Eremocosta calexicensis ( Muma 1951 )

Cushing, Paula E., Channiago, Felix & Brookhart, Jack O., 2018, Revision of the camel spider genus Eremocosta Roewer and a description of the female Eremocosta gigas Roewer (Arachnida, Solifugae), Zootaxa 4402 (3), pp. 443-466 : 451-455

Eremocosta calexicensis ( Muma 1951)

Figs. 1B , 2E–H , 3B , 4B , 5B

Eremorhax calexicensis Muma 1951: 50 –51, figs. 39–43. Eremopus calexicensis ( Muma 1989) : 6.

Eremocosta calexicensis ( Muma 1951) : Harvey 2002: 451.

Type material. Male holotype, female allotype and male paratypes from Calexico, California, USA, coll. M.G. Armstrong, no date ( USNM 2073704). We were able to examine male and female types.

Other specimens examined. Males (13). MÉXICO: Baja California Norte, Bahia de los Ángeles, 29 August 1964, coll. N Vidal ( IBUNAM CNAN-S00180 ) ; USA: Arizona, Maricopa County, 7 miles S. Gila Bend on BLM land, N 32.862222°, W 112.691667° , 284 m elev., 3 August 2008, coll. Paula E. Cushing & Anja Klann, at lantern light ( DMNS ZA.19985); USA: California, Imperial County, Ogilby Rd. N of Highway 8, N 32.76967°, W 114.83682° , 71 m elev., 2002, coll. Dustin A. Wood ( DMNS ZA.16319); USA: California, Imperial County, Salton Sea , N 33.2038°, W 115.8407°, - 68 m elev., April 2002, coll. USGS, pitfall trap ( DMNS ZA.16326); USA: California, Riverside County, Palm Canyon Dr. at junction with Bogert Trail , N 33.776°, W 116.545° , 165 m elev., 31 August 2005, coll. Wendell Icenogle, crawling on pavement below street light ( DMNS ZA.17214); USA: California, Riverside County, Coachella Valley, NE edge of Palm Springs, junction Airport Tachevah Dr. just E junction Highway 111, N 33.83772°, W 116.50958° , 137 m elev., 2 September 2006, coll. Wendell Icenogle, netted ( DMNS ZA.17222); USA: California, Riverside County, Mesa , N 33.96211°, W 116.6692° , 914 m elev., August 2000, coll. USGS, pitfall trap ( DMNS ZA.19159); USA: California, Riverside County, Mesa , N 33.96211° W 116.6992° , 856 m elev., August 2000, coll. USGS ( DMNS ZA.19162); USA: California, Riverside County, Blythe, 21 June 1978 ( UCD no number); USA: California, Riverside County, Blythe, 18 July 1980 ( UCD); USA: California, San Bernardino County, Wonder Valley Amboy Rd., 8.5 mi E Twenty Nine Palms (at Adobe Rd. junction), N 34.1657° W 115.9037° 487, m elev., coll. Wendell Icenogle, 17 May 2007, on or near building with lights (3 males: DMNS ZA.25457).

Females (7). MÉXICO: Baja California Norte, Bahía de Los Ángeles, 19 August 1964, no collector ( IBUNAM +CNAN-Sol00076) ; USA: California, Imperial County, Salton Sea , N 33.1974°, W 115.8374°, - 66 m elev., September 2001, coll. USGS, pitfall trap ( DMNS ZA.16324) ; USA: California, Imperial County, off California 78, 7/ 10 mile west of junction with California 86, N 33.12582°, W 115.86887°, - 49 m elev., 7 September 2010, coll. Wendell Icenogle, on highway in car headlights, feeding on dead male ( DMNS ZA.36261) ; USA: California, Imperial County, Algodones Dunes, 7.5 km n. Glamis , N 33.033333°, W 115.133333°, 80 m, coll. R & L Kimsey & T.J. Zavortink, pitfall at black light ( DMNS ZA.37394) ; USA: California, Riverside County, Santa Rosa Mountains, west rim of canyon, Pinyon Crest area , 1 mile north of California 74 and Carrizo Road junction, N 33.615735°, W 116.412535°, 945 m elev., 13 July 2013, coll. Wendell Icenogle, on ground at base of yellow floodlight beside gate ( DMNS ZA.36257) ; USA: California, Riverside County, San Jacinto Mountains, on road to Palm Springs Tramway , 2 7/ 10 mi W. of Highway 111, N 33.844832°, W 598 m elev., coll. Wendell Icenogle, on road w/ car headlights ( DMNS ZA.36899) ; USA: California, San Diego County, 7/ 10 mile south of center of Borrego Springs , N 33.25218°, W 116.37521°, 183 m elev., 12 September 2008, coll. Wendell Icenogle, on pavement below light at motel ( DMNS ZA.36262).

Diagnosis. Eremocosta calexicensis is closely related to E. titania . The two species can be separated by the length of the fixed finger of the male, shape of the VDC, and relative length of the VDC. Most males of E. calexicensis have the fixed finger somewhat shorter than the movable finger. The edge of the VDC, when viewed from the retrolateral surface ( Fig. 2E ) is slightly convex compared to the same view of the VDC of E. titania . The VDC of E. calexicensis also extends only ½ or less the length of the fixed finger whereas the VDC of E. titania typically extends more than ½ the length of the fixed finger (compare Fig. 2E & W ). Males of E. calexicensis are also generally larger than males of E. titania . The female genital operculum is also distinct from E. titania . The wings of the genital operculum of E. calexicensis are shaped like hockey sticks with the inner margins more or less parallel to one another ( Fig. 4B ), whereas the inner margins of the wings quickly diverge in E. titania ( Fig. 4F ).

Measurements. Male holotype. TL 37.0; CL 10.4; CH 4.0; FNL 0.3; FNH 0.5; FFH 1.0; PL 42; PT and PMT NA (pedipalps of male disassociated in vial and damaged); LI 31.0; LIV 56.0; PPL 5.2; A/CP 8.3; FNL/FNH 0.6; FFH/FNH 2.0.

Males (n = 13). TL 25.0–43.0; CL 6.5–13.6; CH 3.0–9.6; FNL 0.2–0.9; FNH 0.4–1.0; FFH 0.6–1.1; PL 24.0– 43.0; PT 1.3–4.0; PMT 7.0–10.1; LI 12.0–31.5; LIV 26.0–47.0; PPL 3.0–6.4; A/CP 4.4–8.2; FNL/FNH 0.2–1.7; FFH/FNH 0.9–2.0; FFH/ CH 0.1–0.3.

Female allotype. TL 42.0; CL 13.8; CH 6.1; PL 41.0; PT and PMT NA (pedipalps of female disassociated in vial and damaged); LI 30.0; LIV 49.0; A/CP 6.1.

Females (n = 7). TL 28.0–48.0; CL 9.0–15.7; CH 4.0–6.5; PL 26.0–37.0; PT 1.2–3.1; PMT 7.9–10.0; LI 17.0– 34.0; LIV 34.0–43.0; PPL 4.0–6.0; A/CP 4.0–6.3.

Description. Coloration. Male. Pale yellow overall. Appendages slightly darker at distal end of femur and proximal end of tibia. Propeltidium pale ( Fig. 5B ). Abdomen typical with dark, violet-brown rectangles on each segment that give the appearance of a stripe; ventral grey-cream.

Chelicera. Male. Chelicera as in Muma (1951, p. 49, fig. 40). VDC deep, cup-shaped occupying approximately one-third to one-half the length of fixed finger with a slight prolateral orientation ( Fig. 1B ). Fixed finger with no median dentition. Movable finger: large, acute MP-small MSM-small MM; large MPL. ( Figs. 2E & F ). Fondal notch tiny. Sometimes 1–3 RFA on the ventral edge of the fixed finger as well as 2–3 in the fondal notch ( Fig. 3B ). Muma graded the fondal teeth I, II, III, IV but we suggest they might be II, I, III, IV since I and II are about equal in size, tiny or absent IV retrolaterally and I, III, II, tiny serrate IV prolaterally ( Fig. 3B ). FNH smaller than the FFH.

Setation. Male. Typical Eremocosta flagellum complex. Prolateral setal complex typical, plumose pvd extend to base of fondal tooth I, mpd a proximal patch. Numerous long, thin palpal setae. No ctenidia or palpal papillae.

Coloration. Female. Coloration as in the males. Pedipalps dusky on femur as well as tibia, tarsus, and metatarsus. Propeltidium pale with dark anterior margin.

Chelicera. Female. Typical. Fixed finger: FP-FSM-FM-small FSD-FD. Movable finger: MP-MSM-MM; MPL distinct ( Figs. 2G & H ). One large RFA; fondal teeth II, III, I, tiny IV retrolaterally; I, III, II, IV prolaterally.

Setation. Female. Typical eremobatid female prolateral setal pattern. Outer tubular, inner plumose from FD to MM. Pedipalps typical with numerous short, thin setae, paired seta at the base of tibia. Few or no bacilli on coxa.

Genital operculum. Female genital operculum as in Muma (1951, fig. 43) with long anterior arms, club-like wings with two tiny outgrowths/knobs on the interior margin ( Fig. 4B ).

Distribution. Eremocosta calexicensis ranges from at least Bahía de los Ángeles on the east coast of Baja California Norte through the Santa Rosa Mountains of California, USA where it is sympatric with E. titania in the southern part of that species’ range. In fact, a male E. titania from Imperial County, California USA (DMNS ZA.23484) was captured with the carcass of a male E. calexicensis adjacent to it; presumably the E. titania had been eating the E. calexicensis .

Discussion. Because of the morphological similarity between E. calexicensis and E. titania and because the ranges are partly sympatric, there may be instances of hybridization between the two species. Cushing et al. (2015) demonstrated no significant molecular differences between the two specimens used to represent E. calexicensis and E. titania in the phylogenetic analysis. Upon re-examination of these specimens, it was clear that they both represented E. titania . Muma’s (1951) designation of specimens from Arizona are probably E. striatus and those from coastal California are probably E. bajaensis . In his 1951 descriptions of both E. calexicensis and E. titania Muma noted variance that probably reflects these misidentifications.

Figures

FIGURE 1. VDC on the fixed finger of the right chelicera of male Eremocosta. Refer to Figure 2 for scale. A) Eremocosta bajaensis (holotype from CAS).B) Eremocosta calexicensis (holotype from USNM).C) Eremocosta formidabilis (IBUNAM). Note the more proximal locationof the VDC on the fixed finger of thisspecies.D) Eremocosta gigas (holotype from SMK).E) Eremocosta gigasella (DMNS ZA.35465). F) Eremocosta striata (DMNS ZA.21079). G) Eremocosta titania (DMNS ZA.15427).Arrows point to an internal carina in the VDC of some species.

FIGURE 2. Retrolateral (left) and prolateral (right) cheliceral views of the right chelicera of Eremocosta species. Scale bars = 1.0 mm. See text for collection abbreviations. A & B) Eremocosta bajaensis male (holotype from CAS). C & D) Eremocosta bajaensis female (IBUNAM). E & F) Eremocosta calexicensis male (holotype from USNM). G & H) Eremocosta calexicensis female (allotype from USNM). I & J) Eremocosta formidabilis male (IBUNAM). K & L) Eremocosta gigas male (holotype from SMK). M & N) Eremocosta gigas female (IBUNAM CNAN Sol00114). O &P) Eremocosta gigasella male (DMNS ZA.35465). Q & R) Eremocosta gigasella female (DMNS ZA.17350). S & T) Eremocosta striata male (DMNS ZA.21079). U & V) Eremocosta striata female (DMNS ZA.25451). W & X) Eremocosta titania male (DMNS ZA.15427). Y & Z) Eremocosta titania female (DMNS ZA.36256).Arrows in K, O, and S point to MD tooth (see text).

FIGURE 3. Fondal teeth on right fixed fingers of male specimens illustrated in Fig. 2. See Fig. 2 for scale. A) Eremocosta bajaensis (holotype from CAS).B) Eremocosta calexicensis (holotype from USNM).C) Eremocosta formidabilis (IBUNAM). D) Eremocosta gigas holotype from SMK). E) Eremocosta gigasella (DMNS ZA.35465). F) Eremocosta striata (DMNS ZA.21079).G) Eremocosta titania (DMNS ZA.15427).

FIGURE 4. Genital opercula of females. Same specimens as illustrated in Fig. 2. Scale bars = 1.0 mm. A) Eremocosta bajaensis(IBUNAM).B) Eremocostacalexicensis (allotypefrom USNM).C) Eremocosta gigas (IBUNAM CNANSol00114). D) Eremocosta gigasella (DMNS ZA.17350). E) Eremocosta striata (DMNS ZA.25451). F) Eremocosta titania (DMNS ZA.36256).

FIGURE 5. Propeltidia of specimens illustrated in Fig. 2. Scale bars = 1.0 mm. A) Eremocosta bajaensis male (holotype from CAS). B) Eremocosta calexicensis male (holotype from USNM). C) Eremocosta formidabilis male (IBUNAM). D) Eremocosta gigas male (holotype from SMK). E) Eremocosta gigas female (IBUNAM CNAN Sol00114). F) Eremocosta gigasella male (DMNS ZA.35465). G) Eremocosta striata male (DMNS ZA.21079). H) Eremocosta titania male (DMNS ZA.15427).