Henri Goulet.
The Habitat of Platypatrobus Darlington (Coleoptera: Carabidae).
Psyche 72(4):305-306, 1965.

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THE HABITAT OF PLATYPATROBUS DARLINGTON
(COLEOPTERA: CARABIDAE)
BY HENRI GOULET
College Bourget, Rigaud, Quebec, Canada. Since its description in 1938, Platypatrobus lacustris Darlington has remained a great mystery. Despite intensive searches both in Canada and the United States, only six examples had been found. But in 1965 the mystery seemingly was solved, for 51 specimens were cap- tured by the author and his companions during three visits to Meach Lake, Que., in Gatineau Park, near Ottawa. Platypatrobus lacustris was described as a new genus and a new species from a single female taken by Hubbard and Schwarz at Batchawana Bay, Ontario (north of Sault Sainte Marie) on August 15, probably in 1876 or 1877. The species was known only from the type until Dr. C. H. Lindroth and Dr. P. J. Darlington discovered in the C. H. Frost collection a male taken at light by Dr. A. E. Brower at Sinclair, in northernmost Maine, on July 30, probably in the 1950's. Br. A. Robert found another male at light in Mont Tremblant Park, On&, on July 1961. On July 28, 1963, two specimens were captured at light by Mr. and Mrs. R. T. Bell at Stowe, in northern Vermont. Finally Mr. J. Larson found one example on Simpson Island, in Great Slave Lake, N.W.T., Canada, on July 18, 1964; and found another example at light on July 28 at Lethbridge, Alberta, in 1965.
The rarity of P/at.ypatrabus indicates a special habitat. Dr. Dar- lington noted that, unlike species of allied genera, specimens of Platy- patrobus frequently bore mites and he suspected that these might offer a clue to the habitat of the beetle. Dr. E. Lindquist indentified the single mite carried by Mr. Larson's specimen as Protodinych~us sp. and pointed out that Protodinychus occurred commonly in beaver houses in Algonquin Provincial Park, Ontario (collector: Dr. M. Wood).
At Meach Lake, Quk., about 15 miles northwest of Ottawa, Ontario, the author discovered an abandoned beaver pond. The water level was very low and the beaver house was largely surrounded by very wet soil. On June 26, collecting very close to this house pro- duced one teneral specimen of Platypatrobus; 40 specimens, including several that were teneral, were found on July 6 and 10 more on July 10. None were found on August 6, when the soil was less wet;



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306 Psyche [December
and none were found on any date around a nearby beaver house in a drier situation. The beetles occurred beneath embedded logs and under loose bark of old stumps, sometimes several inches beneath the surface of the extremely wet soil which was exposed to the sun and which contained much organic matter and debris. Numerous scarce or local Carabidae that occur in the same general habitat are Elaphrus olivaceus LeConte, Bembidion versutum LeConte, and Agonum cincticolle (Say). We noted other beetles there that bore the mite Protodinychus: Leflinellus validus (Horn), Agonum melanarituin (Dejean), and Q'uedius sp. (those specimens were found around the beaver house only).
BELL, R. T. AND J. R. BELL
1964. Platypatrobus lacustris Darlington in Vermont. Proc. Ent. Soc. Wash. 66: 100.
DARLINGTON, P. J.
1938. The American Patrobini. Ent. Amer. 18: 135-183. LINDROTH, C. H.
1962. The Male of Platypatrobus lacustris Darlington. Psyche 69: 7-10.
ROBERT, A.
1963.
Une premiere station du Platypatrobus lacustris Darlington dans Ie Quebec. Ann. Soc. Ent. Quebec 8: 58-59.



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