438 
PACIFIC SCIENCE, VoL XI, October, 1957 
tr 
bf 
tf 
pa 
ti 
n 
n 
s 3 n 
S3 
n 
s 3 
s 4 
n 
I 
1 
1 
2 5 
15 
4 
1 
1 
6 
II 
1 
2 
1 4 
2 
4 
0 
2 
6 
III 
1 
2 
1 4 
2 
4 
0 
1 
6 
ta 
Si S2 e f n 
1 0 2 1 34 
0 1 1 1 27 
0 0 0 0 20 
separated from telofemora; I with a large ven- 
tral seta, but no dorsal seta, II and III each 
with a large hemipectinate dorsal and a small, 
smooth ventral seta. Telofemur I with two 
dorsal solenidia 3 (Figs. 139-141), II and III 
with one each; otherwise with 5, 4, and 4 
smooth to faintly pectinate setae respectively. 
Vestigial setae and companion setae absent 
from all segments of all legs. Tarsus I (Fig. 
143) with a long famulus at OAlpd and a long 
solenidioni at 0.44V, the latter lacking annular 
structure, but with internal surface granular 
(oil immersion). Solenidion, when seen in 
dorsal view, not straight, but very gently bi- 
sinuate. A long eupathid at 0.66V, but no 
companion seta, and a shorter one at 0.93^. 
A pair ofdong, slender setae at 0.87 and 0.89 ad 
and pd, and another at 0.88^. Otherwise with 
31 bihemipectinate setae in specimen drawn. 
Tarsus II (Fig. 145) with famulus at 0.45- 
0.52, a club-shaped solenidion 2 at 0.55V, three 
slender, smooth setae at 0.80V, 0.83V, and 
0.83^, and a eupathid at 0.89 pv. Otherwise 
with 24 bihemipectinate normal setae in speci- 
men drawn. Tarsus III (Fig. 142) with five 
slender, smooth setae at 0.79 V to 0.86^. Other- 
wise with 15 bihemipectinate normal setae on 
tarsus drawn. Two claws on all tarsi, the an- 
terior one larger than the posterior one; all 
claws smooth. 
type locality: Mono Lake, Mono County, 
California, 0.9 miles north of Leevining (ho- 
lotype female). Type in author’s collection. 
remarks: These mites were first found on 
and under rocks, lying in and near a small 
tricklet of alkaline water running into the 
lake, June 1, 1952. The habitat could be 
termed semiaquatic. The bottom of one rock 
was covered with scores of pink eggs laid 
singly and several other rocks were also ob- 
served with smaller numbers of eggs but 
always in association with these adults (June 
1, 1952). Eight larvae were found attached to 
the pupa of an aquatic beetle found under a 
stone. The larvae were definitely attached to 
the host and appeared to be feeding, but when 
submerged in alcohol the larvae immediately 
detached themselves from the host. The feed- 
ing habits of the adult are unknown at pres- 
ent. The same spot was revisited July 1, 1954. 
A few adults were found at this time, but no 
eggs, indicating that the reproductive season 
terminated sometime during the month of 
June. The same picture was observed when 
the spot was again revisited August 9, 1955 
— although adults and nymphs were fairly 
common, no eggs or larvae whatever were 
found. 
While found at a site in which very high 
summer temperatures are registered in ex- 
posed places, Diplothrombium monoense was 
never found out in the open where it would 
be subject to these high temperatures. Also it 
was never found in situations where there was 
not considerable moisture, and the majority 
were found under rocks in which the surface 
of the ground was actually wet. A few indi- 
viduals were running about over the surface 
of very wet ground covered with a dense 
growth of small plants. Under such circum- 
stances they always appeared restless, espe- 
cially when their cover was removed so as to 
expose them to the direct rays of the sun. A 
species of Microtrombidium was also very com- 
mon at this locality but was frequently found 
running about over the surface of the dry sand 
along the shore of the lake, even in the heat 
of the day. Their movements were generally 
rapid, but at least they did tolerate the expo- 
sure to heat and sun for short periods of time. 
This species of Diplothrombium would appear 
to be considerably less tolerant of heat and 
dryness than species of Microtrombidium. Fur- 
