Genus Eremocosta Roewer 1934

Eremopus Roewer, 1934: 561 [junior homonym of Eremopus Brady, 1910 (Crustacea: Copepoda)]; Muma 1989: 3 (key), 4.

Eremocosta Roewer 1934: 569 (synonymised by Muma 1951: 41); Harvey 2002a: 450, 451; Cushing, Channiago and Brookhart 2018: 445, 446.

Eremacantha Roewer 1934: 571 (synonymised by Muma 1970a: 9).


Eremocosta striata (Putnam 1883). Top photo: male. Bottom photo: female. Both from Santa Cruz County, AZ.
Copyright Warren E. Savary.



Type species:

of Eremopus: Eremopus montezuma Roewer 1934 by original designation.

of Eremocosta: Eremocosta gigas Roewer 1934 by original designation.

of Eremacantha: Eremacantha robusta Roewer 1934 by original designation.


Diagnosis:

Eremobatine species in which the fixed cheliceral finger of the male bears a distinct ventrodistal concavity.  The concavity does not contain an enlarged seta.


 

Above: Tip of fixed cheliceral finger of Eremocosta titania (Muma), mesal view, showing aventrodistal concavity.

Below: Chelicera of male Eremocosta bajaensis (Muma). Illustrations by Warren E. Savary.



Original description:

Roewer 1934: 569:

"Eremobatinae, deren 2. und 3. Tarsus ventral mit jeweils 1.2.1.2.2.4.6 Dornen und deren 4. Tarsus ventral mit 4.2.2.4.2.2.4/2/2.2.4 Dornen bewehrt ist (Abb. 320, f, m).

2 Arten, deren eine nur als ♂ deren andere nur als ♀ bekannt ist."


Subsequent accounts:

Roewer, 1934: 561 (as Eremopus):

"Eremobatinae, deren 2. und 3. Tarsus ventral mit jeweils 4.6 Dornen und deren 4. Tarsus ventral mit 2.2.2/0/4.6 Dornen bewehrt ist (Abb. 320, b, k).

8 Arten, von denen die eine nur als ♂ bekannt ist und möglicherweise zu einer der 7 anderen Arten gehört, die nur als ♀ bekannt sind."


Roewer 1934: 571 (as Eremocantha):

"Eremobatinae, deren 2. und 3. Tarsus ventral mit jeweils 2.2.2.4.6 Dornen und deren 4. Tarsus ventral mit 4.2.2.2.4.2.4/2/2.4.6 Dornen bewehrt ist (Abb. 320, d, p).

Nur 1 Art"


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

(Males Only) Leg 1 with one claw; chelicerae about twice as long as wide; small to large species ................................................................................................ Eremobatinae .......
Fixed chelicera! finger long, style-like or needle-like; mesoventral groove a crease, slot or cup-like structure ; moderate-sized to large species..........................................................
Mesoventral groove a distinct crease, cup, or slot that may or may not extend to base of finger; movable finger dentition normal or increased........................................................
Mesoventral groove short not extending to base of finger; apical striate or plumose setae of male flagellum complex not obviously modified or flattened........................................
Palpal metatarsus, tibia and femur provided with enlarged spine-like setae , but they are not in ventral rows, especially robust, nor obviously movable ............ Eremopus Roewer


"Predominately large Eremobatinae. Fixed chelicera! finger of males with indistinct to distinct short mesal or mesoventral grooves that do not extend to the base of finger. Dorsal setae of flagellum complex striate but often weakly so, ventral setae plumose but often weakly so; apical setae of complex not obviously modified. Females have opercula alate and widely separated posteriorly."


Key to Species groups of Eremopus Roewer
1. Male cheliceral groove a short distinct ventral cup or slot; males with or without process distad to anterior tooth on movable cheliceral finger ; female opercula alate with concave posterior notches, but without anterior pits ................................................. striatus group
1. Male cheliceral groove a short indistinct mesal crease; males without process distad of anterior tooth on movable finger; female opercula angulate with anterior pits..................
..................................................................................................................montezuma group


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.). In addition, Eremopus Roewer, 1934 is here found to be a junior homonym of the copepod genus Eremopus Brady, 1910. However, a replacement name is not needed for Roewer's name because Eremopus currently has two junior synonyms, Eremocosta Roewer, 1934 and Eremacantha Roewer, 1934 (Muma, 1951, 1970), of which Eremocosta is here selected as the valid name. The type species of Eremocosta, E. gigas Roewer, is well defined and the holotype is an adult male lodged in Naturmuseum Senckenburg, Frankfurt, Germany (Muma, 1970), whereas the holotype of the type species of the other synonym, Eremacantha, E. robusta Roewer, is an immature specimen (Muma, 1970) whose specific identity may never be known with certainty."


Cushing, Channiago and Brookhart 2018: 443-446:

"Abstract

A recent phylogenetic analysis demonstrated that the solifuge genus Eremocosta (Eremobatidae), although not monophyletic, formed a strongly supported group, rendered paraphyletic by the exclusion of E. acuitlapanensis, which we herein determine is misplaced in this genus. We revise the taxonomy of the genus Eremocosta. Nine species of the 13 currently placed in the genus are retained, E. bajaensis (Muma 1986), E. calexicensis (Muma 1951), E. formidabilus (Simon 1879), E. gigas Roewer 1934, E. gigasella (Muma 1970), E. spinipalpis (Kraepelin 1899), E. striata (Putnam 1883), and E. titania (Muma 1951). Eremocosta fusca (Muma 1986) and E. montezuma (Roewer 1934) are returned to the genus Eremorhax along with E. arenarum. Eremocosta hystrix and Eremocosta acuitlapanensis (Vázquez & Gaviño-Rojas 2000) are transferred to Eremobates. We re-evaluated E. nigrimana (Pocock 1895) and determined that, since the type shows the ventrodistal concavity (VDC) diagnostic for the genus Eremocosta, it should be retained in that genus; however, because the type locality is identified as Afghanistan, far outside the range of any Eremobatidae, its status and placement remain uncertain. Eremocosta robusta (Roewer 1934) was designated nomen dubium by Muma and we maintain this designation. We provide a key to the species of Eremocosta and provide a description of the female of E. gigas."

"Revised diagnosis. Eremocosta species are relatively large; ranging from 26 to 50 mm in length. Color patterns of the body and pedipalps are variable. The diagnostic synapomorphy of Eremocosta is the male fixed finger with a deep VDC (Figs. 1A–G). Neither Roewer (1934) nor Muma (1951, 1970) described the carina running inside this cavity that is evident in some species (Figs. 1B–F, arrows). The fixed finger of males lacks median dentition (Fig. 2). The movable finger of males has a large MP, one to two MSM, and one MM teeth (Fig. 2). The MP tooth is large and distinct. In E. gigas, E. gigasella, and E. striata the movable finger has what we here call a distal tooth of the movable finger (MD) (Figs. 2K, O & S, arrows). The fondal notch ranges from obscure to distinct (Fig. 2), and ordinarily has two to four RFA in the fondal notch and in some species one to three RFA on the ventral side of the fixed finger (Fig. 3). Pro- and retrolateral fondal teeth vary in gradation among the species (Fig. 3). The retrolateral IV is tiny in some species. Male cheliceral setal formation (sfc) consists of tubular setae dorsally, two rows of tubular setae prolaterally with the inner mesal row being plumose and extending dorsally to and sometimes above fondal tooth I. The prodorsal setae (mpd) consist of a proximal patch in all species except E. gigasella which has a linear row extending to MM. The proventral distal setae (pdp) consist of three robust setae and one proximal thin seta. The female chelicera fixed finger has a large FP, one to two FSM, a large FM, small FSD, and distinct FD (Fig. 2). The female movable finger has a large MP, one or two MSM, and one MM teeth. MPL tooth distinct on males and females (Fig. 2). Eremocosta females demonstrate typical eremobatid female cheliceral setal pattern with pvd and mpd setae forming a continuous plumose row from the FD to the MM teeth. The arms of the genital operculum of Eremocosta are alate and widely separated posteriorly (Fig. 4 and Muma 1989). The genital operculum is largely species-specific with some possessing thin arms with club like wings; others recurved, bent laterally at their posterior ends with no distinct external pits. No palpal papillae or ctenidia are present."

Abbreviations as follows: CL—chelicera length; CH—chelicera height; FNL—fondal notch length; FNH— fondal notch height; FFH—fixed finger height; LI—first leg length; LIV—fourth leg length; other legs designated as LII, LIII; PPL—propeltidium length; PL—pedipalp length; PMT—palpal metatarsus length; PT—palpal tarsus length; TL—total length measured from distal tip of chelicera to posterior edge of the abdomen, although total length is skewed depending on distension of the abdomen (Muma & Brookhart 1988); VDC—ventrodistal concavity of the male fixed finger. Cheliceral tooth character abbreviations are: FD—fixed finger, distal tooth; FM—fixed finger, medial tooth; FP—fixed finger, proximal tooth; FSD—fixed finger, subdistal tooth/teeth; FSM—fixed finger, submedial tooth; MM—movable finger, medial tooth; MD—movable finger, distal tooth; MP—movable finger, proximal tooth; MSM—movable finger, submedial tooth; MPL—movable finger, prolateral series teeth; RFA—retrofondal apical teeth; RF—retrofondal teeth. Bird et al. (2015) does not define or illustrate what we call the MD, but such a tooth, or ridge, is clearly visible on the movable finger of some male Eremocosta species (see arrows, Figs. 2K, O & S).


Cushing, Channiago, and Brookhart also provide a taxonomic summary of the genus and its included species, as well as a discussion of the characters used in their revision and provide a key to the included species (see below).


Notes:

The genus Eremocosta currently includes eight species from the southwestern United States and Mexico and one species [Eremocosta nigrimana (Pocock 1895)] of unknown provenance.


Included species


  •  

    Key to species (modified from Cushing, Channiago and Brookhart 2018)


      • 1. Fondal notch (male) deep and distinct.........................................................................................2
      •     Fondal notch shallow and/or indistinct........................................................................................4
      • 2. Ventrodistal concavity of male extends proximally on ventral edge of fixed finger to level of
            fondal teeth.............................................................................................................E. formidabilis
      •    Ventrodistal concavity of male distal on ventral edge of fixed finger..........................................3
      • 3. Fixed finger of male dagger-like, movable finger with distinct medial tooth and distinct tooth-
           like distal tooth. Genital opercula of female a with wings tear-drop shaped....................E. gigas
      •    Fixed finger of male not dagger-like, movable finger with medial tooth lacking or greatly
            reduced and distal tooth present as a ridge. Genital opercula of female with straight, parallel,
            narrow anterior arms broadening into distinct, rounded club-shaped wings, shaped like hockey
            sticks................................................................................................................................E. striata
      • 4. Movable finger of male with quadrate distal tooth, genital opercula of female with recurved
            anterior arms and recurved posterior margins............................................................E. gigasella
      •    Movable finger of male lacking a distal tooth, genital opercula of female not as above............5
      • 5. Fixed finger of male usually as long as or slightly longer than movable finger. Movable finger
            usually with two small submedial teeth (sometimes only one). Lower edge of ventrodistal
            concavity, when viewed from ectal side of chelicera, slightly concave. Genital opercula of
            female with long straight anterior arms; posterior wings quadrate..............................E. titania
      •    Fixed finger usually slightly shorter than movable finger. Movable finger usually with just one
            small submedial tooth. Lower edge of ventrodistal concavity, when viewed from ectal side of
            chelicera, slightly convex. Female genital opercula not as above.............................................6
      • 6. Movable finger of male with small but distinct medial tooth. Genital opercula of female club-
            shaped with long anterior arms and a posterior knob, posterior wing ovate.......E. calexicensis
      •    Movable finger of male with barely visible medial tooth (sometimes a tiny ridge). Female with
            wings of genital opercula thin and curved...............................................................E. bajaensis

    Bibliography: