| OCR Text |
Show 1893.] ME. E. E. AUSTEN ON NEW DIPTEEOUS INSECTS. 135 apical fourth of the first joint of the posterior tarsi is yellowish white like the remaining joints of this pair of tarsi. BACCHA, F. The genus Baccha seems to m e at present to include at least three distinct groups of species. Of Group I. the European B. elongata, F., may be taken as a type ; the members of this group, which are found in both the Old and N e w Worlds, are species with pedunculate abdomens, more or less dark in colour, usually varied with yellow markings, and hyaline or infuscated wings : the alulae may or may not be rudimentary. Group II. is composed exclusively of Neotropical forms, in which the abdomen is of a more or less ferruginous or ochraceous colour, marked with a series of continuous longitudinal stripes of a lighter tint, spatulate posteriorly and more or less contracted at the base; the dorsum of the thorax is usually covered with ochraceous pollen, and marked with stripes; the front bears a pronounced antenniferous projection, marked with a round black dot; the wings generally have an ochraceous infuscation, and the alulae are of the full size: of this group B. livida, Schin., may be taken as typical; B. conjuncta, Wied., is an aberrant form. Group III. at present also consists entirely of Neotropical species, the characteristics of which are a broad, flat abdomen, which is not contracted basally, but expands regularly to the end of the fourth segment, and is of a more or less ferruginous or yellowish colour, which is divided up by brown bands, & c , into broad and generally notched markings ; infuscated wings, with the third longitudinal vein straight, or somewhat concave posteriorly, and rudimentary alulae ; there is also a small antenniferous process, marked with a round black dot: the shape and colour of the abdomen are thus the most striking features of this group, of which the species described below as Baccha crocaia may be taken as a type. The only previously described species which I can assign to this group is B. luctuosa, Bigot (Ann. Soc. Ent. Fr. 1883, p. 334), from Mexico. Of the species here described, all those from the Oriental and Australian B,egions, as well as B. signifera, levissima, incompta, and pumila, from Brazil, and B. sagittifera, from Jamaica, belong to Group I. B. amphithoe, Wlk., from the Oriental Region, and B. bigoti (nom. nov.), from Brazil, also belong here. Of Group II. the only species here described is B. silacea, from Brazil. Specimens of several other species, which are doubtless new and certainly belong to this group, are in the Collection, but are not in a sufficiently good condition to describe. To Group III. belong B. cultrata, flavens, gilva, crocata, and crocea. B. fervida also belongs here, but has full-sized alulae. I think there is no doubt that the genus Baccha as it now exists ought to be split up; and, while I do not venture to undertake the task myself at present, I have endeavoured to indicate a way in which perhaps it might be done. It seems inconsistent to place |
