470 
Psyche 
[September-December 
Aliatypus erebus new species 
Figures 34 -38, 62, 75, 88, 114-115, 174-187. Map 4. 
Type specimens and etymology. Holotype male from Fossil Ridge 
on south side of Mt. Diablo, Alameda Co., California, 24 November 
to 5 December, 1970 (W. E. Azevedo). Three male and two fe- 
male paratypes. Erebus was the Latin god of darkness. 
Diagnosis. Males: The ratios CL/PED and CL/PCA (Table 1) 
will separate A. erebus males from those of the closely related species, 
A. trophonius, A. plutonis, and A. torridus. For other characters 
useful in separating A. erebus from each of these species, see their 
diagnoses. A. erebus ’ conductor form (Figs. 114-115) and strongly 
swollen pedipalpal tibia (Fig. 88) are distinct from that of most 
other species. The ratios PTT/PTL, CL/ITarL, CL/IFL, CL/ 
PED, and CL/PSL (Table 1) best distinguish A. erebus from the 
less closely related species. Females: A. erebus’ seminal receptacles, 
with large bulbs and short stalks with normally only two (at most 
three) bends (Figs. 174-187), are distinct from those of all species 
except A. torridus. CL/PSL, SW/PSL, or PSL/PSS (Table 2) 
will separate A. erebus specimens nicely from distantly related spe- 
cies. CL/I MS, IMS/PSS, CL/PTSR, PTSR, or IMS (Table 2) 
distinguish A. erebus from A. thompsoni. CL/IMS, CL/AMD, 
CL/PTSR, CL, and IVTarL (Table 2) distinguish A. erebus from 
closely related A. trophonius. IVFL/IVML and CMT (Table 2) 
best distinguish A. erebus from closely related A. plutonis. CMT, 
CL/OQW, CL/CMT, and IMS/CMT (Table 2) are the most 
helpful characters when separating A. erebus specimens from those 
of very similar A . torridus. 
Description. See Tables 1-3. 
Males: Carapace. Thoracic groove a deep circular or elongate 
oval pit; somewhat narrowed posteriorly. Postocular setae numerous 
and form a roughly triangular grouping. Sternum. Fig. 62. Pos- 
terior sigilla large and well separated. Pedipalps. Figs. 88, 114-115. 
Pedipalpal tibia robust; greatly swollen ventrally near distal end. 
Embolus base well separated from ICS base. Proximal branch of 
ICS base elongate. OCS rather broad to near its end where it 
quickly tapers to a fine point. Inner (concave) edge of OCS smooth 
to very rough. Leg I. Ventral tibia and metatarsal macrosetae 
attenuate and ensiform ; background setae rather elongate and not 
closely appressed. Abdomen. Tergites I and III reduced to patches 
or spots at bases of macrosetae. Coloration. Pars thoracica grey- 
yellow. Pars cephalica markedly darker; medium brown to dark 
