A new species of Indo-Papuan groundsnake, genus Stegonotus Duméril et al., 1854 (Serpentes, Colubridae), from the Bird's Head Peninsula of West Papua, Indonesia, with comments on differentiating morphological characters.

We describe a new species of Indo-Papuan groundsnake (Stegonotus) from a single adult male specimen collected in 1953 near Kamro, a village in Maybrat Regency, West Papua, Indonesia. The specimen had been considered a member of S. batjanensis, a well-defined species from the northern Maluku Islands over 500 km to the northwest with which it shares the key characteristic of having the 3rd, 4th, and 5th supralabial scales touching the eyes. The new species can be differentiated from S. batjanensis as well as all other species of Stegonotus by having its 5th supralabial scale projecting forward from behind the eye to form a narrow contact zone with the eye. In addition, it is differentiated by the combination of the following characteristics: seven supralabials, the 3rd-5th touching the eye; eight infralabials, the 1st-4th touching the anterior genial; four scales separating the posterior genial and the first gastrostege; dorsal scales in 17 rows, diminishing to 15 posteriorly; a low number of ventrals (181 in the holotype) combined with a high number of subcaudals (105 in the holotype), the latter comprising 37% of the scales on the ventral surface, the highest proportion in the genus. The description of this species is of interest beyond adding to the species diversity of Stegonotus: it allowed us to explore additional characteristics to resolve taxonomic questions in a morphologically conservative genus, it illustrates the need for additional herpetological survey work on the Bird's Head Peninsula, and its initial misidentification serves as a reminder of the continued relevance and importance of natural history collections as repositories for specimens and data that influence our knowledge today by reaching out from the past.