Morphology of larvae of shrimp ?Spirontocaris arcuata Rathbun, 1902 (Decapoda, Thoridae) from adjacent Kamchatka waters

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  • Authors: N. A. Sedova1,2, S. S. Grigorev2
  • Affiliations:
    1. Kamchatka State Technical University, Petropavlovsk-Kamchatsky, Russian Federation
    2. Kamchatka Branch of the Pacific Institute of Geography, Far Eastern Branch of the Russian Academy of Sciences – (KB TIG) FEB RAS, Petropavlovsk-Kamchatsky Russian Federation
  • Keywords: Spirontocaris arcuata, larvae, stage, form, variability, northwestern Pacific, Sea of Okhotsk, plankton

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Abstract

Description is given of two forms of larvae of the genus Spirontocaris, presumably assigned to the species S. arcuata I–VI stages (family Thoridae) from plankton samples collected in the eastern part of the Sea of Okhotsk and the Kamchatka waters of the northwestern part of the Pacific Ocean. The main differences in morphological features between larvae of different stages were revealed. Significant individual variability in size, rostrum length, degree of antenna development, number of anteroventral spines and telson shape was found. The least variable and reliable characters for determining the species are the morphology of the antennules, pleopods and pereiopods, the armament of the maxillae at all stages, and the armament of the maxillae in younger larvae. The asymmetry of the structure of the antennae, carapace, maxillules, maxillae, pereopods and maxillipeds is shown. Morphological forms differ in size, length of pleonal spines, telson shape, degree of development of antennules and pleopods.

Keywords: Spirontocaris arcuata, larvae, stage, form, variability, northwestern Pacific, Sea of Okhotsk, plankton

Authors

N. A. Sedova
Kamchatka State Technical University, Petropavlovsk-Kamchatsky, Russian Federation / Kamchatka Branch of the Pacific Institute of Geography, Far Eastern Branch of the Russian Academy of Sciences – (KB TIG) FEB RAS, Petropavlovsk-Kamchatsky Russian Federation
S. S. Grigorev
Kamchatka Branch of the Pacific Institute of Geography, Far Eastern Branch of the Russian Academy of Sciences – (KB TIG) FEB RAS, Petropavlovsk-Kamchatsky Russian Federation