Abstract
A new species, Luciogobiusopisthoproctus sp. nov., is described based on 18 specimens collected from Daxi Creek (Yilan) and Babian Creek (Taitung) in Taiwan. The new species is characterized by having a yellowish body with scattered spots on the sides, a black blotch on the caudal fin, the absence of free pectoral-fin rays, and more than 40 vertebrae. The new species can be distinguished from congeners by the following combination of characters: AAA distance (anus to anal-fin origin) shorter than twice the body depth at anus, 4.2-7.2% of standard length (SL); pre-anus length 80.0-92.8% of pre-anal-fin length; snout length 39.7-62.7% of AAA distance; abdominal vertebrae 20-22; caudal vertebrae 20-22; first anal-fin pterygiophore usually inserted behind the second haemal spine.