Epicadinus Simon 1895
Creators: name: Prado, André Wanderley Do
name: Baptista, Renner Luiz Cerqueira
name: Machado, Miguel
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Thomisidae
Epicadinus

description: Epicadinus Simon, 1895
Epicadinus Simon, 1895: 1052 –1053. Mello-Leitão 1929: 98, pl. 7, figs 12–20.
Type species. Thomisus trispinosus Taczanowski, 1872, by original designation.
Diagnosis. Epicadinus is related to Epicadus and Onocolus in the general shape of the male palpus, presenting a discoid tegulum and filiform embolous encircling it, and in the canoe-shaped RTA fused to the DTA. Some Epicadus (e.g. E. heterogaster (Guérin-Menéville, 1829) and E. rubripes Mello-Leitão, 1924) share the presence of a pair of conical projections above the ALE with Epicadinus (Fig. 1A), but the flat carapace of Epicadinus (Fig. 1C) contrasts with the presence of a median dorsal projection in the foveal area, at least in females, of most Epicadus species (heterogaster -clade sensu Machado et al. 2017). Epicadinus species can be recognized by their spiny appearance, since most of their tegument is covered by robust setiferous tubercles, surmounted by elongated, needle-shaped macrosetae (Figs 1D, E, I; 8A–C, G). Additionally, the paired macrosetae present on the tibiae and metatarsi I–II are not quite mobile and inserted directly on the leg surface as in most Thomisidae, but rather located on the largest setiferous tubercles (Fig. 8G). Some Australian species described in Sidymella and juvenile specimens of species in the pustulosus -clade of the genus Epicadus also have spiny tegument, but the setiferous tubercles are not elongated.
Description. Spiders with clear sexual dimorphism. Males about 3/5 of females size. Carapace (Fig. 1B) rather longer than wide, almost flat, without dorsal projections, only with ocular region elevated, presenting two clear projections above ALE, forming a high ocular mound with two acute tips. Dorsum with three median rows of setiferous tubercles and six rows between radial furrows, and others irregularly distributed. Posterior slope of carapace without tubercles or macrosetae. Clypeus high, at least 1.5x AME diameter. Ocular area with anterior row strongly recurved and posterior slightly procurved. MOQ trapezoid. ALE size equal to or slightly larger than AME (Figs 1A, B). Labium up to twice as wide as long. Sternum cordiform, almost as wide as long, bearing abundant spiny or feathery bristles. Endites setaceous.
Opisthosoma generally pentagonal (but with trapezoidal anterior half and semicircular posterior half in E. biocellatus), covered by abundant tubercles of variable size. Dorsum with three prominent, conical projections, with apex directed laterally or perpendicular to midline of opisthosoma. First pair of conical projections of similar size and located at median portion of opisthosoma. Posterior conical projection strongly variable in size and shape in females and slightly variable in males. Anterior border generally with projected angles (except E. biocellatus), usually covering posterior slope of carapace. Venter covered by thick feathery bristles, more abundant anteriorly, without setiferous tubercles, and with two longitudinal and parallel rows of sigils, sometimes almost inconspicuous. Small, triangular spinnerets covered by abundant bristles (Fig. 1H).
Small chelicerae covered by abundant bristles. Fang furrows toothless and with abundant, long and erect bristles. Fangs short and curved (Fig 1A).
Leg formula 1243, with legs I and II up to twice as long as legs III and IV. Legs with abundant setiferous tubercles, larger on tibiae and metatarsi, each one topped by an elongated macroseta. Legs I–II with setiferous tubercles larger and more abundant than in posterior legs. Tibia I-II ventrally with five pairs of macrosetal tubercles and metatarsus I-II with four pairs. Paired macrosetae not mobile and located on top of largest tubercles present in body. Macrosetal tubercles slightly offset to sides and directed externally, nearly lateral to longitudinal axis of article. Areas without setiferous tubercles or bristles with abundant small granules (Fig. 1D). Larger granules, similar to warts, grouped in distinct areas, such as lateral clusters in femurs, two dorsal bands between rows of setiferous tubercles on dorsum of patella and tibia (wider in first article), and two marginal bands on tibia, near patella joint (Figs 1E, F). Tarsus with one pair of unequal pectinated claws; prolateral claw (mesal) with 5–6 acute, sharp and straight teeth in basal portion, 5 thick, blunt and straight teeth in apical portion; retrolateral claw (ectal) with only 5 thick apical teeth, and basal teeth replaced by a gap and a longer basal keel (Fig. 1G). Claw tuft with about 25–30 spatulated setae.
Palpus of male with roundish cymbium, with pointed apex. Alveolus deep, forming a pronounced convexity in dorsal face of cymbium. Tegulum roundish and flattened, covering apex of embolus in some species (Figs 9E–F). When uncovered (Figs 3H, 6E), apex of embolus protrudes into a deep marginal furrow on the triangular, apical glabrous area of tegulum (Fig. 3H). Embolus encircling the margin of tegulum, varying from half a turn up to six turns around tegulum. RTA with central concavity, limited by marginal folds, generally elongated (except E. helenae). Base of RTA partially fused to DTA, both variable in size. DTA hook- or horn-shaped, usually quite distinct and smaller than RTA (Figs 3G, 6G, 9F, 12F).
Epigynum with atrium (or median field) usually very conspicuous (except E. biocellatus) and median septum either covering or not copulatory openings (Figs 2E, 5D, 8E). Septum located posteriorly to atrium (except E. biocellatus). Vulva structure variable, with helicoidal copulatory ducts presenting six to ten turns (E. spinipes and E. villosus, Fig. 8F), or forming an expanded anterior curve (or secondary spermathecae), followed by a few posterior curves (Figs 2F, G; 5F). Spermathecae roundish and well developed, located near epigastric furrow.
Color of specimens variable, from light yellow to orange and dark brown in 70% ethanol (Figs 6A–C, 11A–C, G). Live specimens can show light green hues (Fig. 1I) or more vivid colors (Fig. 1J).
Composition. Four species. Epicadinus biocellatus Mello-Leitão, 1929, Epicadinus trispinosus (Taczanowski, 1872), Epicadinus spinipes (Blackwall, 1862), and Epicadinus villosus Mello-Leitão, 1929.
Distribution. Neotropical region from southern Mexico to northern Uruguay. In South America, there are records only east of the Andes, from Amazonian Ecuador at west, to Bahia, Brazil at east.
Natural history. Despite the scarce knowledge about the ecology and behavior of Epicadinus species, the specimens are usually found on leaves and twigs of different plants, where they hunt by the sit-and-wait behavior, as many other thomisids, and use their strong anterior legs to catch and hold prey (Fig. 2H). Many specimens were captured near ground, over herbs and small bushes in open areas, inside or at the border of forests.
Species groups. The four species of Epicadinus fall in two species groups, clearly set apart by morphological and genitalic similarities. The trispinosus -group includes E. biocellatus and E. trispinosus. Both species have females presenting the posterior conical projection perpendicular to the opisthosoma (Figs 2B, 5C), epigynum with median septum totally fused, visible copulatory openings and sinuous and non-spiral, short copulatory ducts (Figs 2D–G, 5D–F). The males of E. trispinosus and E. biocellatus have a V- or U-shaped notch between the RTA and the DTA, RTA with ventral fold forming a deep basal pouch, and embolus with a clearly visible apex and forming an incomplete turn around the tegulum (Figs 3E–H, 6D–G). This group occurs mainly in the Amazon. E. biocellatus is restricted to eastern Amazonia, while E. trispinosus is a widespread species, occurring in western Amazonia and also in several other biomes, from Mexico to the Bolivian chaco and the Brazilian state of São Paulo. The last two records are from open vegetation biomes (chaco and an ecotone between the Brazilian Cerrado and Atlantic Forest, respectively, Fig. 15). The second group is the spinipes -group, including E. spinipes and E. villosus. Females of both species have an posterior conical projection arranged transversely to the opisthosoma (Figs 8C, 11C), epigynum with medial portion of the median septum covering copulatory openings, and inner genitalia with spiral copulatory duct, composed of six or more coils (Figs 8D–F, 11D–F). Males of these species present the dorsal fold of the RTA directly fused to the base of the DTA, without basal pouch, and a long embolus, with at least three turns around the tegulum, and with apex hidden by the tegulum (Figs 9D–F, 12D–F). This group is restricted to the Brazilian Atlantic Forest and its ecotones. E. spinipes is found near the coast of northeastern and southeastern states of Brazil (Bahia to São Paulo), while E. villosus occurs away from the coast in the northern portion of its range, from Bahia to São Paulo, but is found also near the coast from southern São Paulo to Uruguay (Fig. 15). The records from Brazilian Amazon are considered doubtful (see species description below).
description: Published as part of Prado, André Wanderley Do, Baptista, Renner Luiz Cerqueira & Machado, Miguel, 2018, Taxonomic review of Epicadinus Simon, 1895 (Araneae: Thomisidae), pp. 201-234 in Zootaxa 4459 (2) on pages 203-206, DOI: 10.11646/zootaxa.4459.2.1, http://zenodo.org/record/1458488