454 



Wirth and Stone: Diptera 



— Pollen of face white; wings without spots on the veins; 

 veins broadly yellow at root of wing, sometimes mostly 

 yellow; California praecox (Lehman) 1822 



9. Tip of fore tibia in both sexes .v.ith an acute angle 

 produced toward the femur; fore coxa with from 1-3 

 black bristles on upper /outer corner; central and south- 

 ern California philombreus Wheeler 1890 



— Tip of fore tibia not, or but little, angulated 10 



10. Wing with a cloud on the cross vein; female with a row 

 of longer bristles near the tip of posterior surface, at 

 the lower edge of fore femur; Alameda, Sonora, and 

 San Luis Obispo counties .... breviseta Thomson 1868 



— Wing without a cloud on the cross vein; female with a 

 double row of spines on under side of fore femur .... 11 



11. Pleura with thin brownish or yellowish pollen; length 

 4.5 mm.; both rows of spines on lower surface of fore 

 femur of about equal length; Ventura and Riverside 

 counties magdalenae Wheeler 1899 



— Pleura with white pollen; length 3 mm.; fore femur with 

 a row of 5 spines on lower posterior edge which are 

 much longer than those in anterior row; California 



sodalis Wheeler 1899 



12. Wing with a brown spot on the cross vein and another 

 on the middle of last section of 4th vein; Del Norte 

 County phoca Aldrich 1911 



— Wing without spots on the veins; Del Norte to San 

 Francisco counties innotatus Loew 1864 



Genus Hypo chat -as sus Mik 



Smith (1952) described and figured larvae, pupae, and 

 cocoons of Hypocharassus pruinosus (Wheeler) from 

 the sandy bars and beaches of the bays at Cape Cod, 

 Massachusetts. They are quite similar to those of 

 Hydrophorus. The two known species of this genus 

 are known only from the Atlantic coastal beaches of 

 the United States. 



Subfamily APHROSYLINAE 



Genus Aphrosylus Walker 



(Fig. U-A9e-g) 



The North American species of this Holarctic genus 

 have been considered by some authors as generically 

 or subgenerically distinct under the name Paraphrosy- 

 lus Becker. All the known species are confined to 

 algae-covered intertidal rocks along sea coasts, where 

 the adults prey on adults and larvae of midges and 

 other small Diptera or on small annelids. Both Wheeler 

 (1897) and Saunders (1928) have good accounts includ- 

 ing excellent figures of the immature stages. The 

 larvae are unusual in having nine caudal lobes (fig. 

 14:49e,<?) rather than the usual four, but the super- 

 numerary dorsomedian lobe and small lateral pairs 

 lack the usual hair fringe possessed by the two large 

 dorso- and ventrolateral pairs. 

 California species: 



calif ornicus Harmston 1952. 

 direptor Wheeler 1897. 

 grassator Wheeler 1897. 

 nigripennis (Van Duzee) 1924. 

 praedator Wheeler 1897. 

 wirthi Harmston 1952. 



Orange County 



Humboldt, San Diego 



Monterey County 



Humboldt County 



Humboldt, Monterey 



San Francisco, San Mateo 



Genus Cymatotopus Kertesz 



This genus replaces Aphrosylus in the Australasian 

 region. It is merely mentioned here to call attention 

 to the beautiful figures and fine description by Wil- 

 liams (1939) of all stages of the Hawaiian C. aero- 

 sticalis Parent. 



Genus M elanderia Aldrich 



The only two known species are both found along 

 California sea beaches. The genus is characteristic 

 because of the extreme development of the labella 

 forming a pair of sclerotized, mandiblelike lobes which 

 are used in seizing the prey. The habits are similar 

 to those of the closely related Hydrophorus. 



Key to Adults of the California Species of Melanderia 



1. Front and face purple; 3rd and 4th veins parallel and 

 far apart, ending in the apex of wing; front femur of 

 male with a close bunch of 6-8 bristles on a slight 

 protuberance on inner side near base; Humboldt County 



mandibulata Aldrich 1922 



— Front and face green; 3rd and 4th veins close together, 

 the 3rd curving back near wing tip; front femur of male 

 without such tuft on inner side of front femur; Santa 



Barbara to San Diego counties 



curvipes Van Duzee 1918 



Subfamily RHAPHIINAE 



Genus Systenus Loew 



(Fig. 14:49ti-?) 



Although this genus is at most only semiaquatic it 

 is included here because of the general limnological 

 interest in the study of tree-hole insects. Wirth (1952) 

 has recently described several North American species 

 with figures of the immature stages. The larvae live 

 exclusively in the wet and decaying wood pulp of 

 tree cavities where they prey on other dipterous 

 larvae such as Dasyhelea which breed in the same 

 medium. There are four American species known only 

 from the eastern states. 



