Two new cryptic species of Artemia (Branchiopoda, Anostraca) from Mongolia and the possibility of invasion and disturbance by the aquaculture industry in East Asia

Abstract

Among each of the two different bisexual clades of the brine shrimp Artemia in Asia, at least two cryptic species of Artemia (one in each clade) were found in Mongolia in the present study. As in other, similar cases, once the discreteness of such units at species level is known, meticulous observations using light microscopy will reveal distinguishable morphological differences with other congeners, slight as those features may be. In such classifications, the emphasis usually lies on structures of the copulatory organs, as the small differences present in most cases are best expressed in those organs that primarily ensure the species’ reproductive isolation. Since physical differences in the reproductive organs will tend to (partly) obstruct effective mating, it may be presumed this is likely to result in (some degree of) reproductive isolation, the prime criterion for recognizing biological species. Two cryptic species from Mongolia are described herein, and our results also showed for one of them an extremely rapid individual growth and very early maturity: in fact it makes the most extreme r-strategist documented, at least, as far as we know. One of the consequences of this observation could be, that where such Artemia cysts (i.e., resting eggs) are used as inoculations in aquaculture activities, these should be monitored closely and, as required, be subjected to adequate, perhaps more stringent regulations. The present authors are not aquaculture scientists but researchers of the genus Artemia, so for us, inoculation under natural conditions in the field is our direct concern. We report a highly reproductive Artemia species as new to science, but at the same time, we worry that this new species could escape from the aquaculture industry into the natural environment. This is because in this type of aquaculture no isolated basins are used but only incompletely separated, i.e., only partially screened off, parts of natural water bodies. Artemia franciscana Kellogg, 1906, as well as parthenogenetic populations of Artemia could be disturbed by escapees of that extremely prolific new species.