Demodex neomydis sp. n. from the Mediterranean water shrew, Neomys anomalus, is described as a new species in all developmental stages. This demodecid is classified as a member of the genus Demodex Owen, 1843, but shows several morphological characters described in Soricidex dimorphus Bukva, 1982 and which are absent or very infrequent in other known Demodex species, viz., in the adult stage, a pair of shelf-like lamellae on the dorsum of the podosoma, dorso-lateral extension of the podosoma over the basal part of the gnathosoma, multiple opisthosomal organ in the male, and podosomal position of the vulva in the female. Immature stages of D. neomydis have unusual inflated idiosoma and dorsad deflected gnathosoma. All developmental stages of D. neomydis were found in the lumen of the hair follicles on the host’s muzzle, causing no gross pathological response. On histological level, the main pathological change was distension of infested hair follicles by accumulations of up to a dozen mites, which appear to feed on the epithelial cells of the hair follicle walls.
Morphology of adult parasitic hermaphrodites, free-living males and females, rhabditoid and infective larvae of Rhabdias agkistrodonis Sharpilo, 1976 is described. Adult parasites of the species differ from corresponding stage of other Rhabdias species from snakes in the presence of short cuticular needle on the tip of the tail. Free-living generation stages of R. agkistrodonis have typical rhabditoid morphology. Homogonic infective larvae differ from heterogonic ones in the shape of stoma and oesophagus. Three new hosts: Halys viper (Agkistrodon halys) (Pallas) from Altaiskii Krai (Russia), Okinawa habu (Trimeresurus flavoviridis) (Ilallowell)' and T, elegans (Gray) from Okinawa Island (Japan) are added to the host range of R. agkistrodonis known previously exclusively from short-tailed viper (Agkistrodon blomhoffi) from the Russian Far East.
For a nontrivial connected graph G, let c : V (G) → N be a vertex coloring of G where adjacent vertices may be colored the same. For a vertex v ∈ V (G), the neighborhood color set NC(v) is the set of colors of the neighbors of v. The coloring c is called a set coloring if NC(u) 6= NC(v) for every pair u, v of adjacent vertices of G. The minimum number of colors required of such a coloring is called the set chromatic number χs(G). We show that the decision variant of determining χs(G) is NP-complete in the general case, and show that χs(G) can be efficiently calculated when G is a threshold graph. We study the difference χ(G) − χs(G), presenting new bounds that are sharp for all graphs G satisfying χ(G) = ω(G). We finally present results of the Nordhaus-Gaddum type, giving sharp bounds on the sum and product of χs(G) and χs(G).
The ultrastructure of three types of unicellular scolex gland cells in adult cestode Bothriocephalus claviceps (Goeze, 1782) is described. The first type - apocrine gland cells transport their secretion (small rounded electron dense granules) via thin ducts into the tegument where it accumulates as projections on the body surface. The second type - eccrine gland cells press out their secretion (large oval electron dense granules) through ducts which open to the exterior surface of the tegument. The third type - microapocrine gland cells transport their secretion (large rounded electron dense granules) through thin cytoplasmic processes into the distal cytoplasm of the tegument. The secretory discharge occurs by means of évaginations of the outer tegumental plasmalemma and their subsequent detachment. The possible functions of the scolex gland cells are discussed.