First report of the family Zelinkaderidae (Kinorhyncha: Cyclorhagida) for the Caribbean Sea, with the description of a new species of Triodontoderes Sørensen & Rho, 2009 and an identification key for the family

Abstract

A new species of Kinorhyncha, Triodontoderes lagahoo sp. nov., is described from Tobago Island, Caribbean Sea (western Atlantic Ocean) from a coastal, sandy habitat using both light and scanning electron microscopy. The species is characterized by the presence of middorsal acicular spines on segments 1–11 (that on segment 10 crenulated in males), laterodorsal crenulated spines on segment 10 only in males, lateroventral acicular spines on segments 3–4 and 6–8 (lateroventral spines also on segment 10 in females), lateroventral cuspidate spines on segments 5 and 9, lateral accessory acicular spines on segments 5 and 9, lateral accessory cuspidate spines on segment 8, ventrolateral acicular spines on segment 2 and ventrolateral cuspidate spines on segment 2. Females furthermore possess short papillae in ventrolateral position on segment 8 and ventromedial position on segment 9. The absence of cuspidate spines in lateral accessory position on segment 6 easily distinguishes T. lagahoo sp. nov. from the single known congener, Triodontoderes anulap. Moreover, also the arrangement of female papillae and sensory spots differ between the species. The finding of a new species of Triodontoderes in the Caribbean Sea is the first report of the genus for American waters and the Atlantic Ocean since its original description. Additionally, a dichotomous key for identification of the family Zelinkaderidae to species level, as well as systematic remarks on some morphological characters of the new species are included herein.