The European Subgenus Actedium (Bembidion) in North America.
Psyche 33(2):32-35, 1926.
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32 Psyche [April
THE EUROPEAN SUBGENUS ACTEDIUM (BEMBIDION) IN NORTH AMERICA.1
In a box of Albertan Bembidion recently received for deter- mination from Mr. F. S. Carr, the writer found two specimens of an apparently undescribed species belonging to the subgenus Actedium Mots., a group not heretofore recorded from this con- tinent. Actedium, which was erected" in 1864 (8) for two Euro- pean species, was defined as follows: elytra subquadrate (presque carre); the striae distinctly punctured, effaced toward the apex, not deeply impressed, the 7th visible, the third with two small foveae; head and thorax punctate, the latter cordate with the basal impressions feeble. It may be added that the eyes are prominent, the humeri indistinctly angulate, the 8th stria close to the margin, and the mentum tooth entire and triangular. The two original species of the subgenus, together with a third described from Europe in 1870 (6) and the one described below, form a homogeneous group, the habitus being like that of a very stout Lachnophorus.
In comparing Actedium to our other groups of Bembidion, it seems best to mention the closely related European subgenus Princidium Mots. This was described in the same paper as Ac- tedium, and was separated from it chiefly by having the form narrower and the elytral striae entire. The two sabgenera to- gether are equivalent to the third group of Jacquelin-Duval's monograph, "De Bembidiis Europssis" (7). It may be noted at this point that the several American species included in Princiclium by Motschulsky, notably those now listed as dilatatum Lec., honestum Say, and concolor Kby., have all been referred to Peryphus Steph. by Casey (1). Of the two European species placed in Princidium, only one, punctula- turn Drap., can be retained. The other, rujicolle Gyll., has a very different habitus and has the elytral fovess on the third interval. Since no genotype has been assigned for Princidium thus far, 'Contribution from the Entomological Laboratory of the Bussey Institu- tion, Harvard University, No. 262.
Pncht 33:32-15 (1926). hup flpsycht rntclub org/13/33-012 html
19261 European Subgenus Actedium in North America 33 the writer here designates Bembidion punctulatum Drap. as the genotype of that subgenus.
It may also be noted that the species of Jacquelin-Duval's groups four and five, which were associated with group three in his monograph because of the punctuation of the head, all have the elytral fovese on the third interval, a character noted but not much valued by that author. Since the form described in this paper combines the habitus of Actedium with an elytral striation nearly as complete as in Princidium, the two subgenera may have to be united under the latter name, which has priority by a page.
The species of Actedium, and that of Princidium as restricted above, differ from all hitherto described American species of Bembidion by having the depressions in the posterior angles of the prothorax entirely obsolete, and by having distinct non- setigerous punctures on the head and the sides of the pronoturn. A partial exception is found in B. scopulinum Kby., in which there is a tendency toward rugosity on the floor of the frontal sulci, and of which a considerable percentage of specimens have a few scattered punctures on the front. In B. lcevigatum Say there are a few irregular frontal punctures, but these are setigero& and are not comparable. Several species of the ustulatum group have the base of the thorax, and more rarely an area near the apex, rugose; and this, too, is best developed in scopulinum. The sides of the thorax, however, are quite impunctate even in this species. Except for its subdilated hind body and the unique charac- ters noted above, Actedium is inseparable from Peryphus as the latter is employed by Casey (1); and it seems most closely re- lated to that part of Peryphus containing the more convex species of Hayward's (4) ustulatum group. Princidium, which combines the habitus of a convex Peryphus with the technical characters of Actedium, brings those two subgenera even closer together. The gap remaining, however, seems too great, par- ticularly as regards the structure of the posterior angles of the prothorax, to allow Actedium and Peryphus to be united at present. The two subgenera should, of course, be associated on our lists.
Before proceeding to the description, the writer must ac-
34 Psyche [April
knowledge his indebtedness to the authorities of the Museum of Comparative Zoology at Cambridge for the opportunity of examining specinlens of all the European species mentioned in t,his paper, and of referring to the invaluable collections of Leconte and Hayward.
The following species, as already indicated, seems completely congeneric with the European Bembidion (Actediumj kusteri Schaum and B. (Act.) pallidipenne Illig. Bembidion (Actedium) lachnophoroides n. sp. Convex, posterior parts robust; head and thorax viridiaeneus; elytra I
smoky-yellow, with apex and a slightly post-median transverse fascia blackish, the latter slanting slightly forward from the suture. Head as wide as thorax at widest part, strongly alutaceous, rather sparsely punctured with very dis- tinct punctures; frontal striae broad, shallow, and parallel, the floor longi- tudinally rugose; antennae stout, piceus with the basal joint paler, interme- diate joints about twice as long as wide. Prothorax scarcely wider than an elytron, about one eighth wider than long, subcordate, narrower at base than apex, strongly alutaceous; median line well impressed, transverse impressions indistinct; disk impunctate at middle, slightly wrinkled transversely; sides with sparse, large punctures; base and apex strongly and longitudinally rugose; lateral margins narrow; hind angles not striate, slightly obtuse but not rounded, not prominent; basal impressions entirely obsolete except for the slightly broadened margin where the tactile seta arises. Elytra, alutaceous, together one half longer than wide, sides straight and subparallel in median third; humeri not prominent: striae moderately impressed, modertely punc- tured on basal two thirds; first, second, and seventh distinct at apex, others slightly abbreviated; seventh slightly less impressed on diqk than sixth; third with two moderate foveae. Head and thorax piceous or reddish beneath; abdomen entirely flavo-testaceous; Legs entirely pale. Length (8 9 ) 4.25 mm. Width (8 9 ) 1.8-1.9 mm.
This species is most closely related to B. kusteri Schaum of Europe, but is distinct by the more complete elytral striation, the dark antennae, the posterior rather than anterior elytral markings, and the pale abdomen.
The last character, however,
may be due to the immaturity of the types. Both the cf holytope and 9 allotype were collected by Mr. F. S. Carr at Medicine Hat, Alberta, Sept. 8, 1923. By arran-
gement with Mr. Carr the holotype will be deposited in the Canadian National Museum; the allotype is in my own col- lection.
The occurence of European groups, or even species, in North America is a common phenomenon of which Actedium is only an additional example (2, 3). The subgenus should be looked for
19261 European Subgenus Actedium in North America 35 in the gulf of St. Lawrence region and in Alaska, though it had not been recorded from Siberia up to 1896 (5). The following papers have been referred to, by number, in the proceding pages:
Casey, T. L.-Bembidiinse; Memoirs on Coleoptera, VIII, Lancaster, 1918, p. 46-85, for Peryphus. Champion, G. C.-List of Coleoptera common to Britain and North America; Ent. Month. Mag., ser. 2, VI, 1895, p. 150-155.
Hamilton, ~ohn-catalogue of Coleoptera common to North America and northern Europe and Asia; Trans. American Ent. Soc., XXI, 1894, p. 345-416. Hayward, Roland-On the species of Bembidion of America north of Mexico; Trans. American Ent. Soc. XXIV, 1897, p. 32-143.
Heyden, Lucus von - Catalog der Coleopteren von Siberien; Deutche Ent. Zeits. (special no.), 1881 ; N1achtrag I, 1893; Nachtrag 11, 1896.
Heyden, Lucus von-Reise nach Spanien; Berlin, 1870, p. 63.
Jacquelin-Duval . Camille-De Bembidiis Europseis; Ann. soc. ent. France, s6r. 2, IX, 1851, p. 441-576; 1852, p. 101-236.
Motschulsky, T. Victor von-Enumeration des nouvelles esphes, IV; Bull. Moscou XXXVII, 3, 1864, p. 181 (Princidiwn) ; p. 182 (Actedium) .
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