Eremobates scaber species group
Diagnosis: Muma (1951)
established this group to accommodate species of Eremobates that he characterized as
having.a wide basal notch in the fixed cheliceral finger of males that is visible from dorsal view.
He described the notch as occupying one-third or more
of the length of the finger. The mesoventral groove of the fixed finger, he stated, is dilated basally, and
the first postspiracular abdominal sternite is provided with
two to six
Females, he reported, have roughly triangular genital opercula that are well separated
along most of their mesal margins. Although he reported that both rows of fondal teeth
are graded I, III,
II, IV in size, he later (Muma 1986, 1987)
suggested that fondal tooth formulae are not valid for genus or group
separation, as they are subject to wear, especially by females.
TYPICAL SPECIES: Eremobates scabernm(Kraepelin).
Muma 1989 key
Mesal groove of fixed cheliceral finger mesoventral in
position Mesal groove narrow apically, occupying less than half of finger
width Mesal groove distinctly dilated basally
new species Mesal margins of opercula
lobate, bilobate or sinuate at or just anterior to posteriomesal notch .
Opercula not or only moderately separated posteriorly; broadly triangular in
shape and without distinct pits midway along ectal margins except for
Brookhart and Cushing
2004 In the scaber group the
mesoventral groove is deep and narrow. The female genital opercula are
roughly triangular with species distinguished by differences in the medial
Muma (1951) listed six species in the scaber group including
the typical or defining species
E. scaber (Kraepelin 1899)
although he had not seen the female type specimen. After examining type
specimens in both the U.S. and Europe as well as other specimens from
various collections and collectors Muma (1970) recalled Kraepelin’s 1899
description of Datames
scaber based on the female type from ‘‘Washington Territory’’ as the
correct characterization of
Eremobates scaber. He used his 1951 description, erroneously attributed
to E. scaber, to
establish E. septentrionis
Muma 1970, used his 1951 description of E. geniculatus to erect
E. mormonus (Roewer
1934) and defined E.
geniculatus (C.L. Koch 1842) (Simon 1879, misidentified) using Simon’s
1879 description of a single female from Mexico (Muma 1970).
In 1989 Muma described
six new species. This resulted in 15 species in the scaber group with
E. actenidia Muma 1988,
E. clarus Muma 1989, E.
consors Muma 1989, E.
ascopulatus Muma 1951 and
E. hodai Muma 1989 described from only one sex although Muma included
the male of E. scaber in
the key. Eremobates clarus,
E. actenidia and
E. consors were each described
from a single specimen and
E. ascopulatus from two males.
Eremobates similis (Muma 1951)
was noted as being described in both sexes (Muma 1989), but the female
description has not been found.
E. scaber, Muma (1951) used specimens from an area that extended from
the northwestern United States to Las Vegas, Nevada but noted that it might
include other species of this group. In addition, other species of this
group seemed to have sympatric ranges (Muma 1951, 1962, 1989). In each of
his publications Muma (1951, 1962, 1989) cited several problems with the
distinction between species and problems of sympatric associations.
Muma (pers. comm.) indicated that this group needed to be
more thoroughly studied.
For the most part, this group is an inhabitant of pinon
pine-juniper or desert shrub communities. Muma (1963) identified
E. zinni (Muma 1951),
E. ctenidiellus and E.
mormonus as inhabitants of the Mercury, Nevada Nuclear Test Site, a
Mojave Desert region, although some of the specimens were misidentified.
Allred & Muma (1971) listed
E. septentrionis and E.
ctenidiellus as inhabitants of the Snake River Plain which is part of
the Columbian Plateau. Brookhart (1972) found E. mormonus, later
changed to E. similis,
in the San Luis Valley of Colorado and
E. ctenidiellus in the mesa
regions of western Colorado. The Sevilleta Long Term Ecological Reserve
project at the northern tip of the Chihuahuan Desert surveyed six distinct
desert grassland/high desert areas and found
E. similis in only the pinon-juniper
association (Brookhart & Brantely 2000). At the Hanford Nuclear Site, Rich
Zack’s E. scaber
material (WSU) was collected in Great Basin Desert shrub habitat, and
various Canadian specimens were collected in the sagebrush of the Okanogon
Valley. Eremobates scaber
group species have been collected at 2394 m in Wyoming, 2303 m in the
San Luis Valley of Colorado, and on Mt. Palomar, California. Muma (1951,
1962, 1970, 1989) used length vs. width of the fondal notch, number and
shape of ctenidia, and number of palpal papillae, as well as coloration of
appendages to separate each species. The number of ctenidia ranged from 0–6.
The palpal scopula varied from none to over 120 papillae. Females were
identified by the structure of the genital operculum and the coloration of
appendages. Coloration of eye tubercle and malleoli were noted but were
consistently the same for all species with eye tubercles dark and malleoli
white. Abdominal coloration varied from a pale yellow to a grey background
dorsally and ventrally with lighter pleural membranes between species and
also between specimens of the same species. Many specimens had tergites with
a rectangular, brownish, violet pigmentation which gave the appearance of a
broad stripe to many specimens. Muma (1951) calls this a sclerite although
it is not particularly thick or hardened. It was not found to be diagnostic
in this study. Male chelicerae have no teeth on the fixed finger and some
variation in the shape of the fixed finger in ectal view. The movable finger
follows the general pattern of a large primary tooth, two intermediate
teeth, the posterior being larger and an anterior tooth. The mesal tooth
varies from tiny to absent. Female chelicerae have a fixed finger with teeth
ordered successively posterior to anterior, intermediate tooth, large
primary tooth, two intermediate teeth, medial tooth, a single intermediate
tooth and a smaller anterior tooth. The female movable finger has a large
primary tooth, a variable sized anterior tooth and two intermediate teeth,
the posterior of which is larger. The mesal tooth varies from absent to
medium size. Fondal teeth in both male and female grade out I, III, II, IV
in size, although in some species the fondal tooth III is equal in size to
fondal tooth I. Due to wear, the intermediate teeth on both male and female
movable fingers are sometimes hard to diagnose.
Eremobates actenidia Muma 1989
Eremobates clarus Muma 1989
Eremobates corpink Brookhart & Cushing 2004
Eremobates ctenidiellus Muma 1951
Eremobates hodai Muma 1989
Eremobates icenogelei Brookhart & Cushing 2004
Eremobates legalis Harvey 2002
Eremobates mormonus (Roewer 1934)
Eremobates scaber (Kraepelin 1899)
Eremobates similis Muma 1951
Eremobates socal Brookhart & Cushing 2004
Eremobates zinni Muma 1951