Complete lateral line; 7 scales between lateral lines over the dorsum, on caudal peduncle; dorsal-hypural distance, when carried forward, falling on nostril; origin of dorsal fin behind posterior margin of pelvic fin base; color pattern consisting of a dark lateral stripe from opercle to caudal base, ending in a precaudal spot. This kind of color pattern is shared with R. sumatrana only, from which R. hobelmani differs by the lateral stripe being wider on the body between opercle and vertical of dorsal fin than on the caudal peduncle (versus of regular width) and somewhat diffuse (versus black), a paraxial stripe being distinct (versus under lateral stripe).