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 Scram 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 (Muller-Liebenau), L. ulmeri (Muller-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 (Muller-Liebenau) from Malaysia, was also found in Indonesia, increasing the total number of species in Indonesia to 24. Seven morphogroups 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.

Material collected between 1999 and 2011 in Papua New Guinea and the Papua Province of Indonesia unveiled the enormous diversity ofLabiobaetison this island. Twenty-six new species were identified and delimited by integrative taxonomy using genetic distance (COI, Kimura-2-parameter) and morphology. These new species are described and illustrated based on larvae, augmenting the total number ofLabiobaetisspecies on the island of New Guinea to 32. Seven morpho-groups of species are proposed based on morphological characters and a key to all New Guinea species is provided. The generic attributes of the larvae are summarised and slightly modified based on the examinations of the new species. Results on the genetics of most species (COI) are also provided. The interspecific K2P distances are between 13% and 32%, the intraspecific distances usually between 0% and 2%. Possible reasons for the remarkable richness of this genus in New Guinea are discussed.

Material collected between 2006 and 2016 in Borneo, Sulawesi, and New Guinea further increased our knowledge ofLabiobaetisNovikova & Kluge in these regions. Five species were previously reported from Borneo, two from Sulawesi, and 33 from New Guinea. Six new species have been identified using a combination of morphology and genetic distance (COI, Kimura 2-parameter), one species from Borneo (Brunei), one from Sulawesi, and four from New Guinea. They are described and illustrated based on their larvae and keys to the species of the relevant groups are provided. Additionally, new reports, a complementary description, and the COI sequence forL. dendrisetisKaltenbach & Gattolliat are presented. The distribution ofLabiobaetisin the Wallacea region is discussed based on the new findings. The total number ofLabiobaetisspecies worldwide is augmented to 153.

Investigations of type material and new material from the Philippines (Luzon) revealed that Baetis luzonensis Müller-Liebenau, 1982 and B. realonae Müller-Liebenau, 1982 do not belong to Baetis Leach, 1815. A new genus, Philibaetis gen. nov., is described to accommodate both species and both are re-described based on larvae. The new genus is characterised by having a rectangular labrum with a submarginal row of long, simple setae on the dorsal surface and ventrally on lateral margins long, simple, spine-like setae, on anterolateral margins long, feathered setae and medially long, bifid setae and a partial, submarginal row of lanceolate setae. Both mandibles have blade-like incisors and dorsally, a mediolateral patch of long, spine-like setae; additionally, the left mandible has a tuft of long, partly branched setae at the base of the subtriangular process. Philibaetis gen. nov. is further characterised by a hypopharynx with a medial tuft of stout setae and anterolaterally, two smaller tufts of stout setae, a galea-lacinia with the distal denti-seta tooth-like and directed against canines, a fore femur apically with stout setae, both on anterior and posterior side and without a femoral patch and a claw with one row of denticles and two or three subapical setae. The protogonostyli under the cuticle of male last instar larvae are folded in the Labiobaetis type, excluding their affiliation to the genus Baetis. COI sequences were obtained from both species. The genetic distance (Kimura 2-parameter) between them is 17.5% on average. Very limited genetic distances of 0% to 3% (0.75% on average) were found between specimens of P. luzonensis comb. nov.

Investigations of material collected partly in 1999 and mainly between 2006 and 2016 in New Guinea, mostly along the high, central mountain chain of the island, further increased our knowledge of the diversity of the genusLabiobaetisNovikova & Kluge on this island. Previously, 37 species were reported from New Guinea. We have identified six new species using a combination of morphology and genetic analysis (COI). They are described and illustrated based on their larvae. Five of the six new species belong to the grouppetersorum, which is endemic to the island. Additionally,Labiobaetis xeniolusLugo-Ortiz & McCafferty is also assigned to this group. The morphological characterisation of the grouppetersorumis enhanced, and a key to all species of this group is provided. Complementary descriptions and remarks to the morphology of known species of the grouppetersorumare provided. Additionally, a genetic analysis (COI) including most species and several additional Molecular Operational Taxonomic Units (MOTUs) of the grouppetersorumis discussed. One of the new species belongs to the groupvitilis. The morphological characterization of this group is slightly enhanced, and the obtained COI sequence was added to the genetic analysis of the grouppetersorum. The total number ofLabiobaetisspecies worldwide is augmented to 162.