| Popis: |
Eubosmina is representeNd in the Americas by at least four species, of which two, E. coregoni ( Baird ) and E. Zongkpina ( Leydig ) , are Holarctic; E. hagmanni ( Stingelin ) and E. tubn the more widespread, E. hagmanni, is known from Tierra de1 Fuego and may occur in the Canaclian Arctic. The two can bc difficult to separate unless males arc present, as they rarely are. In typical summer populations, however, the female rostrum shows positive allometry in E. hagmanni but negative allometry in E. tubicen; the mucro shows zero or weakly negative allometry in E. hagmanni but positive allometry in E. tubicen. In no known locality do these two species occur together, but in a few New England and Canadian lakes, where E. longispina is present, populations that otherwise resemble E. tubicen show negative allometry of the mucro. This situation is provisionally attributed to character displacement. |
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