Micrathena yanomami, Magalhães, Ivan L. F. & Santos, Adalberto J., 2011

Magalhães, Ivan L. F. & Santos, Adalberto J., 2011, Two new species and taxonomic notes on the Neotropical spiny orb-weaving spiders Micrathena and Chaetacis (Araneae: Araneidae), with remarks on the development of Micrathena excavata, Zootaxa 2983, pp. 39-56 : 43-45

Micrathena yanomami new species

Figures 9–13 , 41

Type material. Holotype female and paratype female, both from Bebedouro Novo, Parque Nacional do Pico da Neblina, São Gabriel da Cachoeira, Amazonas, Brazil (00º44’53.88”N, 65º58’31.80”W, 860 m), A.A. Nogueira coll., deposited in INPA 6286 and INPA 6287, respectively.

Etymology. The specific name honors the Yanomami , a group of native American people whose territory includes the Pico da Neblina, the type locality.

Diagnosis. Micrathena yanomami females differ from the other species of the triangularispinosa group by the coloration pattern of the carapace, with a black band along its entire edge, by the granulation in the carapace edges and by the setal bases of the femora, which are more projected and domed ( Figs. 9, 10 ). The epigynum is similar to that of M. triangularispinosa (De Geer) ( Levi 1985: figs. 474–476) but differs by the more robust lobe, which is also more detached from the bulge ( Fig. 11, 12 ), and by the median plate of the epigynum in posterior view, which is wider than long and has a mushroom-shaped clear area embracing two dark spots ( Fig. 13 ).

Description. Female (holotype). Carapace orange brown, with a black band along its entire edge and around the eyes ( Fig. 9 ). Chelicerae dark brown. Endites and labium orange brown. Sternum yellowish white. Coxae orange brown, legs dark brown, darkest in the femora. Dorsum of abdomen yellow, sides dark brown, venter pale yellow; spines red, with a black band extending from one posterior spine to the other; sclerotized ring around spinnerets black. Carapace dome-shaped, almost glabrous, with fine granulation on the edges of the thoracic area, and without dimples; thoracic fovea an indistinct circular marking; median ocular area slightly projected. Abdomen trapezoidal, widest posteriorly. Four pairs of spines on the abdomen, the first and the third the longest; the fourth only an indistinct and sclerotized nipple below the large posterior spines ( Figs. 9, 10 ). Total length, 5.13. Carapace 2.02 long, 1.62 wide at its widest point. Abdomen 3.19 long. Length of first femur, 1.66; patella, 0.63; tibia, 1.18; metatarsus, 0.92; tarsus, 0.59. Second femur, 1.5; patella, 0.57; tibia, 1.05. Third femur, 1.13; patella, 0.41; tibia, 0.72. Fourth femur, 2.09; patella, 0.57; tibia, 1.14; metatarsus, 1.13; tarsus, 0.65. Epigynum with a domed bulge, from which a lobe projects posteriorly ( Figs. 11, 12 ). Posterior median plate wider than long, mushroom-shaped and embracing two dark spots that correspond to the region where the copulatory openings lie ( Fig. 13 ).

Male. Unknown.

Relationships. Micrathena yanomami belongs to the triangularispinosa group sensu Levi (1985), based on the domed carapace, projected median eyes and similar morphology of the abdomen and genitalia.

Variation. The holotype has one of the anterior spines shorter than the other; the paratype has both of them long, but they are twisted like a goat's horn (in the first case, probably an abnormality; in the second case, probably an artifact of the process of preservation). Females (N=2) vary in total length from 5.13 to 5.26; carapace length varies from 2.02 to 2.04.

Distribution. Examined specimens come only from the type locality ( Fig. 41 ). According to the collector of the type specimens, the species occurs at two other localities in Pico da Neblina: Cachoeira do Tucano (00º39’54.00”N, 65º56’09.60”W, 100 m) and Bebedouro Velho (00º41’54.96”N, 65º55’40.44’’W, 400 m) (A.A. Nogueira, pers comm.). I. Cizaukas (pers. comm.) reports examining material of this species from the following locality: BRAZIL. Amazonas: Manaus [Projeto Dinâmica Biológica de Fragmentos Florestais, Reserva do Km 41, 2º24’26”S, 59º43’40’’W]. However, these specimens have been lost in the fire that affected the arachnological collection of Instituto Butantan in May, 2010 before they could be examined by the authors of the present study.

Material examined. Only the types.

Figures

FIGURE 41. Geographic distribution records for Micrathena yanomami new species and Chaetacis bandeirante new species, and new records for M. gaujoni, M. ruschii and C. necopinata.

FIGURES 9 – 13. Micrathena yanomami new species, female holotype. 9 – 10, habitus: 9, lateral view; 10, dorsal view. 11 – 13, epigynum: 11, lateral view; 12, ventral view; 13, posterior view. Abbreviations: L = lobe, MP = posterior median plate. Scale bars: 9 – 10, 1 mm; 11 – 13, 0.1 mm.