Gaucha ramirezi, Botero-Trujillo & Ott & Mattoni & Nime & Ojanguren-Affilastro, 2019

Botero-Trujillo, Ricardo, Ott, Ricardo, Mattoni, Camilo I., Nime, Mónica F. & Ojanguren-Affilastro, Andrés A., 2019, Two new species of the sun-spider genus Gaucha from Argentina and Brazil (Solifugae, Mummuciidae), Zootaxa 4551 (2), pp. 180-194 : 183-185

Gaucha ramirezi sp. nov.

Figures 1 , 2–4 ; Table 1

Type material. Holotype : male from ARGENTINA: Córdoba: Pocho, Parque Natural Provincial y Reserva Forestal Natural Chancaní , forest with livestock, 31°22′21.788″ S 65°29′20.706″ W, 05–13.xii.2010, M.F. Nime & C.I. Mattoni, pitfall (MACN-Ar 39101). Paratypes: same data of holotype, 8 males, 6 females (MACN-Ar) ; 9 males, 1 female, 2 juveniles ( LBRE 401 ); 7 males, 1 female, 1 juvenile ( LBRE 402 ); 4 males, 1 female, 1 juvenile ( LBRE 403 ); 1 male, 2 females, 1 juvenile ( LBRE 404 ) .

Additional material examined. ARGENTINA : Córdoba: Same locality and data of holotype but, 03– 09.ii.2011, 1 male, 1 juvenile (LBRE). Parque Natural Provincial y Reserva Forestal Natural Chancaní, mature forest, 31°21′1.192″ S 65°28′56.755″ W, 12–19.i.2010, M.F. Nime & C.I. Mattoni, pitfall, 7 males, 2 females (MACN-Ar); 5 males, 2 females, 2 juveniles (MACN-Ar) ; 6 males, 1 female, 1 juvenile ( LBRE) ; 2 males, 1 juvenile ( LBRE) ; 1 female ( LBRE) ; 1 juvenile ( LBRE) ; 1 male ( LBRE); 6 males, 8 juveniles ( LBRE); 6 males, 1 female, 2 juveniles ( LBRE); 1 male, 1 juvenile ( LBRE); 2 males, 1 female, 1 juvenile ( LBRE); 7 males ( LBRE); 2 males ( LBRE); 1 male ( LBRE). Same locality and data but, 03–11.xi.2010, 2 males ( LBRE); 1 male ( LBRE). Parque Natural Provincial y Reserva Forestal Natural Chancaní , secondary forest, 31°21′28.847″ S 65°29′17.282″ W, 04–12.xii.2010, M.F. Nime & C.I. Mattoni, pitfall, 4 males, 1 female, 2 juveniles ( LBRE). Parque Natural Provincial y Reserva Forestal Natural Chancaní, Jarillal, 31°23′26.617″ S 65°27′17.758″ W, 05–13.xii.2010, M.F. Nime & C.I. Mattoni, pitfall, 1 male ( LBRE). Parque Natural Provincial y Reserva Forestal Natural Chancaní, 10– 14.xi.2010, M.F. Nime & C.I. Mattoni, pitfall, 12 males, 1 juvenile ( LBRE) . Santiago del Estero: Parque Nacional Copo, 26°04′ S 61°44′ W, 23–25.x.2003, collector unspecified, pitfall, 1 male (MACN-Ar 30501).

Etymology. The species name is dedicated to the arachnologist Martín J. Ramírez, from the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”—CONICET (Buenos Aires, Argentina). RBT wants to specially thank him for his academic guidance during the former’s stay at the MACN.

Diagnosis. Gaucha ramirezi sp. nov. differs from the remaining species in the genus by having white marks on the black band of the opisthosomal pleural membranes ( Fig. 3D ), whereas species in the fasciata and ibirapemussu species-groups have black marks on the white band. The flagellum is ovoid in shape ( Figs. 4E,F ), somewhat similar to that of G. fulvipes ( Roewer, 1934) and G. casuhati ; however, in the male of G. ramirezi sp. nov. the fixed finger lacks the subterminal flange (STF) that is present in G. fulvipes , and the flagellum is considerably less inflated than in G. casuhati ( Figs. 4C,D ). The flagellum of G. ramirezi sp. nov. has a very broad apex on dorsal aspect and is densely coated with conspicuous spicules, especially on the dorsal surface and subdistal region of the prolateral surface ( Fig. 4F ). In this respect, the surface ornamentation of the flagellum resembles that of G. avexada Botero-Trujillo, Ott & Carvalho, 2017 , although the spicules are notably longer in the latter species.

Systematic position. The presence of white marks on the opisthosomal pleura of G. ramirezi sp. nov., prevents us from confidently placing this species into any of the species-groups of Gaucha thus far defined. Currently, only the fasciata species-group is supported by a combination of apomorphic discrete-character states and shape configurations of the chelicera of males, whereas the monophyly of the ibirapemussu group is supported by landmark data only ( Botero-Trujillo et al.’s 2017: fig. 8). The internal classification of Mummuciidae is on its early stages, and we find premature to place G. ramirezi sp. nov. into one or the other species-groups of Gaucha . While this species may belong to either of the species groups, having developed the characteristic white marks, it is also possible that it may represent a basal lineage in the Gaucha clade (e.g., with these marks being plesiomorphic).

Description. For most aspects the general morphology fits that described for the genus by Botero-Trujillo et al. (2017). Color: Propeltidium color predominantly whitish, with yellowish-to-brown median area without welldefined borders; ocular tubercle dark except for a median longitudinal light band. Chelicerae with manus predominantly yellowish to brown, with some white areas; limits between the setose and asetose areas often darkened; fingers reddish, especially on the teeth. Meso-, metapeltidium and dorsal surface of opisthosoma with a three-dark-band design typical of the family: tergites with median, longitudinal brown band, and a pair of lateral whitish bands; pleural membranes with sub-dorsal black and sub-ventral white bands; black band of opisthosomal pleural membrane with white marks surrounding the socket of most setae, especially on posterior half; sternites yellowish, immaculate except for posterior margin of one–three posteriormost sternites which is darkened. Ventral surface of prosoma uniformly yellowish; sternum lighter than coxae. Pedipalps and legs yellow to brown; pedipalps progressively becoming darker towards the apex, such that the telotarsus is nearly black. Malleoli whitish, often with distal margin darkened. Morphology: Opisthosoma with ctenidia present, at least on 2 nd to 4 th post-genital sternites (spiracular sternite II and post-spiracular sternites I–II), scarce in spiracular II but more abundant in the others; ctenidia filiform and setiform, similar in thickness to the bifid setae (in male and female); although ctenidia are apparently absent from spiracular sternite I, this is not clear due to the current state of preservation of the material, e.g., ctenidia, if any, may have fallen off. Chelicerae, fixed finger with median teeth series comprising all primary teeth, i.e., FP, FM, FD; with one ( FSM) secondary teeth series and without FSD teeth. Legs II and III: basitarsus with row of three proventral, row of three retroventral, and one distal subventral spiniform setae, in a 2.2.3 rather staggered pattern; telotarsus bi-segmented with pro- and retroventral rows of five and four spiniform setae respectively, in a 1.2.2/2.2 pattern. Leg IV: basitarsus with row of four proventral and one distal retroventral spiniform setae, in a 1.1.1.2 pattern; telotarsus bi-segmented with incomplete (ventral) segmentation on first (basal) tarsomere, with pro- and retroventral rows of six spiniform setae each, in a 2.2.2-2/2.2 pattern. Male: Metric data as in Table 1. Cheliceral fixed finger with primary teeth of normal size for the genus, graded as FP=FM>FD or FP>FM>FD; mucron moderately long, without subterminal flange (STF). Movable finger MP tooth pronounced, markedly taller than MM; mucron short (as compared to that of the ibirapemussu species-group described by Botero-Trujillo et al. 2017), with gnathal edge carina very prominent and convex on lateral aspect. Flagellum inflated and narrowing anteriorly, conspicuously covered with abundant spicules on dorsal and prolateral surfaces. Female: Metric data as in Table 1. Similar to male but without male-specific secondary sexual characters. Chelicera on lateral aspect, fixed finger dorsal margin strongly curved and without angular dorsal crest, with highest elevation near the level of FM tooth. Fixed finger robust, with mucron distinctly curved towards the venter. Movable finger MP tooth moderately taller than MM tooth.

Distribution and habitat. Gaucha ramirezi sp. nov. is primarily known from the Chancaní Provincial Park and Forest Reserve, located in the southernmost portion of the Arid Chaco ecoregion (NT0701 in Olson et al. 2001) in Córdoba province, Argentina. A specimen from the Copo National Park, in Santiago del Estero province, northern Argentina, was also available for this study. Both localities share a similar xerophytic environment and belong to the same biome: Tropical and Subtropical Grasslands, Savannas, and Shrublands ( Olson et al. 2001). Although the latter specimen is herein presumed to be conspecific to those from the type locality, additional scrutiny, when other specimens become available, may be necessary to clarify the specific identity of that population.

The Chancaní Park and Reserve was created and fenced in 1986, and since, its vegetation has been protected from human disturbance ( Cabido & Pacha 2002). Vegetation in the reserve is dry xerophilous woodland. The canopy is discontinuous and ~ 15 m high, whereas the shrub stratum (~ 4 m high) is thorny, dense, and almost continuous ( Carranza et al. 1992). The climate in the reserve is highly seasonal, with a pronounced dry season.

In the Arid Chaco ecoregion, the fire season usually coincides with the frost season, from May to September ( Kunst & Bravo 2003). Wildfire affected the Chancaní Reserve in December 1994. It was an out of season, highintensity fire that started under extremely dry conditions due to a long delay in the onset of the rainy season. The fire covered 32,000 ha of Arid Chaco forest, affecting 230 ha within the western boundaries of the Chancaní Reserve. This fire generated a secondary forest area next to the main forest area.

There are four different ecological-type sites within the study site. (1) The mature forest site shows forest formations that are close to climax conditions, mainly with trees such as Aspidosperma quebracho-blanco and Prosopis flexuosa . The shrub layer is dominated by Larrea divaricata, Mymozyganthus carinatus and Acacia furcatispina ( Carranza et al. 1992) . (2) The secondary forest site shows dense and homogeneous vegetation, dominated by high grasses (about 1 m tall) and shrubs of about 2.5 m in height. In this area, young trees are common and dead trees are still standing ( Pelegrin & Bucher 2010). (3) The Jarillal site is located in the central area of the reserve. In the past, this area was used for the logging of large trees for fuel and charcoal. Currently, it is dominated by shrubs of the genus Larrea (“jarilla”); the area is not used for any activities and is recovering. (4) The forest with livestock is a private area facing the reserve that has been used for years for raising livestock, hence the site is much degraded with low, scattered shrubs.

Gaucha ramirezi sp. nov. appears to be much more abundant in the mature forest (49 males, 8 females, 17 juveniles) and in the forest with livestock (31 males, 11 females, 6 juvs.), compared to the secondary forest (4 males, 1 female, 2 juvs.) and Jarillal (1 male).

Notes. Gaucha ramirezi sp. nov. was found in sympatry with Cordobulgida bruchi , the latter being much less abundant in the sample studied at a ratio of 18: 1 specimens, respectively.

Figures

FIGURE 1. Map plotting known locality records of Gaucha ramirezi sp. nov. and Gaucha santana sp. nov.

FIGURE 2. Habitat of Gaucha ramirezi sp. nov. in Parque Natural Provincial y Reserva Forestal Natural Chancaní and surroundings, Córdoba, Argentina. A. Mature forest. B, C. Secondary forest. D. Forest with livestock.

FIGURE 3. Gaucha ramirezi sp. nov. A. Male holotype, habitus, dorsal aspect (MACN-Ar 39101). B. Male paratype, propeltidium and chelicerae, dorsal aspect (LBRE 402). C. Ibid. for female paratype (LBRE 402). D. Female paratype, opisthosoma, dorsal aspect (LBRE 402). E. Male, opisthosoma, 3 rd and 4 th post-genital sternites (LBRE); selected ctenidia are indicated by arrows (zooming-in is recommended for proper visualization). Scale bars: 1 mm (A, C, D); 0.5 mm (B); 0.2 mm (E).

FIGURE 4. Gaucha ramirezi sp. nov., chelicerae. A, B. Right chelicera of female paratype (MACN-Ar). A. Retrolateral aspect. B. Prolateral aspect. C–F. Right chelicera of male paratype (MACN-Ar). C. Retrolateral aspect. D. Prolateral aspect (under SEM). E. Flagellum. F. Ibid. (under SEM). Scale bars: 0.5 mm (A–D); 0.2 mm (E, F).