20 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



•coxa 



-trochanter 

 --femur 

 —tibia 

 --tarsus 

 ^•claw 



m 



>hook- 



bearing 



plates 



--4)late 5A 

 --plate 5P 



|-- -plate 6 A 



-9 

 -10 



■~^anal 

 processes 



Fig. 20. — Limnephilus submonilijer larva and pupa, illustrating terminology of parts. 



psychidae as the most specialized members of 

 this group. 



The Hydroptilidae comprise an isolated 

 group combining certain primitive adult 

 characters with a great variety of larval 

 and biological specialization. The larvae 

 are peculiar among the entire order, appar- 

 ently, in having a sort of hypermetamorpho- 

 sis in w^hich the young larvae are active 

 and free living, later building cases. The 

 more primitive of these cases are simple 

 adaptations of the saddle cases of some 

 Rhyacophilidae, but the more specialized are 

 similar in construction to the true cases of 

 the Leptoceridae and other families. 



The remainder of the families form the 

 large complex of true case-makers, includ- 

 ing the large families Leptoceridae and Lim- 

 nephilidae. This group presents a real 

 problem in determining the phylogenetic ar- 

 rangement of the families. It may be divid- 

 ed into two or three series on the basis of 

 certain characters as outlined below, but 

 whether or not these segregations are arti- 

 ficial or natural will rest on further evi- 

 dence and investigation: 

 A. Ocellate series (ocelli well developed). 



1. Phryganeidae — probably the most prim- 

 itive member of the case-making group. 



2. Limnephilidae — this family may not be 

 closely related to the Phryganeidae but 



is certainly one of the more generalized 

 members of the case makers. 

 B. Nonocellate series (ocelli absent). 



Many families of this group have been 

 regarded as very primitive. It is certain, 

 however, that having no ocelli they could 

 not have given rise to groups that have, such 

 as the Phryganeidae. The Molannidae are 

 probably the most primitive members of this 

 series. It seems impractical, however, to 

 attempt a phylogenetic analysis of the series 

 at the present time. Also included in it are 

 the Odontoceridae, Calamoceratidae, Goeri- 

 dae, Lepidostomatidae, Leptoceridae, Be- 

 raeidae, Helicopsychidae, Sericostomatidae 

 and Brachycentridae. 



Generic and Specific Characters 



For the diagnosis of genera and species 

 an effort has been made to use such charac- 

 ters as could be seen easily on specimens 

 preserved in liquid and, insofar as possible, 

 on preadults dissected from pupae. This 

 has led to the substitution of head, thoracic 

 and leg characters for wing venation in 

 many places in the keys. In certain families, 

 such as the Hydroptilidae, these new char- 

 acters have proved to be the first satisfac- 

 tory basis for generic separation, at least 

 in key form. 



i 



