Idiops Perty 1833

Genus Idiops Perty, 1833

Idiops Perty, 1833: 197 (type species by monotypy: I. fuscus Perty, 1833).

Acanthodon Guérin, 1838: 163 (type species by monotypy: A. petitii Guérin, 1838). Synonymized by O. Pickard-Cambridge 1870: 107.

Dendricon O. Pickard-Cambridge, 1889: 250 (type species by monotypy: D. rastratum O. Pickard-Cambridge, 1889). Synonymized by Pocock 1895: 223.

Pseudidiops Simon, 1889: 215 (type species by monotypy: P. opifex Simon, 1889). Synonymized by Raven 1985: 139.

Juambeltzia Mello-Leitão, 1946: 6 (type species by monotypy: J. clara Mello-Leitão, 1946). Synonymized by Schiapelli & Gerschman de Pikelin 1971: 58.

Idiops – O. Pickard-Cambridge 1870: 101. — Simon 1892: 89. — Roewer 1953: 5. — Raven 1985: 139. — Dippenaar-Schoeman 2002: 68.

Acanthodon – Walckenaer 1837: 434. — Simon 1892: 90; 1903: 350. — Pocock 1897: 731.

Type species

Idiops fuscus Perty, 1833

Composition

Idiops includes 102 species, of which 24 occur in the Neotropical region, including the four new species herein described: I. fuscus Perty, 1833, the type species, I. argus Simon, 1889, I. bonapartei Hasselt, 1888, I. cambridgei Ausserer, 1875, I. camelus (Mello Leitão, 1937), I. carajas Fonseca-Ferreira, Zampaulo & Guadanucci, 2017, I. clarus (Mello-Leitão, 1946), I. duocordibus sp. nov., I. germaini Simon, 1892, I. guri sp. nov., I. harti (Pocock, 1893), I. hirsutipedis Mello-Leitão, 1941, I. minguito Ferretti, 2017, I. mocambo sp. nov., I. nilopolensis Mello-Leitão, 1923, I. opifex (Simon, 1889), I. petiti (Guérin, 1838), I. piluso Ferretti, Nime & Mattoni, 2017, I. pirassununguensis Fukami & Lucas, 2005, I. sertania sp. nov., I. siolii (Bücherl, 1953), I. rastratus (O. Pickard-Cambridge, 1889), I. rohdei Karsch, 1886 and I. tolengo Ferretti, 2017.

Distribution

South America, Africa, Syria, Israel, Yemen, India, Myanmar and Thailand. Here we present the updated distribution of the Neotropical species of the genus (Figs 3–4).

Diagnosis

The species of Idiops differ from all other Idiopinae by having the coxae without spines and by the chelicerae with a row of large teeth along the retromargin and small teeth concentrated in the basal third of the promargin and arranged in a row or randomly (Fig. 5A–B; except I. harti (Pocock, 1893)). Idiops harti differs from all other species of the genus by having only one prolateral row of large teeth (Fig. 5C).

Description

Small to medium sized spiders, with Neotropical species with total length ranging between 5.4 mm and 19.1 mm. Brown color, with variation between yellowish brown and almost entirely black (Fig. 2A–F). Anterior lateral eyes close to clypeal edge (Fig. 6A). Chelicerae with a prolateral row of large teeth and a retrolateral row of smaller teeth (Fig. 6B), retrolateral teeth occupying basal third of chelicerae, arranged in a row (Fig. 5A) or randomly (Fig. 5B), except I. harti, with retrolateral teeth absent (Fig. 5C), and rastellum consisting of a distinct process with large spines (Fig. 6C). Legs with three tarsal claws, paired claws with teeth and third claw smooth (Fig. 6D). Adhesive scopula absent, pseudoscopula present in males (Fig. 6D). Sternum with two anterior pairs of small marginal sigillae. Abdomen oval, without ornaments or sclerotic spots (Fig. 2A–F). Four spinnerets; posterior lateral spinnerets trisegmented and with a domed apical segment, posterior median spinnerets with one short segment. Males with enlarged palpal tibia, with retrolateral depression bordered by robust spines (Fig. 6E–F). Copulatory bulb presents an embolus with median curvature, subapical torsion, apical expansion, usually in flattened shape (embolar lamella) (Fig. 7E–F) or pointed shape (distal embolar tooth) (Fig. 19E) (with the exception of I. petiti; Fig. 26E–F). Leg I with a double tibial apophysis, with apical branch wider than basal branch (Fig. 6G) (with the exception of I. germaini; Fig. 18H), with putative slit organ between the two branches (Fig. 6H– I). Metatarsus I smooth (with the exception of I. duocordibus sp. nov., I. petiti and I. pirassununguensis, which have a subapical prolateral projection (Figs 17I, 26I, 27I)). Idiops females have cuspules on labium and maxillae. In I. duocordibus sp. nov., I. opifex and I. rastratus, cuspules occupy entire ventral region of maxillae (Figs 17K, 29K). Tibia III presents dorsal depression in I. fuscus, I. camelus, I. pirassununguensis and I. rohdei. Spermathecae with sclerotized basal area, divided into two outward-sloping ducts, each one connected to rounded terminal receptacles (Fig. 7L) (with the exception of I. duocordibus sp. nov., I. petiti and I. siolii; Figs 17L, 26L, 34C) that have receptacles with lobular expansions.

Natural history

Spiders of the genus Idiops live in tubular silk-lined burrows, which are closed by a hinged lid (operculum), which functions as a trapdoor (Fig. 1A–F, H–L). The burrows, which can be found on ravines (Fig. 1G) and on the ground (Fig. 1L), are dug with the help of the rastellum and first legs (Coyle et al. 1992). The opercula are usually camouflaged with mosses (Fig. 1A–D), grains of sand and clay (Fig. 6E–F), and small leaves and pieces of dry grass (Fig. 6H–K) (Coyle et al. 1992; Dippenaar-Schoeman 2002). These burrows provide a suitable microclimate that protects the spiders from predators, parasites and microbial infections, and behave as effective expansions for ambushing prey (Dippenaar-Schoeman 2002; Pérez-Miles & Perafán 2017). Idiops spiders live in a variety of habitats, ranging from dry environments with scattered vegetation and harder soils to more humid environments with dense vegetation and softer soils (Dippenaar-Schoeman 2002; Gupta et al. 2013; RFF pers. obs.). Some species can occasionally be found in termite mounds or in soil deposited near the base of trees (Gupta et al. 2015) and inside tree bark and rotten trunks (Pickard-Cambridge 1889: fig. 5; pers. obs.). Finally, some species can be found in degraded environments, often close to human dwelling and agricultural environments (Mirza & Sanap 2012; Gupta et al. 2013). In Brazil, specimens of Idiops were found in urban vegetation fragments, located even in large cities, such as São Paulo (I. camelus), Rio de Janeiro (I. germaini) and Brasília (I. pirassununguensis) (RFF pers. obs.).

Females and juveniles spend most of their lives in the burrows, leaving only during events of capturing prey and disposing of undigested parts. Males, after reaching adulthood, leave their burrows and wander in search for females to copulate (Dippenaar-Schoeman 2002; Pérez-Miles & Perafán 2017).Although less common, it is possible to find males living in individual burrows (Siliwal et al. 2020; RFF pers. obs.). It is common to find several nearby burrows, with spiders often belonging to the same population (Dippenaar-Schoeman 2002), with records reaching the density of 20 individuals per m² for I. bombayensis Siliwal, Molur & Biswas, 2005 (Mirza & Sanap 2012). At night, the spiders position themselves near the opening, with the trapdoor slightly ajar and wait for the prey that, upon approaching and being noticed, is captured and taken inside (Coyle et al. 1992). If disturbed, the spider closes the operculum firmly, holding the trapdoor with its anterior legs, and as a last resort, goes to the bottom of the burrow (Dippenaar-Schoeman 2002; Pérez-Miles & Perafán 2017; pers. obs.). In case there is an egg sac inside the burrow, the female positions itself on top of it to better protect its contents. The egg sac is usually oval and can contain up to 250 eggs held together by thick silk lining (as in I. joida Gupta, Das & Siliwal, 2013) (Gupta et al. 2013). In cases of adverse environmental events, these spiders can abandon their burrows, migrate to apparently more stable environments and build new burrows (Dippenaar-Schoeman 2002; Pérez-Miles & Perafán 2017).