Listrura costai Villa-Verde, Lazzarotto & Lima 2012

Distinguished from its congeners by having a small anterior process on the first hypobranchial (vs. process absent). Differs also from its congeners, except Listrura nematopteryx and Listrura picinguabae, by having only one ray on pectoral fin (vs. two to four rays). It can be separated from Listrura nematopteryx and Listrura picinguabae by having an inferior row of dots extending only on posterior half of body (vs. over almost the entire body), and posterior tip of ceratobranchial 5 strongly concave (vs. slightly concave or straight. Can be further distinguished from Listrura nematopteryx by having a discontinuous lateral midline row of spots (vs. continuous row), lateral processes of urohyal reaching the anterior region of posterior ceratohyal [vs. reaching the posterior region of posterior ceratohial; more dorsal and anal-fin rays (8-9 vs. 7-8 and 8-9 vs. 6-8, respectively), and more opecular and interopercular odontodes (6-8 vs. 4-6 and 8-12 vs. 5-7 respectively); from Listrura picinguabae by possessing a longer head (head length 11.7-15.3% SL vs. 10.7- 11.7% SL), more dorsal-fin rays (8-9 vs. 7), and anal-fin origin at vertical through region from centra of the 31st to 34th vertebrae (vs. 34th to 36th) (Ref. 91744).

Dorsal soft rays (total): 8 - 9; Analsoft rays: 8 - 9; Vertebrae: 48 - 52

Found mostly in narrow (about 1 m wide) and shallow (about 50 cm deep) clear water stream located in a swampy plain area densely vegetated with grass. Captured at night or dusk, suggesting a nocturnal habit (Ref. 91744).