Epicadus Simon, 1895

Silva-Moreira, Thiago Da & Machado, Miguel, 2016, Taxonomic revision of the crab spider genus Epicadus Simon, 1895 (Arachnida: Araneae: Thomisidae) with notes on related genera of Stephanopinae Simon, 1895, Zootaxa 4147 (3), pp. 281-310 : 283-284

Epicadus Simon, 1895

Epicadus Simon, 1895: 1052 (Replacement name for Eripus Walckenaer, 1833 , preoccupied by Eripus Dejean, 1829 [ Coleoptera : Carabidae ]). Petrunkevitch 1928: 161; Mello-Leitão 1929: 93; Roewer 1954: 755; Brignoli 1983: 604; World Spider Catalog 2016.

Type species. Thomisus heterogaster Guérin-Méneville, 1829 by monotypy.

Composition. Three species: Epicadus heterogaster ( Guérin-Méneville, 1829) ; Epicadus rubripes Mello- Leitão, 1924 and Epicadus planus, Mello-Leitão, 1932 .

Etymology. No etymological explanation was provided in the original description by Simon. Maybe “ Epicadus ” refers to Cornelius Epicadus , servant and biographer of the roman general and statesman Lucius Cornelius Sulla Felix. Epicadus is a masculine anthroponomy from the Southern Illyria (the Roman Dacia). In a similar way, another anthroponomy of the same origin, “ Epidius ” was used by Thorell to name another thomisid genus.

Diagnosis. Epicadus species are distinct from all other Neotropical Thomisidae by having a set of robust and conical opisthosoma projections ( Figs 2 A, 7C, 11C) and a median spire (MS) on the fovea region ( Figs 2 B, 7B, 11B) associated with a white spot. The epigynal plate is glabrous, with a incomplete posterior septum and lower edges, and copulatory orifices sclerotized and located on a C-shaped structure ( Figs 3 A; 8A; 12E). Copulatory ducts S-shaped, with CV about 2–3 times wider that the width of the remaining duct ( Figs 15 A, D, G). Males have a scaly opisthosoma, palp with an elongated and concave RTA sharing its basis with the DTA, whereas DTA is short, acute and curved at the edge ( Figs 5 E, 10D, 14D).

Description. Medium sized spiders, with very marked sexual size dimorphism (total length 2.50–3.70 in males, 10–15 in females). Prosoma as long as wide and higher in the posterior half. Prosoma glabrous, covered with small, colorless granules anteriorly and larger ones in posterior half, along the radial furrows ( Fig. 7 B). Prosoma with a distinct median guanine spot, white in E. heterogaster and E rubripes , or instead a median black stripe or row of black granules ( E. planus ) ( Figs 2 A; 7C; 11C). The female fovea area shows a distinctive median spire, (MS), covered with granules. MS may be discrete ( E. planus , Fig. 11 B) or pronounced ( E. heterogaster , E rubripes , Figs 2 B; 7B). Eyes subequal, arranged in a 4–4 disposition. Eye mound with vertical conical projections, pronounced in E. heterogaster , discrete in E. rubripes and absent in E. planus ( Figs 6 A; 7D; 11D). Chelicerae with three promarginal and two retromarginal teeth; promargin hirsute, with fang basis bearing long and delicate setae. Endites elongated, rounded on the edge, with scarce promarginal scopula. Labium short, truncated, not passing the half of the endites, Sternum oval with concave anterior border. Opisthosoma with distinctive conical abdominal projections distributed as follows: two anterior (absent in males of E. rubripes and E. planus ), two upper lateral, two lower lateral (subtle on males of E. rubripes and E. planus ) and one median posterior. Opisthosoma projections can be directed vertically ( E. heterogaster , Fig. 2 B; median posterior projection in E. rubripes , Fig. 7 B) or horizontally (anterior and lateral projections in E. rubripes , Fig. 7 B; and E. planus — Fig 11 B). The anterior projections might be distinctive, conical ( E. heterogaster , Fig. 4 C) or subtle, like an invagination of the anterior margin of the opisthosoma, slightly flattened dorsoventrally ( E. rubripes ; E. planus , Figs 7 C, 11C). Male opisthosoma covered with small sclerites, darker than the overall opisthosoma color. Spinnerets surrounded by a sclerotized ring ( Fig. 13 E).

Anterior legs laterigrade and superposed (leg I laying over leg II when spider in resting position, Fig. 1 ); leg III anteriorly oriented and leg IV posteriorly oriented. Anterior legs distinctively larger and stouter than the posterior ones. Femora I and II armed with two rows of ventral conical tubercles (FeT, Figs 2 E, 7E), patellae I and II elongated. Tibiae and metatarsi I and II round in cross-section, armed with short, slightly curved macrosetae, with rounded base and acute edge (sometimes bifid, Fig. 3 E). Metatarsi III and IV round in cross-section with distinct setae tuff on the distal third. Anterior tibiae with a concave area on the dorso-retrolateral face ( Fig. 6 B), where a sensorial pit can be found (SPt, Figs 6 C, D) in the proximal part. The same region contains both duster-shaped setae ( Fig. 6 E) and trichobothria ( Figs 6 C, D). Tarsi I and II of similar size as metatarsi, wider near joint to metatarsi. Tarsi III and IV small and rounded in cross-section, forming an acute angle with the metatarsi, with a dense field of setae along its extension. Leg formula I-II-IV-III. Palp with spatulated setae and a tarsal claw. Epigynum with a discrete, colorless incomplete median septum and lowered median area (better seen on SEM, Figs 15 B, E, H). Epigynal plate at the same level as the opisthosoma ( E. heterogaster , E. rubripes ) or slightly elevated ( E. planus ). Copulatory openings sclerotized ( Figs 3 A, 8A, 12A); vestibular edges sclerotized, forming a smooth and rounded atrium ( Figs 15 B, E, H). Copulatory ducts long, S-shaped ( Fig. 3 C) with upper (anterior) curve (CV) enlarged, similar to a secondary spermatheca (see Bonaldo 2000; Machado et al. 2015) at the distal part ( Figs 15 A, D, G) and getting narrower near the copulatory openings and distant from the spermatheca. Spermathecae rounded or bean-shaped. Fertilization ducts long and thin, oriented dorsally near the spermatheca and turning retrolaterally ( Figs 3 C–D, 8B–C, 12B).

Male palp with tibia robust, wider than long, usually bearing colorless setae. Cymbium pyriform and hirsute. Tegulum discoid, without apophyses ( Figs 5 B, 10E, 14E); RTA canoe-shaped, with the concavity facing retrolaterally ( Figs 5 E, 10D, 14D); smaller edge curved to the inner side of concavity. DTA short, acute, curved and sharing the same basis with RTA ( Figs 15 C, F, I). Embolus filiform ( Figs 5 D, 10E, 14E).

Coloration in ethanol (but see comments under “Natural history”): females with yellow or dark yellow prosoma and pearl white opisthosoma. Legs I and II usually bearing black stripes or spots on the dorsum of the femora I and II or (rarely) on metatarsus. Legs and tarsal palp usually black ( Figs 2 , 7 , 11 ). Males are reddish or darkish brown, some specimens dark orange, with very little variation ( Figs 4 , 9 , 13 ). Male opisthosomal sclerites vary between dark orange to dark brown.

Distribution. The genus Epicadus has a classic Neotropical distribution pattern (sensu Morrone 2001) ranging from southern Brazil to central Mexico ( Fig. 17).

Natural history. Knowledge about the ecology and behavior of Epicadus species is very scarce. As many thomisids, Epicadus are usually found on leaves or flowers of different plants, where they hunt by the sit-and-wait behavior, and use their strong anterior legs to catch and hold prey ( Figs 16 C, E).

Figures

FIGURE 1. Epicadus species, color variation. A – C E. heterogaster; D – F E. rubripes; G – I E. planus. Photo credits (and localities): A Maxwel Rocha (Unknown locality); B Carlos Viquez (Costa Rica); C Anonymous (Amazônia, Brazil); D – F, Almir Cândido de Almeida (Ribeirão Grande, São Paulo, Brazil); G Arthur Anker (Peru); H Enio Branco (Aracoiaba da Serra, São Paulo, Brazil); I Projeto Dacnis team (Alex Mariano and Edelcio Muscat) (Ubatuba, São Paulo, Brazil).

FIGURE 2. Epicadus heterogaster (Guérin-Menéville, 1829). Female (IBSP 06247). A – C habitus (A dorsal, B lateral, C ventral); D cephalic region, frontal view; E femur I, dorsal view. Scale bars: 2 mm (A – C); 1 mm (D – E).

FIGURE 3. Epicadus heterogaster (Guérin-Menéville, 1829). Female (IBSP 08491). A – D epigynum / vulva (A ventral – arrows point the atrium, B dorsal – arrows points tto FD, C sagittal, D frontal—arrow points to FD (left one broken )); E metatarsus I, retrolateral view. Arrows point to bifid setae. Scale bars: 0.5 mm (A, E); 0.2 mm (B – D).

FIGURE 4. Epicadus heterogaster (Guérin-Menéville, 1829). Male (MZSP 07721). A cephalic region, frontal view; B, D – E habitus (B lateral, D dorsal, E ventral); C opisthosoma, caudal view. Scale bars: 0.25 mm (A), 0.5 mm (C); 1 mm (B, D, E).

FIGURE 5. Epicadus heterogaster (Guérin-Menéville, 1829). Male (MZSP 07721). A – E Male pedipalp (A dorsal, B ventral, C, E retrolateral, D prolateral). Scale bars: 0.2 mm (A – C); 0.5 mm (D – E).

FIGURE 6. Epicadus heterogaster (Guérin-Menéville, 1829). Female (AMNH 41). A cephalic ocular spiniform projections; B metatarsus I, dorsal view, the box refers to the area depicted in C – E; C and D SPt area, thick arrows shows duster-shaped setae and thinner arrows shows trichobothria; E duster-shaped seta. Scale bars: 0.1 mm (A, C, D); 1 mm (B); 0.01 mm (E).

FIGURE 7. Epicadus rubripes Mello-Leitão, 1924. Female (IBSP 5279). A – C habitus (A dorsal, B lateral, C ventral);. D cephalic region, frontal view; E leg I, dorsal view. Scale bars: 2 mm (A – C, E), 1 mm (D).

FIGURE 9. Epicadus rubripes Mello-Leitão, 1924. Male (MCTP 10255). A – C habitus (A dorsal, B lateral, C ventral); D cephalic region, frontal view; E opisthosoma, caudal view. Scale bars: 0.5 mm (A – C, E), 0.4 mm (D).

FIGURE 11. Epicadus planus Mello-Leitão, 1932 (holotype of E. nigronotatus, MNRJ 58252). A – C habitus (A dorsal, B lateral, C ventral); D cephalic, region frontal view; E opisthosoma, caudal view. Scale bars: 2 mm (A – C), 1 mm (D – E).

FIGURE 13. Epicadus planus Mello-Leitão, 1932. Male (MNRJ 11479). A – C habitus (A dorsal, B lateral, C ventral); D cephalic region, frontal view; E opisthosoma, caudal view. Scale bars: 0.5 mm (A – D), 0.4 mm (E).

FIGURE 15. Comparison between Epicadus species. A – C E. heterogaster (AMNH 41, MCTP 1772); D – F E. planus (MCTP 34653, MPEG 22672); G – I E. rubripes (MCTP 33693, MCTP 21868, MCTP 2855). A, D and G vulva, dorsal; B, E and H epigynum, ventral; C, F and I male palp, retrolateral. Scale bars: 0.1 mm (A), 0.15 (G), 0.2 mm (B, C, D, E, I), 0.25 mm (F, H).

FIGURE 16. Epicadus species, behavior. A (unknown locality) and C (PN Itatiaia, Rio de Janeiro, Brazil) E. heterogaster, sitand-wait behavior using aggressive mimicry; B and D (PN Tijuca, Rio de Janeiro, Brazil) E. heterogaster, female guarding egg sac; E (PN Tijuca, Rio de Janeiro, Brazil) E rubripes, sit-and-wait behavior using aggressive mimicry; F (Costa Rica) E. rubripes, female guarding egg sac. Photo credits: A Maxwel Rocha (Unknown locality); B – E Henrique Cafundó; F Carlos Viquez.