Humbertacalia tomentosa (Lam.) C. Jeffrey

Rabarimanarivo, Marina N., Callmander, Martin W. & Calvo, Joel, 2023, Synopsis of Humbertacalia (Compositae), a genus endemic to Madagascar and Réunion, Adansonia (3) 45 (7), pp. 93-113 : 108-112

10. Humbertacalia tomentosa (Lam.) C. Jeffrey

( Fig. 6 )

Kew Bulletin 47 (1): 83 ( Jeffrey 1992).

Eupatorium tomentosum Lam. , Encyclopédie méthodique, Botanique 2: 410 ( Lamarck 1786). — Eupatorium auriculatum Vahl, Symbolae Botanicae 3: 95 ( Vahl 1794), nom. illeg. ( Turland et al. 2018: ICN Art. 52.1, 53.1), non Eupatorium auriculatum Lam. , Encyclopédie méthodique, Botanique 2: 411 ( Lamarck 1786). — Mikania tomentosa (Lam.) Willd. , Species Plantarum [Willdenow] 3 (3): 1744 (Willdenow 1803). — Cacalia penicillata Cass. , Dictionnaire des Sciences naturelles (ed. 2) 48: 460 ( Cassini 1827), nom. nov., non Cacalia tomentosa Jacq. , Florae Austriacae 3: 20 ( Jacquin 1775). — Senecio penicillatus (Cass.) Sch. Bip. , Flora 28: 499 ( Schultz Bipontinus 1845), non Senecio tomentosus Salisb. , Prodromus Stirpium in Horto ad Chapel Allerton: 196 ( Salisbury 1796). — Senecio tomentosus (Lam.) Cordem. , Flore de l’Île de la Réunion: 543 ( Cordemoy 1895), nom. illeg. [ICN Art. 53.1], non Senecio tomentosus Salisb.( Salisbury 1796 ).

— Typus: Réunion. Isle de Bourbon, VIII.1771, Commerson s.n. (lecto-, designated here, P-LA [ P00308911 ]!; isolecto-, C [ C10007936 image]!, MPU [ MPU011692 , MPU011693 , MPU011694 , MPU023482 images]!), P [ P00150817 , P00150818 , P00150819 ]!), P-LA [ P00308910 , P00308912 ]!) .

Senecio concolor Cordem., Flore de l’Île de la Réunion: 543 (Cordemoy 1895), nom. illeg. [ICN Art. 53.1].

— Typus: Réunion. Grand Tampon, s.d., Frappier? (lecto-, designated here, MARS [ MARS090691 image]!) .

Senecio penicillatus var. glabrescens Humbert , Mémoires de la Société linnéenne de Normandie 25: 141, 306 ( Humbert 1923). — Senecio penicillatus subvar. glabrescens (Humbert) Humbert, Flore de Madagascar et des Comores 189 (3): 768 ( Humbert 1963) , syn. nov.

— Typus: Madagascar. Analamanga Region [Prov. Antananarivo], Angavo à l’E deTananarive, [18°55’S, 47°46’E], 1500 m, VIII.1914, fl., Perrier de la Bâthie 3376 (lecto-, designated here, P [ P00557619 ]! ; isolecto-, P [ P00557620 ]!, TAN [ TAN000173 ]!). — Vakinankaratra Region [ Prov. Antananarivo ], versant E du Mt Tsiafajavona , [19°21’S, 47°14’E], 2000 m, IX.1921, fl., Perrier de la Bâthie 13934 (syn-, P [ P00557621 , P00557622 , P00557623 ]!) .

ICONOGRAPHY. — Vahl (1794: tab. LXXII, sub. Eupatorium auriculatum ); Humbert (1963: 761, fig. 139, 16-17, sub Senecio penicillatus ); Jeffrey (1993: 135, pl. 44).

ETYMOLOGY. — The epithet tomentosa refers to the whitish lanate indumentum that this species has on the abaxial leaf surfaces.

VERNACULAR NAMES. — “Herbe à bouc” ( Lamarck 1786); “petite liane blanche” ( Cordemoy 1895); “liane des lylas” (Commerson s.n., Lin 167).

DISTRIBUTION AND ECOLOGY. — Humbertacalia tomentosa is known from Madagascar and the island of Réunion. In Madagascar, it is found in subhumid and montane bioclimates of the high plateau, mostly in sclerophyllous woodland, highland remnant medium altitude moist evergreen forest, and inselbergs, at elevations of 1200-2300 m, while in Réunion, it occurs in forests at 100-1800 m elevation.

CONSERVATION STATUS. — Humbertacalia tomentosa has an extent of occurrence (EOO) of 210 137 km 2, an area of occupancy (AOO) of 52 km 2, and 12 locations on Madagascar with respect to the most serious plausible threat of fire. It occurs in the protected areas of Ankaratra-Manjakatompo and Andringitra in Madagascar. Based on current information available, H. tomentosa is thus assessed as “Near Threatened” [NT] according to IUCN Red List Categories and Criteria ( IUCN 2012).

Humbertacalia tomentosa is listed as “Least Concern” [LC] in Réunion ( Picot 2010).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Amoron’i Mania Region [Prov. Fianarantsoa]: environs d’Ambositra, mont Vatomavy, [20°27’S, 47°07’E], 1500-1870 m, 23.VII.1928, fl., Humbert & Swingle 4796 ( P) ; Antety près Ambositra, [20°32’S, 47°13’E], 1600 m, V.1912, fl., Perrier de la Bâthie 2945 ( P). — Analamanga Region [Prov. Antananarivo]: Tampoketsa d’Ankazobe, [18°19’S, 47°06’E], 10.VIII.1939, fl., Decary 14962 ( P). — Haute Matsiatra Region [Prov. Fianarantsoa]: Andringitra National Park, 22°09’19”S, 46°56’41”E, 1750 m, 26.V.2004, fl., Rogers 679 ( MO, TAN) ; Ialatsara ( Ambositra ), [21°04’S, 47°12’E], VIII.1953, fl., Bosser 6256 ( P) ; ibid. loco, fl., Bosser 6257 ( TAN [ TAN000978 ]) ; ibid. loco, fl., Bosser 6258 ( MO, TAN) ; Andringitra, district d’Ambalavao, au pied du Tsorana , [22°13’S, 46°55’E], 2300 m, 10.V.1957, fl., Cours 5181 ( P, TAN) ; Mont Belambana (sud Betsileo ) entre les bassins du Mananara et du Mangoky , [21°50’S, 46°56’E], 1200 m, 1911, Perrier de la Bâthie 2961 ( P, TAN) ; RN 5, canton Sendrisoa, district Ambalavao , [22°13’S, 46°55’E], 05.VI.1951, fl., Réserves Naturelles 3062 ( P, TAN). — Vakinankaratra Region [Prov. Antananarivo]: Massif de l’Ankaratra, flanc oriental du Tsiafajavona , restes de forêt à Manjakatompo , [19°22’S, 47°18’E], 1700-2000 m, 15.VII.1928, fl., Decary et al. 4535 ( G, K [ K000377691 ], P [ P04391736 ]) .

Réunion. Benoune, riv. des Pluies, [20°56’S, 55°30’E], 100 m, VII.1945, fl., Rivals s.n. ( P [ P03276421 ]) ; forêt de La Nouvelle près du col de Fourche, [21°04’S, 55°26’E], 1800 m, V.1945, fl. & fr., Rivals s.n. ( P [ P03276419 ]) ; forêt des Hauts de la Raudes Lataniers, [21°02’S, 55°23’E], V.1943, bud, Rivals s.n. ( P [ P03276420 ]) ; Le Tampon, sentier botanique de Notre-Dame-de-la-Paix, southern portion of trail closest to the ridge, 21°15’58”S, 055°36’06”E, 1695 m, 1.IX.2021, Ah-Peng & Wilding 416 ( G) ; trail from Le Brulé to La Roche Ecrite, 1400 m, 23.VII.1961, St. John 26523 ( G) ; [wrongly indicated from Cape of Good Hope], s.d., Ecklon s.n. ( G) ; Isle de Bourbon Cton. Lam. Dct. , s.d., bud & fl., Lin 167 ( MPU [ MPU011692 , MPU011693 , MPU011694 ]) ; Bourbon, 1820, Perrottet s.n. ( G) .

DESCRIPTION

Leaves petiolate; leaf laminas 4-8 × 2-5.2 cm, ovate to ellipticlanceolate, base cordate to rounded (sometimes truncate), apex acute to acuminate, margins remotely mucronate (entire in overall appearance) to irregularly and shallowly dentate, glabrescent on adaxial surface (usually initially arachnoid), arachnoid to whitish-lanate on abaxial surface (rarely quickly deciduous), venation palmately 3-5-veined (conspicuous on abaxial surface), rather chartaceous; petioles up to 2.5 cm long, with reduced or well-developed suborbicular auricles. Synflorescences axillary and terminal, thyrsoid-paniculiform to narrowly thyrsoid-paniculiform (spiciform). Capitula sessile; involucres rather cylindrical, arachnoid at base; involucral bracts 5-8, 2.2-3(-3.7) × 0.6- 1.2 mm; supplementary bracts 3-6, 0.5-1.7 mm long. Florets 5-10, 2.9-3.5 mm long; corollas tubular, 5-lobed, whitish; anther bases caudate, a half to as long as filament collar; style branches penicillate (tuft 0.25-0.3 mm long, rarely absent). Achenes 1.7-2.3 × 0.5-0.6 mm, rather cylindrical, 5-6-ribbed, pubescent to sparsely pubescent (trichomes c. 0.25 mm long), straw-coloured; pappus 2.2-3.8 mm long, whitish ( Fig. 6 ).

NOTES

Humbertacalia tomentosa is characterized by having palmately veined leaves, usually whitish-lanate indumentum on the abaxial leaf surfaces, and pubescent achenes. It is the only member of the genus displaying penicillate style branch apices, with the tuft of longer trichomes reaching 0.25-0.3 mm long (rarely absent). It is a variable species concerning the leaf shape, which can be ovate with cordate bases to elliptic-lanceolate with rounded to truncate bases, as well as in regard to the leaf margins that vary from remotely mucronate (entire in overall appearance) to irregularly and shallowly dentate. Some specimens display well-developed leaf auricles (e.g. St. John 26523) but in other specimens these appear to be much reduced or almost absent (e.g. Ecklon s.n.).

Humbert (1963) recognized the plants from Réunion as Senecio penicillatus subvar. penicillatus (homotypic synonym of Humbertacalia tomentosa ), a taxon that is also recorded from Madagascar (e.g. Perrier de la Bâthie 2961) and that he differentiated from Senecio penicillatus subvar. glabrescens by the higher density of the indumentum on the abaxial leaf surfaces. The multiple intermediate forms between both taxa did not allow him to separate them at a higher rank ( Humbert 1963: 768). He also stated that some specimens from Réunion were characterized by having 5-6 involucral bracts with 5-6 florets, but were otherwise identical to the Malagasy populations with usually c. 8 involucral bracts and c. 10 florets. In Madagascar, there are certainly some specimens with very sparse arachnoid trichomes on the abaxial leaf surfaces (e.g. Perrier 13934), but the typical forms are also found (e.g. Cours 5181). As Humbert, we also studied several intermediate forms (e.g. Humbert & Swingle 4796). This, together with the fact that we did not find any other difference, makes unadvisable recognizing more than a single taxon.

P-LA harbours three specimens of Eupatorium tomentosum . The specimen P00308911 is the only one that bears a label with the provenance of the material (“isle de bourbon”) and the collector name (“Commers.”); P00308910 lacks any label; and P00308912 indicates Commerson as the collector but Brazil as the origin of the material, which is clearly a mistake because this species is not known in this country. Because of the similar phenology and the overall preservation conditions of the material, the three specimens are considered as belonging to the same collection, as well as several specimens that are kept in the general herbarium of P and MPU. The specimen P00308911 from P-LA is therefore designated as the lectotype.

Vahl’s name Eupatorium auriculatum was treated as a heterotypic later synonym of E. tomentosum and the specimen at C (C10007936) was indicated as the holotype of the name ( Jeffrey 1993). In our opinion, this specimen is a duplicate of the Commerson collection from 1771 although no label explicitly indicates that. The fact that Vahl indicated that the provenance of the plant was “Brasilia”, as it appears on one of the specimens in P-LA, reveals that it most probably originated from P. The specimen may have reached C through A. Thouin (1747-1824), who sent other Commerson’s collections from Réunion to Vahl such as the original material of Cacalia reticulata Vahl (1794: 91) . It is known that considerable numbers of Commerson’s duplicates were sent from P to several European herbaria ( Stafleu & Cowan 1976). Here, Eupatorium auriculatum Vahl [1794] and E. tomentosum Lam. [1786] are treated as homotypics, the former being illegitimate on account both of its superfluity and for being a later homonym of E. auriculatum Lam. [1786] .

In the protologue of Senecio concolor, Cordemoy cited a Frappier specimen from “Grand Tampon” and also indicated that the plant was found by himself in “Rivière Saint-Denis” (both in Réunion), though it remains unclear if material from the latter locality was collected or not. The single specimen of S. concolor originating from Cordemoy’s personal herbarium we found is kept at MARS and bears a label where both localities are indicated and no collector specified. Jeffrey (1993) considered this specimen as a syntype, which seems appropriate considering the ambiguity of the protologue and that other collections may exist as the whereabouts of Cordemoy’s herbarium are poorly known ( Stafleu & Cowan 1976). In pursuit of establishing the usage of this name, we here lectotypify S. concolor on the MARS specimen.

Humbert (1923) described Senecio penicillatus var. glabrescens on the basis of the syntypes Perrier de la Bâthie 3376 and 13934, which separated from the typical variety by the laxer arachnoid indumentum on both leaf surfaces. The collection 3376 is taxonomically informative and consists of three specimens kept in two different herbaria. The specimen P00557619 is accordingly designated as the lectotype of the name S. penicillatus var. glabrescens .

Finally, it is interesting to note that the name Cacalia cuspidata Klatt was included in the synonymy of Humbertacalia tomentosa by Jeffrey (1993), who did not study the type material. We also failed in locating it, but according to Cordemoy (1895: 544) we believe that the original description does not fit well with the concept of H. tomentosa . Therefore, the name Cacalia cuspidata is, for the time being, excluded from the synonymy of this species.

Figures

FIG. 6. — Humbertacalia tomentosa (Lam.) C. Jeffrey (Rogers 679, TAN):A, habit; B, capitulum; C, supplementary bract; D, involucral bract;E, floret; F, floret with style branch apex detail (ovary and pappus removed); G, anthers. Scale bars: A, 1 cm; B-F, 1 mm. Drawings: Roger Lala Andriamiarisoa.