Micrathena ruschii ( Mello-Leitão, 1945 ), Mello-Leitao, 1945

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 : 46-48

Micrathena ruschii ( Mello-Leitão, 1945) , revalidated, new combination

Figures 17–19 , 41

Acrosoma ruschii Mello-Leitão, 1945: 266 , figs. 7–9. Female lectotype and three female paralectotypes, here designated, from Santa Tereza [19º55’S 40º35’W, 655 m], Espírito Santo, Brazil, deposited respectively in MNRJ 2566 and MNRJ 4255. First synonymized with Micrathena triangularis by Levi 1985: 512.

Micrathena cicuta Gonzaga & Santos, 2004: 332 –334, figs. 1–5. Female holotype from Área de Relevante Interesse Ecológico Floresta da Cicuta , Volta Redonda [22º31’S 44º7’W, 390 m], Rio de Janeiro, Brazil, deposited in IBSP 36322, not examined, nor found after the Butantan fire of May 2010. NEW SYNONYMY.

Synonymy. As many of Mello-Leitão’s type specimens, that of A. ruschii was not available to H.W. Levi at the time of his Micrathena revision. Based on the original description by Mello-Leitão, Levi placed A. ruschii as a doubtful synonym of M. triangularis . Examination of the type specimens revealed that this species is, in fact, a senior synonym of the recently described M. cicuta . It comes from a locality which represents the northernmost record for the species, but is nonetheless not far away from the known range of M. cicuta . It is noteworthy, however, that Mello-Leitão’s (1945) original illustrations and descriptions are not quite adequate for identifying the species, and that Gonzaga & Santos (2004) description should be used for this purpose.

Diagnosis. The palp morphology is most similar to that of M. brevispina Keyserling ( Levi 1985: fig. 393), with whom it shares a squared median apophysis. It differs by having the terminal apophysis with a distal, sclerotized tooth that points towards the apex of the embolus, by the conductor apex divided in two sclerotized parts, by the lightly sclerotized paramedian apophysis that points posteriorly and by the wider margin of the tegulum ( Fig. 19 ). For the diagnosis of the female, see Gonzaga & Santos (2004: 332).

Description. Male from Parque Nacional do Itatiaia, Itatiaia, Rio de Janeiro, Brazil (UFMG 4987). Carapace yellow, with two light brown bands on the sides ( Fig. 18 ). Chelicerae, endites, labium and sternum yellow. Legs yellow proximally, brown distally. Abdomen dorsally white, bordered with black on the sides of the anterior half and in the posterior margin ( Fig. 18 ); venter whitish gray, with a median black band extending from the posterior margin of the spinnerets to the end of the abdomen. Carapace with rounded thoracic region, a circular fovea and no dimples ( Fig. 18 ), slightly dorsoventrally flattened in lateral view ( Fig. 17 ). First coxa with hook and second femur with corresponding prolateral groove. Tibiae and femora I and II and tibia IV ornamented with macrosetae on the dorsal surface, strongest in femur I ( Fig. 18 ). Abdomen rectangular, elongated, narrowest behind and with slightly undulated sides ( Fig. 18 ). Total length, 4.95. Carapace 2.17 long, 1.81 wide at widest point. Abdomen 3.19 long. Length of first femur, 1.91; patella, 0.65; tibia, 1.35; metatarsus, 1.13; tarsus, 0.48. Second femur, 1.64; patella, 0.54; tibia, 1.07. Third femur, 0.99; patella, 0.41; tibia, 0.61. Fourth femur, 1.83; patella, 0.46; tibia, 1.03; metatarsus, 1.14; tarsus, 0.50. Palp with a large, membranous, flattened terminal apophysis with a distal sclerotized tooth, covering the embolus. Embolus thick, curved and with a truncate, almost bifid, apex. Conductor composed of two sclerotized parts, the larger posteriorly directed, and a membranous digitiform lobe. Paramedian apophysis lightly sclerotized, not attached to the conductor, posteriorly directed. Median apophysis comprised of three parts: a small basal projection located between the paramedian apophysis and the radix, a lobe and a bended rim ( Fig. 19 ). Paracymbium large and bilobed, otherwise unmodified.

Female. Described by Gonzaga & Santos (2004: 333).

Notes. The male was collected at the periphery of a female’s orb-web, in one of the supporting threads, in an area where two other females had been collected. The collecting site is 50 km away from Floresta da Cicuta , Volta Redonda, the type locality of M. cicuta . The specimen was collected with the left palp missing and the right one slightly expanded. To facilitate comparisons with other species, we illustrate the mirror image of this palp, as it was the right one ( Fig. 19 ). The species is recorded for the first time for Parque Nacional do Itatiaia, Itatiaia, Rio de Janeiro; and Juiz de Fora, Minas Gerais (both localities in Brazil; Fig. 41 ).

Natural history. Specimens were collected by visual searching in the understory vegetation of montane Atlantic rainforest.

Material examined. BRAZIL. Minas Gerais: Juiz de Fora, Reserva Biológica Municipal Poço D’Anta (21º45’37.84’’S 43º19’10.24’’W, 810 m), G.H.F. Azevedo & A.J. Santos coll., 02/IV/2011, 1Ƥ ( UFMG 5224). Rio de Janeiro: Itatiaia, Parque Nacional do Itatiaia (12º27’17’’S 44º36’29.8’’W, 720 m), G.H.F. Azevedo et al. coll., 15–22/II/2011, 13, 3Ƥ ( UFMG 4987).

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 17 – 19. Micrathena ruschii (Mello-Leitão, 1945), male (UFMG 4987). 17 – 18, habitus: 17, lateral view; 18, dorsal view. 19, mirror image of right palp, mesal view. Abbreviations: BP = basal projection of the median apophysis, C = conductor, CL = conductor lobe, Cy = cymbium, E = embolus, M = median apophysis, PM = paramedian apophysis, R = radix, TA = terminal apophysis, Ti = tibia. Scale bars: 17 – 18, 1 mm; 19, 0.1 mm.