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

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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.
Caddisflies of the Yukon 853 Hydroptilidae Ithytrichia clavata Morton This species is widely distributed in North America from British Columbia to California, through Texas, Kansas, Oklahoma to Quebec and New Hampshire; it is widespread through northern and western Europe (L. BotojAneanu, pers. comm.). It is not now a far northern species in either North America or Europe, and would seem unlikely to have dispersed across the Bering land bridge during a glacial climate regime. Moreover, the larvae live in running water, a habitat used by only very few successful Pleistocene dispersants. This evidence suggests that Holarctic distribution was achieved before the Quaternary glacial periods occurred, and perhaps the Nearctic and Palaearctic forms have diverged to some extent not yet recognized, as in the Agraylea multipunctata complex (Vineyard and Wiggins in prep.). In any event, the name I. clavata was based initially on populations in New York (Ithaca), and further taxonomic resolution is focussed on European populations. Oxyethira mirabilis Morton The range of this species in northern Europe has been extended to eastern Canada with recognition of O. barnstoni Harper as a junior subjective synonym (Kelley 1984). The pattern of distribution, if now adequately understood, suggests a north Atlantic dispersal. It is the only European representative in the aeola group of O. (Oxytrichia), which is otherwise entirely confined to North and South America (Kelley 1984). Polycentropodidae Polycentropus picicornis Stephens This species occurs through most of Europe (BotojAneanu and Malicky 1978), Siberia and Mongolia to Kamchatka (Lepneva 1964; Mey and Dulmaa 1985). It is known locally in North America from the Northwest Territories to New Hampshire and may yet be recorded from the Yukon. Larvae live in small bodies of standing water and in slow currents of rivers (Lepneva 1964). This pattern of northern distribution suggests that P. picicornis could have passed between Asia and North America more recently than other species of category V, possibly during the Pleistocene. Psychomyiidae Psychomyia flavida Hagen This species was described from North America where it is transcontinental and abundant in running waters. The Asian P. composita Martynov was proposed as a junior subjective synonym of P. flavida (Schmid 1965b); consequently, a wide distribution through Siberia, Mongolia, and North America now has to be attributed to P. flavida. In this context, the absence of records of any Psychomyia from the Russian Far East (e.g. Levanidova 1982) is of interest. In North America, P. flavida has not been recorded in the extreme northwest, but only to the edge of treeline at Churchill, Manitoba (Lehmkuhl and Kerst 1979), and ranges from British Columbia to California and Nova Scotia to North Carolina. Thus, whatever its place of origin, dispersal of P. flavida across the Bering land connection between North America and Asia probably occurred in a climate more moderate than the Pleistocene glacial periods. Limnephilidae Grammotaulius betteni Hill-Griffin Known originally from Oregon, this species has also been recorded from China (Schmid 1950a). Larvae live in slow streams and small marshy ponds (Hill-Griffin 1912), some of
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Caddisflies of the Yukon FRONTISPIE
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Caddisflies of the Yukon 789 and ta
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Caddisflies of the Yukon 791 impose
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Caddisflies of the Yukon 793 outlin
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Caddisflies of the Yukon 795 Genus
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Caddisflies of the Yukon 797 25. Ch
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Caddisflies of the Yukon 799 are de
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Page 25 and 26: Caddisflies of the Yukon 811 Genus
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Page 35 and 36: Caddisflies of the Yukon 821 above
Page 37 and 38: Caddisflies of the Yukon 823 was mu
Page 39 and 40: Caddisflies of the Yukon 825 recogn
Page 41 and 42: Limnephilus extractus Walker (99) L
Page 43 and 44: Apataniidae Apatania zonella (Zette
Page 45 and 46: Integripalpia Apataniidae Apatania
Page 47 and 48: Caddisflies of the Yukon 833 wester
Page 49 and 50: Caddisflies of the Yukon 835 Micras
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Page 53 and 54: Caddisflies of the Yukon 839 years,
Page 55 and 56: other reasons, most Palaearctic-Eas
Page 57 and 58: Caddisflies of the Yukon 843 In add
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Page 69 and 70: Caddisflies of the Yukon 855 TABLE
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Page 77 and 78: Caddisflies of the Yukon 863 Gislas
Page 79 and 80: Caddisflies of the Yukon 865 Reeves
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Caddisflies of the Yukon - Department of Biological Sciences ...

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