Zum Feinbau des Komplexauges von Stylops spec. (Insecta,Strepsiptera)

Zusammenfassung Unter den Cornealinsen des Komplexauges von Stylops befindet sich ein Kristallkegel vom pseudoconen Typ, der von zahlreichen Pigmentzellen umhüllt wird. An seinem proximalen Ende liegen 6 meist pigmentfreie Zellen (Sempersche Zellen).Das Ommatidium besteht aus etwa 60 Retinulazellen. Ihre distal kranzartig miteinander verbundenen Mikrovillisäume bilden ein einziges offenes Rhabdom, das extrazelluläres (?) granuläres Material und die Basis der Semperschen Zellen umgibt. Stellenweise wird das Rhabdom samt granulärem Material von homogen erscheinenden distalen Ausläufern einzelner Retinulazellen überlagert. Proximad zerfällt das Rhabdom zunehmend in kleinere Rhabdomteile. Im zentralen Teil des Ommatidiums liegen 1–2 auffallend große Retinulazellen, die meist weniger elektronendicht erscheinen und kleinere Pigmentgrana haben.Die einzelnen Ommatidien werden von ungemein zahlreichen, sehr pigmentarmen Stützzellen umhüllt. Diese werden — wie die basalen Teile der Retinulazellen — teilweise durch Gliazellfortsätze isoliert.Bei Stylops, einem Vertreter der Strepsipteren, handelt es sich nicht um ocelläre Komplexaugen (Strohm, 1910), auch nicht um eucone Ommatidien (Kinzelbach, 1967), sondern um Ommatidien vom pseudoconen Typ. Zumindest der Bau des Rhabdoms ähnelt dem des Larvenauges (Stemma), dessen rezeptorischer Teil entgegen den Annahmen früherer Autoren in der Imago nicht reduziert wird.

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On the fine structure of the compound eye of Stylops spec. (Insecta, Strepsiptera)

Summary In the compound eye of Stylops a crystalline cone of the pseudocone type is found beneath the corneal lens. It is enveloped by several pigment cells. At the proximal part of the cone there are 6 cells (Semper cells) mostly pigment-free.The ommatidium consists of approximately 60 retinula cells. Their rhabdomeres distally rim-like connected to another form a single open rhabdom which encircles extracellular granular material as well as the bases of the Semper cells. Here and there the rhabdom plus granular material is overlain with distal protrusions of single retinula cells which appear to be homogeneous. Towards the proximal part the rhabdom increasingly divides up into smaller rhabdomal segments. One or two conspicuous large retinula cells were found in the central part of the ommatidium, appearing to be less electron-dense and containing pigment granules of a smaller size. Each ommatidium is surrounded by numerous cells (Stützzellen) lacking in pigment. These cells are partially insulated from another—as well as the basal parts of retinula cells—by protrusions of glia cells.Our investigations show that the eyes of Stylops (as a representative of Strepsiptera) are not of the ocellar complex eye type. At least the structure of the rhabdom resembles to that of the larval eye (stemma), the receptor part of which is not reduced in the imago.

Herrn Prof. Dr. Helmcke danke ich für die freundliche Unterstützung am Raster-Elektronenmikroskop.     

A case of mistaken identification of an amber fossil male strepsipteran (Insecta: Strepsiptera)

A well-preserved specimen of amber Strepsiptera was erroneously described as Stylops neotropicallis Kogan and Poinar, 2010. The taxonomic position of the species was based on a count of six antennomeres (typical of the Stylopidae); however, further observations showed that there are actually seven antennomeres, which places the fossil in the family Myrmecolacidae, and it is herein redescribed in the genus Palaeomyrmecolax Kulicka, 2001. Furthermore, nuclear magnetic resonance spectroscopy analysis of a sample of the amber piece containing the fossil revealed that it was Baltic rather than Dominican amber as originally thought. The fossil was compared with another specimen from Baltic amber in the Poinar collection, which shows close affinity to Palaeomyrmecolax succineus Kulicka, 2001, the type species of the genus. Palaeomyrmecolax neotropicallis (n.comb.) differs from that specimen and seems to differ also from the other four species in the genus Palaeomyrmecolax.