Morphological variation of the endemic sisorid fish, Glyptothorax platypogon (Teleostei: Sisoridae) from Java, Indonesia: conventional and truss-based morphometrics

Landmark-based morphometrics approaches including conventional morphometric and truss-based measurements, are widely used to assess fish population status and understand adaptation to environmental diversity. This study aimed to investigate the morphometric variations of Glyptothorax platypogon , an endemic Javan sisorid fish. The comprehensive analysis involved 226 specimens collected from 10 rivers across three Java regions, obtained from the Museum Zoologicum Bogor (MZB). The Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) were used to analyze the collected morphometric data. In this study, the PCA showed overlap among populations, while DFA effectively identified population differentiation, showing the East Java (Brantas River) population as distinctly separate from the remaining regional groups. Furthermore, sub-regional analysis within West Java showed differences for the Cisanggarung and Cimanuk populations. The significant variations were reported in seven morphometric characters, including adhesive apparatus length (AAL), adhesive apparatus width (AAW), mouth width (MW), interorbital distance (Iod), eye diameter (ED), nasal barbel length (NBL), and snout length (SnL) and in eleven truss-based measurements (A-C, D-E, D-G, F-I, H-K, K-L, H-J, A-C, C-D, E-G, and J-K). This study provides valuable information for future investigations into the taxonomic status of G. platypogon , as well as for informing its ecological assessment within Java region.