Neuropteroidea--different ovary structure in related groups

Three different ovariole types have been described in the Neuropteroidea. In this review, comparative analysis of their structure and function is presented, and the results are used for phylogenetic considerations. Neuropteran polytrophic ovaries exhibit deviations from the basic polytrophic pattern found in other insects. Asynchronous divisions of germ cells result in a variable and unfixed number of cystocytes per cluster. In contrast to the typically branched system, spatial organization of the cystocyte connections in neuropteran egg chambers is almost linear. A more precise comparative study of ovariole structure and function within Neuroptera brings further support for the placement of Coniopterygidae as an early off-shoot from the main neuropteran phylogenetic lineage. Ovaries of Raphidioptera and Megaloptera: Sialidae represent a distinct type of telotrophic organization. Its almost identical character in both groups favours the concept on the origin of this telotrophy from the common ancestral polytrophic condition. Ovarioles of Megaloptera: Corydalidae are neopanoistic and it is emphasized here that this organization must have evolved independently from the polytrophic background. A hypothesis on paraphyletic origin of Megaloptera is thus supported.