Geometric Morphometrics Reveal Body Shape Variation in Freshwater Shrimps of the Genus Macrobrachium Lacking a Mandibular Palp (Formerly Pseudopalaemon Sollaud, 1911) (Decapoda: Palaemonidae)
Year: 2025
Type: article
Abstract: ABSTRACT Shape variation in the cephalothorax of Macrobrachium species without mandibular palp using geometric morphometrics was used as a tool to support species differentiation and propose new diagnostic characters for taxonomic identification. A total of 170 specimens from six species of the genus Macrobrachium without palp were analysed: Macrobrachium amazonensis (Ramos‐Porto, 1979); M. bouvieri (Sollaud, 1911); M. chryseus (Kensley & Walker, 1982); M. gouldingi (Kensley & Walker, 1982); M. iquitoensis (García‐Dávila & Magalhães, 2004); and M. nigramnis (Kensley & Walker, 1982). Nineteen landmarks and semi‐landmarks were digitised for 2D landmark‐based morphometric geometric procedures. Principal component analysis and canonical variation analysis revealed significant shape distinction between species within the group of Macrobrachium species without palp. Macrobrachium amazonensis exhibits the greatest shape variation, while M. bouvieri is the most morphometrically distinct. Relevant morphometric variation among species of Macrobrachium species without palp was detected with high accuracy (> 91%; p < 0.05), suggesting that the shape of the lateral cephalothorax, rostral curvature and position of the antennal teeth are the main morphological features for species discrimination. Species shape distinction in the cephalothorax also revealed relevant discrimination between the Río de la Plata Basin and the Amazonian species. The shape of cephalothorax appears to reflect adaptations to different hydrodynamic regimes and geological separations between basins.
Source: Acta Zoologica
DOI: 10.1111/azo.70014
Authors: Thaís Arrais Mota, Ana Carla Soares da Silva, Lucas Jhones de Santana Neves, Carlos Eduardo Rocha Duarte Alencar, Fabrício Lopes Carvalho
Language: English
Subfield: Geometry and Topology
Field: Mathematics
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,400
OpenAlex ID: W4415674187