Functional morphology of spicules and the role of the male gonoduct secretions in the diplogastrid nematode, Diplogasteriana schneideri

The mating behaviour of the diplogastrid nematodeDiplogasteriana schneideri is described with respect to functional morphology of spicules and male gonoduct secretions. Four phases of mating are differentiated: phase I, the male seeks, with its bursa, for the female vulva; phase II, the interval between attachment to the female using a sticky secretion (which is expelled from the male cloaca) and insertion of spicules; phase III, the interval between insertion and withdrawal of spicules; and phase IV (postcopula), the interval between withdrawal of the spicules and detachment from the female. The spicules in D. schneideri function as an attachment dowel, keeping the male joined to the female even through periods of rapid movement. The reproductive strategy of D. schneideri males is to produce a few highly competitive giant spermatozoa that are transferred to the female. The results are discussed with respect to an alternate reproductive strategy associated with transfer of a high number of less competitive smaller spermatozoa. The possibility that the function of male gonoduct secretions in D. schneideri may represent a condition plesiomorphic for nematodes is discussed.Se describe el comportamiento de apareamiento del nematodo diplogástridoDiplogasteriana schneideri en relación con la morfología de las espículas y de las secreciones del gonoducto del macho. Se distinguen cuatro fases en el apareamiento: fase I, el macho busca con su bursa la vulva de la hembra; fase II, el intervalo entre la unión a la hembra mediante una secreción pegajosa (que es expulsada desde la cloaca del macho) y la inserción de las espículas; fase III, el periodo entre la inserción y la retirada de las espículas; y fase IV (postcópula), el intervalo entre la retirada de las espículas y la separación del macho. Las espículas en D. schneideri funcionan a modo de clavija de enganche, manteniendo la unión de macho y hembra incluso en periodos de movimiento rápido. La estrategia reproductora de los machos de D. schneideri consiste en producir unos pocos espermatozoides gigantes y altamente competitivos que se transfieren a la hembra. Estos resultados se discuten en relación con estrategias reproductoras alternativas como la transferencia de una gran número de espermatozoides más pequeños pero menos competititvos. Se discute también la posibilidad de que la función de las secreciones del gonoducto masculino in D. schneideri represente una condición plesiomórfica para nematodos

Revision and phylogeny of Myolaimus Cobb, 1920 (Secernentea, Nematoda) with the description of four new species

The four new speciesMyolaimus cotopaxus sp. n., M. hermaphroditus sp. n., M. hortulanus sp. n., M. xylophilus sp. n. and an unnamed fifth one are described from different habitats. Cross-breeding experiments for three very similar species revealed that they are distinct. The stemspecies pattern both of the Myolaimidae and of Myolaimus is reconstructed. This pattern allows for critical comments on and reinterpretations of descriptions of the nine Myolaimus species known from the literature. In the descriptions, only those characters are mentioned that are divergent from the stemspecies pattern of Myolaimus. A pictorial identification key is presented for all 14 species. One species is hermaphroditic, one other is phoretic. Spermatozoa are significantly smaller in the hermaphrodite as compared with in males of the gonochoristic species. Different molecular analyses do not propose a coherent taxonomical position of Myolaimus within the Secernentea. Morphological arguments are presented to show that Myolaimus and Deleyia are sistergroups; and both are placed in Myolaimidae, a taxon grouped within Secernentea as incertae sedis

Teratodiplogaster fignewmani gen. nov., sp nov (Nematoda: Diplogastridae) from the Syconia of Ficus racemosa in Australia

During the course of a survey of fig-associated nematodes in eastern Australia, we discovered an unusual diplogastrid nematode that we describe herein as Teratodiplogaster fignewmani gen. nov., sp. nov. This nematode was isolated as adults and juveniles from the syconia of Ficus racemosa in Queensland and Western Australia. It is presumed to be associated with the agaonid fig wasp, Ceratosolen fusciceps, for dispersion to new phase-B sycones. Teratodiplogaster fignewmani gen. nov., sp. nov. was inferred to be the sister taxon to the genus Parasitodiplogaster based upon molecular phylogeny using nearly full-length sequences of the SSU and D2/D3 LSU ribosomal RNA genes. It is sufficiently distinct in morphology (with many autapomorphies) to justify a new monotypic genus with the hypothesis that further species of Teratodiplogaster gen. nov. will be discovered when sycones from other Ficus from tropical Australasia and possibly Africa are sampled.Natsumi Kanzaki, Robin M. Giblin-Davis, Kerrie Davies, Weimin Ye, Barbara J. Center and W. Kelley Thoma