Population variability in New Guinean parastacid crayfish Cherax papuanus Holthuis, 1949

New Guinea is the largest tropical island and hosts a rich native astacofauna represented by numerous parastacid crayfish from the genus Cherax. Thus, the island is a so-called enigmatic hotspot of crayfish diversity. Many of these species are endemics and remain poorly studied. Although more than 30 species occur in the western part of the island, only Cherax papuanus (Holthuis, 1949) is currently the known crayfish species with an exclusive native range in the eastern half of the island. The only detailed information published about this crayfish is its formal description. The present study provides new morphological and, for the first time, genetic data based on specimens collected from Lake Kutubu, Papua New Guinea, in 1970, 1973, and 2023. Here is provided the most extensive examination to date in terms of population variability and refining some of the key morphological characteristics of the species. The findings presented are crucial for accurate species identification, which is important for future research, sustainable exploitation, management, and potential conservation measures.