884 Charles Paul Alexander 



Family Ptychopteridae 



The family Ptychopteridae has generally been understood to include 

 the tanyderid flies, as well as the three genera herein considered as con- 

 stituting it. The resemblance between the Tanyderidae and the 

 Ptychopteridae seems to be superficial only, however, and the differences 

 are very considerable. 



The immature stages of the Ptychopteridae are very remarkable. 

 The larva lives in an aquatic or a semi-aquatic habitat, and its caudal 

 extremity is provided with an extensile elongated breathing tube which 

 bears the spiracles at the end. The pupa has one of the two thoracic 

 breathing horns enoraiously elongated, while the other is considerably 

 atrophied. Both these elongated processes in the immature stages serve 

 to provide the insect with air while the body is submerged beneath the 

 mud and water. The larvae of Bittacomorpha are of a peculiar rust-red 

 color; those of Bittacomorphella are almost black, with the short breathing 

 horns yellow; those of Ptychoptera are more yellowish brown. 



The following key divides the family into its genera: 



1. Antennae 20-segmented ; wings with cell M2 lacking; legs banded with black and white. 



(Subfamily Bittacomorphinae.) 2 



Antennae 16-segmented; wings with cell M2 present; legs not banded with black and 

 white. (Subfamily Ptychopterinae.) Ptychoptera Meig. (p. 884) 



2. Apex of the wing not pubescent; metatarsi swollen Bittacomorpha Westw. (p. 884) 



Apex of the wing pubescent; metatarsi not swollen Bittacomorphella Alex. (p. 885) 



SUBFAMILY Ptychoptefinae 



Genus Ptychoptera Meigen 



1803 Ptychoptera Meig. Illiger's Mag., vol. 2, p. 262. 



Ptychoptera rufocincta 0. S. 



1859 Ptychoptera rufocincta 0. S. Proc. Acad. Nat. Sci. Phila., p. 252. 



Ptychoptera rufocincta is the only eastern species of Ptychoptera. It 

 is deep black, with rusty-red bands on the abdominal segments; the wings 

 (Plate XXX, 2) have brown crossbands, presenting an appearance super- 

 ficially very like that of Limnophila macrocera. 



SUBFAMILY Bittacomorphinae 

 Genus Bittacomorpha Westwood 



1835 Bittacomorpha Westw. London and Edinburgh Phil. Mag., vol. 6, p. 281. 



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