OCR Text |
Show The general colour of the beetle is reddish ochreous, the prothorax is clothed with a fine golden pubescence ; the prominent black eyes, the somewhat flattened antennae, and long hind legs closely correspond with the same organs of the *S'alius; further, the elytra, though not shortened, are much reduced in width, rapidly narrowing from a breadth of 3'5 mm. at the base to 1 mm. at the apex, so that the clear golden wings are very imperfectly hidden and add not a little to the general wasp-like appearance. When seized, this beetle curved down its abdomen in the most characteristic wasp-like manner, and it was only with the greatest reluctance and most careful precautions that my Dyak collectors, to whom I pointed out the insect, captured it. As in the Obereas, no representatation has here been made in dorsal view of the wasp-waist of the model, and for the same reason, namely, that this is hidden, when the Salius settles, by its wings, and it is only at such periods of rest that the full effect of the deceptive resemblance can be appreciated; that part, however, of the first abdominal segment of the Notliopeus which is visible from the side and below is clothed with a golden-grey pubescence, which produces the same effect as in the Obereas. It is possible that this species of JVothopeus is itself distasteful like the mimicked genera Chloridolum and Leontium (see later), but I could distinguish no pungent odour like that emitted by those genera, and I am inclined to think that its mimetic resemblance is its sole defence. I have lately become acquainted with a mimetic species belonging to the subfamily Necydalinat (Plate XIX. fig. 12, 110. 16 in Table I.), described in Appendix II. as Psebena brevipennis, and I therefore add some details of its habits and of the mode in which the mimetic resemblance is attained. The species in question mimics with a remarkable degree of accuracy one of the common red-and-black Braconidse : these Hymenoptera, as already shown, serve as models to a considerable number of species of Oberea, but in none of these latter is a Hymenopterous appearance so admirably borne as in this, a member of a subfamily for the most part characterized by a reduction of the elytra. The head and prothorax are of an Indian red, the wings are purplish-black, the two anterior pairs of legs are testaceous, the long slender posterior pair black with the bases of the femora white; the body is so slender that the necessity of producing a wasp-waisted effect by means of lateral white patches, as in some of the above-noted Obereas, can be dispensed with. Most of the life of this beetle, as in all Longicorns with reduced elytra, is spent on the wing, when it is simply indistinguishable from its model; when it comes to rest the resemblance is still remarkably exact, and its quick restless movements and habit of flickering the antennae in all directions are very Bracon-like. No specimen at all resembling this remarkable species has hitherto existed in the British Museum. Of the Necydalin-ce, one species Epania singaporensis (Plate P r o c . Z o o e . S o c .- 1902, V o l . II. No. X V I. 16 1 9 0 2 . ] SPIDERS FROM BORNEO AND SINGAPORE. 241 |