On Two New Species ofPolyplax(Anoplura) from Egypt
Authors: Cummings Bruce F. 
Published: August 2010

An examination of the immature forms in these three species ofPolyplaxreveals that the metamorphosis in all three consists probably of at least three distinct stages, although there may be more than two moults. The differences between Stages II. and III. are slight. In the first stage the louse is very soft and delicate for the most part, although even thus early the mouth‐parts, thorax, and legs are well chitinised. On the abdomen segmentation is absent except at the end, and sclerites are absent in all three stages, although inP. oxyrrhynchusandP. spinulosaminute pleurites appear in Stage II., and in Stage III. ofP. brachyrrhynchusalso there are present weak pleurites of indefinite outline. The spiracles are large. In the last stage the head and thorax closely resemble the adult.

In all three stages the chætotaxy of the head and thorax is almost identical with that of the imago.

The abdominal chætotaxy and the abdomen itself, however, undergo a very considerable metamorphosis at the last ecdysis into the imago.

The metamorphosis of all three shows that there is a tendency for the hairs to develop from behind forwards, inasmuch as the terminal pleuræ develop hairs while the rest are still bare, and inP. oxyrrhynchusandP. spinulosathe sterna are at first also bare except in the last segment.

Two hairs on each tergum and sternum is invariably the number if hairs are present at all.

Some of these early stages may represent stages in the phylogeny of the group, and in this connection it is suggestive to recall that the Anopluran genusLinognathusis characterized by the large size of its spiracles and the absence of abdominal plates, just asPolyplaxis characterized by the small size of the spiracles and the presence of the plates, so that in future it may be convenient to speak of the larva ofPolyplaxas the “Linognathus larva.”

The larva ofP. brachyrrhynchusdescribed above recalls in particular such species asLinognathus brevicepsPiaget,L. gazellaMjöberg,L. limnotragiCummings,L. africanusKell. & P., andL. caviœ‐capensis(Pallas), in which there is on each pleura of the 3rd abdominal segment an elongate bristle and on the pleuræ of the 7th and 8th two long bristles.

The chætotaxy ofL. caviœ‐capensis(see figs. 2 & 3, Bulletin of Entomological Research, iv. May 1913, pp. 38 & 39) bears a close resemblance to that of thePolyplaxlarvæ. Some later work further reveals the fact that a somewhat similar plan of abdominal chætotaxy exists also in the larvæ of at least two species ofLinognathusin which the imaginal chætotaxy is more complex. This general plan of chætotaxy, therefore, is perhaps a primitive one in the Anoplura, andLinognathusis perhaps a more primitive genus thanPolyplax, and perhaps the most primitive of all the Anopluran genera, an hypothesis which, however, cannot be supported by reference to the systematic position of the host‐species,Linognathusoccurring withHœmatopinuson Ungulates such as the Antelope,CapraandOvis, and also on the Dog.

It would be interesting to know whether Linognathoid types of a, more primitive character than any Anoplura hitherto known remain to be discovered on the primitive Insectivora and other ancient mammalian groups. Hitherto, Anoplura have not been found on Monotremes and Marsupials. It should be remembered thatL. caviœ‐capensisis a parasite of the Cape Hyrax—a member of a very isolated group.