Humbertacalia madagascarensis Y.L. Peng & Li Bing Zhang

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 : 102-103

6. Humbertacalia madagascarensis Y.L. Peng & Li Bing Zhang

Phytotaxa 283 (3): 291 ( Peng & Zhang 2016).

TYPUS. — Madagascar. Sava Region [Prov. Antsiranana], Réserve naturelle intégrale de Marojejy , 10.5 km NW of Manantenina, along tributary at head of Andranomifototra River , Campement 4, 14°26’24”S, 49°44’30”E, 1625 m, 4-13.XI.1996, fr., Rakotomalaza et al. 850 (holo-, MO [ MO798972 ]!; iso-, G [ G00398316 ]!, P [ P02478358 ]!, TAN!) .

Senecio leucopappus var. austro-orientalis Humbert , Notulae Systematicae 15 (4): 372 ( Humbert 1959). — Senecio leucopappus subsp. austro-orientalis (Humbert) Humbert , Flore de Madagascar et des Comores 189 (3): 764 ( Humbert 1963), syn. nov.

— Typus: Madagascar. Anosy Region [Prov. Toliara], massif de Beampingaratra (sud-est), du col de Bevava au sommet de Bekoho , [24°26’S, 46°53’E], 1100-1500 m, 6-7.XI.1928, fl., Humbert 6446 (lecto-, designated here, P[P00557667]!; isolecto-, G[ G00007641 ]!, P[ P00557666 ]!) .

ICONOGRAPHY. — Humbert (1963: 761, fig. 139, 12-13, sub Senecio leucopappus subsp. austro-orientalis); Peng & Zhang (2016: 292, fig. 1).

ETYMOLOGY. — The epithet madagascarensis obviously refers to Madagascar.

VERNACULAR NAMES. — Unknown.

DISTRIBUTION AND ECOLOGY. — Humbertacalia madagascarensis occurs in subhumid bioclimate. It is known from medium altitude moist evergreen forest (Marojejy, corridor between Marojejy and Anjanaharibe-Sud, Manongarivo) in Sava and Diana Regions, subhumid forest of central Madagascar (Analamanga region), to eastern humid evergreen forests of Madagascar (Alaotra-Mangoro Region) up to the Massif of Kalambatritra, Beampingaratra (Anosy Region) and Midongy du Sud (Atsimo-Atsinanana Region), mostly degraded forests, on laterite of gneiss, between 1000-1900 m elevation.

CONSERVATION STATUS. — Humbertacalia madagascarensis has an estimated extent of occurrence (EOO) of 168 168 km 2, an area of occupancy (AOO) of 36 km 2 and eight locations with respect to the most serious plausible threat for agriculture. We inferred continuing decline in its habitat quality, even if the species occurs within the protected areas of Ambatofotsy, Ambohitantely , Befotaka-Midongy du Sud , Kalambatritra , Manongarivo , Marojejy and Mangabe. Therefore , H. madagascarensis is assessed as “Vulnerable” [VU B2 ab(iii)] according to IUCN Red List Categories and Criteria ( IUCN 2012).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Alaotra-Mangoro Region [Prov. Toamasina]: Anosibe an’Ala, Tratramarina , Ambonihiboka , forêt Ambatofotsy , 19°32’23”S, 48°18’43”E, 1193 m, 8.X.2010, fr., Razakamalala et al. 5718 ( MO, P, TAN) ; Moramanga, Ambohibary, Ampahitra , forêt de Ranomena , 19°11’50”S, 48°09’36”E, 1011 m, 08.IX.2012, fl., Razakamalala & Randrianaivo 7152 ( MO, P [ P00820812 ], TAN) . — Analamanga Region [Prov. Antananarivo]: Ambohitantely, ad occidentem Tananarive , NNE civitatis Ankazobe , [18°09’30”S, 47°18’00”E], 1500-1550 m, 29.X.1967, Bernardi 11108 ( G) . — Anosy Region [Prov. Toliara]: Massif du Kalambatritra (centre-sud), Mont Analatsitendrika , [23°22’30”S, 46°29’30”E], 1650-1850 m, XI.1933, Humbert 11921 ( P [ P02397481 , P02397482 ]) . — Atsimo-Antsinanana Region [Prov. Fianarantsoa]: Befotaka, Parc National Befotaka-Midongy , 23°50’28”S, 46°57’17”E, 1308 m, 15.IX.2005, fl., Rakotovao et al. 2080 ( MO, P [ P02473417 ], TAN) . — Diana Region [Prov. Antsiranana]: Special Reserve of Manongarivo, SE of Beraty, trail to summit of Antsatrotro , 14°05’S, 48°22’E, 1600-1700 m, 25-29.IX.1991, fl. Malcomber et al. 878 ( G, MO, P [ P02818086 ], TAN) . — Sava Region [Prov. Antsiranana]: Réserve du Marojejy, Camp 3, [14°27’S, 49°42’E], 1250 m, 28.X.1967, fl., Jacquemin H615J ( P [ P03288991 ]) .

DESCRIPTION

Leaves petiolate; leaf laminas 7.5-11.5 × 3.8-6.5 cm, oblanceolate to broadly elliptic, base attenuate to obtuse (sometimes remarkably oblique), apex acute to obtuse (usually mucronate), margins entire (rarely shallowly dentate), pilose to glabrous on adaxial surface, pilose to tomentose-hirsute on abaxial surface, venation pinnate (conspicuous on both surfaces), rather coriaceous; petioles up to 4 cm long. Synflorescences axillary and terminal, narrowly thirsoid-paniculiform. Capitula subsessile (rarely short-pedunculate with peduncles usually up to 2 mm); involucres campanulate, glabrous to slightly arachnoid; involucral bracts 8(-9), 4.4-5.3 × 1-2.4 mm; supplementary bracts 4-6, 1.8-2.4 mm long. Florets c. 20, 3.9-5.7 mm long; corollas tubular, 5-lobed, whitish?; anther bases long-caudate, as long as to longer than filament collar (almost twice longer); style branches obtuse with a crown of sweeping trichomes. Achenes c. 3 × 0.7 mm (immature), rather cylindrical, glabrous, straw-coloured; pappus 4.5-5.2 mm long, whitish.

NOTES

This species can be differentiated by its large capitula with c. 8 involucral bracts 4.4-5.3 mm long and the pilose abaxial leaf surfaces. Other species with 8(-9) involucral bracts are Humbertacalia abbreviata comb. nov., stat. nov. and H. racemosa , both displaying shorter involucral bracts, 1.8-2 and 3.6-4 mm long, respectively. The indumentum resembles that of H. coursii but it is less dense and the trichomes somewhat shorter. It is a variable species mainly concerning the indumentum of the adaxial leaf surfaces and involucres; the original material of H. madagascarensis has sparsely pilose adaxial leaf surfaces and somewhat arachnoid involucres, whereas the type of Senecio leucopappus var. austro-orientalis has almost glabrous adaxial leaf surfaces and involucres. Otherwise, all the characters of the latter taxon match the diagnostic characters of H. madagascarensis , and for that reason it is placed in the synonymy. The capitula of this species are subsessile or shortpedunculate but we studied a collection with a few capitula displaying c. 5 mm long peduncles (Jacquemin H615J, P). As most capitula are subsessile or short-pedunculate, this is also treated as part of the variability of H. madagascarensis . The collection Razakamalala & Randrianaivo 7152 shows a denser indumentum very similar to the typical one of H. coursii , however, the number and length of the involucral bracts are useful for discriminating each other. Lastly, it is interesting to note that the abaxial leaf surfaces were described as violet in Rakotomalaza et al. 850 but pale green in Malcomber et al. 878.