Humbertacalia abbreviata (Humbert) Rabarim., Callm. & J. Calvo, 2023

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 : 95-96

1. Humbertacalia abbreviata (Humbert) Rabarim., Callm. & J. Calvo , comb. nov., stat. nov.

( Fig. 1 )

Senecio exsertus var. abbreviatus Humbert , Notulae Systematicae 15(4): 370 ( Humbert 1959).

— Typus: Madagascar. Ihorombe Region [Prov. Fianarantsoa], Ifandana, [22°49’S, 47°07’E], 6.IX.1926, fl., Decary 5226 (lecto-, designated here, P [ P00835897 ]!; isolecto-, P [ P04391738 ]!; US [ US01832483 image]!) ( Fig. 1 ).

ETYMOLOGY. — The epithet abbreviata probably refers to the small involucres of this species.

VERNACULAR NAMES. — “Vahimary” (Decary 5226).

DISTRIBUTION AND ECOLOGY. — Humbertacalia abbreviata comb.nov., stat. nov. is endemic to the humid and subhumid bioclimatic areas ( Cornet 1974) in southeastern Madagascar within the Anosy, Ihorombe and Atsimo-Atsinanana administrative regions. This species grows in lowland and medium altitude moist evergreen forests (sensu Gautier et al. 2018a) on laterite of gneiss, mostly in clearing or forest margins, at elevations of c. 500- 900 m.

CONSERVATION STATUS. — Humbertacalia abbreviata comb. nov., stat. nov. has an estimated extent of occurrence (EOO) of 3365 km 2, an area of occupancy (AOO) of 16 km 2 and four locations. Even though the species occurs in the protected areas of Ivohibe, Befotaka – Midongy du Sud and Andohahela, at these sites it is nevertheless threatened by ongoing degradation or destruction of its habitat due to shifting agriculture, annual fire, logging and wood harvesting ( Goodman et al. 2018); all of which will result in continuing decline in its EOO, AOO, habitat quality, number of subpopulations and number of mature individuals. Therefore, H. abbreviata comb. nov., stat. nov. is assessed as “Endangered” [EN B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)] according to IUCN Red List Categories and Criteria ( IUCN 2012).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Anosy Region [ Prov.Toliara ]: Bassin de la Manampanihy (sud-est), Col de Fitana , [24°44’S, 46°51’E], 300-700 m, 15.X.1928, fl., Humbert 6038 ( G, P [ P02397476 , P02397477 ], TAN, US [ US01832484 ]). — Atsimo-Atsinanana Region [Prov. Fianarantsoa]: Midongy du Sud , forêt d’Anamangy, 23°31’16”S, 47°05’19”E, 640 m, 13.IX.2005, fl., Andrianjafy et al. 1184 ( MO, P [ P00860315 ], TAN). — Ihorombe Region [Prov. Fianarantsoa]: Ivohibe, Ambatovita , 4.5 km NE d’Ivohibe, 22°28’08”S, 46°55’34”E, 874 m, 28.XI.2010, fl., SNGF 2649 ( K, MO, P, SNGF, TAN, TEF) .

DESCRIPTION

Leaves petiolate; leaf laminas 6-8 × 2.9-4 cm, lanceolate to ovate, base obtuse to rounded, apex attenuate to acuminate, margins entire, glabrous on both surfaces, venation pinnate (conspicuous on both surfaces, including tertiary veins), rather coriaceous; petioles up to 1.8 cm long. Synflorescences mostly axillary, narrowly thyrsoid-paniculiform. Capitula shortly pedunculate (peduncles 1-2.5 mm long); involucres cupuliform, glabrous; involucral bracts 8, 1.8-2 × c. 1 mm; supplementary bracts 4-5, 0.3-0.4 mm long. Florets c. 10, 3.8-4 mm long; corollas tubular, 5-lobed, whitish; anther bases caudate, as long as or slightly longer than filament collar; style branches obtuse with a crown of sweeping trichomes. Achenes c. 2.8 × 0.6 mm, rather cylindrical, c. 9-ribbed, glabrous except for few trichomes on the upper part, straw-coloured; pappus c. 3.7 mm long, whitish.

NOTES

Humbertacalia abbreviata comb. nov., stat. nov. is well-characterized by the glabrous leaves with conspicuous venation on both surfaces, the shortly pedunculate capitula, and the small involucres with the involucral bracts somewhat fused at the base. It is similar to H. racemosa (Bojer ex DC.) C. Jeffrey , from which it differs in involucre shape (strictly cupuliform, with the bracts somewhat fused at the base in H. abbreviata comb. nov., stat. nov. vs rather campanulate, with the bracts partite along their whole length or almost so in H. racemosa ), involucral bract length (1.8-2 mm long in H. abbreviata comb. nov., stat. nov. vs 3.6-4 in H. racemosa ), and peduncle length (1-2.5 mm long in H. abbreviata comb. nov., stat. nov. vs 2-5 in H. racemosa ), and floret number (c. 10 in H. abbreviata comb. nov., stat. nov. vs c. 20 in H. racemosa ).

It is interesting to note that the collections Decary 5222 and 5226, which come from the same locality and were collected on the same day, were both treated as belonging to Senecio exsertus var. abbreviatus ( Humbert 1963) . However, Decary 5222 clearly corresponds to Humbertacalia racemosa .

Humbert (1959), when describing the new variety, designated the collection Decary 5226 at P as the holotype of the name. As two specimens corresponding to this collection are kept at P and there is no explicit indication suggesting that Humbert selected one of the two duplicates to serve as holotype, the name S. exsertus var. abbreviatus is lectotypified on the best preserved specimen P00835897 ( Fig. 1 ).

Figures

FIG. 1. — Lectotype of Senecio exsertus var. abbreviatus Humbert, Decary 5226 (P00835897).