Revisions and phylogenies of Malesian Euphorbiaceae: Subtribe Lasiococcinae (Homonoia, Lasiococca, Spathiostemon) and Clonostylis, Ricinus, and Wetria

A cladogram of the subtribe Lasiococcinae (Homonoia, 2 species, Lasiococca, 3 species, and Spathiostemon, 2 species) is presented with the genus Wetria as outgroup. All three taxa are monophyletic groups of species with Lasiococca and Spathiostemon as sistergroups and Homonoia related to both of them. Within Lasiococca, L. comberi and L. malaccensis are probably closest related. The two species of Homonoia are rheophytes, one is restricted to India where it shows two distinct forms, the other species is widespread from India throughout Malesia. Lasiococca is represented by one species in Malesia, L. malaccensis, only known from three localities, ranging from the Malay Peninsula to Sulawesi and the Lesser Sunda Islands. Spathiostemon has two species in Malesia, one is widespread in Malesia, the other one is restricted to part of Peninsular Thailand. Clonostylis, a monotypic genus only known from the Sumatran type specimen, is not synonymous with Spathiostemon. Clonostylis is seemingly most similar to Mallotus and Macaranga. Ricinus, also a monotypic genus, is introduced to Malesia and is generally cultivated. It is not part of the Lasiococcinae. The presence of phalanged stamens, also typical for the Lasiococcinae, is a parallel development as Ricinus shows many more androphores and the connective is often appendaged. Ricinus cannot readily be classified and retaining it in its present monotypic subtribe seems to be the best solution. Wetria shows two species in Malesia. One is restricted to West Malesia, the other one is found in New Guinea and appears to be similar to the recently described W. australiensis of Queensland.