Introduction
A recent review of the Malagasy Bignoniaceae for the Catalogue of the Vascular Plant of Madagascar (Madagascar Catalogue, 2011) has enabled us to refine species delimitations and nomenclature, and to discover new species in most of the genera (Callmander & al., 2011a; in press a; Callmander & Phillipson, in press b, c). The family is currently represented in Madagascar by c. 70 species, all endemic, but we estimate that the total will reach close to 100 once our revisionary work is complete (Callmander & al., 2011b). Certain species require lectotypification, among these are Rhodocolea boivinii (Baill.) H. Perrier and Stereospermum variabile H. Perrier, which are the subjects of this note. We designate lectotypes, provide some additional observations and present conservation threat analyses (IUCN, 2001) for both species. Lists of all the corresponding collections and distribution maps for these and related species can be found in the Madagascar Catalogue (2011).
Lectotypification
Rhodocolea boivinii (Baill.) H. Perrier in Ann. Mus. Colon. Marseille ser. 5, 6: 23. 1938.
≡ Colea boivinii Baill. in J. Linn. Soc., Bot. 25: 308. 1888.
Lectotypus (designated here): MADAGASCAR. Prov. Antsiranana: Nosy-Be, IX.1879, fl., Hildebrandt 3224 (P [P00648798]!; isolecto-: BM!, G [G00191496, G001953 26, G00191455]!, M [M-0105565] image seen, P [P00648 799]!, W image seen).
= Colea glaucescens Palacky, Cat. Pl. Madagasc. 3: 54. 1907 [nom. nud.].
Observations. — Rhodocolea boivinii is based on two syntypes (Boivin 2105/2, Hildebrandt 3224). Both are gatherings of flowering specimens. Even though the species is named after Louis H. Boivin, we choose Hildebrandt 3224 as the lectotype because both the number and the quality of duplicates available are superior. The species occurs in north-west Madagascar within the Sub-humid bioclimatic region in low elevation forest (the Sambirano Domain sensu Humbert, 1951, 1955) (Fig. 1). It is characterized by its large sub-coriaceous imparipinnate leaves, its long terminal paniculate inflorescences bearing flowers with large pink corollas with white margins and marked yellow in the throat. It is related to a small group of distinctive species of Rhodocolea Baill. that includes R. telfairiae (Hook.) H. Perrier and two or three as yet undescribed species that also possess terminal panicles but differ in other floral and vegetative characters.
Conservation status. — With an EOO of 1695 km2, an AOO of 63 km2 and 5 subpopulation, one encompassed in a protected area (Lokobé), R. boivinii is assigned a preliminary status of Vulnerable (VU B1ab[i, iii]; B2ab[i, iii]) (calculation following Callmander & al., 2007).
Stereospermum variabile H. Perrier in Ann. Mus. Colon. Marseille ser. 5, 6: 13. 1938.
Lectotypus (designated here): MADAGASCAR. Prov. Mahajunga: Morondava, s.d, fl. & fr., Perrier de la Bâthie 10296 (P [P00093992]!; isolecto-: P [P00093990, P0009 3991]!).
Observations. — Stereospermum variabile is based on five syntypes (Louvel 163, Grevé 27, 41, 50, and Perrier de la Bâthie 10296). Only Perrier de la Bâthie's collection bears both flowers and mature fruits and therefore, being the most representative of the species, it is designated as the lectotype. The species occurs in south-western Madagascar in forest and secondary vegetation on sandy soils, between the Onilahy and Tsiribihina Rivers and essentially within the Sub-arid bioclimatic region (Fig. 1) and is characterized by its narrow pubescent silvery leaflets borne on long petiolules. Like most Malagasy species of Stereospermum Cham. it has flowers with pure white corollas. It is partially sympatric with S. euphorioides DC. (which also occurs further to the North and further inland) and S. nematocarpum DC. (which is widespread throughout the South-West and South). Perrier de la Bâthie remarked on the probable existence of natural hybrids between S. variabile and these species in their areas of overlap, and we concur with this point of view.
Conservation status. — With an EOO of 45,946 km2, an AOO of 171 km2 and 15 subpopulation, one encompassed in three protected area (Isalo, Kirindy Mitea and Zombitsy), S. variabile is assigned a preliminary status of Least Concern (LC) (calculation following Callmander & al., 2007).
Acknowledgements
Our research was supported by grants from the U.S. National Science Foundation (0743355) and the Andrew W. Mellon Foundation.