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 : 334-341

36. Cyathea dregei Kunze

( Figs 36; 45A ; 51E )

Linnaea 10: 551 (1836); Hooker, Species Filicum 1: 23, pl. 17a (1844); Sim, The Ferns of South Africa (ed. 2): 82, pl. 6 (1915); Peter, Flora von Deutsch-Ostafrika: 17 (1929); Christensen, Dansk Botanisk Arkiv 7: 30, pl. 7 figs 18-21 (1932); Brenan, Checklist of Trees and Shrubs of the British Empire 5 (2): 180 (1949); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 23, fig. 6(1) (1951); Eggeling, Indigenous Trees of the Uganda Protectorate: 103 (1952); Tardieu, Mémoires de l’Institut français d’Afrique Noire 28: 52 (1953); Alston, Ferns of West Tropical Africa: 27 (1959); Schelpe, Flora Zambesiaca, Pteridophytes: 74, pl. 21e (1970); Holttum, Kew Bulletin 36 (3): 473 (1981); Schelpe & Anthony, Flora of Southern Africa, Pteridophyta: 69 (1986); Burrows, Southern African Ferns and Fern Allies: 84 (1990); Johns, Pteridophytes of Tropical East Africa: 51 (1991); Roux, Conspectus of Southern African Pteridophyta: 86 (2001); Edwards, Flora of Tropical East Africa, Cyatheaceae : 8 (2005). — Alsophila dregei (Kunze) R.M.Tryon, Contributions from the Gray Herbarium 200: 30 (1970); Schelpe in Fernandes et al., Conspectus florae angolensis : 60 (1977); Schelpe & Diniz, Flora de Moçambique, Pteridophyta: 73 (1979); Jacobsen, Ferns and Fern Allies of Southern Africa: 201 (1983). — Type: Inter cataractam magnam et Omsamcaba, in valle rupestri umbrosa ad rivulum, 500 p., 1838, Drège s.n. (LZ†; lecto-, BM! [BM000600677], designated by Roux (1986), Botanical Journal of the Linnean Society 92: 378; isolecto-, K!, P! [fragment in hb. Luerssen no. 6147: P00404133]).

Cyathea burkei Hook. , Species Filicum 1: 23, pl. 17b (1844). — Type:Transvaal, Macalisberg, Burke “150” (holo-, K!; iso-, BM).

Cyathea angolensis Welw. ex Hook. , Synopsis Filicum 1: 22 (1865). — Type: Angola, Benguella , Huilla , Welwitsch 83, 83bis?, 186 (syn-, K!, BM, fide Edwards [2005], Flora of Tropical East Africa: 9).

Cyathea segregata Baker , Journal of the Linnean Society 20: 303 (1883). — Cyathea dregei Kunze var. segregata (Baker) C.Chr. in Perrier, Catalogue des plantes de Madagascar, Ptéridophytes: 21 (1931); Christensen, Dansk Botanisk Arkiv 7: 31, pl. 7 figs 26-31 (1932); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 24 (1951). — Type: Central Madagascar, Baron 997 (holo- K! [K000227906]; iso-, B!).

Cyathea polyphlebia Baker , Journal of the Linnean Society 20: 303 (1883). — Cyathea dregei Kunze var. polyphlebia (Baker) C.Chr. in Perrier, Catalogue des plantes de Madagascar, Ptéridophytes: 21 (1931); Christensen, Dansk Botanisk Arkiv 7: 31, pl. 7 figs 22-25 (1932); Tardieu in Humbert, Flore de Madagascar et des Comores, IVe famille, Cyathéacées : 24 (1951). — Type: Central Madagascar, Baron 840 (“ 440 ”; holo-, K! [K000009953]; iso-, K!, B!).

Alsophila baronii Baker , Journal of the Linnean Society 21: 455 (1885). — Type: Madagascar, Baron 3143 (holo-, K! [K000009926]; iso-, P! [fragment, P00316084]).

Cyathea rigidula Baker , Journal of the Linnean Society 22: 534 (1887). — Type: Madagascar, Baron 3845 (holo-, K! [K000009927]).

Cyathea flavovirens Kuhn ex Diels, Natürliche Pflanzenfamilien 1 (4): 127 (1902). — Type: Maroharona pr. Tananarivo, 14.VI.1880, Hildebrandt 3473 (putative holo-, B! [B200129562]; putative iso-, B!, BM!).

ADDITIONAL MATERIAL EXAMINED. — Cameroon. Ngaoundéré à Meiganga, VI.1939, Jacques-Félix 4145 (P). — Montagne de Tabenken, 10 km SE Nkambe, 14.XI.1974, Letouzey 13251bis (P). — Entre Bayangam et Bafousam, 29.V.1947, s. coll. 23 (P).

Congo. Bogozo, 8.VII.1914, Bequaert 4938 (P). — Kisantu, à Kiyala, 26.X.1948, Callens 1908 (P). — Rives du Lac Tanganika, 8.V.1910, Lechaptois s.n. (P). — Regione del lago Kivu, lungo la costa della penisola di Cofonya nella baia di Nguba, 22.X.1953, Pichi-Sermolli 4421 (P).

Guinea. Fouta Djalon, Mt. Laura, 23.II.1945, Portères s.n. (P).

Madagascar. Tananarive à Antsirabe, 1300 m, 26.VII.1956, Abbayes 2306 (P). — Baron 3829 (K, P). — North West, Baron 5302 (K). — Baron 6956 (K). — Baron 9829 (P). — Ankazondandy, 18°42’S, 47°47’E, 22.IX.1966, Boiteau 258 (P). — Station forestière de l’Angavokely près Carion, 18°55’S, 47°46’E, 23.IV.1970, Boiteau 2090 (P). — P.K. 39 route du Sud, VIII.1953, Bosser 6205 (P). — Environs de Tananarive, X.1956, Bosser 10087 (P). — Campenon s.n. (P). — Antananarivo, Ankadivavala, 19°13’S, 47°19’E, 30.IV.1889, Catat 209 (P). — Sarobaratra, 7.V.1889, Catat 455 (P). — Colin s.n. (P). — Ankafana, 21°12’S, 47°12’E, 1880, Cowan s.n. (BM). — Antananarivo, Imerina, 1881, Cowan s.n. (BM). — Cowan s.n. (BM). — Ankazobe, 18°19’S, 47°06’30’’E, IX.1921, Decary s.n. (P). — Tananarive (Observatoire), 18°55’S, 47°31’E, 3.IV.1921, Decary s.n. (P). — Decary s.n. (P). — Antananarivo, 18°55’S, 47°31’E, 3.IV.1921, Decary s.n. (P). — Mahajanga, Ankaizinana, 14°30’S, 48°55’E, 1100 m, 17.IV.1923, Decary 1719 (P). — Antananarivo, 18°55’S, 47°31’E, 6.XI.1927, Decary 6045 (P). — Environs de Tananarive, Soamanandrariny, 19°39’S, 47°17’E, 28.VII.1928, Decary 6606 (P). — Antananarivo, Ankazobe, 18°19’S, 47°06’30’’E, 11.III.1930, Decary 7417 (P). — Tampoketsa au nord-est de Fenoarivo, 16.III.1930, Decary 7586 (P). — Vavavato (Betafo), 19°34’S, 46°52’E, 25.XI.1938, Decary 13829 (P). — Ankazomanga (Vakinankaratra), 19°54’S, 46°55’E, 6.XII.1939, Decary 15270 (P). — District d’Ambohimalasoa, Ialatsara, 21°04’30’’S, 47°12’E, 7.II.1942, Decary 17499 (P). — 1869, Garnier 93 (B). — 1839, Goudot s.n. (G, G-DEL). — Central Plateau, 1914, Hodgkin et al. s.n. (K). — Fianarantsoa, Ambositra, Mont Vatomavy, 20°27’S, 47°07’E, 1500- 1870 m, 23.VII.1928, Humbert 4709 (BM). — Massif du Kalambatitra, 23°22’S, 46°29’30’’E, 1600 m, XI.1933, Humbert 11890 (P). — Massif de l’Ivakoany, 23°50’30’’S, 46°26’E, 1933, Humbert 12172 (P). — Environs de Fianarantsoa, 21°27’S, 47°04’E, 15.XI.1946, Humbert 19297 (P). — Montagnes à l’ouest d’Itremo, 20°34’30’’S, 46°37’30’’E, 1500-1700 m, 1955, Humbert 28282 (P, TAN). — Isalo, W de Ranohira, 22°24’S, 45°17’E, 800-1250 m, 1955, Humbert 28724 (P). — Montagnes à l’ouest d’Itremo, 20°34’30’’S, 46°37’30’’E, 1500-1700 m, 1955, Humbert 30087 (P). — Fianarantsoa, PN d’Andringitra, forêt de Riambavy, 22°07’38’’S, 46°53’40’’E, 1550-1650 m, 17.XI.2004, Janssen et al. 2586 ( MO, P, TAN). — Idem, forêt de Ramihova, 22°07’38’’S, 46°53’40’’E, 1550-1650 m, 17.XI.2004, Janssen et al. 2587 (P, TAN). — Ambatofitorahana, environs de Tanandava, 20°49’07’’S, 47°11’54’’E, 1705 m, 15.IV.2005, Janssen et al. 2762 ( MO, P, TAN). — PN d’Andringitra, haute vallée de l’Antsifotra, 22°11’18’’S, 46°55’49’’E, 2043 m, 18.IV.2005, Janssen et al. 2779 ( MO, P, TAN). — Mahajanga, Plateau de Tampoketsa, Antokonana, 76 km N Ankazobe, 17°52’55’’S, 47°04’43’’E, 1500 m, 19.V.2005, Janssen et al. 2966 ( MO, P, TAN), 2967 ( MO, P, TAN). — Fianarantsoa, Ambatofitorahana, 20°49’S, 47°11’E, III.1960, Keraudren 270 (P). — Fianarantsoa, massif de l’Itremo, 20°34’30’’S, 46°37’30’’E, 1.XII.1970, Keraudren-Aymonin et al. 25752 (P). — Idem, 24.XI.1993, Labat et al. 2419 (K, P). — Forêt d’Analandraisoa (Ambohijatovo), SW de Tsiroanomandidy, 19°09’S, 45°49’E, 1200-1300 m, XI.1952, Leandri et al. 1892 (K, MO, P, TAN). — Antananarivo, 25 km N of Ankazobe, 17°58’30’’S, 47°12’E, 1600 m, 22.XI.1985, Leeuwenberg 13724 (BR, WAG). — Près de la Betsiboka, à Bemakampy, 17°24’S, 46°01’E, 400-500 m, VI.1911, Mazières s.n. (P). — Fianarantsoa, PN Andringitra, forêt de Ravaro, SW Antanitotsy, 22°13’30’’S, 46°55’30’’E, 1500 m, 15.I.2000, Messmer et al. 876 (G, P). — Entre Ambohitiolomahitsy et Savabe, 10.XI.1963, Peltier 4292 (P). — Pont de la Manankazo, 18°09’S, 47°14’E, 17.XI.1963, Peltier 4375 (P). — Mahitsy, 11.I.1964, Peltier 4594 (P). — Fianarantsoa, Isalo, 22°24’S, 45°17’E, 16.IV.1965, Peltier 5521 (P). — Entre Sandrandahy et Fiadanana, 20°21’S, 47°18’E, I.1966, Peltier 5638 (P). — Bords de l’Isandrano, affl uent de l’Ikopa, 16°58’S, 46°43’E, XI.1902, Perrier de la Bâthie 349bis (P). — Le Berizoka, X.1897, Perrier de la Bâthie 349 (P). — Antananarivo, Manankazo, 18°09’S, 47°14’E, Perrier de la Bâthie 7072 (P). — Environs d’Anstirabe, 19°51’S, 47°02’E, 1600 m, VI.1913, Perrier de la Bâthie 7595 (P). — Mahiatra, VI.1912, Perrier de la Bâthie 7890 (P). — Ampasimena, bassin du Demoka, Menabe, 24°22’S, 47°10’E, 200 m, VII.1911, Perrier de la Bâthie 7898 (P). — Environs d’Antsirabe, 19°51’S, 47°02’E, 1500 m, Perrier de la Bâthie 11527 (P). — Environs de Midongy ouest, III.1919, Perrier de la Bâthie 12535 (P, TAN). — Analamahitso, Ht Bemarivo, VIII.1907, Perrier de la Bâthie 15842 (P, TAN). — Bongoloka près de Malaimbondy (Tiribihina), VIII.1910, Perrier de la Bâthie 15856 (P, TAN). — Fianarantsoa, Isalo, 22°24’S, 45°17’E, 1000 m, X.1924, Perrier de la Bâthie 16561 ( BM, G, P). — Tananarive, 18°55’S, 47°31’E, 15.IV.1897, Prudhomme 63 (P), 65 (P), 68 (P). — Antananarivo, RS d’Ambohitantely, 18°13’S, 47°17’E, 1300-1400 m, 11.XII.1997, Rakotondrainibe 4517 (P). — Idem, 12.XII.1997, Rakotondrainibe 4532 (P, TAN). — Forêt de Mahatsinjo, 10 km SE de Tsinjoarivo, 19°37’30’’S, 47°41’30’’E, 7.I.1999, Rakotondrainibe 4561 (P). — Fianarantsoa, RNI Andringitra, Anjavidilava, 22°09’S, 46°57’E, 1990 m, 5.III.1997, Randriambololona et al. 14 (P). — Ibity, Antelisarotra, 7 km SW cimetiere Holcim, 20°06’52’’S, 46°59’23’’E, 1541 m, 9.II.2003, Rasolohery et al. 895 (P), 919 (P), 920 (P). — Prov. Toliara, Ivahona, Kalambatritra, 23°27’30’’S, 46°24’40’’E, 1540 m, 7.XI.2004, Razafitsalama et al. 661 ( MO, P). — Fianarantsoa, Ambositra, 20°31’30’’S, 47°15’E, 1300 m, 16.XII.1959, Schlieben 8168 (B, BM, BR, G, K, M). — Antananarivo, Antsirabe, NW Ambohiponana, 20°04’S, 47°03’E, 1600 m, 20.XI.1912, Viguier et al. 1486 (B, P). — Betafo, pentes des Vavavato vers Antanifotsy, 19°34’S, 46°52’E, 2000-2100 m, 29.XI.1912, Viguier et al. 1605 (P). — Tananarive, 18°55’S, 47°31’E, VII.1914, Waterlot s.n. (P). — S. coll. s.n. (P). — Rive de la Betsioka, Nadinilatsaka près de Tsaratanana, 2.VIII.1911, s. coll. s.n. (P).

Mali. XII.1944, Schnell 2369 (P) .

South AFrica. Natal, Buchanan s.n. (P). — Cap, Drège s.n. (B). — “P. b. sp.” (promontorio bonae spei), Drège s.n. (B). — Portus Walaleas, Gucingius s.n. (B).

Tanzania. Iringa District, 1962, Polhill et al. 1715 (P) . — Kilimandjaro, Mkuu , 3°12’S, 37°36’E, 1510 m, 29.VI.2004, Hemp 4178 ( DSM) .

Zimbabwe. Elephant Forest Vumba, Umtali Distr., 19.I.1949, Chase 5018 (BM).

FIELD OBSERVATIONS IN MADAGASCAR. — Trunk: HT up to 2.5 m, erect, reclining, or creeping, often several times bifurcate, rarely simple, DT 13-22(-30) cm, always covered with a dense mantle of adventitious roots or with persistent dead petiole bases, occasionally with adventitious buds; creeping trunks may be many times bifurcate forming a more or less circular population of up to 10 crowns.

Petiole: with 1 or 2 irregular to subcontinuous rows of white to brown aerophores, 0.2-1 cm long, on either side; petiole base straight to shortly sigmoid.

Leaf scars: visible in dead trunks where the adventitious roots are decayed, contiguous, their lower half distinctly raised, with conspicuous orifices on their lower rim; spirally arranged.

Crown: infundibuliform with erect (c. 15-45°) and straight rachises in creeping forms, more or less horizontal in plants with an erect trunk.

Trunk apex: densely scaly with dark brown scales, usually visible through the more or less spaced petioles; some dead leaves persistent and hanging from the apex, only rarely forming a dense skirt.

Lamina: more or less narrowly elliptic to oblong; LL (80-)115-170(-250) cm, WL 55-85(-110) cm, FW 45- 70 cm, NP 11-16(-20).

DESCRIPTION

Petiole: 35-50(-90) cm long, 2.5-3 cm in diameter; green to stramineous, abaxially reddish brown, blackish at its base, rarely completely reddish brown, distantly muricate, the tubercles rather blunt and not stinging, with a moderately dense, brown, caducous, squamulate tomentum; 1 or 2 pairs of reduced pinnae, 10-30 cm long, usually present at 2-20 cm from the petiole base, acroscopic.

Lamina: bipinnate-pinnatisect to tripinnate, subcoriaceous to coriaceous; shiny green to shiny dark green above, below light to pale green, but not glaucous, lamina base attenuate to truncate, basal pinnae patent and more or less conduplicate; rachis of the same colour as the petiole, becoming completely green to stramineous and smooth distally.

Largest pinnae: 30-50 cm long, i.e. smaller than in C. boivinii s.l., distant by 6.5-10.5 cm, forming an acute acroscopic angle (c. 30-45°) with the rachis, adjacent pinnae overlapping; costae and costulae of the same colour as the rachis.

Largest pinnules: (5-)6-8 × (1-) 1.4-2 cm, adjacent pinnules contiguous to spaced by less than their width, triangular to rarely oblong, their apex acute to shortly caudate; divided to the costula into broadly adnate segments, 1 or 2 proximal segment pairs sessile, the bases of adjacent segments confluent only near the pinnule apex; pinnule segments 0.1-0.2 cm wide, spaced by less than to about their width, straight to slightly falciform, with a crenate to subentire, slightly to conspicuously revolute margin, their apex rounded to acute; lateral veins in the segments once to twice furcate.

Scales and hairs: scales present from the petiole base upwards to 5-15(-25) cm on the petiole, dense and overlapping, persistent at the petiole base, caducous further up on the petiole, narrowly triangular, (2-)3-5.5 × 0.1-0.2 cm, straight to rarely crispate, more or less twisted and with a crispate apex, shiny brown to dark brown, concolourous, their margin more or less erose, antrorse, not appressed to the petiole, not indurated; a usually dense indument of ramified, crispate, soft, light brown hairs and scattered soft, lanceolate to filiform, light brown, shiny to dull, long ciliate scales loosely attached to the abaxial face of the lamina axes and veins, sometimes sparse in older leaves; adaxial face of the costae and costulae densely tomentose with long, crispate, soft, brown, multicellular hairs that decay rapidly, becoming short, whitish and scattered in older leaves; caducous, shiny brown, filiform scales on the adaxial face of the costae and costulae in young leaves; rachis subglabrous; appressed trichomidia sometimes abundant on the abaxial face of the lamina.

Sori: very close to the midvein, contiguous, about 0.1 cm in diameter, covering the entire segment or restricted to its lower quarter; indusia cup-shaped to hemitelioid, i.e. a scale-like rudiment inserted at the costular side of the receptacle, light brown to brown, membranous to subcoriaceous, cup-shaped indusia at maturity with an entire rim or opening with a slit towards the margin of the segment and consequently with a more or less oblique rim; receptacle capitate to elongate, as long as or longer than the rim of mature indusia, with inconspicuous filiform paraphyses shorter than the sporangia.

DISTRIBUTION

Widespread in tropical Africa and in Madagascar, where the species is most frequently encountered on the central high plateau.

ECOLOGY

1050-2200(-2600) m ( Edwards 2005: 8). In Madagascar 1500-2000 m, along streams in open grassland, sometimes in rock crevices, on wet meadows, forest remnants and on forest margins, rarely in dense evergreen rainforests.

REMARKS

Edwards (2005: 8) describes the trunk of African C. dregei as “ 0.4-5 m tall [...] rarely with one or more small branches, many old leaves persistent as a pendulous skirt” in agreement with illustrations in Sim (1915: pl. 6) and Roux (2001: cover photo). In Madagascar, C. dregei is frequently observed having creeping and several times bifurcated trunks forming more or less circular colonies of apparently trunkless, erect crowns ( Figs 36E; 51E bottom). Th is peculiar habit has been previously described by Koechlin et al. (1974: 120, fig. 6) and Christensen (1932: 31). Hallé (1966) showed that trunk ramifications frequently occur in certain species of West African tree ferns, but, to our knowledge, a creeping habit of C. dregei has never been reported for Africa. In Madagascar, the mantle of adventitious roots covering the trunk has often been observed to be blackened by fire and may have a protective function. We hence suggest that the creeping habit is either a result of fires frequently occurring in the Madagascan grasslands and weakening the supporting structures of young trunks, which subsequently recline, or that it is an adaptation improving resistance to fire as the creeping trunks are usually covered with a thin layer of soil. Christensen (1932) discusses a putative correlation of erect trunks with a denser abaxial indument of branched, crispate hairs in the African specimens. However, all specimens that we have seen from Africa and Madagascar perfectly agree in all leaf characters. Th e density of the lamina indument is variable and not correlated with the habit of the plant and we hence do not propose distinct varieties. We suggest that the different trunk habits most likely represent ecological modifications.

Indusium shape and density of the hairy indument in C. dregei and closely related Madagascan species is variable. In the field, C. dregei is most easily recognized by its habit, i.e. with creeping or short erect trunks densely covered with adventitious roots and relatively small crowns, and its habitat in open grasslands. In herbarium specimens, C. dregei may be most easily distinguished from the closely related C. boivinii by its smaller pinnae (two or three usually fit on one sheet at P, but only one pinna of C. boivinii ) and pinnules, the rather constant presence of reduced basal pinnae and a denser abaxial indument of crispate hairs. See under C. boivinii for a more detailed discussion of the closely related tripinnate Madagascan species.

Humbert 12172 has pinnae up to 48 cm long and pinnules up to 9.5 × 2.2 cm. Th e presence of a distinctly erect acroscopic reduced basal pinna (Humbert in sched.) and a very dense tomentum, which is never found in leaves of C. boivinii of similar age distinguish this specimen as C. dregei . Furthermore, pinnae and pinnules are usually distinctly bigger in C. boivinii , although smaller forms occur. Some specimens, e.g., Baron 5302, have strongly revolute margins and consequently acute segment apices. Diels (1902: 127) notes that in Southern Africa C. dregei grows on mountain slopes among bushes or fully exposed to the sunlight. In the latter case, the crown is said to be smaller and the lamina margins to be strongly revolute with the most strongly revolute margin and accordingly narrowest segments found in the southernmost specimens.

TYPIFICATION AND SYNONYMY

Three sheets of Drège s.n. are marked as types at B, but only B200129536 carries a label with the original collection locality. The other specimens are from the Cape (“ P.b.sp.”, i.e. promontorio bonae spei) and should not be regarded as being part of the original material. A fragmentary isotype at P does not carry any locality information, but undoubtedly is part of the original material as it has been sent from Kunze to Luerssen about one year before the publication of the name as is obvious from the annotations and as it is morphologically identical to the lectotype at BM.

Epitypification might be less crucial for differentiating C. dregei from African taxa, but it will be useful in unambiguously distinguishing the taxon from C. boivinii and C. hildebrandtii in Madagascar. We suggest that an epitype be chosen including the basal pinnae and scales and entire middle pinnae from which their size may be assessed. We prefer that such an epitype be chosen from material coming from near the type locality, i.e. Southern Africa, and not Madagascar. As we did not scrutinize the African material sufficiently for this account to choose an epitype, we here refrain from designating an epitype.

Baron 840 is the type of C. polyphlebia Baker. The number 440 on Baker’s original label has been corrected to 840 in Baker’s writing. This emendation is lacking on a second sheet at K!, which should nevertheless be regarded as an isotype. It is morphologically identical. Th e specimen distributed to B! only carries the number 840 indicating this to represent the correct designation of Baker’s specimens.

Diels (1902: 127) cites the name of C. flavovirens Kuhn only stating that the pinnule segments have entire and revolute margins as opposed to C. kirkii . “Inner Madagascar ” is given as the collection locality, but no type is cited. Hildebrandt 3473, carries the name “ C. flavovirens n. sp. ” in Kuhn’s writing and is consequently cited as the putative type of the name.

The shape of the pinnule segments of C. rigidula Baker is close to that of the “humblotii-morphotype” of C. boivinii to which it was assigned as a synonym by previous authors ( Christensen 1932: 33). However, judging from the comparatively small size of pinnae and pinnules and the acute acroscopic angle the costae form with the rachis, we now rather include this taxon as a synonym in C. dregei .

Cyathea segregata Baker has been described from a fragmentary specimen carrying detached pinnae, agreeing in size with C. dregei , and sori with a hemitelioid indusium, i.e. a big costular “scale”. Appressed trichomidia are rather abundant and the margin of the pinnule segments is fertile in its lower half to lower third, where it has a crenate and slightly revolute margin. Cyathea polyphlebia Baker has been described from a fragmentary specimen carrying detached pinnae agreeing in size with C. dregei , being subglabrous and displaying cup- shaped indusia. Th e pinnule segments are fertile and crenate in their lower quarter. Trichomidia are abundant on the lower face of the lamina. None of the characters of C. polyphlebia and C. segregata is differential considering that indusium shape continuously varies from cup-shaped to hemitelioid ( Fig. 36H) and that pinnule shape and indument are subject to continuous intraspecific variability in C. dregei . Supposing that the fragmentary type material comprises middle pinnae, we include both taxa as synonyms in C. dregei on the basis of pinna and pinnule sizes.

All specimens cited by Christensen (1932) under the name C. dregei var. polyphlebia are currently determined as C. dregei except for Humbert 3731 ( C. boivinii var. parahildebrandtii ). All specimens cited by Tardieu-Blot (1951) under the name C. dregei var. polyphlebia are currently determined as C. dregei except for Alleizette 226 ( C. boivinii ), Humbert 11167 ( C. similis var. similis ), Humbert 13576, Perrier 13508 ( C. boivinii var. bevolo ), Humbert 22671, 23768 ( C. similis var. montana ). All specimens cited by Christensen (1932) under the name C. dregei var. segregata are here included in C. dregei . Th e same is true for all specimens un- der that name in Tardieu-Blot (1951) except for Alleizette 54 ( C. boivinii var. boivinii ).

Figures

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

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.