4 cm longis prope basim petioli. Lamina pinnato-pinnatisecta, basi attenuata, petiolus 35-40 cm longus, dense obtecta paleis anguste triangularibus, 0.7-1 cm longis et 0.1-0.15 cm latis, strictis vel plusminusve contortis, nitide cupreo-brunneis. Paleae similes densae ad 0.7 cm longae in pagina abaxiali rhachidis, costarum et costularum. Pinnulae maximae 1.5-2 cm longae et 0.3 cm latae, costae late adnatae, spatium inter eas latitudinem aequans, margine crenulata et revoluta, apice obtusa.

TYPUS. — Madagascar, Province d’Antsiranana , district d’Andapa , Befingotra, RS d’Anjanaharibe-Sud, sur le versant Sud-Est, à 12 km à l’WSW de Befingra, 14°44’48’’S, 49°26’0’’E, 1920 m, 25.XI.1994, Rakotondrainibe & Raharimalala 2524 (holo-, P! [P00046991]) .

FIELD OBSERVATIONS. — Trunk: HT 0.2-0.3 m. Lamina: elliptic; LL 90 cm, NP 20-25.

DESCRIPTION

Petiole: 35-40 cm long, 1 cm in diameter and dark brown when dry; with 2 pairs of aphlebia near its base, these 3-4 cm long.

Lamina: pinnate-pinnatisect, subcoriaceous, lamina base shortly attenuate, basal pinnae reflexed; rachis brown, abaxial face copper brown.

Largest pinnae: 20-22 cm long, distant by 2.5-3 cm; adjacent pinnae overlapping, their apex shortly caudate, pinnatifid; costae and costulae of the same colour as the rachis.

Largest pinnules: 1.5-2 × 0.3 cm, spaced by about their width, the 2 or 3 proximal pinnule pairs sessile, other pinnules broadly adnate to the costa, linear-oblong, straight, margin crenulate and revolute, apex obtuse; veins once furcate.

Scales and hairs: scales present from the petiole base upwards to at least 40 cm on the petiole and rachis, persistent, at the petiole base dense and overlapping, contiguous to scattered and smaller in the upper half of the petiole, narrowly triangular with a long caudate apex, 0.7-1 × 0.1-0.15 cm, straight to contorted, shiny copper brown with a light brown erose margin, appressed to the petiole or not and then antrorse, somewhat indurated at their base; the same type of scales, narrower and up to 0.7 cm long, with a conspicuous but not very prominent apical spine, densely covering the abaxial face of the costae and costulae as well as scattered on both faces of the rachis; adaxial face of the costae, costulae and, to a lesser extent, of the veins densely tomentose with whitish multicellular hairs.

Sori: subcostular, contiguous to slightly spaced, about 0.1 cm in diameter, covering the lower three quarters of the pinnules; indusia globular, hyaline, membranous, dehiscing irregularly at maturity; receptacle capitate, shorter than the rim of mature indusia, paraphyses inconspicuous.

DISTRIBUTION

Northern Madagascar: Anjanaharibe-Sud; endemic.

ECOLOGY

About 1900 m. On siliceous rock in low ericoid vegetation.

ETYMOLOGY

The epithet obtecta refers to the petiole and the abaxial surface of the rachis and costae that are densely covered with scales.

Figures

FIG. 28.— A-F, Cyathea melanocaula Desv.; A, basal part of the leaf (from the petiole base up to the first several pinna pairs),basal part in lateral view,upper part in adaxial view,folded part in abaxial view;B, leaf scars and trunk surface;C, habit; D, scales from the base of the petiole (left:dorsal view;right:lateral view);E, pinnae abaxially with a fragment of the rachis,sori omitted from one pinna;F, pinnules abaxially with a fragment of the costa; G-K, C. obtecta Rakotondr.& Janssen;G, pinnae abaxially with a fragment of the rachis,sori only partly indicated; H, pinnules abaxially with a fragment of the costa; I, detail from the base of a pinnule, note the obliquely cup-shaped indusia and dense scaly indument on the costa and costula; J, scale from the base of the petiole; K, basal part of the leaf (from the petiole base up to the first pinna pair), lateral view, note the two pairs of aphlebioid pinnae near the base of the petiole. A-F, Janssen et al. 2608 (P); G-K, Rakotondrainibe 2524 (P). Scale bars: A, E, G, K, 5 cm; B, F, H, 1 cm; C, 1 m; D, 0.5 cm; I, J, 0.1 cm.