OCR Text |
Show 1885.] COLEOPTERA FROM JAPAN. 193 I can only compare this species with D. sulcicollis, from North America, to which it is certainly closely allied. The thorax is, however, much more narrowed behind than in that species and the anterior callosities are much more developed; another difference is to be found in the more elongate joints of the antennae and their comparative different length. D. discolor, Hoppe, may be at once distinguished from the present insect by the more opaque and con-fluently punctured thorax; the latter in D. constricticollis having a highly polished appearance. DONACIA SERICEA, L., var. SIBIRICA? Solsky. The dozen specimens obtained at Nikko show scarcely any difference from our European form ; but may very well be referred to Solsky's variety according to the description given by this author. In colour the specimens vary from reddish cupreous to green or aeneous like the European D. sericea. Structural differences I can see none. DONACIA SIMPLEX, Fab. Of this species Mr. Lewis obtained nine specimens at a pond at Hakodate. They also, like the preceding species, do not differ from the European form in any way whatever, and vary in size like it ; D. simplex has also been recorded from Siberia. Genus SYNETA, Eschsch. S Y N E T A ADAMSI, Baly. Of this species, of which I have the type for comparison, several specimens were obtained by Mr. Lewis which agree very nearly with the latter; but a number of others, partly from the same locality, seem at first sight certainly to represent a different species; and I have hesitated long before I came to a conclusive opinion in regard to their specific value. The very many intermediate forms, however, of which scarcely two are of the same size, sculpturing, and colour, which are before me, prove the insect to be an extremely variable one. On the same principle I am very much inclined to believe that those species described by LeConte from America, established principally on colour and more or less distinctly visible elytral costae, may eventually prove to belong to one species only. At all events, the specimens collected by Mr. Lewis defy a satisfactory separation : in some the thorax is much more elongate than is the case in S. adamsi, but intermediate stages are not wanting; in others two very distinct costae are visible, these dwindling away again to the form with one distinct lateral costa only, as described by Baly. The thorax in all of them is like that of the type, angulateat the middle, the angle itself generally 3-dentate, in some specimens the intermediate tooth being only distinct, the others obsolete. The following are the varieties with their localities :- Var. a. Head and thorax as well as the terminal joints of the antennae fuscous or black; elytra with a sutural and lateral broad longitudinal fuscous band. (Niohozan, Kiga, on birch.) PROC. ZOOL. Soc-1885, No. XIII. 13 |