Scanning electron microscope study of the development of mandibular structure and the molar surface morphology of Branchinella maduraiensis and Streptocephalus dichotomus (Crustacea, Anostraca)

Abstract

In the present study, the molar surface morphology of Streptocephalus dichotomus Baird, 1860 and Branchinella maduraiensis Raj, 1961 is analyzed and correlated with the distribution of these species in ephemeral pools. The larval stages of S. dichotomus are characterized by scanning electron microscopy in relation to their feeding physiology, which shows their morphological complexity during developmental stages. The larval mandible consists of a coxa with a three-segmented palp, and further development leads to its gradual transition into the adult mandible. Muscles involved in mandibular movement exhibit rotatory and counter-rotatory movement, which enhances the grinding of food materials. Analysis of the molar surface morphology of B. maduraiensis and S. dichotomus reveals that the mandibles are asymmetrical. Detailed analysis of the topography of the molar illustrates specific structural differences between the species. Gut content analysis also perfectly matches the molar morphology of these species, confirming that B. maduraiensis handles zooplankton more preferentially than S. dichotomus. Our investigation of these fairy shrimps provides information on their molar surface morphology and feeding biology, which increases the understanding of their coexistence.