• M H S Yacoob

      Articles written in Proceedings – Animal Sciences

    • Biosystematics of Tingidae on the basis of the biology and micromorphology of their eggs

      David Livingstone M H S Yacoob

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      The biology and micromorphology of the eggs of 40 species belonging to 26 genera and two subfamilies of Tingidae from southern India have been studied and considered for an assessment of their biosystematics. The oviposition strategy is intimately correlated with the selection of oviposition site on the host plant, determined by the shape and size of the egg and accomplished by appropriately developed ovipositing mechanism involving the structural features of the first gonapophyses. The oviposition pattern is accordingly classified and the eggs are classified on the basis of the nature of development of the chorionic collar cum opercular apparatus. Characterization of the eggs and assessment of their systematic importance have been linked with the origin and evolution of adaptive radiation of oviposition strategies of their egg parasitoids as well. Production of season oriented dimorphic eggs is common among species that oviposit their long operculate eggs vertically in clusters, either into stems or rachis or pistil. Lamina ovipositors preferentially oviposit into the mesophyll horizontally, without cluster formation, on the undersurface of the leaves and the significant reduction in the number of aeropyles of such oval, short operculate eggs could be correlated with the abundance of oxygen supply of the ambient air. More elongate, long operculate eggs in Tingidae, characterized by their multiplicity of aeropyles and vertical oviposition in clusters into stems, rachis and pistil, signify primitiveness, as observed in Cantacaderinae and some large sized Tinginae. Micropyles are absent in tingid eggs, as fertilization occurs before chorion formation and a true spermatheca is wanting.

    • Female accessory glands and sperm reception in Tingidae (Heteroptera)

      David Livingstone M H S Yacoob

      More Details Abstract Fulltext PDF

      Studies on the anatomy of the female internal organs of reproduction and the intromittent organs of 34 species of Tingidae confirm the absence of spermathecae. The accessory glands are vesicular and primitively unpaired. There is no vermiform gland and the term pseudosperrnatheca, introduced by Carayon in heteropteran literature, is a misnomer. The lateral oviduct and all the 7 pedicels of each ovary develop a permanent swelling in the middle that receive the spermatozoa, syringed into them through the minute pores of the armature of ejaculatory pouches of the endotheca, when it is lodged inside the bursa during copulation. The ejaculatory pouch and the bursa are so designed and adjusted for the purpose of sperm transmission. In a few species of Tingidae a median diverticulum that arises from the endotheca plugs the unpaired vesicular accessory gland, preventing wrongful lodging of the ejaculatory pouch and such a mechanism, not known so far, has been described as a unique feature. A scheme to trace the evolution of accessory gland, from a median unpaired contacaderine condition, to a paired independent gland, having its opening either in front or behind the lateral oviduct, has been detailed.

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