Can be diagnosed by its unique dorsal color pattern, composed of numerous white to creamy-white vermiculate markings over a light brown, tan or gray background color. This species is tentatively further separated from H. gomesi by presenting a slightly more slender tail width at base (5.5% DW in holotype of H. rosai vs. 4.5% DW in holotype of H. gomesi), slightly greater preorbital snout length (31% DW in holotype of H. rosai vs. 33.2% DW in holotype of H. gomesi), and smaller pectoral axil to pelvic inner length (4.6% DW in holotype of H. rosai, ranging from 1.3 to 4.9% DW in all specimens, with a mean of 3.7% DW vs. 2.1% DW in holotype of H. gomesi, and ranging from 1.0 to 3.3% DW in all specimens, with a mean of 1.9% DW) (Ref. 86515).