Pachomius areteguazu sp. nov. (Araneae: Salticidae: Freyina), and the first description of the epigynum of a member of the nigrus group Rubio, Gonzalo D. Stolar, Cristian E. Baigorria, Julián E. M. Peckhamia 2021 2021-05-12 234 1 1 8 98YV8 Rubio & Stolar & Baigorria, 2021 Rubio & Stolar & Baigorria 2021 [595,924,1296,1326] Arachnida Salticidae Pachomius Animalia Araneae 1 2 Arthropoda species areteguazu sp. nov.   Figures 1-22  Type material.  Male holotype(IBSI-Ara 1453) from Argentina, Misiones, Candelaria, Santa Cecilia Ranch( 27.45046°S, 55.716375°W),  6 February 2019, J . E. M. Baigorria coll.; female allotype(IBSI-Ara 1248), same place and collector, 13 January 2019.  Paratypes: 1 female(IBSI-Ara 1479), San Pedro, Cruce Caballero, Forestal Belga Ranch( 26.572361°S, 53.801667°W),  22 October 2019, G . D. Rubio, A. A . Toroand C. E. Stolar coll.; 1 male(IBSI-Ara 1535), same place and collector as holotype, September 2020.  Etymology. The specific epithet, “areteguazu,” refers to one of the most important and traditional celebrations of the year for the Guaraní indigenous community, whose meaning is “big party” or “important party.” In this event, Guaraní people use masks that resemble the pattern observed on the carapace of this species.  Diagnosis. The male  P. areteguazu sp. nov.resembles  P. nigrus( Caporiacco, 1947)and  P. lehmanni( Strand, 1908)by the presence of a sclerotized, spine-shaped (possibly derived by the loss of the membraneous part of the LSA) LSA on the tegulum, next to the embolus, and for this reason we place it in the  nigrusgroup ( Edwards 2015). It can be distinguished from the other two species by the wider and shorter LSA ( Figures 3, 4, 11), the shorter embolus with the tip directed prolaterally (retrolateral in  P. nigrus), and by the absence of a pPL on the TDD (present in those two species of the group) ( Figures 3, 11). The nigrus group is completed with  P. lehmanniand  P. nigrus, and several undescribed species ( Edwards 2015; Galvis 2018). The female  P. areteguazu sp. nov.differs from those of other congeners by the structure of the epigynal plate, with a CO at the center of each of two conspicuous, non-circular atria ( Figures 1, 2, 12, 13). No female in the  nigrusgroup has been described previously, therefore the first description of the epigynum for this group is presented here.   Figures 1-5.Sexual structures of  Pachomius areteguazu sp. nov. 1-2,Paratype ♀. 3-5,Holotype ♂. 1,Epigynum, ventral view. 2,Same, cleared. 3,Left palp, ventral view. 4,Copulatory bulb, cleared, ventral view. 5,Left palp, retrolateral view. AT,atrium; CO, copulatory opening; E, embolus; FD, fertilization duct; LSA, lateral subterminal apophysis; pRL, proximal retrolateral lobe of TDD; RTA, retrolateral tibial apophysis; S, spermophore; TDD, tegulum distal division.  Description. The male( holotype) is shown in Figures 3-7 and 11. Medium-sized salticid, total length 5.10. Carapace longer than wide, length 2.45, width: 1.70. Carapace dark brown, cephalic region blackish with three conspicuous spots of white setae, two between PME and PLE, and one between PLE. Wide white marginal bands continued from below ALE. Clypeus with a row of 14 to 16 long, inconspicuous hairs. Chelicerae dark mahogany brown, paturon with some scaly, translucent white hairs, with two promarginal teeth and one retromarginal tooth. Sternum blackish, with some scattered white translucent hairs; labium blackish and endites dark brown. Legs equal, hairy, brown color, ringed dark brown, femurs blackish; coxae I dark brown, coxae II-IV pale yellow. Abdomen length: 2.40, width: 1.50, color in ethanol greenish-gray ( Figure 7), pale orange-brown in life ( Figures 18, 22); with an abdominal basal band of lighter hairs on the anterior edge of the abdomen. Dorsal scutum absent. Palp: femur strong, slightly curved ( Figure 5), with femoral organ on the distal prolateral side, tibia with a conspicuous RTA with a wide base, narrower towards the apex, tip somewhat triangular, directed ventrally ( Figure 5). Division of the tegulum inconspicuous, with the border between TBD and TDD oblique in ventral view. TDD with pRL narrow, rounded edges and a lobed tip ( Figure 3). Embolus short, thick, sclerotized with conspicuous base and prolaterally directed tip ( Figures 3-4, 11). Lateral subterminal apophysis (LSA) sclerotized, prolateral to the embolus and shaped like a short and thick spine, retrolaterally directed tip. TBD with a short, curved, and small visible stretch of the spermophore ( Figures 3-4).   Figures 6-13.Preserved specimens of  Pachomius areteguazu sp. nov.6-7, 11, Holotype ♂. 8-10,Allotype ♀. 12-13,Paratype ♀. 6,Dorsal view of male, dry. 7,Same, submerged in ethanol. 8,Dorsal view of female, dry. 9,Same, submerged in ethanol. 10,Same, ventral view. 11, Copulatory bulb, cleared, ventral view. 12,epigynum, cleared, ventral view. 13,Same, different focus. Scale bar 2 mm, specimens in figures 6-10 shown at the same scale.  Female( paratypeIBSI-Ara 1479) illustrated in Figures 1-2, 12-13. Total length: 6.50. Carapace longer than wide, length: 2.70, width: 1.80. Carapace dark brown to blackish, cephalic region darker with some scattered black hairs, most conspicuous on the edge of the first row of eyes. Wide whitish marginal bands continued from the clypeus. Clypeus covered with long white hairs. Chelicerae dark mahogany brown, with two promarginal teeth and one retromarginal tooth. Sternum, labium and endites as in male ( Figure 10). Legs equal, brown with paler coxae, as in the male but somewhat paler ( Figures 8-10). Abdomen length: 3.55, width: 2.25, hairy, color in ethanol greenish-gray, with a lighter abdominal basal band on the anterior edge of the abdomen, a similar transverse band in the middle, and a small chevron-shaped band at the rear, all bordered in black ( Figure 20). Epigynum: medium epigynal plate, as long as wide (length: 0.47, width: 0.47), forming two broad atria with two small COs, one at the center of each atrium ( Figures 1-2, 12-13); CD short, oriented in an anteroposterior direction, connecting anteriorly to a somewhat spherical spermatheca, FD anterior and dorsal to spermatheca ( Figure 2).   Figures 14-22.Photographs from nature of  Pachomius areteguazu sp. nov.from Urutaú Nature Reserve (14-15, 22) and Santa Cecilia Ranch (16-21) in Candelaria, Misiones. 14-19, 22,Males. 20, 21,Females.  Variation. Males (n = 9): Total length 4.50–5.55. Carapace length 2.30–3.00, width 1.65–2.20. Abdomen length 2.10–2.80, width 1.50–1.60. Some males have coxae I darker or all legs darker; also, some males have the spots and thoracic stripe on the carapace yellowish instead of white ( Figures 17-18). Females (n = 13): Total length 5.30–7.00. Carapace length 2.40–2.90, width 1.80–2.00. Abdomen length 3.10–4.10, width 2.15–2.95. The color pattern of the legs varies, being paler in some females. Some specimens do not have white spots or thoracic stripe on the carapace ( Figure 22).   Figures 23-25.Map with specimen records for  Pachomius areteguazu sp. nov.shown as blue dots (23), and grasslands where this species lives at the type locality, Santa Cecilia Ranch, Candelaria (24-25).  Natural history. Appearance in life as in Figures 14-22.  Pachomius areteguazu n. sp.inhabits dense grasslands at the ecoregion known as “Southern Cone Mesopotamian Savanna.” We have collected these spiders mostly at Candelaria, southern Misiones province, in northeastern Argentina. This species is usually found near the ground on the leaves of tall grass species like  Andropogon lateralisor  Sorghastrum setosum( Figures 24-25). It seems to be relatively common and is probably one of the most numerous salticid species within this environment. Adults are found throughout the year, but especially from October to April.  Distribution(map, Figure 23). This species is known from northeastern Argentina: Chaco, Misiones, and north of Corrientes.  The LSA and its relationship to the epigynum described here. The presence of an atrium can be explained by its role in mating. Galiano (1995)wrote that a group of  Pachomius, the one previously represented under  Uspachus, differs by having an epigynum with circular atria, and the bulb of the male palp with an LSA (she called it “lamella”) accompanying the embolus. When the embolus enters the CO, a structure must necessarily exist to accommodate the LSA, since the LSA moves together with the embolus. It seems highly probable that the LSA lodges in the side pocket of the atrium contributing to fixation ( Galiano 1995). Since the LSA of the  nigrusgroup is spine-shaped, possibly derived by loss of the membranous part of the LSA ( Edwards 2015; Galvis 2018), that can explain the epigynum described here for this group, with two non-circular atria with conspicuous edges ( Figures 1-2).  Other material examined.  Misiones province, Leandro N.  Alem, Estación Experimental Agropecuaria Cerro Azul( 27.654757°S, 55.435562°W), 1 ♀(IBSI-Ara 1112), beating on pastures,  28 August 2018, C . E . Stolarand G. D. Rubio coll.; same place and coll., 1 ♂(IBSI-Ara 1128), beating on foliage, 30 August 2018; same place, 1 ♂(IBSI-Ara 1144), 10 September 2018, C . E. Stolar coll .; Candelaria, Santa Cecilia Ranch( 27.45046°S, 55.716375°W), 1 ♂(IBSI-Ara 1514), 1 ♀(IBSI-Ara 1515), 2 ♀(IBSI-Ara 1530) and 1 ♂(IBSI-Ara 1545),  September 2020, J . E. M. Baigorria coll.; same place and coll.,  1 ♀(IBSI-Ara 1542) and 2 ♀(IBSI-Ara 1544),  October 2020; Candelaria, Urutaú Nature Reserve( 27.48024°S, 55.792547°W), 2 ♀(IBSI-Ara 1548), grasslands,  5 February 2021, G . D. Rubio, J. E. M . Baigorriaand C. E. Stolar coll .; Corrientes province, Iberá Wetlands, Cambyretá( 27.82679°S, 56.855668°W), 1 ♂(IBSI-Ara 0646) and 1 ♂(IBSI-Ara 0647), g-vac on grassland,  7 November 2013, G . Avaloscoll .; Iberá Wetlands, San Nicolás( 27.98185°S, 57.438223°W), 1 ♀(IBSI-Ara 0658), g-vac on grassland,  20 November 2012, same coll.;  Iberá Wetlands, Puerto Valle( 27,613429°S, 56.438505°W), 1 ♂(IBSI-Ara 0662) and 1 ♀( CNNE), g-vac on grassland,  23-24 March 2015, same coll.;  Chaco province, Sargento Cabral( 26.5756°S, 59.7567°W), 1 ♀(IBSI-Ara), 1 ♀( CNNE 9208) and 1 ♀( CNNE), grassland,  5 December 2017, G . D . Rubioand M. F. Nadal coll .; 1 ♂( CNNE 8755) and 1 ♂(IBSI-Ara), same place,  9 March 2017, G . Avalosand M. F. Nadal coll.; Presidencia de la Plaza, Est.  Los Alisos( 27.0794°S, 59.7486°W), 1 ♀( CNNE) and 1 ♀( CNNE 9213), trawl neton grassland,  7 October 2006, G . Avaloscoll.; Bermejo, Est.  San Carlos, La Leonesa( 26.9781°S, 58,6508°W), 1 ♀(IBSI-Ara), g-vac on grassland,  8 December 2015, G . Avaloscoll .; 1 ♀( CNNE), same place and coll.,   15 December 2015; General Vedia( 26.9306°S, 58.6478°W), 1 ♀( CNNE 9033),  10 December 2014, G . Avaloscoll .; Primero de Mayo, RNE Colonia Benitez( 27.3178°S, 58.9500°W), 1 ♀( CNNE), g-vac on grassland,  20 December 2011, M . J. Escobar coll .; 2 ♀( CNNE 9210), same data; 1 male( CNNE 9209), beating on forest foliage,  25 October 2011, same coll.;  Veinticinco de Mayo( 26.4569°S, 59.9578°W), 1 male( CNNE 8753), g-vac on grassland,  8 March 2017, G . Avalosand M. F. Nadal coll .; 1 ♂( CNNE 8879), same place and coll., 30 May 2018; San Fernando, Est. La Querencia ( 27.7106°S, 59.2231°W), 1 ♂( CNNE), grassland,  16 November 2015, G . Avaloscoll .; 1 ♂( CNNE 8754), same data; Chaco National Park( 26.7889°S, 59.6122°W), 1 ♂( CNNE), g-vac on grassland,  7 November 2016, G . Avalosand M. F. Nadal coll. 3320625318 2019-02-06 Argentina Santa Cecilia Ranch -27.45046 Male 1 -55.716373 Candelaria 1 2 1 holotype 3320625309 [771,807,1442,1470] 2019-02-06 Argentina Santa Cecilia Ranch true -27.45046 Male 1 -55.716373 Candelaria 1 2 1 holotype 3320625301 2019-10-22 Saint Pierre and Miquelon -26.572361 Cruce Caballero 1 -53.801666 Forestal Belga Ranch 1 2 1 1 paratype 3320625323 [1248,1286,1517,1546] 2019-10-22 Saint Pierre and Miquelon true -26.572361 Cruce Caballero 1 -53.801666 Forestal Belga Ranch 1 2 1 paratype 3320625308 Saint Pierre and Miquelon Toro 1 2 1 paratype 3320625328 [450,856,661,690] Leandro N Misiones province 6 7 1 Misiones 3320625324 2018-08-28 -27.654757 Estacion Experimental Agropecuaria Cerro Azul 1 -55.435562 Alem 6 7 1 1 Misiones 3320625306 [1409,1441,698,727] 2018-08-28 true -27.654757 Estacion Experimental Agropecuaria Cerro Azul 1 -55.435562 Alem 6 7 1 Misiones 3320625310 Stolar 6 7 1 Misiones 3320625315 [845,885,773,802] true Stolar 6 7 1 Misiones 3320625338 2020-09 -27.45046 Santa Cecilia Ranch 1 -55.716373 Candelaria 6 7 5 3 2 Misiones 3320625333 [585,617,849,877] 2020-09 true -27.45046 Santa Cecilia Ranch 1 -55.716373 Candelaria 6 7 1 Misiones 3320625329 2020-10 2021-02-05 2020-10 Candelaria -27.48024 Urutau Nature Reserve 1 -55.792545 6 7 5 5 Misiones 3320625317 [799,841,923,952] 2020-10 2021-02-05 2020-10 Candelaria true -27.48024 Urutau Nature Reserve 1 -55.792545 6 7 1 Misiones 3320625320 [1064,1314,923,952] Baigorria 6 7 1 Misiones 3320625326 2013-11-07 -27.82679 Cambyreta 1 -56.855667 Ibera Wetlands 6 7 2 2 Corrientes 3320625302 [951,1122,998,1027] 2013-11-07 Avalos true -27.82679 Cambyreta 1 -56.855667 Ibera Wetlands 6 7 1 Corrientes 3320625304 2012-11-20 -27.98185 San Nicolas 1 -57.438225 Ibera Wetlands 6 7 1 1 Corrientes 3320625334 2015-03-23 2015-03-24 2015-03-23 CNNE -27.613428 Puerto Valle 1 -56.438503 Ibera Wetlands 6 7 2 1 1 Corrientes 3320625313 2017-12-05 CNNE -26.5756 Sargento Cabral 6 -59.7567 6 7 CNNE 9208 3 3 Chaco 3320625311 [1194,1228,1148,1177] 2017-12-05 CNNE true -26.5756 Sargento Cabral 6 -59.7567 6 7 1 Chaco 3320625340 [1228,1414,1148,1177] Rubio 6 7 1 Chaco 3320625331 [152,1128,1185,1215] 2017-03-09 CNNE 6 7 CNNE 8755 2 2 Chaco 3320625303 [1128,1334,1185,1215] 2017-03-09 CNNE true Avalos 6 7 1 Chaco 3320625322 2006-10-07 CNNE -27.0794 Los Alisos 6 -59.7486 6 7 CNNE 9213 2 2 Chaco 3320625319 [627,803,1260,1290] 2006-10-07 CNNE Avalos true -27.0794 Los Alisos 6 -59.7486 6 7 1 Chaco 3320625316 2015-12-08 -26.9781 La Leonesa 6 -58.6508 San Carlos 6 7 1 1 Chaco 3320625337 [1079,1249,1298,1327] 2015-12-08 Avalos true -26.9781 La Leonesa 6 -58.6508 San Carlos 6 7 1 Chaco 3320625341 CNNE 6 7 1 1 Chaco 3320625335 2014-12-10 2015-12-15 2014-12-10 CNNE General Vedia -26.9306 6 -58.6478 6 7 CNNE 9033 1 1 Chaco 3320625336 [360,532,1373,1402] 2014-12-10 2015-12-15 2014-12-10 CNNE Avalos true -26.9306 6 -58.6478 6 7 1 Chaco 3320625314 2011-12-20 CNNE de Mayo -27.3178 Colonia Benitez 6 -58.95 6 7 1 1 Chaco 3320625321 [794,819,1411,1439] 2011-12-20 CNNE de Mayo true -27.3178 Colonia Benitez 6 -58.95 6 7 1 Chaco 3320625327 2011-10-25 CNNE de Mayo true -27.3178 Colonia Benitez 6 -58.95 6 7 CNNE 9210, CNNE 9209 3 2 1 Chaco 3320625332 2017-03-08 CNNE -26.4569 Veinticinco de Mayo 6 -59.9578 6 7 CNNE 8753 1 1 Chaco 3320625307 [1080,1279,1485,1514] 2017-03-08 CNNE true -26.4569 Avalos 6 -59.9578 6 7 1 Chaco 3320625305 CNNE 6 7 CNNE 8879 1 1 Chaco 3320625312 2015-11-16 CNNE -27.7106 6 -59.2231 6 7 1 1 Chaco 3320625330 [928,1095,1560,1589] 2015-11-16 CNNE Avalos true -27.7106 6 -59.2231 6 7 1 Chaco 3320625325 2016-11-07 CNNE Avalos true -26.7889 National Park 6 -59.6122 6 7 CNNE 8754 2 2 Chaco 3320625339 2016-11-07 CNNE Avalos true -26.7889 Avalos 6 -59.6122 6 7 1 Chaco