Zoraptera
Winged or apterous insects with 9-segmented moniliform antennae. Y-shaped ecdysial cleavage line present. Normal maxillae, 3-segmented labial palps. Wings, when present, capable of being sized by means of basal fractures; venation specialized by reduction
- PDF / 522,251 Bytes
- 3 Pages / 439.37 x 666.142 pts Page_size
- 79 Downloads / 126 Views
ZORAPTERA Winged or apterous insects with 9-segmented moniliform antennae. Y-shaped ecdysial cleavage line present. Normal maxillae, ]-segmented labial palps. Wings, when present, capable of being shed by means of basal fractures; venation specialized by reduction. Pro thorax well developed. Tarsi 2-segmented. Cerci very short, 1-segmented. Ovipositor absent; male genitalia specialized, sometimes asymmetrical. Metamorphosis slight. The first Zoraptera were described by Silvestri in 1913, among insects obtained from W. Africa, Ceylon and Java. Weidner (1969, 1970) recognizes 22 species from all zoogeographical regions except the Palaearctic. The known species belong to the genus Zorotypus which constitutes the family Zorotypidae; they are minute insects, less than 3 mm long, and the alate forms have a wing-expanse of about 7 mm. They occur under bark, in decaying wood, humus, etc., and are sometimes found near the galleries of termites. Though the alate forms of some species have not yet been described, two distinct types can be recognized in most species of the Zoraptera. The commoner form is apterous, only slightly pigmented and without compound eyes or ocelli while the rarer alates are darker, with eyes and ocelli and differ in details of thoracic structure (Delamare-Deboutteville, 1948a). The causes of this dimorphism are not known, but it is not a castedifference since each form is made up of sexually functional males and females. The mouthparts of the Zoraptera are of a generalized type (Fig. 303). The mandibles are more or less quadrangular and adapted for mastication; the maxillae do not call for special mention and their palps are s-segmented; the labium is characterized by the completely divided prementum, and 3segmented palps. The wings are capable of being shed as in termites, but the fractures are not very definitely located though they are situated near the bases of the veins. The wing-stumps persist in dealated individuals as in termites. The venation (Fig. 302) is greatly specialized by reduction and according to Crampton (1922) it approaches that of some Psocoptera, probably through convergent evolution. The abdomen is u-segmented and genitalia are wanting in the female; in the male, genitalia are present but their homologies are not known (Snodgrass, 1937). There are ten pairs of spiracles, two being thoracic and the remainder abdominal in position. The O. W. Richards et al., Imms’ General Textbook of Entomology © O. W. Richards and R. G. Davies 1977
644
GENERAL TEXTBOOK OF ENTOMOLOGY
FIG. 301
Zorotypus guineensis, Africa After Silvestri, Boll. Lab. Zoo/. Portici, 1913.
internal structure has been only partially investigated (Silvestri, 1913; Gurney, 1938). The digestive system is characterized by the large crop which extends backwards to about the 5th abdominal segment; the mid gut is an ovoid, obliquely disposed sac, and the hind intestine is convoluted. There are six Malpighian tubules and six rectal papillae. The nervous system is highly specialized, there being three thoracic and only tw
