Charadracarus n. gen, — N ewell 
163 
C. aelleni has moved distally and become modi- 
fied in form and size. 
Structure of Rostrum . An interesting fea- 
ture in the structure of the tip of the rostrum 
is found in C. hurdi and C. delitescens. This is 
a sexual difference, and not an interspecific one. 
In the females, the tip of the rostrum is simple, 
the velum being a flattened and fairly regular 
disc (Fig. 34). In the males of both species, 
however, the velum is rather elaborately drawn 
out around the margins into a number of fine 
points (Fig. 21 ) . 
FORMULA KEY TO SPECIES OF 
Charadracarus 
Based on Adults 
la. Sensilla fusiform, greatly swollen near 
middle, the tapering distal portion of the 
sensillum as long as or nearly as long as 
the basal portion (Fig. 36). 
lb. Sensilla essentially clavate, filiform distal 
portion greatly reduced or absent (Fig. 9). 
2a. Major setae of hysterosoma tapering to a 
fine point, no terminal tuft of barbs (Fig. 
29 ). 
2b. Virtually all major setae of hysterosoma 
with distal end inflated, hollow, and with a 
tuft of fine barbs (Fig. 45). 
3a. Tarsus of palp with terminal seta eupath- 
idiform, hollow throughout most of length 
(Fig. 7). 
3b. This seta solid throughout virtually the 
entire length of the shaft, not eupathidi- 
form (Fig. 48). 
4a. Tibia of palp with a terminal odontus plus 
six slender, tapering normal setae; paradont 
absent (Figs. 7; 44). 
4b. Tibia of palp with a terminal odontus and 
a paradont (Cooreman, 1954: 17, fig. 8). 
5. Length of idiosoma, to tip of nasus, by sex. 
NOTES ON MORPHOLOGY AND TERMINOLOGY 
IN THE PARASITENGONA 
In a previous paper, the writer ( 1957 : 407 ) , 
presented a table of terms applied to the spe- 
cialized setae of the legs of the Parasitengona 
in which "microfemorala, microgenuala, micro- 
tibiala (in part)” were listed as equivalent to 
solenidion3 or S3. The prefix micro should be 
deleted from each of these names. Likewise, 
solenidion 4 or s 4 has as its equivalent the term 
tibiala (in part) — not microtibiala as errone- 
ously indicated in the table. 
The term prosensillar setae was introduced by 
the writer (1958: 360-367) but was not de- 
fined. It had been shown in an earlier study 
(Newell, 1957: 398-400) that the most anterior 
setae of the scutum of Johnstonianidae could 
be (a) present and typically sensillar in form, 
closely resembling the posterior sensilla, (b) 
present, but more nearly resembling the other 
setae of the scutum than they do the sensilla, 
and (c) absent. In those Johnstonianidae, Trom- 
biculidae, and Trombidiidae in which the homo- 
logues of the anterior sensilla are present but 
not sensilliform, these setae may be designated 
by the term prosensilla. These are typically the 
two anteromedian setae of the scutum. In many 
Trombiculidae, they are represented by an un- 
paired anteromedian prosensillum. 
In the same paper (p. 384) the terms odontus 
and paradont were introduced. The name odon- 
tus is applied to the heavy terminal clawlike 
seta found on the tibia of the pedipalp. The term 
is utilized in preference to "claw,” to avoid the 
implication of relationship to the tarsal claws. 
There is no relationship between the two types 
of "claw” in position, structure, or function, and 
different terms are desirable for the two kinds 
of structure. In many species a second and sub- 
terminal seta is found, usually quite near the 
insertion of the odontus, and this has been called 
the paradont. 
Distribution of Character Variants, Adults 
1 2 3 4 5 
C. hurdi n. sp b a a a $711/“ 
C. delitescens n. sp a b b a $ 513-711 (628) 
C. grandjeani (Andre) a b a a $ 504 
C. aelleni (Cooreman) a a ? b 900 
