Material collected between 2000 and 2014 on the island Borneo, including the Indonesian province of Kalimantan, the Malaysian province of Sabah and Brunei Darussalam, substantially increased our knowledge of Labiobaetis on this island. The total number of Labiobaetis species in Borneo increased to five, as only one species, L. borneoensis (Müller-Liebenau, 1984), was previously reported. Three new species were identified by morphology and partly by using genetic distance (COI, Kimura 2-parameter). They are described and illustrated based on their larvae (Labiobaetis bakerae sp. nov., L. penan sp. nov. and L. dayakorum sp. nov.); in one case, the imago is described as well. New reports of L. borneoensis are presented and the imago of this species is described for the first time. Labiobaetis moriharai (Müller-Liebenau, 1984), originally described from mainland Malaysia (Province Selangor), is reported from Borneo for the first time. The interspecific K2P distances in Borneo are between 19% and 25%, the intraspecific distances are usually between 0% and 1%. The total number of Labiobaetis species worldwide is augmented to 126.
Material collected between 2010 and 2014 on the Indonesian islands of Sumatra, Bali, Sumba, Sumbawa, Sulawesi, and Seram unveiled the enormous diversity of Labiobaetis Novikova & Kluge in this country. Five species were reported from Indonesia previously (L. fulmeki (Ulmer), L. obscurum (Ulmer), L. necopinatum (Müller-Liebenau), L. ulmeri (Müller-Liebenau), and L. boettgeri (Ulmer)); all were described from adults only and no species were previously known at larval stage. We identified 18 new species by integrative taxonomy using genetic distance (COI, Kimura-2-parameter) and morphology, and they are described and illustrated based on their larvae. Another species, L. multus (Müller-Liebenau) from Malaysia, was also found in Indonesia, increasing the total number of species in Indonesia to 24. Seven morpho-groups of species are proposed based on morphological characters and a key to the larvae of all species from Indonesia and adjacent countries is provided. The total number of Labiobaetis species worldwide is augmented to 123. The examination of the new species allowed us to slightly modify the generic attributes of the larvae. The interspecific K2P distances are usually between 11% and 24%, the intraspecific distances are usually between 0% and 3%. The remarkable richness of the genus in Indonesia is discussed.
A reinvestigation of type and other material of Baetisjavanicus Ulmer, 1913 and Baetissabahensis Müller-Liebenau, 1984, together with new material from Southeast Asia revealed a new genus, Branchiobaetis gen. nov. The above species are formally assigned to the new genus Branchiobaetis gen. nov. It is characterized by the presence of accessory gills ventrally near fore coxa and at the base of maxillae, a peculiar folding of the gonostyli developing under the cuticle of last instar male larvae, together with a unique combination of other larval characters. Besides the two formerly described species, five new species are identified using a combination of morphology and molecular characters (COI, Kimura 2-parameter distances), four species from Sumatra and one from the Philippines. They are described and illustrated at the larval stage. Additionally, a complementary description of larva and adult stages of the generic type species B.javanicus comb. nov. as well as the first description of the eggs are provided. Furthermore, new reports of B.javanicus comb. nov. and B.sabahensis comb. nov. are indicated. The distribution of Branchiobaetis gen. nov. includes the Indonesian Sunda Islands, Borneo, and the Philippines. A key to the larval stage of all species is provided.