Hibiscus vohipahensis M. Hanes & G.E. Schatz, 2020

Hanes, Margaret M., Schatz, George E. & Callmander, Martin W., 2020, Transfer of the Malagasy genera Humbertianthus and Macrostelia to Hibiscus (Malvaceae) with description of four new species, Candollea 75 (2), pp. 193-202 : 201-202

Hibiscus vohipahensis M. Hanes & G.E. Schatz , sp. nov. ( Fig. 3C , 4C ).

Holotypus: MADAGASCAR. Reg. Atsimo-Atsinanana [Prov. Fianarantsoa]: Vangaindrano, Vohipaho , Ankara Bolava Forest , 23°31'34"S 47°30'01"E, 27 m, 26.VIII.2008, fl., Bussmann 15177 (MO-6152851!; iso-: G [ G00341945 ]!, P, TAN).

Hibiscus vohipahensis M. Hanes & G.E. Schatz differs from H. analalavensis M. Hanes & G.E. Schatz in having longer petioles and pedicels, large pure white petals that are widest at the apex with filaments about twice as long as the long staminal column.

Tree 3–6 m tall, 6 cm dbh; twigs covered with light golden stellate trichomes. Leaves 7.8– 13.7 × 2.9– 4.5 cm, narrowly obovate, the base acute, the margin strongly revolute, the apex acuminate, glabrous above, nearly glabrous below with the occasional stellate trichome below, venation brochidodromous with 8–10 secondary veins per side, midvein raised above and below, secondary veins slightly raised above and below, tertiary venation reticulate, slightly raised above and below; petiole 6–10 mm, 1 mm in diam., covered with stellate trichomes. Flowers solitary, axillary, pendent; pedicels 45 mm, 1.2 mm in diam., densely covered with golden, erect, simple, fasciculate and stellate trichomes; epicalyx with 5 lobes fused at the base for 2 mm, the lobes 12–17 × 12–18 mm, broadly ovate, the apex acute to obtuse, densely covered with golden stellate trichomes on the outside, densely covered with light golden, erect simple and fasciculate trichomes inside; calyx with 5 lobes, fused at the base for 12 mm (about half of length), the lobes 20 × 18 mm, ovate, the apex acute, densely covered with golden stellate trichomes outside, densely covered with appressed curly beige trichomes inside; petals 5, c. 55 mm, obovate, the apex rounded, white, widest at apex, turning reddish with age, densely covered with light golden stellate trichomes outside, glabrous inside with evident venation; staminal column 50 mm long, 2 mm in diam., white, glabrous, with a tuft of dense golden erect simple trichomes at the apex; stamens c. 70, filaments 20 mm, white, anthers 1.5 × 2 mm; styles 5, 25 mm, white, slender, delicate, covered with white erect simple and fasciculate trichomes, stigma c. 1.7 mm, bulbous. Fruit unknown.

Vernacular name. – “Hafatra-rora” (Birkinshaw 2040).

Distribution and ecology. – Hibiscus vohipahensis has the most southern distribution of all species discussed here and is known from two protected patches of lowland moist evergreen forests near Vangaindrano from 10 to 135 m elevation.

Conservation status. – Hibiscus vohipahensis is known from 6 locations from two protected areas (Agnakatrika and Ankarabolava). Despite the very restricted extent of occurrence (EOO) and area of occupancy (AOO) of c. 9 km ², there appear to be no current threats to H. vohipahensis . Thus, the species is assigned a status of “Least Concern” [LC] IUCN Red List Categories and Criteria ( IUCN, 2012), with the caution that this status is highly dependent on continued effective protection.

Notes. – Hibiscus vohipahensis differs from H. analalavensis in having longer petioles, 6 – 10 mm (vs. 4– 5 mm), longer pedicels, 45 mm (vs. 30–32 mm), and wider petals, 12–18 mm (vs. 6–9 mm) that are pure white (vs. white to pink blush) that are widest at the apex (vs. widest in the middle of the petal). The staminal column in H. vohipahensis is also longer than that in H. analalavensis , 50 mm (vs. 30 mm) with filaments about twice as long, 20 mm (vs. 10 mm).

Paratypi. – MADAGASCAR. Reg. Atsimo-Atsinanana [Prov. Fianarantsoa]: Vangaindrano, Vohipaho , forêt d’Ankarabolava, 23°31'51"S 47°29'48"E, 72 m, 17.IX.2009, fl., Andriamihajarivo 1679 ( MO, P, TAN, TEF); ibid. loco, 23°31'32"S 47°30'12"E, 13 m, 29.V.2014, bud, fl., Birkinshaw 2040 ( MO, P, TAN); Marofototra, NAP Ankarabolava-Agnakatrika , 23°30'24"S 47°30'51"E, 65 m, 5.VII.2010, fl., Randrianarivony 164 ( MO, P, TAN); c. 5 km au SE du village Sahavia, 23°26'21"S 47°30'34"E, 135 m, 19.X.2010, fl., Razafitsalama 1409 ( MO, P, TAN); forêt de Vohipaho , 23°26'34"S 47°30'50"E, 80 m, 22.IX.2009, bud, Razanatsima 780 ( MO, P, TAN).

Figures

Fig. 3. – Photographs of flowers of Hibiscus L. A. Hibiscus analalavensis M. Hanes & G.E. Schatz; B. Hibiscus ankeranensis M. Hanes & G.E. Schatz; C. Hibiscus vohipahensis M. Hanes & G.E. Schatz. [A: Ratovoson 2092; B: Antilahimena 7544; C: Razafitsalama 1409] [Photos: A: F. Ratovoson; B: P. Antilahimena; C: C. Birkinshaw]

Fig. 4. – Photographs of epicalyx and calyx of Hibiscus L. A. Hibiscus analalavensis M. Hanes & G.E. Schatz; B. Hibiscus ankeranensis M. Hanes & G.E. Schatz; C. Hibiscus vohipahensis M. Hanes & G.E. Schatz.