Myrmecicultor chihuahuensis Ramírez, Grismado, and Ubick, 2019

Ramírez, Martín J., Grismado, Cristian J., Ubick, Darrell, Ovtsharenko, Vladimir, Cushing, Paula E., Platnick, Norman I., Wheeler, Ward C., Prendini, Lorenzo, Crowley, Louise M. & Horner, Norman V., 2019, Myrmecicultoridae, a New Family of Myrmecophilic Spiders from the Chihuahuan Desert (Araneae: Entelegynae), American Museum Novitates 2019 (3930), pp. 1-24 : 6-16

Myrmecicultor chihuahuensis Ramírez, Grismado, and Ubick , new species

Figures 1–12 , map 1

Cf. Gnaphosoidea TEX, Ramírez, 2014 (provisional name in phylogenetic analysis).

TYPES. Male holotype ( CAS 9067289 ; temporary preparations CJG-1504, 1508), from the United States: Texas, Brewster Co., Dalquest Desert Research Station ( DDRS), Big Sandy #4, N 29°33′05.7″, W 103°47′38.3″, 1232 m, Oct. 16–Nov. 1, 2014 , N. V. Horner, propylene glycol pitfall traps, in 100 % ETOH. Male and female paratypes ( CAS 9067288 ) , DDRS, Big Sandy #3, N 29°33′04.2″, W 103°47′38.3″, elev. 1232 m, Sept. 24–Oct. 15, 2014 , N. V. Horner, in 100 % ETOH. Female paratype ( CAS 9067293 ; temporary preparation CJG-1505) , DDRS, below Alamo #4, N 29°33′20.00″, W 103°47′04.7″, 1143 m, Oct. 16–Nov. 1, 2014 , N. V. Horner, propylene glycol pitfall traps, in 100 % ETOH. Female paratype ( AMNH [ ARANP19 ], temporary preparations CJG-620, 632, MJR-1382–1383) , DDRS, Sandy Canyon Sept. 22–Oct. 4, 2005 , N. V. Horner and G.H. Broussard, pitfall covered, in propylene glycol .

ETYMOLOGY. The specific epithet is an adjective referring to the Chihuahuan Desert, where most specimens were collected.

DIAGNOSIS. By the characters of the family.

MALE (holotype): Total length 2.89. Carapace length 1.47, width 1.20. Clypeus 0.26 (at AME), 0.19 (at ALE). Eye sizes and interdistances: AME 0.13, ALE 0.10, PME 0.13, PLE 0.09, AME-AME 0.06, AME-PME 0.08, AME-ALE 0.02, PME-PME 0.03, PME-PLE 0.07, ALE-PLE 0.02, AER 0.39, PLE-PLE 0.03, PER 0.43. Leg lengths: Leg I: total 4.70 (femur 1.55, patella 0.56, tibia 1.32, metatarsus 1.27, tarsus broken); Leg II: 4.98 (1.32 0.56 1.10 1.18 0.78); Leg III: 4.43 (1.19 0.49 0.97 1.13 0.65); Leg IV: 5.70 (1.47 0.56 1.29 1.55 0.83). Leg formula 4123. Color in alcohol: Carapace whitish, black in eye region; sternum whitish. Abdomen uniformly whitish both dorsally and ventrally. Legs also whitish, but distal podomeres slightly darker. Live specimens darker, with pale brown coloration (fig. 11F). Vestiture: Carapace almost glabrous, chelicerae with few needlelike setae at promargin. Sternum with marginal setae, some setae on posterior extension. Abdomen dorsum with two types of setae, mostly needlelike, with some thickened setae scattered irregularly; appendages densely clothed with thick setae, but with few spines (see below); metatarsi III and IV with distal preening brush of plumose setae. Carapace broadly oval in dorsal view, highest in front of fovea; thoracic fovea narrow, dark longitudinal line. Eyes mostly surrounded by black pigment, contrasting sharply with pale carapace (fig. 4D); AME largest, most convex, lateral eyes subequal, partly surrounded by black pigment, PME nearly rectangular, with oblique tapeta at 90° angle. AER procurved in dorsal view, PER strongly procurved in dorsal view; both eye rows procurved in anterior view. Clypeus high, about twice ALE diameter (fig. 4C). Chelicerae as in female. Sternum heart shaped, anteriorly truncate, with posterior pointed extension between coxae IV, with marginal setae. Precoxal triangles absent. Labium trapezoidal, wider than long; endites quadrate, with serrula on anterior margin. Abdomen lacking dorsal scute. Epiandrum with two spigots (observed in KOH-digested specimen). Respiratory system consisting of two book lungs and wide tracheal spiracle slightly separated from spinnerets, giving origin to four simple, unbranched tracheae, all limited to abdomen, gradually attenuated. Spinnerets superficially as in female, but not examined with SEM; PMS apparently lacking spigots (as observed with stereomicroscope). Leg spines: I: femur d1-1-0, p1-0-0, metatarsus v2ap; II: femur 1-1-0, p1 (very small)-0-0, metatarsus v2ap; III: femur d1-1-0, tibia v2ap, metatarsus v2ap (below preening brush); IV: femur d1-1-0, tibia v2ap, metatarsus v2ap (below preening brush). Palp: femur with 1-1 dorsal macrosetae, lacking ventral process; tibia cup shaped, with RTA forming procurved concavity with retrolateral dorsal small, pointed protrusion; cymbium with dorsoapical patch of chemosensory setae (fig. 9G) situated in a cavity, dorsal surface with widened bipectinate setae (probably scales) (fig. 9F), and seven trichobothria in two longitudinal rows. Copulatory bulb: subtegulum simple, visible from retrolateral side; tegulum simple bearing spermophore without loops; median apophysis articulated, small hook in retrobasal position; two conductors (C1 and C2; figs. 9D, 10D), latter larger than former, more sclerotized, coiled, anteriorly directed. Embolus articulated, bent at right angle to retrolateral side; tip widened.

FEMALE (paratype CAS 9067293): Total length 2.73. Carapace length 1.26, width 1.09. Clypeus 0.13 (at AME), 0.07 (at ALE). Eye sizes and interdistances: AME 0.14, ALE 0.09, PME 0.12, PLE 0.09, AME-AME 0.05, AME-ALE almost touching, AME-PME 0.06, PME-PME 0.02, PMEPLE 0.06, ALE-PLE 0.03, AER 0.37, PER 0.41. Palpus and leg lengths: Palpus: 1.35 (0.39 0.21 0.29 0.46); Leg I: 4.86 (1.33 0.51 1.14 1.09 0.79); Leg II: 4.27 (1.12 0.45 0.97 1.02 0.71); Leg III: 3.91 (1.03 0.40 0.84 1.03 0.61); Leg IV: 5.04 (1.28 0.49 1.16 1.35 0.75). Leg formula 4123. Leg spines: Palp: tarsus d1-1; I: femur d1-1-0, p1 (very small)-0-0; metatarsus v1ap; II: femur 1-1-0; metatarsus v1ap; III: femur d1-1-0, metatarsus v1ap (below preening brush); IV: femur d1-1-0, tibia v1ap, metatarsus v1ap (below preening brush, fig. 6B). Tarsal organ (observed on leg II) as simple pit, not domed (fig. 7C). Patellar indentation narrow, leading to retrolateral lyriform organs (fig. 7A). Tarsal step opposing metatarsal sensory organ with irregular, mainly longitudinal ridges (fig. 6G). Two tarsal claws, pectinate, without claw tuft or any other adhesive setae (fig. 6E, F); only two large setae with many barbs oriented distally, but without expanded tips. Trichobothrial shaft with expanded base covered by bumps, hood with several proximal transverse ridges (fig. 7B), on single row on leg tarsi. Palpal claw well developed, with teeth, tarsus apically with dorsal cavity containing a patch of chemosensory setae (fig. 5F, G). Color and general morphology (fig. 3) as in male. Vestiture as in male, widened bipectinate setae as that of male cymbium present on prolateral sides of palpal tibia and tarsus. Chelicerae slightly expanded anteriorly, anterior surface (fig. 5B, D) with row of rake setae and row of whisker setae parallel to fang, one promarginal whisker seta large (the promarginal escort seta), weak promarginal mound in front of fang base, promargin with one very small tooth (seen in male digested with KOH), retromargin without teeth, retromarginal escort seta present (socket observed, fig. 5E). Cheliceral fang very long, falcate, flat, with shaft serrula, venom duct opening present (fig. 5B–E). Genitalia: epigynum as single sclerotized plate with unpaired, shallow median concavity (fig. 3E). Posterior margin sinuous, with two rounded cavities (fig. 10F). Copulatory openings not visible, probably near central depression. Copulatory ducts fused anteriorly, with tortuous lumen, leading to simple spermathecae, copulatory duct and spermatheca together in uniformly sclerotized, solid piece (fig. 10F). Spinnerets small, clustered together, arising from slightly projecting base (fig. 8). ALS with basal articles conical, adjacent to each other, distal articles crescent-shaped, sclerotized, ectal area with setae (fig. 8C); seven piriform gland spigots tightly grouped, with shafts well defined from base, two major ampullate gland spigots with shafts larger than those of piriforms; no setae associated with piriform bases. PMS, PLS much shorter than ALS. PMS conical, with single spigot with thick shaft, probably cylindrical gland spigot. PLS with basal spigot with thick shaft, probably cylindrical gland spigot, and four smaller ones, probably aciniform gland spigots.

ADDITIONAL MATERIAL EXAMINED. MEXICO: Coahuila: Municipio de Cuatrociénegas de Carranza: Cuatrociénegas Protected Area, ca. 9.7 km S Cuatrociénegas, N 26°54′31.896″, W 102°07′6.718″, Sep. 23, 2011, D.C. Lightfoot, 3♂ ( MSBA 51822 ). Aguascalientes: Municipio de Tepazalá : 12 km (7.5 mi) N Tepezalá, Aug. 30, 1965, W. Gertsch, R. Hastings, 3♂ (AMNH; discovered by N.I.P. in May of 2019 while sorting unidentified specimens). U.S.A.: Texas: Hudspeth Co.: Indio Mountains Research Station (UTEP), N 30°46′34.7″, W 105°01′09.3″, Jul. 28–Aug. 30, 2017, N.V. Horner, 3♂, 1 juv. ( CAS 9063001 ). Presidio Co.: Big Bend Ranch State Park: Ojito Adentro , N 29°29.5′, W 104°03.7′, Oct. 14, 2000, under rock, P.W. Hyder, 3♀ ( AMNH 1256 ). DDRS Camp , N 29°33′25.91″, W 103°47′37.95″, 1266 m (4154 ft), propylene glycol pitfall trap [PGPT], G.H. Broussard: Sep. 5, 1999, 1♂ (AMNH); Sep. 15, 2000, 1♀ (AMNH). White Canyon Rd. #6, N 29°33′46.9″, W 103°48′03.2″, 1273 m (4177 ft), PGPT, N.V. Horner: Aug. 15–Sep. 9, 2015, 1♂ (MSU); Oct. 4–20, 2015, 1♀ (MSU). Brewster Co.: Below Alamo Springs , N 29°33′15.6″, W 103°47′08.4″ to N 29°33′17.8″, W 103°47′11″ to N 29°33′20″, W 103°47′04.7″, 1121–1158 m (3742–3798 ft), PGPT, N.V. Horner: May. 30–Jun. 30, 2014, 8 juv. (MSU), 7 juv. ( CAS 9067292 ); Jul. 18–Aug. 17, 2012, 4♂ ( CAS 9076507 ); Jul. 4–Aug. 12, 2013, 3 juv. ( CAS 9067290 , 9067291 ); Jul , 30– Sep. 2, 2014, 7♂ (MSU); Aug. 15–Sep. 9, 2015, 3♂ (MSU); Aug. 24–Oct. 1, 2016, 3♂, 1♀ (MACN-Ar 38650), 1♂ (MACN-Ar 38649); Sep. 2–27, 2007, 1♂ (AMNH); Sep. 21–Oct. 6, 2007, 1♀ ( CAS 9076536 ); Sep. 14–Oct. 9, 2010, 1♀ ( CAS 9076511 ); Sep. 10–Oct. 3, 2015, 8♂, 3♀ (MSU); Oct. 7–Nov. 5, 2012, 1♂, 1♀ ( CAS 9076528 ); 1♀ ( CAS 9076530 ); Oct. 16–Nov. 1, 2014, 1♀ ( CAS 9067293 ); Oct. 21– Nov. 21, 2015, 2♀ (MACN-Ar 38651, 38663); Main Canyon , N 29.55512°, W 103.78561°, 1137 m, inside ant nest, P.E. Cushing, N.V. Horner, K. Sanko, C. Dowling, 10–11 Jun 2015, 1♂ (DMNS ZA.40328), 11 Jun 2015, 1 juvenile (DMNS ZA.40329); same, N 29.55506°, W 103.78536°, 12 Jun 2015 (DMNS ZA.40330). Brewster and Presidio Counties: Sandy Canyon , [N 29°33′07″, W 103°47′36″, 1215 m (3988 ft)], PGPT, G.H. Broussard: Oct. 7, 1999, 2♂ (AMNH); Sep. 15, 2000, 2♂, 1♀ ( CAS 9076539 , ♂ used for SEM); Big Sandy Canyon , N 29°33′07.38″, W 103°47′37.51″ to N 29°33′01.2″, W 103°47′38.1″, 1207–1260m (3960–4133 ft), PGPT, N.V. Horner: May. 23–Jun. 16, 2010, 1 juv. ( CAS 9076513 , 1♂ used for SEM); May. 30–Jun. 30, 2014, 1♂, 1♀, 4 juv. (MSU); Jun. 27–Jul. 13, 2009, 1 juv. (AMNH); Jun. 17–Jul. 22, 2010, 1 juv. ( CAS 9076510 ); Jun. 14–Jul. 9, 2011, 1 juv. ( CAS 9076519 ); Jun. 21–Jul. 17, 2012, 6 juv. ( CAS 9076522 , 9076526 ); Jun. 25–Jul. 24, 2016, 4 juv. (MSU); Jul. 14–Aug. 22, 2009, 4♂ (AMNH); Jul. 23–Aug. 10, 2010, 2 juv. ( CAS 9076512 ); Jul. 10–Aug. 12, 2011, 1 juvenile ( CAS 9076532 ); Jul. 18–Aug. 17, 2012, 3♂ ( CAS 9076516 ), 1♂, 1♀, 3 juv. ( CAS 9076518 ); Jul. 30–Sep. 3, 2014, 2 juv. ( MSU) ; Aug. 15–Sep. 3, 2006, 1♀ ( MSU) ; Aug. 29–Sep. 19, 2008, 1♀ ( CAS 9076523 ) ; Aug. 10–28, 2010, 3♂ ( MSU) ; Aug. 29–Sep. 13, 2010, 1♀ ( MSU) ; Aug. 13– Sep , 14, 2011, 2♂, 1♀ ( CAS 9076533 , 9076540 , 9076537 ) ; Aug. 24–Oct. 1, 2016, 1♂ ( MSU) , 1♀ (MACN-Ar 38636); Sep. 22–Oct. 4, 2005, 1♀ ( AMNH) ; Sep. 26–Oct. 10, 2006, 1♀ ( MSU) ; Sep. 28–Oct. 9, 2008, 1♀ ( CAS 9076535 ) ; Sep. 19–27, 2008, 2♂ ( CAS 9076538 ) ; Sep. 14– Oct. 9, 2010, 2♂, 2♀ ( CAS 9076509 , 9076514 , 9076517 ) ; Sep. 15–Oct. 19, 2011, 1♂, 2♀ ( CAS 9076520 , 9076525 , 9076527 ) ; 24 Sep–15 Oct 2014, 4♂, 1 juv. ( MSU) , 1♂, 1♀ ( CAS 9067288 ) ; 9 Oct–2 Nov 2008, 1♂, 2♀ ( AMNH) ; 4–14 Oct 2009, 1♀ ( AMNH) ; 6 Oct–5 Nov 2012, 4♀ ( CAS 9076521 , 9076529 , 9076534 ) ; 16 Oct–1 Nov 2014, 1♂, 1♀ ( DMNS ZA.40327), 1♂ ( CAS 9067289 ) .

DISTRIBUTION. Known only from the Big Bend region (Presidio, Brewster and Hudspeth counties) of Texas, and in Mexico from Cuatro Ciénegas, Coahuila, and Tepezalá, Aguascalientes ( map 1 ) .

Figures

MAP 1. Known localities of Myrmecicultor chihuahuensis, new species, plotted on a political map of North America (A) and three topographic maps (B–D) at increasing magnifications, as indicated by the rectangular boxes, with D showing the most densely sampled sites at the DDRS. The vertical line in C and D is the Presidio/Brewster County border.

FIG. 1. Phylogenetic tree obtained from the Bayesian analysis of sequence data from six markers in the mitochondrial (12S rDNA, 16S rDNA, cytochrome oxidase subunit I) and nuclear (histone H3, 18S rDNA, 28S rDNA) genomes. Circles on nodes indicate support values.

FIG. 2. A. Phylogenetic tree obtained from the parsimony analysis of morphological data under implied weights; the tree shown under concavity constant k = 12 is also the majority-rule consensus of trees obtained with values of k between 3 and 30. B. Phylogenetic tree obtained from the Bayesian analysis of sequences and morphological data. Circles on nodes indicate support values.

FIG. 3. Myrmecicultor chihuahuensis, new species, female structures. A. Habitus, dorsal view. B. Same, ventral view. C. Prosoma, ventral view. D. Same, anterior view. E. Epigyne, ventral view. (A–D, paratype CAS 9067293; E, AMNH [ARANP19]).

FIG. 4. Myrmecicultor chihuahuensis, new species, male structures. A. Habitus, dorsal view. B. Prosoma, dorsal view. C. Same, anterior view. D. Eyes, dorsal view. E. Right palp, mirrored image, prolateral view. F. Same, ventral view. G. Same, retrolateral view. (A–D, holotype; E–G, CAS 9076539).

FIG. 5. Myrmecicultor chihuahuensis, new species, female structures. A. Eyes, dorsal view. B. Left chelicera, anterior view. C. Same, posterior view. D. Same, detail of promarginal setae and fang, anterior view. E. Fang and retromargin, posterior view, arrow to socket of retromarginal escort seta. F.Palpal tarsus tip, dorsal apical view, arrow to patch of chemosensory setae. G. Same, detail of claw and chemosensory setae. Abbreviations: Ch = chemosensory seta; FgS = fang shaft serrula; PEs = promarginal escort seta; Rk = promarginal rake seta; Wh = cheliceral whisker seta.

FIG. 6. Myrmecicultor chihuahuensis, new species, female structures. A. Left tarsus II, dorsal view, white arrows point to trichobothrial sockets, black arrow to tarsal organ. B. Same, retrolateral view. C. Metatarsus II, dorsal view, white arrows point to trichobothrial sockets.D. Tip of metatarsus III showing preening brush. E. Left claws II, apical view. F.Same, retrolateral apical view, inset to barbs of setae, showing unexpanded tips. G. Metatarsus-tarsus II articulation, arrow to irregular longitudinal ridges on tarsal step. H. Tibia-metatarsus II articulation.

FIG. 7. Myrmecicultor chihuahuensis, new species, female structures of left leg II. A. Patella, retrolateral view. B. Trichobothrium on metatarsus. C. Tarsal organ and slit sensilla. D. Chemosensory seta on metatarsus. Abbreviations: PIn = patellar indentation; Ly = lyriform organ; TO = tarsal organ; SS = slit sensillum.

FIG. 8. Myrmecicultor chihuahuensis, new species, female spinnerets. A. Spinnerets, ventral-posterior view. B. Right ALS. C. Left ALS, arrows to sclerotized ectal area of distal article, bearing setae. D. Left PMS. E. Right PMS. F. Right PLS. G. Left PLS. Abbreviations: Ac = aciniform gland spigot; ALS = anterior lateral spinneret; Cy = cylindrical gland spigot; MaAm = major ampullate gland spigot; Pi = piriform gland spigot; PLS = posterior lateral spinneret; PMS = posterior median spinneret.

FIG. 9. Myrmecicultor chihuahuensis, new species, male left palp (CAS 9076539). A. Prolateral view. B. Same, retrolateral-ventral view. C. Same, ventral view. D. Same, detail of copulatory bulb, retrolateral-ventral view. E. Same, dorsal view. F.Same, detail of setae (probably scales). G. Tip of cymbium, detail of apical patch of chemosensory setae. H. Tibia and RTA, dorsal view. Abbreviations: C1, C2 = conductors; E = embolus; MA = median apophysis; T = tegulum.

FIG. 10. Myrmecicultor chihuahuensis, new species, genitalia. A. Left male palp, prolateral view. B. Same, ventral view. C. Same, retrolateral view. D. Same, detail of copulatory bulb, cleared. E. Female genitalia, ventral view, cleared. F. Same, dorsal view. (A–E, CAS 9067289; E–F, AMNH [ARANP19]). Abbreviations: C1, C2 = conductors. CD = copulatory duct; E = embolus; FD = fertilization duct; MA = median apophysis; RTA = retrolateral tibial apophysis; S = spermatheca; St = subtegulum; T = tegulum.

FIG. 11. Nests and habitats of harvester ants and Myrmecicultor chihuahuensis, new species A. South Fork of Alamo De Cesario Creek. B. Dry creek (1118 m), habitat of Novomessor albisetosis which requires adequate moisture and soil depth. C. Habitat of Novomessor cockerelli (1272 m), which requires sparse vegetation and less moisture. D. Mound nest of Pogonomyrmex rugosus (1276 m), soil mixed with desert pavement (small stones) and limited moisture. E. Nest of P. rugosus with 10 specimens of M. chihuahuensis (arrows). F.Same nest, spiders beside a host worker of P. rugosus; inset to a female. G. Excavation of N. albisetosis nest. (E–F, photos by D. Lightfoot, University of New Mexico).

FIG. 12. Phenology of Myrmecicultor chihuahuensis, new species, including all collection records. All but 12 (labelled “o”) of the 159 specimens collected are from the Dalquest Desert Research Station (DDRS) and, except for those excavated from an ant nest (“x”), were collected in pitfall traps. Juvenile specimens (i) are indicated in orange, males (m) in blue, and females (f) in red. Intermonth records are from trap runs that spanned two months, where each month contained at least 20% of the trap days. For example, results of a trap from 14 September to 9 October are recorded as intermonth, whereas one from 7 October to 5 November is recorded as October.