Spintharus gracilis Keyserling, 1886

LeMay, Gabriel A. & Agnarsson, Ingi, 2020, New species of smiley-faced spider Spintharus (Araneae, Theridiidae) from Brazil, and comments on unobserved diversity in South America, ZooKeys 915, pp. 17-24 : 17

Spintharus gracilis Keyserling, 1886 Figure 1A-O

Spintharus gracilis Keyserling, 1886: 244, plate 20, fig. 298a, b (Holotype unknown, however syntypes from Blumenau, Santa Catarina, Brazil, deposited in the British Museum of Natural History have been re-examined; Levi 1963a: 227, figs 2v, 10-13).

Material examined.

Brazil, Rio Grande do Sul, São Leopoldo, 19.viii.1986, C.J. Becker, 1 female, (MCTP); São Leopoldo, 19.viii.1986, C.J. Becker, 1 male, (MCTP); Eldorado do Sul, 30°05'32.2"S, 51°40'20.4"W, 25.vii.1995, A.A. Lise, 1 male, (MCTP); Novo Hamburgo, 1.x.1986, C.J. Becker, 2 females, 1 male, (MCTP); Campo Bom, 19.x.1987, C.J. Becker, 1 male, (MCTP); Viamão, 30°04'42.7"S, 51°03'02.0"W, 19.viii.1994, A.A. Lise, 1 female, 4 males, (MCTP).

Diagnosis.

Spintharus gracilis females differ from all other Spintharus species by the long and narrow abdomen being>3 × longer than wide (Fig. 1A-C ). Males differ from all other Spintharus species by the extremely long embolus traversing the entire outer edge of the tegulum (Fig. 1J, K, O ).

Description.

Female. Total length 4.21 (mm). Cephalothorax 1.05 long, 0.92 wide, 0.67 high, light yellow.

Sternum 0.77 long, 0.51 wide, extending half way between coxae IV, light yellow. Abdomen 3.16 long, 1.04 wide, 0.88 high. Narrow to oval without humps (Fig. 1A-C ). Fragmented white lines follow the dorsolateral edge from anterior to posterior, excluding the posterior third of the total abdomen length. Terminuses of white lines are inflected slightly medially, being more pronounced at the anterior terminus. White markings nearly join to form a strip just anterior of the abdomen center, but remain separated by an unpigmented gap. All eyes approximately equal in size, anterior median eyes 0.06 in diameter, anterior lateral eyes 0.11 in diameter. All eyes slightly elevated on cephalothorax and located within one eye diameter apart from each other, except the posterior median, which are 0.18 apart. Leg I femur 1.92, patella 0.45, tibia 1.37, metatarsus 1.90, tarsus 0.59. All legs pale yellow.

Epigynum with widely spaced and distinctly round copulatory openings and copulatory ducts spirals extending beyond the ectal margin of spermathecae.

Male. Total length 3.56. Cephalothorax 0.97 long, 0.99 wide, 0.60 high, yellow with slightly darker shading on lateral sides. Sternum 0.69 long, 0.50 wide, extending half way between coxae IV, light yellow. Abdomen 2.5 long, 0.67 wide, 0.71 high. All eyes approximately equal in size, anterior median eyes 0.09 in diameter, anterior lateral eyes 0.12 in diameter. All eyes slightly elevated on cephalothorax and located within one eye diameter apart from each other, except the posterior medians, which are 0.18 apart. Leg I femur 2.28, patella 0.41, tibia 1.58, metatarsus 2.12, tarsus 0.50. All legs yellow. Darker brown shading on leg IV on patella and where tibia meets metatarsus.

Male pedipalp with an extremely long spiral traversing the entire outer edge of the tegulum, leaving a large area of the tegulum exposed (Fig. 1J ).

Taxonomic note. The specimens examined here are from the southeast coast of Brazil but to the south of the hitherto documented locations. Given the strong genetic structure found in the Caribbean ( Dziki et al. 2015) over relatively short distances, we cannot rule out that our redescription represents a new species. However, detailed sampling coupled with DNA data will be necessary to test the limits of S. gracilis , as was the case for " S. flavidus " ( Agnarsson et al. 2018).

Figures

Figure 1. Spintharus gracilis Keyserling from Rio Grande do Sul, Sao Leopoldo. Female (A-C); A dorsal B ventral C lateral. Male (D-F); D dorsal E ventral F lateral G-I epigynum: G digested dorsal H digested ventral I undigested ventral J palp ventral K male syntype palp illustrated by Levi (1963 a). L-N Male from Rio Grande do Sul, Eldorado do Sul (30 ° 05 ' 32.2 " S, 51 ° 40 ' 20.4 " W) L dorsal M ventral N lateral O palp ventral. While we hypothesize that all illustrated palps belong to S. gracilis, note that the male from Eldorado do Sul is smaller, has smaller palp, and differs subtly in conformation, e. g., area of tegulum exposed.