Perrierophytum macranthum (Hochr.) 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 : 163-166

Perrierophytum macranthum (Hochr.) M.M. Hanes & Callm. , comb. nov. (F ig. 4A).

Kosteletzkya macrantha Hochr. in Annuaire Conserv. Jard. Bot. Genève 20: 98. 1917. Kosteletzkya macrantha var. lignosa Hochr. in Annuaire Conserv. Jard. Bot. Genève 20: 99. 1917 [nom. inval.]. Kosteletzkya macrantha f. lignosa (Hochr.) Hochr. in Humbert, F l. Madagascar Comores 129: 107. 1955 [nom. inval.].

Holotypus: MADAGASCAR. Aeg. Haute Matsiatra [Prov. Fianarantsoa]: rocailles du massif d’Andringitra , 2200 m, s.d., fl., Perrier de la Bâthie 5473 [as “ 70 ” at G] ( G [ G00014378 ]!; iso-: P [ P00037090 ]!) .

= Kosteletzkya macrantha var. herbacea Hochr. in Annuaire Conserv. Jard. Bot. Genève 20: 99. 1917. Kosteletzkya macrantha f. herbacea (Hochr.) Hochr. in Humbert, F l. Madagascar Comores 129: 107. 1955, syn. nov. Holotypus: MADAGASCAR. Aeg. Haute Matsiatra [Prov. Fianarantsoa]: pentes W du massif d’Andringitra , IX.1911, fl., Perrier de la Bâthie 5465 [as “ 75 ” at G] (G [ G00014377 ]!; iso-: P [ P00037088 , P00037089 ]!).

Distribution and ecology. – This species is restricted to granite outcrops in montane ericoid thicket on the Andringitra massif, and in the nearby “haute vallée de la Menarahaka”, from 1700–2200 m (F ig. 3). Though not commonly collected, it is possibly abundant in locations where it is found: “très abondant à la cascade du roi et de la reine, près d’Antanifotsy” (specimen label on Cours 5155 in P [P00574213]).

Conservation status. – Perrierophytum macranthum is known from a handful of collections that are tightly clustered in south-central Madagascar, in and near Andringitra National Park. The collections made outside the national park (e.g. Boiteau 2078, RNM 111189) are now over 50 years old. Given the ongoing habitat loss in areas surrounding the national park since these collections were made, a reduction in the number of subpopulations can be inferred, both historically and projecting into the future. Even within the national park, a majority of specimens were collected before 1970, though there is one more recent collection (2006, Skema 202), suggesting that at least one subpopulation is extant. If the subpopulations outside the national park have been lost, a highly likely scenario, P. macranthum has an EOO of c. 6 km ² and an AOO of 16 km ². The tight clustering of collections in the park suggests that the number of locations is limited to one or two, which are threatened by fire, deforestation, and animal grazing. Thus, P. macranthum is assessed as “Critically Endangered” [CR B1ab(i,ii,iii,iv,v)].

Notes. – Perrierophytum macranthum can be distinguished by its long, filiform, densely pubescent, caducous stipules, and serrate leaf margins with teeth coming to a sharp point. The species has large flowers comprised of 15 epicalyx lobes that are filiform, reddish in color, and densely pubescent with long, cream to gold-colored hairs; large sepals (1.5 cm long), similarly pubescent; and large mauve petals (2.5–3.2 cm long) with dark purple veins.

Hochreutiner described two varieties under P. macranthum . The first one, var. lignosa , that he referred to as “Varietas typica”, while the second one was named var. herbacea . He wrote: “Ces deux variétés ne sont peut-être que des formes altitudinaires, néanmoins, à cause de leur différence de port [These two varieties are perhaps only altitudinal forms, that nevertheless results in their different growth-forms].” (HOCHREUTINER, 1917: 99–100). Later, Hochreutiner considered these varieties as forms in the Flore de Madagascar treatment. We do not retain these formally described infraspecific taxa.

Hochreutiner did not explicitly cite a type for Kosteletzkya macrantha but his citation of Perrier de la Bathie’s collection, under his “typical variety”, can be interpreted as a nomenclaturally valid typification. A specimen at G [G00014378] that he cited under his typical variety can be considered as a valid act of typification, and we consider the specimen deposited at G as the holotype.

Additional specimens examined. – MADAGASCAR. Aeg. Haute Matsiatra [Prov. Fianarantsoa]: sentier du pic Boby , Andringitra , IV.1964, fl., Bosser 19469 ( P [ P00569773 , P00574212 ], MO-3332244 , MO-6071571 ) ; massif de l’Andringitra , 2050 m, s.d., fl., Cours 5155 ( P [ P00574213 , P00574863 ]) ; ibid. loco, IX.1942, fl., Jard. Bot.Tana. 5149 ( P [ P00574214 ]) ; ibid. loco, VI.1956, fl. & fr., Morat 1291 ( P [ P00569772 ]) ; ibid. loco, 2000 m, IV.1921, fl., Perrier de la Bâthie 13751 ( P [ P00553053 , P00553054 ]) ; ibid. loco, 6.V.1955, fl., Réserves Naturelles 7509 ( P [ P00574215 ]) ; Distr. Ambalavao , 30.V.1958, fl., Réserves Naturelles 9873 ( P [ P00574216 ]) ; ibid. loco, 23.III.1960, fl., Réserves Naturelles 11189 ( G, P [ P00574217 ]) ; Andringitra NP , F okotany Namoly, on tourist trail in Ivangomeina F orest, 22°11'12"S 46°54'03"E, 2115 m, 26.IX.2006, bud & fl., Skema et al. 202 ( BH) . Aeg. Ihorombe [Prov. Fianarantsoa]: Haute vallée de la Menarahaka , près de la Réserve de l’Andringitra , 10.IV.1970, fl., Boiteau 2078 ( MO-6071570 , P [ P00574210 , P00574211 ]) .