1974] 
Coyle — Genus A liatypus 
463 
fewer stout peripheral sternal setae than most Los Angeles area 
specimens; a few of the latter possess many stout setae scattered along 
the entire sternal margin. The Chatsworth specimen is markedly 
variant. All its peripheral sternal setae are stout, the very long 
sternal setae are almost completely limited to the anterior half of the 
sternum, the sternum is exceptionally wide (SL/SW == 1*02), and 
femur I is longer than femur IV (IFL/IVFL — 1.05). Some 
minor and non-geographic variation occurs in the relative positions 
of the seminal receptacles (Figs. 1 51-154). 
Distribution. The Los Angeles Basin of southern California 
(Map 2) . 
Records. California. Los Angeles Co.: Eaton Canyon Park, 
3 Jan. 1965, cT i 7$- —Sierra Madre, Bailey Canyon, $. — 
Crescenta Valley Park, 9- — Chatsworth, . Orange Co.: Salt 
Creek, 1.5 mi. N of Dana Point, 60 ft., 6 Dec. 1968, 2cf, 4$ ; 
5 Sept. 1969, cf ; 12 Nov. 1969, <A ; 13 ? . 
Aliatypus thompsoni new species 
Figures 27-33, 40-44, 50-53, 60, 71-73, 86, 93, m-113, 155-171- 
Map 4. 
Type specimens and etymology. Holotype male from Chatsworth, 
Los Angeles Co., California, 25 November 1967 (M. E. Thompson). 
Three male and 15 female paratypes. This species is named after 
Mel Thompson, who has collected most of the male specimens studied. 
Diagnosis. Males: A. thompsoni is distinct from all other species 
in two ratio characters (Table 1), PSL/PSS and CL/IML. The 
posterior sigilla are large, faint, and closely spaced (Fig. 60) and 
metatarsus I is relatively long ( Fig. 93 ) . The relatively short ventral 
macrosetae, all of which are ensiform, and the appressed background 
setae of tibia and metatarsus I (Fig. 93) are also distinctive. The 
thoracic groove is nearly always absent or shallow (Figs. 50-51). 
Females: Unlike all other species, A. thompsoni females either have 
no thoracic groove or only a shallow vestige (Figs. 52-53). The 
small PSS (Table 2; Figs. 71-73) distinguishes this species from all 
others except A. tropkonius. The large numbers of PTSR and IMS 
(Table 2) distinguish this species from many others. An appropriate 
ratio from among the following will distinguish A. tho?npsoni from 
any other species: CL/PSS, SW/PSS, and IMS/PSS (Table 2). 
A. thompsoni seminal receptacles (Figs. 1 55-1 7 1 ) , with their long, 
many-looped, non-tapered stalks and relatively small to medium sized 
bulbs, are diagnostically useful. 
Description. See Tables 1-3. 
