Brunei

Sharing the species rich island of Borneo (WWF) with portions of Indonesia and Malaysia, Brunei can claim several dozen species known only from within its borders. 

Fish species recently discovered in Brunei include a silurid catfish Ompok platyrhynchus (Zootaxa pdf file), a halfbeak Dermogenys bruneiensis (FishBase), a barb Systomus xouthos (pfeil-verlag.de pdf file), and three species of river loach: Gastromyzon cranbrooki (Raffles Museum), Gastromyzon venustus (FishBase), and Neogastromyzon brunei (FishBase). 

A recently described amphibian found only in Brunei is the Belalong Tree Frog Rhacophorus belalongensis (Frogs of Borneo).

Invertebrates unique to Brunei include a dragonfly Eupahaea ameeka (Asia Dragonfly), a scarab beetle Bruneixenus squamosus (p. 6 of eResearch Archive pdf file), a lasiocampid moth Trabala bouraq (Moths of Borneo), a water strider Rheumatogonus esakii (p. 10 of Naturalis pdf file), an endemic genus of wasp Agmostigma (Universal Chalcidoidea Database), a fruit fly Euphranta belalongensis (p. 3 of Raffles Museum pdf file), a stonefly Phanoperla belalong (p. 8 of Illiesia pdf file), a water bug Aphelocheirus bruneiensis (p. 14 of nhm-wien.ac.at pdf file), a jumping spider Brettus storki (p. 3 of Peckham Soc. pdf file), the goblin spiders Ischnothyreus barus (AMNH) and Ischnothyreus elvis (AMNH), a freshwater crab Terrathelphusa telur (p. 10 of Raffles Museum pdf file), and a freshwater prawn Macrobrachium leucodactylus (p. 7 of Raffles Museum pdf file).

About 35 species of vascular plants are so far known exclusively from Brunei including are the palms Livistona exigua (PACSOA), Calamus maiadum (PALMweb), and Pinanga yassinii (PALMweb).  Other endemic plants include an orchid Coelogyne bruneiensis (IOPSE), a ginger Boesenbergia belalongensis (Kew), and an endemic genus of bamboo Temburongia simplex (Martin Dančák). Other plants endemic to Brunei include Pothos laurifolius (p. 86 of Botanic Gardens Trust - Sydney 3 MB pdf file), Horsfieldia disticha (JSTOR), Amischotolype sphagnorhiza (Kew), Henckelia coodei (JSTOR), Albertisia triplinervis (JSTOR), Connarus peltatus (JSTOR), Schismatoglottis nicolsonii (p. 96 of Botanic Gardens Trust - Sydney 2 MB pdf file), Etlingera belalongensis (JSTOR), and Knema minima (Nationaal Herbarium Nederland).