Macrobiotus hyperboreus Biserov 1990

The cuticle had pores. Buccal armature was observed in most of the 125 specimens examined, showing four rows of small teeth in posterior and anterior bands, and transverse crest system (three ventral and three dorsal crests). In two samples, the anterior band of teeth was lacking or not visible. I observed two macroplacoids and a microplacoid within the pharyngeal bulb. In some specimens, small teeth were observed on the lunules of the double-claws on the fourth pair of legs. A total of 29 eggs from eight out of thirteen samples were examined with no remarkable differences with respect to the original description (Biserov 1990), namely, free eggs with inverted chalice-shaped processes, distal dish with dentated margins, distal dish diameter smaller than the base process diameter, and egg surface between processes with uniformly distributed pits also present at the base of each process. A total of 67% of the specimens did not show ocular spots, while 3% had these structures. Mean body size was 727 μm (SD 234), range 363 to 1507 μm. The species has been cited for Eurasia. This is the first time for this species to be found in the Iberian Peninsula (Table 2). Macrobiotus hyperboreus was identified at thirteen sampling points (Table 3) from LF, LR, and MT samples.