Fig.1 Male copepod belonging to the genus Leptopsyllus of the harpacticoid family Paramesochridae. Found at the center of the trench at station 9 as well as in the northern slope of the trench. Stained with Rose Bengal, hence the bright pink spermatophore.  

First of their kind: Two new Paramesochridae species from the Aleutian Trench, North Pacific

Species within the harpacticoid family Paramesochridae are typically associated with intertidal and subtidal habitats, as well as with groundwater ones (Gheerardyn & Veit-Köhler 2009). Until now, no species of this family was found in habitats deeper than 5,389 m (Wells 2007, Gheerardyn & Veit-Köhler 2009, Plum & George 2009). Our two new specimens (Fig. 1 and Fig. 2) were assigned to the genus of Leptopsyllus Scott T., 1984 based on the following characteristics: the 1st swimming leg (Pereiopod 1, short P1) is biramous, this means that an outer part (exopod) and an inner part (endopod) exist. The 2nd and 3rd swimming leg (P2 – P3) just have an exopod. The 4th swimming leg is biramous again and the endopod is just one segmented.

Both specimens were found at station 9. One specimen (Fig. 1) was found in the central axis of the trench (-7,137 m), as well as in the northern slope of the trench (-6,470 m). However, the other specimen (Fig. 2) was found only in the southern slope of the trench (-6,499 m).

Identifying copepods is a time-consuming work, as one must carefully investigate all the appendages. But with the challenge comes the fun! Morphological and species knowledge is still a fundamental skill within the ecology. Without the correct identification of species – in my case of the copepods – further work might present less accurate results. This basic research will help to improve my results of the next step within my project – metabarcoding analysis and constructing of a reference library with copepods. And maybe we can shed some light on the genetic connectivity beyond the trench.



Fig. 2 Other male copepod found at the southern slope of station 9. Also stained with Rose Bengal.