RESUMO
The sperm ultrastructure of a few representative species of Tenebrionoidea was studied. Two species belong to the Mordellidae (Mordellistena brevicauda and Hoshihananomia sp.), one species to Oedemeridae (Oedemera nobilis), and one species to Tenebrionidae (Accanthopus velikensis). It is confirmed that Mordellidae are characterized by the lowest number of spermatozoa per cyst (up to 64), a number shared with Ripiphoridae. In contrast, in the two other families, up to 512 spermatozoa per cyst are observed, the same number present, for example, in Tenebrionidae. Also, as in the other more derived families of tenebrionoids studied so far, during spermatogenesis in O. nobilis and A. velikensis, sperm nuclei are regularly distributed in two sets at opposite poles of the cysts. On the contrary, the Mordellidae species do not exhibit this peculiar process. However, during spermiogenesis, the bundles of sperm bend to form a loop in their median region, quite evident in the Hoshihananomia sp., characterized by long sperm. This process, which also occurs in Ripiphoridae, probably enables individuals to produce long sperm without an increase in testicular volume. The sperm looping could be a consequence of the asynchronous growth between cyst size and sperm length. The sperm ultrastructure of the Mordellidae species reveals that they can be differentiated from other Tenebrionoidea based on the shape and size of some sperm components, such as the accessory bodies and the mitochondrial derivatives. They also show an uncommon stiff and immotile posterior flagellar region provided with only accessory tubules. These results contribute to a better knowledge of the phylogenetic relationship of the basal families of the large group of Tenebrionoidea.
RESUMO
The male and female reproductive apparatus of Zorotypus magnicaudelli (Malaysia), Zorotypus huxleyi (Ecuador) and Zorotypus weidneri (Brazil) were examined and documented in detail. The genital apparatus and sperm of the three species show only minor differences. The testes are larger in Z. magnicaudelli. Z. huxleyi lacks the helical appendage in the accessory glands. A long cuticular flagellum is present in Z. magnicaudelli and in the previously studied Zorotypus caudelli like in several other species, whereas it is absent in Z. weidneri, Z. huxleyi, Zorotypus hubbardi, Zorotypus impolitus and Zorotypus guineensis. Characteristic features of the very similar sperm are the presence of: a) two dense arches above the axoneme; b) a 9 + 9+2 axoneme with detached subtubules A and B of doublets 1 and 6; c) the axonemal end degenerating with enlarging accessory tubules; d) accessory tubules with 17 protofilaments; e) three accessory bodies beneath the axoneme; and f) two mitochondrial derivatives of equal shape. The first characteristic (a) is unknown outside of Zoraptera and possibly autapomorphic. The sperm structure differs distinctly in Z. impolitus and Z. hubbardi, which produce giant sperm and possess a huge spermatheca. The presence of the same sperm type in species either provided with a sclerotized coiled flagellum in males or lacking this structure indicates that a different organization of the genital apparatus does not necessarily affect the sperm structure. The flagellum and its pouch has probably evolved within Zoraptera, but it cannot be excluded that it is a groundplan feature and was reduced several times. The fossil evidence and our findings suggest that distinct modifications in the genital apparatus occurred before the fragmentation of the Gondwanan landmass in the middle Cretaceous.
Assuntos
Evolução Biológica , Insetos/anatomia & histologia , África , Animais , Feminino , Genitália Feminina/anatomia & histologia , Genitália Feminina/citologia , Genitália Masculina/anatomia & histologia , Genitália Masculina/citologia , Insetos/citologia , Insetos/ultraestrutura , Malásia , Masculino , América do Sul , Especificidade da Espécie , Espermatozoides/ultraestruturaRESUMO
In the seminal vesicle of the 'symphyta'Arge pagana the spermatozoa are stored in motile spermatodesm bundles, maintained by an anterior cap of extracellular material. This cap consists of a denser cortex and of an internal matrix, where part of the sperm heads are embedded. The number of spermatozoa per bundle is variable. The spermatozoa are short, only 30microm long, with a head region of about 23microm, and a very short flagellum of about 7microm. The head includes the acrosome, with a perforatorium, and the nucleus. The flagellum consists of an axoneme, with a 9+9+2 microtubule pattern, a centriolar adjunct, two mitochondrial derivatives and two accessory bodies. The mitochondrial derivatives are very slender and of different lengths. The longer begins at the base of the nucleus, while the shorter one starts just below the base of the centriolar adjunct. This latter is asymmetric and appears at the nuclear base, extending parallel to the axoneme up to the anterior end of the smaller mitochondrial derivative. The short spermatodesmata and the small mitochondrial derivatives characterize the A. pagana sperm. In addition, the centriolar adjunct asymmetry and the occurrence of spermatodesm bundles might be considered plesiomorphic states present in the basal Tenthredinoidea.