Tetrachaelasma southwardi Newman & Ross, 1971. Intraspecific variation of opercular plates among the material collected at 2934 m depth. Specimen (MACN-In 44479h): A, D. Right scutum in external and internal views, respectively; B, C. Right tergum in external and internal views, respectively; E. Left scutum in external view, slightly slanted to make the apico-basal ridge more visible; F. Joined right tergum and scutum in internal view. Specimen (MACN-In 44479d): G, J. Left tergum in external and internal views, respectively; H, I. Left scutum in external and internal views, respectively. Specimen (MACN-In 44479a): K, N. Left tergum in external and internal views, respectively; L, M. Left scutum in external and internal views, respectively. Abbreviations: abr – apico-basal ridge; in – indentation (worn) on articular margin. Scale bars: 10 mm.

 
 
  Part of: Chiesa IL, Pereira E, Roccatagliata D (2024) On the occurrence of the deep-sea barnacle Tetrachaelasma southwardi Newman & Ross, 1971 (Cirripedia, Balanomorpha, Bathylasmatidae) in the Mar del Plata Submarine Canyon, Argentina: supplementary description and taxonomic remarks on the genus. Zoosystematics and Evolution 100(2): 603-623. https://doi.org/10.3897/zse.100.118912