Eremocosta calexicensis (Muma 1951)
Eremorhax calexicensis Muma, 1951: 49–51, figs 39–43; Muma, 1970a: 7; Muma, 1976: 14; Muma, 1987: 19; Vázquez Rojas, 1995: 30; Vázquez Rojas, 1996: 76.
Eremopus calexicensis (Muma): Muma, 1989: 5,6 (key).
Eremocosta calexicensis (Muma): Harvey, 2002: 451; Cushing, Channiago and Brookhart, 2018: 447, 448, 451-455, Figs. 1B, 2E–H, 3B, 4B, 5B.
Chelicerae of male similar to that of Eremocosta calexicensis (Muma), but distinguished by the much smaller and more ridge-like (rather than tooth-like) medial tooth of the movable finger. Fondal notch short but distinct. Anterior edge of propeltidium dark. Wings of females' genital opercula thin and curved.
Male holotype, female allotype, and male paratype from Calexico, California (M. G. Armstrong), in
United States National Museum. Paratypes also in the Museum of Comparative Zoology, the American
Museum of Natural History, California Academy of Sciences, Cornell University, University of Utah, and
University of Nebraska.
Muma, 1951: 45 (key), 50–51, figs 39–43:
45 - KEY TO MALES
"1. Movable finger without an additional process, mesoventral groove elliptical, not
3. Groove of fixed finger shallow and mesoventral in position....Eremorhax calexicensis,
50-51 - "Eremorhax calexicensis, new species
MALES: Total length, 30.0 to 37.0 mm.
Holotype, larger measurements.
All specimens badly discolored by alcohol but coloration apparently light yellow to dark yellow, with dusky markings as follows: anterior margin of propeltidium bordered with a dark line, eye tubercle lightly dusky but eyes with dark rings, legs and palpi unmarked or at most lightly dusky at distal ends of femora and proximal ends of tibiae. Malleoli white.
Dentition of chelicerae variable but following the general pattern shown in figures 39 to 41. Movable finger with principal tooth large, anterior tooth small, one intermediate tooth near the base of the anterior tooth, and a small but distinct mesal tooth. Fixed finger nearly straight, undulate on the ventral margin, and lightly hooked downward at tip. Fondal teeth occurring in two rows of four each, ectal row graded in size I, II, III, IV, mesal row I, III, II, IV. Fourth fondal teeth scarcely distinguishable from dentate socket margin of movable finger. Fondal notch U-shaped, about one-half as wide as base of fixed finger, and commonly bearing two or three denticules.
Groove of fixed finger a flat, half-oval concavity on the mesoventral surface which occupies a little more than the distal half of the finger. Flagellum complex composed entirely of simple tubular spines. Mesal setae of movable finger simple on distal half and plumose on proximal half of finger at the dorsal margin of the setal area.
Eye tubercle situated on anterior margin of propeltidium. Eyes separated by slightly less than a diameter. Propeltidium wider than long by a ratio of 1 to 1.6.
Metatarsus, tarsus, and tibia of palpus provided with numerous cylinder bristles, but there is no scopula on metatarsus. Metatarsus of palpus about three and one-half times as long as tarsus.
First spiracular abdominal sternite not normally provided with ctenidia.
FEMALES: Total length, 40.0 to 42.0 mm.
Allotype, larger measurements.
Coloration similar to that of male. Discolored by alcohol.
Dentition of chelicerae as shown in figure 42. Movable finger with principal and anterior teeth large, one small intermediate tooth, and a distinct mesal tooth. Fixed finger with principal and medial teeth large, anterior tooth small, two intermediate teeth, of which one is very small, behind principal tooth, one between principal and medial teeth, and one between medial and anterior teeth. Fondal teeth as in male.
Structure similar to that of male.
Opercula of genital segment shown in figure 43.
TYPE LOCALITY: Male holotype, female allotype, and male paratype from Calexico, California (M. G. Armstrong), in United States National Museum. Paratypes also in the Museum of Comparative Zoology, the American Museum of Natural History, California Academy of Sciences, Cornell University, University of Utah, and University of Nebraska.
RECORDS: Arizona: Yuma, two males and one female; Hot Springs, August 16, one male (C. W. North); Tucson, August 6, 1936, one female (Wehle), May 7, 1936, one male (D. L. Ryerson); Congress Junction, July, 1938, one male (J. P. Klein); Hope, Yuma County, August 12, 1948, one male. California: 10 miles southeast of Palm Springs, October, 1947, one male (C. M. Bogert); El Centro, August 13, 1917, one male; Holtville, July 2, 1929, one male (R. H. Beamer); Coachella, May 18, 1929, two males (E. C. Van Dyke); Poway, San Diego, one male (F. E. Blaisdel). State unknown: Horseshoe Bend of the Colorado River, St. Albatross, one female.
REMARKS: This species is very closely related to titania, new species, from which it differs principally in the genital opercula of the female and position of the ventral groove of the fixed finger of the male.
Muma 1970: 245:
245 - "Eremocosta calexicensis (Muma)
Eremorhax calexicensis Muma, 1951, p. 50
DIAGNOSIS: This species is closely related to E. titania Muma. It is distinguished by the mesoventral position of the apically located groove of the male fixed cheliceral finger and the anteriorly parallel female genital opercula.
The species is adequately described by Muma (1951).
TYPE LOCALITY: Male holotype, female allotype, and male paratype from Calexico, California, by M. G. Armstrong, in USNM.
DISTRIBUTION: USA: Arizona, California; Mexico: Baja California.
DISCUSSION: E. titania Muma and this species are closely related.
Muma 1986: 19:
19 - "E. calexicensis Muma , 1951; Muma (1970) recorded this species from Baja California, Mexico."
Muma 1987: 19:
19 - "E. calexicensis Muma , 1951; Muma (1970) recorded this species from Baja California, Mexico."
Muma 1989 (as Eremopus calexicensis (Muma)): 5,6 (key):
5,6, - Key to species of striatus group (Males)
1.' Movable cheliceral finger without a process distal of anterior teeth, a fixed finger that is
gradually enlarged basally, and an elliptical mesoventral, ventral, or ectoventral groove
not distinctly enlarged basally...........................................................................................4
4.' Distinct groove of fixed cheliceral finger distal in position; minor teeth of movable
cheliceral finger not on anterior margin of principal tooth...............................................5
5.' Anterior tooth of movable cheliceral finger normal; palpi and legs dusky at union of
femora and tibia at least ventrally on palpi and leg 4.......................................................6
6.' Groove mesoventral in position; duskiness on palpi and legs restricted to femoral tibial
unions..............................................................................................E. calexicensis (Muma)
Vázquez Rojas, 1995: 30:
Vázquez Rojas, 1996: 76:
Harvey 2002: 451:
451 - Recognized Eremopus Roewer 1934 as a junior homonym of the copepod genus Eremopus Brady 1910, resurrected Eremocosta Roewer 1934, transferred Eremorhax calexicensis Muma 1951 to Eremocosta.
Harvey 2003: 245:
245 - "Eremocosta calexicensis (Muma)
Eremorhax calexicensis Muma, 1951: 50–51, figs 39–43; Muma, 1970a: 7; Muma, 1976: 14; Muma, 1987: 19; Vázquez Rojas, 1995: 30; Vázquez Rojas, 1996: 76.
Eremopus calexicensis (Muma): Muma, 1989: 6.
Eremocosta calexicensis (Muma): Harvey, 2002: 451.
Type locality: Calexico, Imperial County, California, U.S.A.
Distribution: Mexico, U.S.A. (Arizona, California).".
Brookhart & Brookhart 2006: 303:
303 - "Eremocosta calexicensis (Muma 1951)
Eremorhax calexicensis Muma 1951:50.
Eremopus calexicensis (Muma): Muma 1989:6.
Eremocosta calexicensis (Muma): Harvey 2002: 451.
Type material.—Male holotype, female allotype and male paratypes from Calexico, California, USA (USNM).
Recorded specimens.—Numerous males and females.
Distribution.—USA: Arizona, California. Mexico: Baja California Norte. Biome: Sonoran Desert.
Cushing, Channiago and Brookhart, 2018: 447 (Fig. 1B) 448 (Figs. 2E–H), 451 (Fig. 3B and text), 452, 453 (Fig. 4B), 454 (Fig. 5B), 455.
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.
UNITED STATES: Arizona, California. MEXICO: Sonora.
Cushing et al. (2015) demonstrated no significant molecular differences between the two specimens used to represent E. calexicensis and E. titania in their phylogenetic analysis of the family Eremobatidae. Cushing, Channiago, and Brookhart (2018) note, however, that upon re-examination of these specimens, it is clear that they both represent E. titania.