Stigmaphyllon patricianum-firmenichianum (Malpighiaceae), a new species from Loyalty Islands, New Caledonia

Abstract A new species of Stigmaphyllon (Malpighiaceae) is described: Stigmaphyllon patricianum-firmenichianum Butaud. It is restricted to the coral islands of Ouvéa, Lifou and Maré in the Loyalty Islands Province (New Caledonia) and is most similar to Stigmaphyllon discolor (Gand.) C.E.Anderson, known from New Caledonia and Solomon Islands. Previously, plants now known as Stigmaphyllon patricianum-firmenichianum were included in Stigmaphyllon taomense (Baker f.) C.E.Anderson, endemic to the northern part of Grande-Terre and Belep Islands (New Caledonia). A new circumscription of Stigmaphyllon taomense is proposed. The regional key for New Caledonian species of Stigmaphyllon is updated.


Introduction
Th e family Malpighiaceae is represented by three native genera in New Caledonia: Acridocarpus Guill. & Perr. with a single endemic species, Tristellateia Th ouars with one indigenous species, and Stigmaphyllon A.Juss. with eight indigenous species, of which fi ve are endemic (Morat et al. 2012); a sixth endemic is added here.
Stigmaphyllon was recently revised by Anderson (2011Anderson ( , 1997 in both the Old and the New World. Th e Old World species, known from South-East Asia and the Western Pacifi c, traditionally had been assigned to the genus Ryssopterys A.Juss., which was found to be nested in Stigmaphyllon (Davis and Anderson 2010). Anderson (2011) recognized this group as Stigmaphyllon subg. Ryssopterys, comprising 21 species, of which ten were described as new.
Of the New Caledonian species of Stigmaphyllon, only one is known in the Loyalty Islands, which Anderson included in Stigmaphyllon taomense (Baker f.) C.E.Anderson, a species of Belep Islands and the northern part of Grande-Terre, the main island of the New Caledonian archipelago, ca. 200 km west of the Loyalty Islands (Anderson 2011;Baker 1921). Formerly, specimens from the Loyalty islands (Lifou or Maré) were labelled Ryssopterys timoriensis (DC.) A.Juss. (e.g., Schmid 1966Schmid , 1967, a synonym of S. timoriense (DC.) C.E.Anderson; S. timoriense is not known from New Caledonia (Anderson 2011).
Examination of living plants and herbarium specimens, and discussions with specialists of the genus Stigmaphyllon (C.E. Anderson, pers. comm. 2014) and New Caledonian fl ora (G. Gâteblé, pers. comm. 2014) revealed that the Loyalty Islands taxon differs from S. taomense. It is here described as S. patricianum-fi rmenichianum. Stigmaphyllon subg. Ryssopterys now includes 22 species, of which nine occur in New Caledonia. Diagnosis. Stigmaphyllon patricianum-fi rmenichianum is most similar to S. discolor (Gand.) C.E.Anderson and S. mcphersonii C.E.Anderson in the tomentose vesture of the abaxial surface of the blade which diff erentiates them from the other New Caledonia Stigmaphyllon species. Stigmaphyllon patricianum-fi rmenichianum diff ers from S. discolor by the number of stamens, respectively 10 and 12-16, and by the number of fl owers in each umbel, respectively 4-9 and 8-18 (-20), and from S. mcphersonii by the number of functional styles of the male fl owers, respectively 3 and none (styles absent or rarely 1, rudimentary and without stigma), by the sepals length, respectively 2.8-3 mm and 1.5-2 mm, by the petals length, respectively 8-10 mm and 6-27 mm, and by the dorsal wing of samara, respectively 2.6-2.9 cm and 1.7-2 cm long.
Phenology. Flowers (emitting a pleasant odor) from November to April; fruits from February to May.
Distribution. New Caledonia, endemic to Loyalty Islands; known only from Ouvéa, Lifou and Maré islands. Not recorded on the smaller islands of Beautemps-Beaupré, Tiga and Walpole.
Discussion. Stigmaphyllon patricianum-fi rmenichianum is the sole member of the genus Stigmaphyllon in the Loyalty Islands. It is allied with S. discolor and S. mcphersonii with which it shares an abaxial tomentose vesture of the blade. Its inclusion under S. taomense, a species with an abaxially sericeous blade, by Anderson (2011), may stem from the patchily deciduous vesture of some leaves, which can give the impression of a sericeous blade. Moreover, S. patricianum-fi rmenichianum, S. mcphersonii and S. taomense have all 10 stamens, whereas S. discolor bears 12-16 stamens. Nevertheless, its closest affi nity in New Caledonia apparently is with S. discolor, which occurs on most of the southern part of Grande-Terre and Isle of Pines. In South-East Asia and the Western Pacifi c, it is most similar to S. albidum (Blume) C.E.Anderson, which can be diff erentiated by the absence of a style in male fl owers. Th is new species is also clearly diff erent from the widely distributed S. timoriense, which has male fl owers usually without styles and blades abaxially sericeous to glabrate.