Phenotypic variability in the shield morphology of wild- vs. lab-reared eumalacostracan larvae

Abstract

Morphological identification of planktic crustacean larvae is required in many scientific contexts, such as ecology or taxonomy. Due to a still low availability of genetic sequences for many ingroups of Eumalacostraca, this task is still more feasible by morphological methods. Our understanding of eumalacostracan larval morphology is challenged by phenotypic variability. We investigated four eumalacostracan ingroups: Galatheidae, Hippoidea, Raninidae and Stomatopoda. Representatives of all four groups develop through spine-bearing planktic larval stages. Incorporating dorsal and lateral shield outlines into three-dimensional shape analysis of the shields, we compare specimens from the wild with laboratory-reared specimens. Using graphical and statistical analysis methods, we find that at least the lateral morphology of the shields of Hippoidea and Raninidae seems to be too strongly dependent on phylogeny to show phenotypic variability with our current sample size, but Hippoidea do show phenotypic variability in their dorsal shield morphology. In Galatheidae and Stomatopoda, a clear difference in shield morphology can be found between wild-caught and laboratory-reared specimens. This difference likely represents phenotypic variability. The exact environmental signals causing this phenotypic variability are still unknown, but some candidates are discussed.

Morphological diversity in true and false crabs reveals the plesiomorphy of the megalopa phase

“…However, this divergent pattern could simply be an artifact of the earlier described diversity differences between true and false crabs. In any case, these results highlight the importance of larvae for biodiversity studies, which are often still overlooked 38,40 .…”

“…Material used for this study originated from published images and reconstruction drawings in literature, open databases, collections, and museums. Some of the material was documented and published by the authors (for documentation methods, see Eiler et al 50 ) 40 , 51 , 52 . Our material included extant and fossil species of Meiura.…”

“…Going through more zoea stages usually takes more time and therefore equals a longer zoea phase. This longer time period may provide potential for additional adaptations or even require these, especially since it also leads to a larger body size, again requiring new morphological adaptations to deal with buoyancy and predator avoidance 15,40 .…”

Outline analysis as a new method for investigating development in fossil crabs

“…We used a Canon Rebel T3i digital camera with a MP-E 65 mm macro lens and distance rings. We used a Yongnuo YN24EX twin-flash equipped with polarization filters and a cross-polarized filter in front of the camera lens, to reduce light-reflection induced artefacts (for a detailed description see Eiler et al, 2016;Braig et al, 2023a).…”

The Diversity of Larvae with Multi-Toothed Stylets from About 100 Million Years Ago Illuminates the Early Diversification of Antlion-like Lacewings

“…This decomposition involved representing the outline as a harmonic sum of trigonometric functions, with the shape described by weighted harmonic coefficients [174,175]. We aligned, centred, and scaled the harmonic coefficients and then used a principal component analysis (PCA) to extract the dimensions of the largest variation [175][176][177].…”