447] 



LARVAE OF THE TENTHREDINOIDEA—YUASA 



129 



The morphological characters discussed are summarized in the following 

 table: 



Comparison of Various Structures in the Families o* the Tenthredinoidea 



The Pamphiliidae, with its long seven-segmented antennae, setiform 

 three-segmented subanal appendages, setiform five-segmented thoracic 

 legs, well-developed typical mouth-parts, together with the absence of 

 larvapods, is unquestionably one of the most generalized families of the 

 Tenthredinoidea. This family differs from the hypothetical type only 

 in the absence of larvapods and reduced metaspiracles. 



The Xyelidae, with its fairly long seven-and six-segmented antennae, 

 five-segmented thoracic legs, well-developed typical mouth-parts, together 

 with the presence of ten pairs of larvapods and the absence of subanal 

 appendages, is undoubtedly a very generalized family, quite different 

 from the preceding. The only striking difference from the hypothetical 

 type is the absence of the subanal appendages and functional metaspiracles. 



The Tenthredinidae, with its one- to five-segmented antennae, well- 

 developed thoracic legs, and six to eight pairs of larvapods, together with 

 the absence of the subanal appendages, is unquestionably related to the 

 Xyelidae, and if it has not been evolved directly from the latter the two 

 families must have arisen from a common stock. The Tenthredinidae is a 

 phylogenetic complex in itself, and some of the more specialized genera are 

 further removed from the more generalized genera, biologically as well as 

 morphologically, than the latter are from the Xyelidae or their xyelid- 

 like ancestors. 



The Cephidae, with its segmented antennae, vestigial subanal append- 

 ages, vestigial thoracic legs, normal mouth-parts, absence of larvapods, 

 presence of suranal process, vestigial ocellarae, and large functional 

 metaspiracles, is considered an offshoot of the ancestral stem from which 



