The Comparative Internal Larval Anatomy of Sawflies (Hymenoptera: Symphyta)

Abstract

AbstractExamination of 132 recognized species of sawflies (Hymenoptera: Symphyta) from America, Europe, Africa, and Australia, has demonstrated the value of internal anatomical larval detail as a taxonomic tool and an indicator of phylogenetic relationship. Two characters, the salivary glands and Malpighian tubules, proved of major importance. The salivary glands fall into three main categories, narrow squared ducts and incorporated gland cells (the Orthandria with the exception of the Xyelidae), narrow ducts and sheathlike gland cells (the Xyelidae), and either increased cell numbers and narrow branching ducts or expanded ducts (the Tenthredinoidea). Three divisions of the Tenthredinidae are suggested, viz. the Selandriinae-Dolerinae-Athaliinae-Lycaotinae, the Nematinae, and the Blennocampinae-Allantinae-Heterarthrinae-Tenthredininae, corresponding to Malpighian tubule groupings of primitive, intermediate-advanced, and advanced. Character trends are discussed in the light of existing adult arrangements (Ross and Benson), and external larval (Yuasa). The survey emphasizes the need of a revision of family and subfamily limits. Where identification is difficult, internal anatomy is of use in determination to genus and species as well as to family and subfamily. The frequency of parallel evolution does not affect the use of certain characters indicative of progressive change within a group.