Perrierophytum thouarsianum (Baill.) M.M. Hanes & Callm.

Hanes, Margaret M., Mashburn, Brock & Callmander, Martin W., 2022, Transfer of the endemic Malagasy species of Kosteletzkya to Hibiscus and Perrierophytum (Malvaceae), Candollea 77 (2), pp. 161-171 : 169

Perrierophytum thouarsianum (Baill.) M.M. Hanes & Callm. , comb. nov.

Kosteletzkya thouarsiana Baill. in Bull. Mens. Soc. Linn. Paris 1: 541. 1883.

Lectotypus (designated here): MADAGASCAR: sine loco, s.d., fl., Du Petit-Thouars s.n. ( P [ P00037076 ]!) .

Kosteletzkya humbertiana Hochr. in Mém. Soc. Hist. Nat. Afrique N., Hors Sér. 2: 157. 1949. Kosteletzkya thouarsiana var. humbertiana (Hochr.) Hochr. in Humbert, F l. Madagascar Comores 129: 104. 1955, syn. nov. Lectotypus (designated here): MADAGASCAR. A e g. A n o s y [Pro v. To l i a r a]: A n d r a h o m a n a, 21.IX.1932, fl. & fr., Decary 10659 (P [ P00037077 ]!; isolecto-: G [ G00014372 ]!, K [ K000580217 ] image!, MO-6089630!, P [ P00037078 , P00389394 ]!).

Conservation status. – Perrierophytum thouarsianum is known from only a few collections in south-east Madagascar. No collections are known to have been made since 1931, and GPS coordinates have been estimated from the descriptions on the specimens. With these estimates, it is unlikely that collections have been made inside any current protected area. The species has an estimated EOO of 83 km ² and an AOO of 16 km ². Given the limited EOO, the known habitat degradation in this region in the last 100 years, and the time since the last collection, P. thouarsianum can be assessed as “Critically Endangered” [CR B1ab(iii)].

Notes – Kosteletzkya thouarsiana was placed in sect. Azanzoides by HOCHREUTINER (1955). Nevertheless, he wrote: “espèce ± intermédiaire entre les deux sections du genre, par son port presque herbacé et son ovaire déprimé ainsi que sa capsule [species ± intermediate between the two sections of the genus, by its almost herbaceous habit and its depressed ovary as well as its capsule].” (HOCHREUTINER, 1955: 103). These characters nevertheless place this species in sect. Eukosteletzkya and K. thouarsiana is therefore now transferred to Perrierophytum .

Perrierophytum thouarsianum is distinctive in having its epicalyx and calyx similar in size and form (both fused at base, and with triangular lobes). Leaves range from almost triangular to distinctly trilobed.

Hochreutiner described Kosteletzkya humbertiana in 1949 but reduced it to a variety of K. thouarsiana in his Malvaceae flora treatment in 1955. We do not maintain this variety here as we do not see any convincing morphological character to distinguish it as distinct from the typical variety.

BAILLON (1883: 342) cited the type of Kosteletzkya thouarsiana in “hb. Juss” but no specimen has been located in P-JU. The specimen deposited in P with Baillon’s handwriting is therefore designated here as the lectotype. HOCHREUTINER (1949: 158) cited the type of K. humbertiana as “Hb. Mus. Paris et G”. The best-preserved material of Decary 10659 is at P [P00037077] and designated here as the lectotype.

Additional specimens examined. – MADAGASCAR. Aeg. Androy [Prov. Toliara]: Ampasimpolaka , 6.X.1924, fl., Decary 2832 ( G, P [ P00574034 ]) ; ibid. loco, 5.IX.1924, fl., Decary 3127 ( P [ P00574035 ]) ; Ambovombe , 24.II.1931, fl., Decary 8557 ( P [ P00574036 ]) ; env. d’Ambondro, à l’O d’Ambovombe , 7.VIII.1931, fl., Decary 9119 ( P [ P00553051 ]) ; Ampasimpolaka à l’E d’Ambovombe , 29. VI.1931, fr., Decary 9047 (MO-1492389, MO-5594153, P [ P00574037 ]) . Aeg. Anosy [Prov. Toliara]: Lac Anony, X.1956, Bosser 10439 (MO-3332245); F ort-Dauphin, s.d., fl., Cloisel 4 ( P [ P00574033 ]) ; ibid. loco, 16. VI.1926, fl., Decary 4111 ( G, P [ P00553052 ]) .

Distribution and ecology. – Known only from the extreme south-east of Madagascar on fixed dunes, from F ort Dauphin to the west of Ambovombe (F ig. 3).