Emertonia

Mathiske, Annabel, Thistle, David, Gheerardyn, Hendrik & Veit-Köhler, Gritta, 2021, Deep sea without limits-four new closely related species of Emertonia Wilson 1932 (Copepoda: Harpacticoida: Paramesochridae) show characters with a worldwide distribution, Zootaxa 5051 (1), pp. 443-486 : 480

Rareness of Emertonia species

The new species were found in a small number of stations (11) compared to the total number of 74 investigated stations—most of them sampled during the Census of Abyssal Marine Life (CeDAMar). A total of 875 sediment samples (mainly collected with multicorers) were checked in the course of this study ( Fig. 2 ). The number of copepods examined (adults and copepodids) totalled more than 73,000 individuals. Assuming a percentage of 30% adults in deep-sea harpacticoid communities ( George et al. 2014), the 49 collected adult individuals of the four new species (out of approx. 22,000 inspected adult copepods) show their rareness compared to other, more typical deep-sea taxa (e.g. Argestidae : cf. Menzel 2011). However, species such as E. andeep , described from only two specimens found during the ANDEEP II expedition to the Weddell Sea ( Veit-Köhler 2004), proved to be extremely wide-spread when samples of other expeditions were taken into account ( Gheerardyn & Veit-Köhler 2009). The same is true for E. serrata sp. nov. which was reported only from the Southeastern Atlantic (Gheerardyn & Veit- Köhler 2009; as their putative species Kliopsyllus sp. 1 ). Three of the four new species proved to be extremely widespread. Consequently, the rareness of Paramesochridae in the deep sea does not necessarily exclude their suitability as model organisms for distribution range studies of benthic copepods. Moreover, their easy-to-assess simple morphology with a reduced segmentation and setation of the swimming legs, and their ubiquity makes biogeography studies on deep-sea Paramesochridae a straightforward and rewarding task.

Figures

FIGURE 2. Distribution of Emertonia serrata sp. nov., E. ilse sp. nov., E. berndi sp. nov., and E. hessleri sp. nov. in the Pacific, Atlantic, and Southern Oceans (filled symbols, see legend). All stations checked for Paramesochridae in the course of this study are indicated (white circles). Closely situated stations or deployments represented by a single symbol. Isobaths given in 1,000 m contours. Source: General Bathymetric Chart of the Oceans (GEBCO), 30” grid.