Ligia occidentalis in Canada??
The Pacific Coast of North Amer from Alaska to Baja CA have 2 native species of Ligia or 'rock louse'. Based on GBIF records and this atlas, the native Ligia pallaisi is supposed to range from Alaska to the San Francisco bay (with a disjunct Santa Cruz population). The native Ligia occidentalis is supposed to range from the California border south to ~ the tip of Baja in Mexico.
The above pic compares the two with Ligia occidentalis at the top. Ligia pallaisi and Ligia occidentalis can be distinguished by the width between the eyes (wide in the former, narrow in the latter) and the length of the 'uropods' (forked tail parts) which are shorter in the former and longer in the latter.
There's also the introduced Ligia exotica from Southern California south into the tropics with even longer uropods which are greater than 1/2 the body length
Odd then to find these two (here by @nanorca13 and here by @chlorophilia) observations of whats pretty clearly Ligia occidentalis in Canada based on uropod length. Here's one of @chlorophilia's photos:
This site does mention Ligia occidentalis in BC, but as I mentioned above, GBIF records and the recent major treatment on these guys don't have any records of these north of CA. So this counts as a discovery in my book. Nice work gang, keep the observations coming!
Comments
Very interesting! Surprised L. exotica is only found from southern CA south since it's on the east coast at least as far north as New Jersey. I guess it doesn't like cold water.
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