Eurythemora velox is characterized by the last thorax segment which is greatly expanded backwards and posteriorly forms a broad extending lamellae. There are a limited number of records of the species.

Key characteristics

Eurythemora velox is characterized by its last pair of legs and the long furca. E. velox is distinguished from E. lacustris by the shape of the last thorax segment which in E. velox is greatly expanded backwards and posteriorly forms a broad extending lamellae, terminating in a number of somewhat outward-curving points. Its furca is slightly shorter than that of E. lacustris. The body of E. velox is more or less pellucid, and in some cases tinged with a yellowish brown colour.

Female: Length 1.3–2.2 mm

Male: Length 1.0–1.9 mm

Ecology and distribution

There are few records of this plankton/littoral calanoid species in Norway. Except one, they are from euthropic localities (lakes and river sites), all situated south of Oslo (<100 m a.s.l.). The last one is from a floodplain pond about 200 km north of Oslo, which is located 200 m a.s.l. pH in water bodies containing E. velox is close to neutral (6.5–7.5), while the contents of electrolytes are relatively high (5–19 mS/m).

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