144 
Psyche 
[June 
Mychocerus arizonensis, New Species 
This species may be distinguished from either M. depressus or 
M. pilifer Lewis (1888: 241) by the larger size and by the shape 
of the pronotum, which is more abruptly narrowed apically. From 
M. depressus it also differs in the form of the mesosternal lines. 
Description. Length 1.1-1.3 mm. Color reddish-brown; vestiture 
of short, fine, decumbent, yellow hairs, which are barely visible under 
25 X magnification. Antennae with segments 4-6 distinctly serrate, 
the club about 1.35 X as long as wide. Pronotum about 0.48 X 
as long as wide, sides subparallel for basal three-fourths, abruptly 
converging apically, the apical angles produced and subacute; lateral 
margins distinct and slightly elevated, especially towards base; disc 
slightly convex; punctation somewhat irregular, coarser than in M. 
depressus. Elytra about 1.15 X as long as wide and 3.0 X as long 
as pronotum, widest at apical fourth; rows of punctures lightly im- 
pressed and not distinct, the punctures smaller than those of M. 
depressus, intervals shiny, but with a fine reticulation. Apical edge 
of prosternum distinctly concave; mesosternal lateral lines gradually 
converging anteriorly, each line posteriorly forming an angle of about 
150° with the line of the metasternum (fig. 3). Aedeagus about 
0.6 X as long as abdomen, parameres longer and narrower than 
those of M. depressus , about 3 X as long as wide at base (figs. 5-6). 
Types. Holotype, 3 mi. NW Arivaca, Pima Co., ARIZONA, 
Dec. 21, 1969, under bark of mesquite (K. Stephan) [No. 32239 
M.C.Z.]. Paratypes: ARIZONA: Pima Co.: 11, same data as 
holotype; 5, same locality, Jan. 25, 1970, under bark of mesquite 
(K. Stephan) [KS, MCZ, USNM]. Four other specimens were 
collected at East Stronghold, Cochise Co., Arizona, April, 1972 and 
1973, by K. Stephan, and a single specimen was collected 10 mi. 
SE Alamos, Sonora, Mexico, Oct. 1972 (D. Chandler). 
Distribution. Southeastern Arizona and southern Sonora, Mexico. 
In Arizona, known from low elevations in the extreme southern part 
of the state and from higher elevations in the Chiricahua Mountains. 
Biology. Individuals from the lowland Arizona population were 
taken under dry mesquite bark and were not associated with running 
wounds. Those from the montane locality were collected under oak 
bark. u 
