Thwaitesia

Durán-Barrón, César G., Rosas, María V. & Contreras-Ramos, Atilano, 2013, Phylogenetic relationships of the comb-footed spider subfamily Spintharinae (Araneae, Araneoidea, Theridiidae), with generic diagnoses and a key to the genera, Zootaxa 3666 (2), pp. 171-193 : 188

Thwaitesia O. P.-Cambridge, 1881

( Figs. 9 D, 10A)

O. P.-Cambridge, 1881. Proc. Zool. Soc. London, p. 766. Type species by monotypy: T. margaritifera O. P.-Cambridge, 1881, op. cit., p. 767, pl. 66, fig. 1.

Diagnosis. The posterior median eyes have a distance between them about an eye diameter. Other spintharine genera present the posterior median eyes separated for less than an eye diameter or twice or more an eye diameter. Dorsally the opisthosoma presents a pigmentation pattern conformed by silver spots that become longitudinal bands ( Figs. 9 D, 10A). In the rest of genera, pigmentation forms a leaf-like pattern, just spotting, or points with no pattern defined. The male pedipalp cavity is sclerotized, only in this genus, observed dorsally in cleared specimens ( Fig. 7 D). An “H”-like web architecture is shared with Episinus and Spintharus . Levi and Levi (1962) comment that Thwaitesia is close to Spintharus and Episinus and that some species are probably intermediate between them.

Distribution. Africa, Australia, Southeast Asia, Indonesia, Caribbean, Central America, South America; probably worldwide in the tropics (Platnick 2013).

Material examined. Thwaitesia affinis : BRAZIL, [Municipality Rio de Janeiro], [Town] Petropolis, April 1946, 850 m, H. Sick, 1 3 (AMNH). PANAMA, Canal zone, Summit, October 1946, N. L. H. Krauss, 1 Ƥ (AMNH); Summit C[anal] Z[one], November 1946, N. L. H. Krauss, 1 Ƥ (AMNH). CO-OPERATIVE REPUBLIC OF GUYANA, Rupununi River, near mountains Makavapan, 5 October 1937, W. G. Hassler, 1 3 (AMNH). Thwaitesia bracteata : BRAZIL, [Rio de Janeiro], [City] Sumaré, January 1946, 200– 300 m, H. Sick, 1 3 (AMNH); Rio de Janeiro, [Municipality] Paineiras, 22 January 1959, A. M. Nadler, 5 Ƥ, 1 3 (AMNH). COLOMBIA, [Department] Amazonas, [City] Leticia, February 1956, J. N. Layne, 1 Ƥ (AMNH). PARAGUAY, Jaguarazaga, Alto Paraná, 7 Ƥ, 2 3 (AMNH-3721).

Figures

FIGURE 7. Male pedipalp. A, Steatoda grossa (left palp, ventral view, arrow = cymbial hood); B, Episinus cognatus (left palp, ventral view); C, Spintharus flavidus (left palp, ventral view, arrow = cymbial hood); D, Thwaitesia affinis (left palp, dorsal view, arrow = alveolar cavity of cymbium); E, Euryopis californica (left palp, dorsal view); F, Chrosiothes portalensis (left palp, ventral view, arrow = apex of flagellum); G, C. silvaticus (left palp, ventral view, arrow = apex of flagellum).

FIGURE 9. Opisthosoma (dorsal view). A, Spintharus flavidus Ƥ; B, Stemmops orsus Ƥ; C, S. ornata Ƥ; D, Thwaitesia bracteata Ƥ.