Ruellia quartziticola Callm., E. Tripp & Phillipson, 2014

Callmander, Martin W., Tripp, Erin A. & Phillipson, Peter B., 2014, A new name in Ruellia L. (Acanthaceae) for Madagascar, Candollea 69 (1), pp. 81-83 : 82

Ruellia quartziticola Callm., E. Tripp & Phillipson , nom. nov.

÷ Eusiphon longissimum Benoist in Not. Syst. (Paris) 15: 6. 1955.

÷ Ruellia longissima (Benoist) E. Tripp in Int. J. Pl. Sci. 74: 122. 2013, nom. illeg. [non Ruellia longissima D. N. Gibson in Fieldiana, Bot. 34: 79. 1972].

Typus: MADAGASCAR. Prov. Fianarantsoa: entre la Mania et l’Ivato , II.1919, fl., Perrier de la Bâthie 12374 (holo-: P [ P00091305 ]!; iso-: P [ P00091306 , P00091307 ]!).

Observations. – Ruellia quartziticola is a striking species with its exceptionally long white corollas (up to 18 cm), which are densely covered by a greyish indumentum. This species possesses the longest corolla of all known Acanthaceae in Madagascar ( BENOIST, 1955). Crossandra nobilis Benoist also has exceptionally long white corollas and interestingly, both of these species are restricted to quartzite substrates of the highlands of Madagascar. Several species in other families are also endemic to this substrate including Ipomoea perrieri Deroin (Convolvulaceae) , Perrierodendron quartzitorum J.-F. Leroy, Lowry, Haev., Labat & G. E. Schatz ( Sarcolaenaceae ), Psiadia quartziticola Humbert , Senecio quartziticolus Humbert and Vernonia quartziticola Humbert (Asteraceae) .

Conservation status. – Ruellia quartziticola is apparently very rare in its natural habitat. H. Perrier de la Bâthie collected the type nearly a hundred years ago, and P. Morat collected it 50 years later (Morat 3139). Both known localities are on the quartzite outcrops of the Malagasy highlands to the south-west of the town of Antsirabe ( Fig. 1 ). Two important quartzite outcrops in this area, the Ibity and Itremo massifs, currently hold temporary protection status and are in the process of being established as new protected areas. However, despite intensive collection efforts at these sites, the species has not been located. With only two known collections, an “Area of Occupancy” (AOO) of 18 km 2 (following CALLMANDER & al., 2007), neither of which are within Madagascar’s protected area network, Ruellia quartziticola can be assessed as “Critically Endangered” (CR A3c) following the IUCN Red List Categories and Criteria ( IUCN, 2012).

Figures

Fig. 1. – Detailed map of the Central Highlands including quartzite substrate in the region (grey) and proposed new protected areas (hatched); collections of Ruellia quartziticola Callm., E. Tripp & Phillipson (squares: Perrier de la Bâthie 12374 [P]; Morat 3139 [M]).