Gaucha santana, 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 : 186-192

Gaucha santana sp. nov.

Figures 1 , 5–9 ; Table 1

Gaucha sp.: Botero-Trujillo et al. 2017: 39 [in part, records from Santana do Livramento only], figs. 3c–f.

Type material. Holotype : male from BRAZIL: Rio Grande do Sul: Santana do Livramento—Área de Proteção Ambiental do Rio Ibirapuitã , Fazenda Rincão dos Moraes, 185 m elev., 30°29′08.99″ S 55°34′35.51″ W, 30.xi.2013, R. Ott (MCN-Sol-018). Paratypes: same data of holotype, 1 male (MCN-Sol-016); 1 female (MCN-

Sol-017); 2 males, 1 female, 3 juveniles (MCN-Sol-041). Same locality and data but, xii.2014, R. Ott & R. Botero Trujillo, 1 male, 1 female, 10 juveniles (MCN-Sol-047); 1 male (MCN-Sol-046, tissue sample Sol-M00054, BOLD process ID SSA054-16) ; 1 male (MCN-Sol-044, tissue sample Sol-M00055, BOLD process ID SSA055-16) ; 1 subadult female (MCN-Sol-043, tissue sample Sol-M00056, BOLD process ID SSA056-16). Same locality and data but, Fazenda Sr. Caio, 185 m elev., 29.xi.2013, R. Ott , 4 males, 2 females, 4 juveniles (MCN-Sol-015).

Additional material examined. BRAZIL : Rio Grande do Sul: Santana do Livramento—Área de Proteção Ambiental do Rio Ibirapuitã, “Cerrito Reserva”, 263 m elev., 30°36′33.87″ S 55°38′30.18″ W, xii.2014, R. Ott & R. Botero Trujillo, 1 male (MCN-Sol-045); unknown date, R. Ott, 1 female (MCN-Sol-042). Área de Proteção Ambiental do Rio Ibirapuitã, “Afloramento Passo do Ferrão”, 174 m elev., 30°27′15.97″ S 55°43′25.71″ W, 14.xi.2011, 2 males, 2 females, 2 juveniles (MCN-Sol-019). Área de Proteção Ambiental do Rio Ibirapuitã , 01.xi.2013, R. Ott, 1 male, 1 female (MACN-Ar).

Etymology. Noun in apposition taken from the municipality ‘Santana do Livramento’, part of whose territory forms the Ibirapuitã Environmental Protection Area where this species was collected. Diagnosis. Gaucha santana sp. nov. belongs to the fasciata species-group of Gaucha , as defined by Botero- Trujillo et al. (2017: 15). In various respects, males of G. santana sp. nov. most closely resemble those of G. curupi among species in this group. These include that the fixed finger FP and FM teeth are elongated, whereas the FD tooth is much smaller, such that primary teeth are graded as FP=FM>>FD ( Fig. 8C ). Likewise, the fixed finger mucron is markedly long, similarly shaped in males of both species, and a subterminal flange (STF) is not present in either ( Figs. 8C,E ), besides both have the flagellum moderately inflated ( Figs. 8E,F ) (e.g., unlike that of G. casuhati ). Gaucha santana sp. nov. can be recognized by the absence of the fixed finger FSD tooth (regardless of sex or maturity of the specimens) ( Figs. 8A,C ); in contrast, females of G. curupi always bear the FSD tooth, while FSD is most often present (though reduced) in males. Furthermore, the FD tooth, which is reduced in males of the two species, is comparatively larger in those of G. santana sp. nov. ( Fig. 8C ).

Description. For most aspects the general morphology fits that described for the genus and the fasciata species-group by Botero-Trujillo et al. (2017). Color: Propeltidium brown, with some slightly lighter areas; ocular tubercle brown to black. Chelicerae with manus predominantly brown and fingers reddish. Meso-, metapeltidium and dorsal surface of opisthosoma with a three-dark-band design typical of the family: tergites with broad, median, longitudinal brown band, and paired, thinner lateral whitish bands; pleural membranes with sub-dorsal black and sub-ventral white bands; white band of opisthosomal pleural membrane with black marks surrounding the socket of most setae, and black pigment along the inter-segmental transversal vertices especially on posterior half; sternites yellowish brown, with lateral margins conspicuously darkened, especially on two/three posteriormost sternites. Ventral surface of prosoma uniformly yellowish; sternum lighter than coxae. Pedipalps and legs dark brown especially on dorsal and prolateral surfaces, lighter on ventral and retrolateral surfaces; pedipalp with telotarsus darker than the rest of pedipalp. Malleoli whitish, often with distal margin darkened. Morphology: Opisthosoma with scarce ctenidia on 1 st and 2 nd post-genital sternites (spiracular sternites), more abundant on 3 rd and 4 th postgenital sternites (post-spiracular sternites I–II); ctenidia filiform and setiform, similar in thickness to the bifid setae (in male and female). 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 well-developed FP and FM primary teeth, FD tooth much smaller, graded as FP=FM>>FD; mucron markedly long, without subterminal flange (STF). Movable finger MP tooth pronounced, markedly taller than MM; mucron short, typical of the fasciata species-group, with gnathal edge carina very prominent and convex on lateral aspect. Flagellum inflated and narrowing anteriorly, with minute spicules along prodorsal and proventral margins. 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 moderately curved and without angular dorsal crest, with highest elevation at level between FM and FD teeth. Fixed finger robust, with mucron distinctly curved towards the venter. Movable finger MP tooth moderately taller than MM tooth.

Distribution, habitat and biological observations. Gaucha santana sp. nov. is known only from the type locality, Santana do Livramento—Área de Proteção Ambiental do Rio Ibirapuitã, in the state of Rio Grande do Sul, southern Brazil. The Ibirapuitã Environmental Protection Area is a conservation unit located in the northernmost portion of the Uruguayan Savanna ecoregion (NT0710 in Olson et al. 2001), into the biome of Tropical and Subtropical Grasslands, Savannas, and Shrublands. Grasslands dominate the area, and local geology is characterized by shallow, sandy or stony soils with low capacity for water retention ( Overbeck et al. 2015). Rocky outcrops of basalt are notable formations; in the easternmost part of the protected area there is a place where sandstone emerges below the basalt cover, in a formation known as "Costa do Haedo". Specimens of G. santana sp. nov. have been observed in open fields of stony soils with little grassy vegetation, often resembling small rocky islands, or running on large basalt outcrops.

No specimens of G. santana sp. nov. were found in morning hours. The peak of activity of this species seemingly starts at noon, and activity can be noticed until right before twilight begins. With respect to seasonality, the species exhibits the greatest activity in spring and summer, especially from November to January, and this presumably coincides with the breeding season.

In the field, adult females were sometimes observed digging burrows in the late afternoon. In early December 2012, one of these specimens was taken to the laboratory where shortly afterwards, in its new place over a litter layer, laid 73 eggs, but none hatched. A year later, in December 2013, another female was captured in digging behavior and taken to the laboratory; there she laid 25 eggs, 23 from which larvae emerged after 37 days. All larvae died and no other observations could be performed. Images of the cited egg-laying females are available in Botero- Trujillo et al. (2017: figs. 3E,F).

Notes. No any other mummuciid species was found in the area inhabited by G. santana sp. nov.

Barcode. Three COI sequences (657 bp) obtained from different specimens of G. santana sp. nov. had identical nucleotide composition (0% intra-specific divergence). An identification search in BOLD Systems for this sequence (Barcode Index Number: BOLD:ADD5797) indicated closer match with Gaucha fasciata (BIN:BOLD:ADD5134) followed by Gaucha curupi (BIN:BOLD:ADD8503), with 90.66–90.67% and 89.76– 90.21% similarity range values, respectively. Figure 9 shows the clustering pattern of sequences of the three species.

Figures

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

FIGURE 5. Live specimens of Gaucha santana sp. nov., photographed in the field. A. Male. B, C. Two different females.

FIGURE 6. Habitat of Gaucha santana sp. nov. in Santana do Livramento—Área de Proteção Ambiental do Rio Ibirapuitã, Rio Grande do Sul, Brazil. A, B. Fazenda Rincão dos Moraes, showing typical sandy and stony soils. C, D. Large basalt outcrops, “Afloramento Passo do Ferrão”.

FIGURE 7. Gaucha santana sp. nov. A. Male holotype, habitus, dorsal aspect (MCN-Sol-018). B. Male paratype, propeltidium and chelicerae, dorsal aspect (MCN-Sol-044). C. Ibid. for female paratype (MCN-Sol-047). D. Male paratype, opisthosoma, lateral aspect (MCN-Sol-044). E. Male paratype, opisthosoma, 1 st to 4 th post-genital sternites (MCN-Sol-044); selected ctenidia are indicated by arrows (zooming-in is recommended for proper visualization). Scale bars: 2 mm (A); 1 mm (B–D); 0.25 mm (E).

FIGURE 8. Gaucha santana sp. nov., chelicerae. A, B. Right chelicera of female paratype (MCN-Sol-015). A. Retrolateral aspect. B. Prolateral aspect. C–F. Right chelicera of male paratype (MCN-Sol-041). C. Retrolateral aspect. D. Prolateral aspect (under SEM). E. Flagellum. F. Ibid. (under SEM). Scale bars: 1 mm (A,B); 0.5 mm (C,D); 0.2 mm (E,F).

FIGURE 9. Neighbor-Joining clustering for selected species of the fasciata species-group of Gaucha Mello-Leitão, 1924.