Adcatomus Karsch, 1880

Rheims, Cristina Anne, 2008, On the Neotropical genus Adcatomus Karsch (Araneae: Sparassidae), Zootaxa 1809, pp. 61-66 : 62-63

Adcatomus Karsch, 1880

Type species: A. ciudadus Karsch, 1880 , by monotypy.

Adcatomus Karsch, 1880: 386 ; Simon, 1897: 89 ( Clubionidae ); Petrunkevitch, 1928: 171 ( Clubionidae ); Roewer, 1954: 476 ( Clubionidae ); Bonnet, 1955: 158 ( Clubionidae ); Jäger, 2000: 238 (transf. to Sparassidae ); Platnick, 2008. Spatala Simon, 1897: 37 , 41, 43, 47 _(Type species: S. flavovittata Simon, 1897 , by monotypy); Simon, 1903: 1023; Mello-Leitão, 1918: 39; Petrunkevitch, 1911: 512; 1928: 158; Roewer, 1954: 711; Bonnet, 1958: 4111; Platnick, 2008. New synonymy.

Diagnosis. The males of Adcatomus are distinguished from those of the remaining Sparassidae by the chelicerae fang with a median indentation ( Figs. 3–4 ) and by the male palp with a slightly spiraled tegulum, embolus bent ventrad and hidden behind a laminar triangular projection at base ( Figs. 5–8 ). The females are distinguished by epigynum with strongly sclerotized median septum with a large, wide anterior atrium bearing the copulatory openings ( Figs. 9 , 15 ) and vulva with anterior part of plate-like copulatory ducts covering the spermathecae ( Figs. 10 , 16 ).

Description. Total length (males and females) 12.7–20.4. Prosoma slightly longer than wide. Cephalic region slightly higher than thoracic region, gradually flattening posteriorly. Fovea conspicuous on posterior third of prosoma. Eyes arranged in two rows, anterior slightly recurved and posterior straight. AME slightly larger than ALE and farther apart from each other than laterals. PME slightly smaller than PLE in males and subequal in females, as distant from each other as from laterals. Clypeus low, less than AME diameter. Chelicerae three times longer than wide in males ( Fig. 3 ), slightly shorter in females. Fang with a median constriction, most pronounced in males ( Figs. 3–4 ). Cheliceral groove with two promarginal teeth, the basal one smallest, and four to six retromarginal teeth, three subequal and the remaining basal ones smaller ( Figs. 4 , 11 ). Intermarginal denticles, if present ( Fig. 11 ), agglomerated at base of furrow. Ventrally with 7–8 long setae arranged in an irregular row at the base of fang. Labium rebordered, slightly longer than wide. Endites longer than wide, slightly convergent, with dense scopulae on internal margin. Serrula with a single row of strong denticles. Sternum as long as wide, slightly projected between coxae IV. Legs laterigrade (2143). Spination in males: femora I–III: p1-1-1; d0-1-1; r1-1-1; femur IV: p1-1-1; d0-1-1; r0-0-1; tibiae I–II: p1-0-1; d1-0-1; r1-0- 1; v2-2 -2; tibiae III–IV: p1-0-1; d0-0-1; r1-0-1; v2-2 -2; metatarsi I–III: p1-1-0; r1-1-0; v2-2 -0; metatarsi IV: p1-1-2; r1-1-2; v2-2 -0. Spination in females as in males except tibiae I–II: d0-0-1. Metatarsi I–IV with trilobate membrane with median hook much more developed than lateral projections ( Fig. 12 ). Tarsi and distal half of metatarsi scopulate. Trichobothria present on dorsal tibiae, metatarsi and tarsi, arranged in two parallel rows that converge to a single file on posterior half of tarsi and on metatarsi. Tarsi with pair of pectinate claws with 10–15 teeth ( Fig. 13 ) and claw tufts. Female pedipalp with single unmodified claw similar to those of legs, but shorter and with 5–6 teeth ( Fig. 14 ). Opisthosoma oval, longer than wide. Six spinnerets: ALS contiguous, conical and bi-segmented. Basal segment slightly elongate and cylindrical. Distal segment short and truncated. AMS conical and short. PLS conical and bi-segmented. Basal segment elongate and cylindrical. Distal segment short and truncated.

Male palp. Tibia elongate, almost as long as cymbium, with three prolateral, one dorsal and one retrolateral spines. RTA small and triangular. Cymbium with round basal alveolus. Bulb with slightly spiraled tegulum ( Figs. 5–6 ). Embolus long and filiform with tip hidden behind large, laminar projection, proximally with thin and elongate tooth, at base ( Figs. 5–8 ). Conductor hyaline and laminar hidden behind embolus projection ( Fig. 8 ).

Female epigynum. Lateral lobes smooth, not touching each other at any point. Median septum strongly sclerotized with anterior, slightly rectangular atrium bearing a pair of copulatory openings ( Figs. 9 , 15 ). Vulva with strongly sclerotized duct system. Copulatory ducts with anterior glandular projection, covering spermathecae. Spermathecae with large irregular head, elongate, slender stalk and small slightly globose base. Fertilization ducts short and hook shaped ( Figs. 10 , 16 ).

Distribution. Known from northern South America: Peru and Venezuela.

Composition. Two species: Adcatomus ciudadus Karsch, A. flavovittatus (Simon) new combination.

Remarks. As suggested by Jäger (2000), it is probable that this genus belongs to Sparassinae, due to the presence of two promarginal teeth on the chelicerae and the well developed median hook of the trilobate membrane. The striking similarity between the female genitalic structures of A. ciudadus and A. flavovittatus leaves no doubt that both species are congeneric, although A. flavovittatus exhibits denticles in the cheliceral furrow, a character usually used to distinguish taxa at a higher phylogenetic level. Nevertheless, some genera such as Eusparassus Simon and Barylestis Simon exhibit a variable pattern of this character ( Jäger 2001 and pers. comm.) suggesting that these denticles can be convergently acquired or lost in some species, as is the present case.

Figures

FIGURES 3 – 10. Adcatomus ciudadus Karsch. 3 Male, eye area and chelicerae, frontal view; 4 Left chelicerae, ventral view, arrow points at median indentation on fang; 5 Palp, ventral view (E = embolus; EP = embolic projection); 6 Left palp, retrolateral view; 7 Detail of bulb, ventral view (To = tooth of embolic projection); 8 Detail of expanded palp (BH = Basal haematodochae; C = conductor; E = embolus; ST = subtegulum; T = tegulum); 9 Female epigynum, ventral view (A = atrium; LL = lateral lobe; MS = medium septum); 10 Vulva, dorsal view (CD = copulatory duct; FD = fertilization duct; GP = glandular projection; SB = spermathecae base; SH = spermathecae head). Scale lines: 0.5 mm.

FIGURES 11 – 16. Adcatomus flavovittatus (Simon). 11 Female, left chelicerae, ventral view; 12 Leg I, trilobate membrane, dorsal view; 13 Leg I, claw, prolateral view; 14 Pedipalp claw, prolateral view; 15 Epigynum, ventral view; 16 Vulva, dorsal view. Scale lines: 0.5 mm.