Caddisflies of the Yukon - Department of Biological Sciences ...

852 G.B. Wiggins and C.R. Parker
FIG. 28. Adult of Sphagnophylax meiops Wiggins and Winchester (126) (Limnephilidae). Brachyptery and
anomalous venation suggest that this species is probably flightless, and perhaps was preserved from extinction only
by the unglaciated Beringian refugium. Forewing length 4 mm. (From Canadian Journal of Zoology)
predators in these sites may be a factor in the survival of relict Trichoptera (Wiggins 1984).
Occurrence of this species in wet tundra is also interesting because the Beringian refugium
for at least part of the Pleistocene is inferred to have been a region of low precipitation
throughout the year and a predominantly dry upland region with little muskeg where
Sphagnum was absent (Schweger et al. 1982). Survival of S. meiops, and also of Lenarchus
expansus (see above) which evidently lives under similar conditions, indicates that areas of
wet tundra persisted in Beringia.
Reduced wings (Fig. 28) and anomalous venation suggest that this species has limited
ability to fly and perhaps is even flightless; and the eyes are unusually small for adult
Trichoptera. Similar modifications occur in a number of arctic Lepidoptera (Downes 1964).
V. Holarctic Species Not in Beringia
Because categories II, III and IV include almost all of the North American Trichoptera
now recognized as occurring in Europe and Asia as well, it is useful for comparison to add
here the few remaining Holarctic species. Six species are assigned to category V, and none
has been recorded from the Yukon; most of them probably dispersed from one continent to
the other under more equable conditions of climate some time before the separation of Asia
and North America in the Pliocene. With Holarctic distribution established long ago, these
species appear now to be disjunct relicts, still resistant to cladogenetic divergence.