Popperaneus, 2020

POPPERANEUS CABRA-GARCÍA & HORMIGA View in CoL GEN. NOV.

Type species: Wixia gavensis Camargo, 1950 .

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Diagnosis: Males of Popperaneus can be distinguished from all other araneids with a paramedian apophysis by the morphology of the conductor, which has two distinct portions with a shared attachment to the tegulum ( Figs 83A, B, D, 84A, C, 100E, F, 103B, C). The females are distinguished by the cylindrical aggregate spigots ( Figs 55F–H, 56A) and the morphology of the copulatory ducts, which have two distinct, almost perpendicular portions ( Figs 118D, 119D).

The monophyly of Popperaneus (Goodman–Bremer support = 126) is supported by ten unambiguous phenotypic synapomorphies, four of which are unique and non-homoplastic ( Fig. 17): pale lateral spots on the female carapace (character 3), cylindrical aggregate spigots (character 67), conductor with two distinct portions (character 87) and terminal apophysis with a well-developed perpendicular ridge (character 115).

Description: Total body length 5.1 mm – 5.5 mm in males and 5.5–7.7 in females. Carapace longer than wide, with dusky sides and a medial pale yellow to brown longitudinal region. Females with two lateral pale spots on the cephalic region ( Figs 19I, J). Female carapace densely covered by type II white setae on the cephalic region ( Figs 18E, F, 19I,J; character 1) and some scattered ones on the thoracic region ( Fig. 18E). Male carapace more hirsute than that of females. Sternum pale yellow to brown, approximately as long as wide and with imbricate cuticle texture. Labium pale yellow to brown, wider than long. Lateral eyes subequal in size. Posterior median eyes larger than anterior median eyes and surrounded by black rings ( Figs 7B–D, 8D). Clypeus low, subequal to the diameter of the AME and with imbricate cuticle texture. Chelicerae pale yellow to dark brown. Female paturon with a pale area in the frontal surface. Legs yellowish, with dusky rings. Leg formula I>II>IV>III. Male coxae I with ventral hook ( Fig. 26H), femora II with prolateral groove ( Fig. 30I), and tibia II with enlarged macrosetae in the prolateral surface ( Fig. 32J) and macrosetae in the ventral sector of the retrolateral surface ( Fig. 33D). Male coxae IV and trochanter IV without macrosetae.

Abdomen longer than wide. Dorsal and lateral surfaces with white, brown and black irregular marks, forming highly variable patterns among individuals. Ventral surface with a dusky median band from the epigynum to the spinnerets, flanked by two thin, white longitudinal bands. Booklungs cuticle obscurely imbricate ( Fig. 46E). Dorsal and lateral surfaces of the abdomen covered by white to pale brown short setae type II (see characters 41 and 42; Fig. 41A, B). Abdominal tubercles disposed in four lateral pairs, the first bifid, and one posteromedian ( Figs 8D, 19I, J, 41A). ALS with a large PI field and one MAP accompanied by a nubbin ( Figs 48F, 49A). Posterior median spinneret with numerous AC anterior to a central CY. One to three AC are located between the CY and the posterior mAP, which is accompanied by a posterior nubbin ( Fig. 52A, B). Posterior lateral spinnerets with numerous AC ( Figs 55F, 56A). Females AG –FL triplet anterior to the AC and almost parallel with the anterior CY spigot. AG cylindrical, with smooth cuticle texture and not embracing the flagelliform spigot ( Figs 55F–H, 56A). Posterior CY surrounded by AC. Epiandrous fusules arranged in a transverse line ( Fig. 60H) .

Male palpal coxae with a tooth-like projection facing a ventrobasal femoral projection ( Fig. 62H). Palpal patella with one macroseta. Paracymbium with a median ridge ( Figs 83C, 84B). Tegulum basal knob well developed, projecting between the conductor upper portion and the terminal apophysis ( Fig. 83A, B). Median apophysis with a strongly sclerotized ridge ( Figs 65E, F, 83A, 84A). Conductor divided into two main portions connected to the tegulum by a shared medial attachment ( Figs 65E, F, 83A, B, D, 84C, 100E, F, 103B, C). Outer margin of the paramedian apophysis stalk oriented towards the conductor and apical fold, decreasing abruptly in width towards the tip ( Fig. 103B, C). Paramedian apophysis connected to the conductor through a short membrane ( Fig. 100E, F). Terminal apophysis surpassing the tegulum upper border, with a well-developed median ridge and attached to the radix by a thin, membranous region ( Figs 65E, F, 83A, 84A). Embolus elongate and fused with the terminal apophysis ( Figs 64E, F, 83A, 84A). Epigynum with a small scape ( Fig. 118A, B), lightly sclerotized. Epigynal lateral plates wider than the medial plate ( Figs 118B, 119B). Copulatory ducts longer than fertilization ducts, with two almost perpendicular portions ( Figs 118D, 119D). Spermathecae oval to spherical ( Figs 118E, 119E).

Composition: The genus consists of two species: Popperaneus gavensis ( Camargo, 1950) comb. nov. and Popperaneus iguape ( Levi, 1991) comb. nov. Complementary descriptions of Popperaneus species will be published in a forthcoming paper.

Etymology: The generic name is a patronym honoring Sir Karl R. Popper (1902–1994), in recognition of his eminent contributions to the philosophy of science. The ending is derived from the genus Araneus . The gender is masculine.

Distribution: Known from Brazil and Paraguay. It occupies a broad elevational range from sea level to 1500 m.

Natural history: Popperaneus species are nocturnal spiders found in the Atlantic Forest. Popperaneus gavensis builds its vertical web at different heights above ground level, from ~ 5 cm to 1.5 m in vegetation associated with ravines. The web has an open hub, with relatively few radii and sticky spirals ( Fig. 7A). The spider rests at the centre of the web, hanging upside down. If the spider is disturbed, it moves quickly towards an attachment point, usually twigs or leaf petioles, where it remains immobile with its legs pressed to its body. There is no retreat. Popperaneus gavensis and P. iguape have been reported as prey of several hunting-wasp species of the genus Trypoxylon ( Hymenoptera : Crabronidae ) ( Gonzaga & Vasconcellos-Neto, 2005; Buschini & Wolff, 2006; Buschini et al., 2006, 2008, 2010a). A male specimen of P. gavensis was collected in a female web frame in Parque Nacional do Itatiaia, Rio de Janeiro.