Genus: Porhydrus
| Site | Municipality (county) | Num. obs. | Num. species | Num. images | Last obs. | |
|---|---|---|---|---|---|---|
| Kolbjørnviksjøen | Østfold, Norway | 2 | 1 | 0 | 1992-09-02 | |
| Korssjøen | Vestfold, Norway | 1 | 1 | 0 | 1997-09-09 |
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