Genus Acanthoctenus Keyserling, 1877

Acanthoctenus Keyserling, 1877: 693, plate 8, fig. 60. Type species Acanthoctenus spiniger Keyserling, 1877, designated by Simon (1892: 229).— Simon 1893: 430.—F.O. Pickard-Cambridge 1897: 101.— Dahl, 1901b: 186.—F.O. Pickard-Cambridge 1902: 354.— Tullgren 1905: 19.— Kraus 1955: 51.— Simon 1906: 288.— Strand 1909: 402.— Petrunkevitch 1925: 95.—Mello-Leit„o 1936: 181.— Reimoser 1939: 364.—Mello-Leit„o 1945: 256.— Soares & Soares 1946: 53.— Caporiacco 1947: 28, 1948: 684, 1955: 290.— Chickering 1960: 81.— Lehtinen 1967: 208.— Forster & Wilton 1973: 293.—Griswold 1993: 3.— Bosselaers 2002: 141.— Silva-Dávila 2003: 3.— Griswold et al. 2005: 17.— Polotow & Brescovit 2008: 706, 2012: 40, 2014: 334.— Ramirez 2014: 28.— Polotow et al. 2015: 134.— World Spider Catalog 2020.

Paracantheis Kraus, 1955: 51 . Type species Paracantheis virginea Kraus, 1955 by original designation.— Lehtinen 1967: 256 (Syn).— World Spider Catalog 2020.

Diagnosis. Acanthoctenus species resemble other Acanthocteninae as Nothroctenus and Viracucha by the presence of a cribellum and calamistrum (Figs 5E, F; 6E), three retromarginal teeth on the chelicerae (Fig. 5A; Polotow & Brescovit 2014: char. 64) and the distal pair of spines on tibia I distant from the apical margin of tibia (Polotow & Brescovit 2014: char. 73). Males resemble those of Nothroctenus and Viracucha by the palp with swollen patella (Polotow & Brescovit 2014: char. 1, fig. 5a), retrolateral cymbial process (Fig. 8A; Polotow & Brescovit 2014: char. 16, fig. 5A; Silva-Dávila 2003: fig. 19c–d), and curved papal tibia (Fig. 11C; Polotow & Brescovit 2014: fig. 5a). Males of Acanthoctenus can be distinguished from those genera by the short and cylindrical embolus (Fig. 8B) and by the elongated and thin median apophysis with an apical hook (Fig. 8B) whereas the males of Nothroctenus (Silva-Dávila 2003: fig. 19c) and Viracucha (Polotow & Brescovit 2014: fig. 5a) have embolus with a laminated base and median apophysis reduced or massive, respectively. Furthermore, males can be distinguished from Nothroctenus by the absence of a folded spermatic duct (Fig. 11C), present in the latter (Dias & Brescovit 2004: figs 7–8). Females resemble those of Nothroctenus (Dias & Brescovit 2004: fig. 9) and Viracucha (Lehtinen 1967: fig. 415) by the lack of lateral projections on the epigynum (Fig. 9A; Polotow & Brescovit 2014: char. 52). Females of Acanthoctenus can be distinguished from Nothroctenus (Lehtinen, 1967: fig. 417; Dias & Brescovit 2004: fig. 9) and Viracucha (Lehtinen 1967: fig. 415) by their large atrium (Figs. 13C, 16C; Lehtinen, 1967: fig. 414), reduce or absent in the other genera, respectively, and from Nothroctenus by the shorter copulatory ducts (Fig. 9B), elongated and convoluted in the latter (Dias & Brescovit 2004: fig. 10).

Description. Small to medium-sized cribellate spiders. Total body length (males and females) 7.26–16.20. Carapace piriform, light brown with a wide longitudinal stripe of lighter coloration (from light brown to beige) from ocular area to the posterior border; thoracic groove longitudinal and located in the posterior third (Figs 1A, 3A, 4 A–B, 11A, 13A, 15A, 17A, 20A, 22A, 24A, 27A, 30A, 31A, 33A, 36A, 38A, 40A, 42A, 44A, 46A, 48A). Carapace profile higher at the ocular area (Figs 1B, 3B). Clypeus with long dark bristles (Fig. 13B, 15C). Ctenid eye pattern 2-4-2, with the anterior and posterior row recurved in dorsal view (Figs 4B, 5B, 13B). Eyes round, except oval anterior lateral eyes, mounted over black mounds (Figs 5B, 13B, 20C), with grade-shaped tapetum (barely shown in Fig. 22C). Anteriorly with a dark band with two lateral stripes of white setae extending from the anterior border of the carapace to the anterior median eyes (Figs 1C, 3C, 13B, 15C, 20C, 22C, 24C, 27C, 30B, 36C, 38C, 40C, 42C, 44C, 46C, 48C). Chelicerae with a large boss (Fig. 40C), thickened setae next to the fang base (Fig. 5A), three promarginal teeth, median largest, three retromarginal teeth, basal smaller, and without intermaginal denticles (Figs 5A, 22B). Chilum divided (Fig. 15C). Long endites and labium short in relation to the size of the endites; light brown sternum, oval, not extending between legs IV (Figs 11B, 15B, 17B, 20B, 22B, 24B, 27B, 31B, 33B, 36B, 38B, 40B, 42B, 44B, 46B, 48B). Leg formula 1423 in males, female leg formula is variable and is described for each species. Shallow trochanteral notch (Fig. 15B). Legs usually longer in males than females. Spination: ventral surfaces of tibia I-II with nine pairs of spines and metatarsus I-II with five pairs of spines, except A. remotus (tibia I with seven pairs, tibia II with six pairs and metatarsus I-II with three pairs of spines). All legs in males and females with a patch of tenant setae (claw tufts) arising from a movable plate (claw tuft plate) (Fig. 6C). Third small tarsal claw present on each leg tarsus (Fig. 6D, arrow). Trichobothria bases with four transversal grooves on proximal hood (Fig. 6A). Distal capsulated tarsal organ with a drop-shaped opening (Fig. 6B). Calamistrum oval with several rows of setae (Fig. 6E). Pedicel divided (Fig. 5C). Opisthosoma oval with tufts of elongated white setae in two longitudinal rows (Figs 1A, 4B, 5D). Cribellum divided into two fields of strobilate spigots that are clumped in short, longitudinal linear rows (Fig. 5 E–F; Griswold et al. 2005: figs 97a, 115a), larger in females than males. Six spinnerets, ALS, and PLS two-segmented (Fig. 7A, C), PMS one-segmented (Fig. 7B). The ALS has a bare margin, a two large MAP, and several PI spigots interspersed with tartipores (Fig. 7A; Griswold et al. 2005: figs 115b, 116b, 117a). The PMS has a pair of mAP spigots with a tartipore in between and many small AC spigots interspersed with three large CY spigots; without paracribellar spigots (Fig. 7B; Griswold et al. 2005: figs 115c–e, 116d, 117d). The PLS has several AC spigots and an apical anterior MS (Fig. 7C; Griswold et al. 2005: figs 115d, 116c, 117b–c). The silks used for the construction of egg sacs and shelters are irregular (Fig. 7 D–F). Males lack epiandrous spigots. Male palp: patella swelled (Fig. 11A, D); tibia curved with only one tibial projection (RTA) (Figs 11C, D, 12 A–B); conical RTA; cymbium longer than tibia and with a basal retrolateral projection (Figs 11C, 12A); subtegulum prolateral, partially visible behind embolus; tegulum suboval with a central hyaline area where the median apophysis emerges (Figs 11C, 12A); embolus emerging prolaterally, flexibly attached to the tegulum, cylindrical, with a larger base tapering distally (Fig. 8A); median apophysis elongated and scoop-shaped, with a subtriangular distal projection (Fig. 8 A–B); conductor apical and hyaline (Figs 8 A–B, 12B); some species with modified setae distally on the cymbium (Fig. 8 C–D). Female genitalia: epigynum divided into the median and lateral sectors (Figs 9A, 12C); median sector suboval, subpentagonal, or subrectangular, longitudinally elongated, extending or not into the atrium, partially covered by the lateral sectors (Figs 9A, 12C, 14A, 17C); lateral sectors large, anteriorly straight or curved, forming an angle between 30° and 90° with the median sector longitudinal axis, partially transparent, spermathecae visible through transparency (Figs 14A, 17C, 18A, 20D); copulatory opening small, connected to the lateral sector (Figs 14A, 16C, 19A, 21A, 23C); copulatory ducts sinuous, first half bordered by the lateral sectors, strongly or slightly S-shaped (left side) (Figs 12D, 14B, 16D, 18B 21B); head of spermathecae quote-shaped, with apical glandular openings (Figs 12D, 14B, 18B, 21B); the base of spermathecae scalloped (Figs 12D, 14B, 18B, 21B); fertilization ducts short, tubular and sclerotized, emerging from the base of spermathecae (Figs 9B, 14B, 21B, 25B).

Distribution. Neotropical region, from Bolivia to Mexico, in tropical humid forest and mountains (Fig. 10).

Composition. Thirteen species: Acanthoctenus spiniger Keyserling, 1877, Acanthoctenus spinipes Keyserling, 1877, Acanthoctenus dumicola Simon, 1906 stat. res., Acanthoctenus gaujoni Simon, 1906, Acanthoctenus plebejus Simon, 1906, Acanthoctenus kollari (Reimoser, 1939), Acanthoctenus virginea (Kraus, 1955) stat. res., comb. nov., Acanthoctenus remotus Chickering, 1960, Acanthoctenus alux sp. nov., Acanthoctenus chickeringi sp. nov., Acanthoctenus lamarrei sp. nov., Acanthoctenus manauara sp. nov., and Acanthoctenus torotoro sp. nov.