Eidonomie und Gespinstbau der Juvenilstadien von Leptomorphus Walken Curtis 1831 (Diptera, Mycetophilidae) Von Harald Plachter'-' Abstract External Morphology and Web Building of the Immature Stages of Leptomorphus Walkeri Curtis 1831 (Diptera, Mycetophilidae) Larval and pupal stage oi Leptomorphus Walkeri Curtis 1831 and their webs are described in detail including fine-structure as seen in SEM. Especially concerning the larva there are many structures characteristic for the subfamily Sciophi-linae. Within the subfamily the larva of L . Walkeri is distinguished by 8 conical processes on the la-brum (Sciophila :0; Phthinia : 7), by its size and by its colour. The fine-structures of labrum, man-dible and maxilla are rather similar to those of Phthinia humilis Winn. The pupa is very slim with a stiff cuticle and a striking pigmentation consisting of orange and black spots and stripes. Whereas the larval web is similar to those of the other species of the subfamily, the pupal web is re-duced to a vigorous rope of 2 to 4 cm length on which the pupa is hanging head down. There is no additional web protecting the pupa. Therefore larvae and pupae were only found at very damp loca-lities. The rope consists of hundreds of subunits drawn out by the larva by use of the labral proces-ses and the conical maxillary palps and bind together by additional secrete. Near to the substratum the rope splits up wedge-shaped, thus assuring safe fastening. Appearance and web of the pupa are specialisations with regard to certain environmental condi-tions. Therefore they are useless in discussing questions of relationship within the superfamily. On the other band isolated members of other subfamilies of Mycetophiloidea as Speolepta dissona and Arachnocampa luminosa show quite similar specialisations among similar environmental condi-tions. Those uniform specialisations point to similar genetic abilities within the superfamily. 1. Einleitung Die Larve von Leptomorphus Walken Curtis 1831 fand in der Literatur bereits mehr-fach Erwähnung (Landrock 1927, Brocher 1931, Madwar 1937, Plassmann 1971). Wenn im folgenden dennoch eine weitere Beschreibung der Juvenilstadien dieser Pilz-mückenart wiedergegeben wird, so zum einen deshalb, weil insbesondere die Kenntnis über Puppe und larvalen Gespinstbau bisher unvollständig ist, zum anderen, weil durch die Anwendung rasterelektronenoptischer Arbeitsmethoden weitergehende Aussagen zur Eidonomie der Larve und zur Taxonomie der Art ermöglicht wurden. Mit Unterstützung durch die Deutsche Forschungsgemeinschaft 11
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