Laimosemion ubim Costa & Lazzarotto 2014

Laimosemion ubim can be diagnosed from all other species of rivulids by its epipleural ribs branching at their-basal portion, and again at the sub-distal part of the dorsal branch formed by the sub-basal branching (vs. unbranched in all other rivulids, except for some species of Laimosemion with a single basal branching, but the branches formed are joint by an osseous flap. It also differs from all congeners by the possession of hypertrophied teeth on the anterior part of the outer row of the premaxillary and dentary in males (vs. teeth never hypertrophied) (Ref. 95522).Description: longitudinal series of scales 29-30; transverse series of scales 6;

Dorsal soft rays (total): 5 - 6; Analsoft rays: 8 - 10; Vertebrae: 29 - 30

The type locality of this species is composed of a small terra-firme stream (not affected by large rivers flooding during the wet season) and adjacent pools that drain into the Igarapé do Ubím, a tributary of the Lago Amanã. Collected under dense forest vegetation commonly found in central Amazon upland areas with Mauritia flexuosa palm trees. The collection site is characterized by black water with high transparency, width of up to about 2 m and depth at the stream bed up to about 0.5 m. Mostly encountered in adjacent pools and next to palm-tree roots, where depth was about 0.1 m or less (Ref. 95522).