Johnstonianidae — Newell 
425 
The material available is not suitable for 
counts of the setal types. In general the chae- 
totaxy appears to resemble that of C. distans 
very closely. Tarsus I bears either 2 or 3 
clavate solenidia 2 , with the normal two being 
located at 0.67 and 0.74/? in the specimen 
studied. One of the tarsi I of the holotype 
has a third s 3 at 0.52 pd. Eupathidia of tarsi 
I extending from 0.34^ to 0.83 pd. Famulus 
elongate, straight, its alveolus at 0.88 pd. Claw 
fossa extending from 0.12d to end of tarsus. 
Tarsus II with a clavate s 2 at 0.6lpd and a 
spikelike famulus at 0.81 pd. These positions 
correspond almost precisely with the positions 
of the same setae in the holotype of C. distans , 
but the famulus appears to have a normally 
recessed alveolus, and not a vesicular one as 
in C. distans. 
type locality: About 4 miles north of 
Tonasket, Washington, on border of a small 
permanent pond (holotype female). August 
14, 1952, collected by the writer. This is also 
the type locality of C. approximatum new spe- 
cies. Type in author’s collection. 
remarks: The type locality of this species 
is the only point at which more than one 
species of Centrotrombidium has been observed 
by the writer, all three forms newly described 
in this paper having been found here. The 
differences between C. distans and C. hadroseta 
cannot be fully evaluated at present because 
of lack of sufficient specimens of the latter 
species. However, 50 specimens of both sexes 
of C. distans have been seen by the writer, and 
there is no indication of convergence in setal 
type between any of these specimens and the 
type of C. hadroseta. While it is possible that 
further study will change this, the most prob- 
able explanation at present appears to be that 
we have here two sibling species. 
Centrotrombidium misellum 
(Berlese) 1918, new combination 
This was originally described as Diplothrom- 
bidium misellum Berk (sic) . A translation of 
Berlese’s description is given above. 
395 .Diplothrombidium misellum Berl. n. sp. Dark 
red, small. Abdomen subquadrate-rounded, 
very slightly excavated in lateral margin, front 
truncate, well-armed posteriorly. Crista metop- 
ica with a single area sensilligera, anterior and 
posterior sensilla very close together; anterior 
sensilla spiniform, moderately swollen, poste- 
rior sensilla long, very slender. Body completely 
clothed with hemispherical papillae, setae short 
arcuate, directed posteriorly. Legs very short, 
anterior ones shorter than body, tarsus broad, 
ovate, little longer than broad (140 \ u long, 80 
ju broad), tibia three times narrower than the 
tarsus. Palpi rather large, barely swollen, un- 
uiculate, provided with a stout spine at the 
ase of the main claw three times shorter than 
the claw. Papilla, (tarsus?) conical, short, apex 
armed with three spiniform setae, 30 \i long, 
cuticle of legs, rough, warty, covered with simple 
short setae. Eggs in hysterosoma of the single 
specimen which I saw spherical, 140 /jl in diam- 
eter. Adult 800 /x long, 650 /x wide. 
habitat: A single specimen collected by Cl. 
Alph. Duges, in Mexico (Guanajuato), which 
Cl. Trouessart kindly sent to me. 
The swollen form of the leg tarsi, the pres- 
ence of a single pair of true sensilla on the 
scutum, and the description of the tarsus of 
the palp and its terminal setae leave little 
doubt that this is not a Diplothrombium but 
more likely a Centrotrombidium. The eupathi- 
dia at the end of the tarsus of C. approximatum 
are almost exactly 30 /x long, while those of 
Diplothrombium micidium are 62 /x long. No 
known species of Diplothrombium has a palpal 
tarsus which could be described as "conical,” 
but this term could be applied to Centrotrom- 
bidium. The length of the body is also much 
more in keeping with Centrotrombidium than 
with Diplothrombium. The species should there- 
fore be transferred to the genus Centrotrom- 
bidium. If it does not belong in that genus, 
its position there is at least no more untenable 
than it was in Diplothrombium. The only point 
in which Berlese’s diagnosis was out of char- 
acter with Centrotrombidium is in the form of 
the sensilla. However, a trend toward more 
slender sensilla is seen in C. australasiae , and 
it is not inconceivable that there might be 
some species in which these are not swollen. 
