Four species (Chelarctus aureus, C. crosnieri, C. cultrifer, and C. virgosus) have been described in the genus Chelarctus of the subfamily Scyllarinae, of which mid to final stage phyllosoma larvae in three species (C. aureus, C. crosnieri, and C. virgosus) have been reported. Ueda et al. (2021) found phyllosoma larvae morphologically assigned to the genus Chelarctus but having distinct DNA sequences from the above four species, designating ?Chelarctus sp-1. Additional specimens (n = 8) of mid to final stage phyllosoma larvae of this species were collected in the western North Pacific. The 16S rDNA sequence data supported ?Chelarctus sp-1 to be a member of the genus Chelarctus. Based on the shape of the cephalic shield, the ratio of the cephalic shield width and length, length of posterolateral spines on the telson, and body size of each stage, mid to final stage phyllosoma larvae of ?Chelarctus sp-1 could be discriminated from those of the other species of the genus reported to date.