Genus Eremorhax Roewer 1934

Eremorhax Roewer 1934: 553; Muma 1951: 41–43; Muma 1970a: 3 (key), 4; Muma 1976: 14; Harvey 2001: 198–199; Harvey 2002a: 450, 451.

Arenotherus Brookhart and Muma 1987:1, 3; Muma 1989: 4 (synonymised by Harvey 2002a: 451).

Type species:

of Eremorhax: Datames magna Hancock 1888 by original designation.

of Arenotherus: Datames magna Hancock 1888 by subsequent designation of Harvey, 2002: 450.


Eremobatine species in which the fixed cheliceral finger of the male bears a weak crease (as opposed to a distinct groove) on its mesal margin and lacks an apical-ventral cup. Setae of the flagellar complex simple and tubular.

Original description:

Roewer 1934: 553:

"Eremobatinae, deren 2. und 3. Tarsus ventral mit jeweils 4.6 Dornen und deren 4. Tarsus ventral mit Dornen bewehrt ist (Abb. 319, a, b).

Nur 1 Art"

Roewer placed the genus in its own subfamily, which he characterized as:

"Eremobatidae, deren 1. - 4. Tarsus jeweils 1-gliedrig ist (Abb. 319, a, b, g, h)."

Subsequent accounts:

Muma 1951: 41-43:

Muma characterized a broadly interpreted genus Eremorhax, which included both the currently recognized genus Eremorhax and the genus Eremocosta, as follows:

"Large Eremobatinae. Fixed finger of males with an apical, mesoventral groove that does not extend the length of the finger. Flagellum complex composed entirely of simple tubular bristles that may sometimes be striate. Mesal tooth of movable finger of both males and females distinct. First post-spiracular abdominal sternite of males usually without ctenidia on its posterior margin. Genital opercula of females adjacent at anterior end and widely divergent at posterior end."


Muma characterized members of his magnus group (to which the name Eremorhax has been subsequently restricted) as follows:

"Males of this group are characterized by indistinct mesoventral grooving of the fixed finger and very tiny anterior and intermediate teeth of the movable finger. Females have a deep oval pit on each genital operculum. Fixed finger of female chelicerae with only one intermediate tooth between the principal and medial teeth, one in front of the medial tooth, and no anterior tooth. Both sexes have a distinct mesal tooth of the movable finger that is visible over the posterior margin of the principal tooth from a lateral view. Both rows of fondal teeth graded in size I, III, II, IV."

Muma 1970a: 3 (key), 4:

Muma characterized the genus Eremorhax in a key to the subfamilies and genera of Eremobatidae on page 3:

"Leg I with 1 claw; large, robust, short legged species....

Palpus with or without spinelike setae; when present, apparently not movable and not on metatarsus and tarsus....

Fixed finger elongate and need1elike or stylelike....
Mesoventral groove of fixed finger not extending to base of finger; apical seta of flagellum-complex tubular, at most striate .....Eremorhax Roewer"

Muma 1976: 14:


Brookhart and Muma 1987: 1, 3:

"The genus Eremorhax was erected by Roewer (1934) to include his designated type species Datames magna Hancock and related forms. Roewer stated that he had not seen the type when he described the genus, and examination of his drawings, 126, 319c, 319i, and 324a, indicate that his specimens were also not magnus. His (1934) drawings of the male chelicerae show no tiny to small teeth distal of the principal tooth on the movable finger; two small but distinct teeth are always present on magnus. His drawings of the female chelicerae do not show the normal reduced dentition of the fixed finger, nor the reduced size of the intermediate and anterior teeth of the movable finger. Further, his drawings of the female opercula fail to illustrate the highly visible anterio-ectal pits that seem to invade the lateral margins of the opercula. Although color and color patterns are often suspect as diagnostic characters, it may also be noted that Roewer (1934) in his description of his "magnus" stated that the pedipalpi (palpi) were browned only on the apical half of the metatarsi and tarsi; the magnus of Hancock (1888), Muma (1951 and 1970), and here is dusky purple on the tarsus, metatarsus, and apical end of the tibia of the palpus. On the bases of these findings, it is apparent that the genus Eremorhax Roewer is a junior synonym of Eremobates Banks. Arenotherus new genus is here erected to include the species previously placed in the magnus group of Eremorhax."


In erecting the genus Arenotherus (now a synonym of Eremorhax), Brookhart and Muma characterized it as follows:

"Males with mesoventral groove narrow to wide, indistinct to distinct, but shallow, and extending to or below the origin of the flagellar setal complex of the fixed finger when it is viewed meso-anteriorly. Flagellar complex with no specialized setae, composed of tubular to slightly striate setae dorsally, and slightly striate setae ventrally. Setae of the fondal notch and movable finger composed of a row of reddish tubular setae ventrally and plumose setae as an underlying row in the fondal notch, fond, and basal end of the movable finger setal articulation area. Males without a scapula of papillae on the tarsus and metatarsus of the palpus, and without ctenidia on the first post-spiracular sternite. Fixed finger without teeth or modified teeth. Fondal teeth graded I, III, II , IV. Fondal tooth IV often indistinguishable. Movable finger of males and females with a large principal tooth; on males at most a ridge with or without tiny to small abortive teeth anteriorly; on females, a small anterior tooth and smaller intermediate tooth. Mesal tooth generally distinct and often forming a cup-like structure when viewed anterio-dorsally. Females with only three teeth anterior to the principal tooth of the fixed finger. Genital opercula with pits ranging from distinct to tiny, lateral and or anterior to or on the sclerotized portion of the opercula."

They recognized two species groups (complexes) within the genus:  the magnus complex and the pulcher complex.


Muma 1989: 3 (key), 4 (as Arenotherus):

"These moderate to large Eremobatinae have been delineated and described as 10 species which are distributed from s outh Texas to California. New species were described in the above paper and are not included here."

"Leg 1 with one claw; chelicerae about twice as long as wide; small to large species ....
Fixed  cheliceral finger long, style-like or needle-like; mesoventral groove a crease, slot or cup-like structure; moderate-sized to large species....
Mesoventral groove an indistinct hollow or crease that does not extend to base of finger; movable finger dentition greatly reduced ..........Arenotherus Brookhart and Muma"


Harvey 2001: 198–199:

"B. Eremobates Banks, 1900 and Eremorhax Roewer, 1934 (family EREMOBATIDAE)

8. The solifuge genus Datames was established by Simon (1879, p. 133; ref. 1879a) for nine species of solifuges from the U.S.A. and Mexico, none of which was elected as the type species: Datames formidabilis Simon, 1879 (ref. 1879a), Gluvia geniculata C.L. Koch, 1842, Galeodes pallipes Say, 1823 (p. 3. footnote). Datames sulfureus Simon. 1879a and Datames californicus Simon, 1879a, and four doubtfully included species. Gluvia praecox C.L. Koch. 1842, Gluvia cinerascens C.L. Koch, 1842. Gluvia gracilis C. L. Koch, 1842 and Gluvia formicarius C. L. Koch. 1842. Later that year in a list of solifuge genera published (p. 78) in vol. 7 of Les arachnides de France, Simon (1879b) designated Datames formidabilis Simon, 1879a from Mexico as the type species of Datames.

9. Banks (1900. p. 426) noted that Datames Simon, 1879 was a junior homonym of Datames Stål, 1875 (Insecta) and proposed the replacement name Eremobates Banks, 1900 for the solifuge genus. Eremobates Banks is the type genus of EREMOBATINAE Kraepelin, 1901 (family SOLPUGIDAE). which was first elevated to family rank by Roewer (1934).

10. Apparently unaware of Simon's (1879b) type designation. Pocock (1902. p. 59) designated Gluvia cinerascens C. L. Koch. 1842 (p. 355) from Mexico as the type species of Eremobates. noting that Simon (1879a) had misidentified the male(s) but correctly identified the female(s) of Datames pallipes (Say, 1823). Roewer (1934, p. 555) listed D. pallipes as the type species of Eremobates, and placed G. cinerascens in a new genus. Roewer's (1934) type designation for Eremobates has been followed by other authors. including Muma (1951 ). Muma ( 1951, p. 72) synonymised G. cinerascens with D. pallipes which he later confirmed (Muma, 1970). The holotype of G. cinerascens is a male specimen (catalogue no. ZMB 188) in the Zoologisches Museum, Berlin, as recorded by Moritz & Fischer ( 1980, p. 140). Brookhart & Muma (1981, p. 292) designated a male specimen from Highway 205c, Byers. Arapahoe County, Colorado, U.S.A. and deposited in the American Museum of Natural History, New York, as the neotype o f D. pallipes.

11. Muma (1951, p. 92) established the new species Therobares bilobatus. now placed in the genus Eremochelis Roewer, 1934. for specimens misidentified as Datames pallipes (Say) by Simon (1879a), Banks (1900), Kraepelin (1901) and Roewer (1934).

12. Datames formidabilis Simon, 1879 is currently included in the genus Eremorhax Roewer, 1934 (p. 553) with the type species Datames magna Hancock, 1888 (p. 107, figs. A, B, a-h) (Harvey, in press). Despite the confused history of the identity of many North American solifuge species described in the 19th century it is clear that, if Simon's (1879) designation of D. formidabilis as the type species of Eremobates Banks, 1900 is left unchallenged, then the name Eremorhax becomes a junior synonym of Eremobates, and all species currently included in Eremorhax would be known as Eremobates. In addition. all species currently included in Eremobates would take the next available name, Eremoperna Roewer, 1934, which is currently treated (see Muma, 1951. p. 51) as a junior synonym of Eremobates.

13. Both the names Eremobates and Eremorhax are in current usage. A representative list of publications include Fichter (1940). Cloudsley-Thompson (1968, 1977). Brookhart (1972), Muma (1974a, 1974b, 1975a, 1975b, 1976, 1985, 1989). Brookhart & Muma (1981), Rowland & Reddell (1976) and Punzo (1998) for Eremobates, and Roewer ( 1952). Muma (1966a. 1966b. 1966c, 1967. 1974a, 1976, 1987). Rowland & Reddell ( 1976) and Punzo (1993, 1995. 1998) for Eremorhax. Therefore, in the interest of nomenclatural stability, I propose that the type designation for Eremobates Banks, 1900 made (under Article 67.8 of the Code) by Simon (1879b) be set aside, and that Galeodes pallipes Say, 1823 be confirmed as the type species following the designation by Roewer (1934). This will allow the accustomed usages of the names Eremobates and Eremorhax Roewer, 1934 to continue. Although preceded by type designations by Simon (1879b) and by Pocock (1902) and therefore invalid, Roewer's (1934) type designation was of a species originalJy included in Datames (= Eremobates) and it has been followed by subsequent authors.

14. The International Commission on Zoological Nomenclature is accordingly asked:

(1) to use its plenary power to set aside all previous fixations of type species for the following nominal genera:


(b) Eremobates Banks, 1900 (= Datames Simon, 1879) prior to the designation by Roewer (1934) of Galeodes pallipes Say, 1823;

(2) to place on the Official List of Generic Names in Zoology the following names:


(c) Eremobates Banks, 1900 (gender: masculine), type species by subsequent designation by Roewer (1934) Galeodes pallipes Say, 1823. as ruled in (1)(b) above;

(d) Eremorhax Roewer. 1934 (gender: masculine), type species by monotypy Datames magna Hancock, 1888;

(3) to place on the Official List of Specific Names in Zoology the following names:


(c) pallipes Say, 1823, as published in the binomen Galeodes pallipes and as defined by the neotype designated by Brookhart & Muma (1981) (specific name of the type species of Eremobates Banks. 1900);

(d) magna Hancock, 1888, as published in the binomen Datames magna (specific name of the type species of Eremorhax Roewer. 1934);

(4) to place on the Official Index of Rejected and Invalid Generic Names in Zoology the following names:


(b) Datames Simon, 1879 (Solifugae) (a junior homonym of Datames Stål, 1875)."

Harvey 2002a: 450, 451:

"Roewer (1934) described numerous new eremobatid genera from the Americas, including Eremorhax Roewer with the type and only species, Datames magna Hancock, 1888. Although the types of this species from Laredo, Texas, are apparently lost (Muma, 1951, 1970), Roewer (1934) had access to five specimens, two males and three females, from Texas that he identified as E. magnus. The genus Eremorhax was later enlarged by Muma (1951, 1970) with the synonymy of Eremopus Roewer, 1934 (type species Eremopus montezuma Roewer, 1934 by original designation), Eremocosta Roewer, 1934 (type species Eremocosta gigas Roewer, 1934 by original designation), and Eremacantha Roewer, 1934 (type species Eremacantha robusta Roewer, 1934 by original designation). Eremorhax was made the type genus of Eremorhaxinae Roewer, 1934, although this subfamily was later synonymized under Eremobatinae Kraepelin by Muma (1951). Brookhart and Muma (1987) discussed the identity of the species described as E. magnus (Hancock, 1888) by Roewer (1934), concluding that it was not conspecific with the species described and illustrated by Hancock (1888) and Muma (1951). Rather, they considered it a representative of the genus Eremobates Banks, but did not speculate any further on its identity. They then placed Eremorhax Roewer as a junior synonym of Eremobates Banks, 1900, and described a new genus, Arenotherus Brookhart and Muma, 1987 for Datames magna Hancock, 1888 and several other species. Although they consistently referred to the new genus as accommodating those species previously placed in the Eremorhax magnus group of Muma (1951), they did not specify a type species, in contravention of Article 13(b) of the International Code of Zoological Nomenclature, 3rd edition. The remaining species previously placed in Eremorhax were transferred to Eremopus by Muma (1989). The lack of a type designation for Arenotherus was clearly a lapsus by Brookhart and Muma (1987), and I hereby designate Datames magna Hancock, 1888 as type species (new designation), as they so obviously intended. In addition, when Brookhart and Muma (1987) discovered that Roewer (1934) had misidentified the type species when describing the genus Eremorhax, they were required by Article 70(b) of the International Code of Zoological Nomenclature then in effect (3rd edition) to request the Commission to resolve the case. Article 70.3 of the 4th edition of the Code (International Commission on Zoological Nomenclature, 1999) gives authors the power to designate as type species that species which best serves stability and universality - either the nominal species previously cited as type species, regardless of misidentification, or the species actually involved which was wrongly named in the type fixation - without application to the Commission. Designation of the nominal species previously cited as the type species would render Arenotherus Brookhart and Muma (1987) as a junior synonym of Eremorhax. Designation of the species actually involved would render the misidentified specimens available to Roewer (1934) as representing the type species. The identity of these specimens is unclear and my attempts to locate the material have proved fruitless - Roewer (1934) did not state from which institution they were borrowed, and they were not part of Roewer's collection now lodged in Naturmuseum Senckenburg, Frankfurt (Zilch, 1946). However, Brookhart and Muma (1987) did state (p. 1) that Roewer's description fitted a species of Eremobates but without access to these specimens it will be difficult to determine their identity. In the interests of stability, I here propose that the first option is the best solution and I here designate Datames magna Hancock, 1888 as the type species of Eremorhax, regardless of the misidentification made by Roewer (1934). This automatically places Arenotherus as a junior objective synonym of Eremorhax Roewer, 1934 (syn. nov.).

The following species are here referred to Eremorhax: Eremorhax arenus (Brookhart and Muma, 1987), comb. nov., E. joshui (Brookhart and Muma, 1987), comb. nov., E. latus Muma, 1951, E. magnellus (Brookhart and Muma, 1987), comb. nov., E. magnus (Hancock, 1888), comb. nov., E. mumai Brookhart, 1972, E. pimanus (Brookhart and Muma, 1987), comb. nov., E. puebloensis Brookhart, 1965, E. pulcher Muma, 1963 and E. tuttlei (Brookhart and Muma, 1987), comb. novo. 


Muma (1951) recognized Eremorhax as containing two species groups: the magnus group (currently retained as Eremorhax) and the striatus group (currently recognized as the genus Eremocosta). Members of the magnus group [Eremorhax] were characterized as having the fixed finger of the male weakly creased or hollowed mesoventrally, while members of the striatus group [Eremocosta] were characterized as having the fixed finger of the male distinctly grooved mesoventrally.  Muma (1970a) later characterized members of the genus Eremorhax in his  key to the subfamilies and genera of Eremobatidae as "robust, short legged species", although in the paragraph preceding the key, he makes reference to "[s]everal long legged species of the Eremorhax striatus species-group". The genus contains ten species from the southwestern United States and Mexico.

Included species

  • Eremorhax arenus (Brookhart & Muma 1987)
  • Eremorhax joshui (Brookhart & Muma 1987)
  • Eremorhax latus Muma 1951
  • Eremorhax magnellus (Brookhart & Muma 1987)
  • Eremorhax magnus (Hancock 1888)
  • Eremorhax mumai Brookhart 1972
  • Eremorhax pimanus (Brookhart & Muma, 1987)
  • Eremorhax puebloensis Brookhart, 1965
  • Eremorhax pulcher Muma, 1963
  • Eremorhax tuttlei (Brookhart & Muma, 1987)