A Brazilian scientist has named a new species of miniature rivulid killifish from central Brazil.
Wilson Costa, an expert on killifishes, describes Simpsonichthys nigromaculatus in a paper published in the most recent issue of the journal Ichthyological Exploration of Freshwaters.
Simpsonichthys nigromaculatus is a member of the western clade of the subgenus Simpsonichthys.
It can be distinguished from other members of the genus in having 2"4 black spots on the dorsal fin in males.
Simpsonichthys nigromaculatus is additionally diagnosed by lacking a pelvic fin and girdle, 24"25 vertebrae, second pharyngobranchial teeth absent, ventral process of posttemporal absent, 17"20 anal-fin rays in females, body depth 33.5"36.0% SL in males, maximum adult size 26 mm SL, bright blue bars on flanks in males much narrower than interspaces, five alternating bright blue and pink to red bars on the sides of the head in males, short postorbital pinkstripe conecting pink bars 2 and 3, anterior and posterior margins of iris bright blue, dark grey band bordered by bright blue line on distal margin of, dorsal, anal and caudal fins in males, orange ground colour of dorsal and anal fins in males, no bars on unpaired fins in males, and yellow dots on the caudal fins in males.
The new species is thought to be most closely related to S. parallelus.
Its type locality is temporary shallow canals in the floodplains of the da Prata River in the upper Paran River drainage that are open and exposed to sunlight; the water was light yellow, with a pH of 5.5.
For more information, see the paper: Costa, WJEM (2007) Simpsonichthys nigromaculatus, a new miniature seasonal killifish from the upper rio Paran basin, central Brazil (Teleostei: Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 18, pp. 199"203.