Eusarcus didactylus Hara & Pinto-Da-Rocha 2010, sp. n.
Creators: name: Hara, Marcos Ryotaro
name: Pinto-Da-Rocha, Ricardo
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Opiliones
Gonyleptidae
Eusarcus
Eusarcus didactylus

description: Eusarcus didactylus sp. n.   
(Figs. 12, 43C,D, 50A)  
 Type material: BRAZIL. Rio de Janeiro: Teresópolis (Parque Nacional Serra dos Órgãos), Eq. Biota leg., viii.2001, ma holotype (IBSP 2032 b); idem, 1 fe paratype (IBSP 2014); idem, 1 fe paratype (IBSP 2187).   
 Diagnosis: E. didactylus resembles E. incus, E. pusillus, E. nigrimaculatus, E. acrophthalmus, E. alpinus and E. geometricus because of the cylindrical prolateral median process on the male trochanter IV and because of generally large body size, and can be distinguished by: The ocularium with 2 blunt spines; a rectangular projection on the retrolateral margin of the prolateral apical apophysis of coxa IV; the shape of the cylindrical prolateral median process of male trochanter IV: Apically bifurcated in a finger-shaped projection slightly curved anteriad; basally with a small, blunt, slightly conical apophysis. Penis without ventral process of glans (unusual within the genus); stylus curved ventrad, without trichomes and angular medio-ventral projection; ventral plate trapezoidal, with a transversal median groove.   
 Etymology: From Greek “dio”, meaning two, and “daktylos”, meaning finger, in reference to the two finger-shaped projections on the apex of the trochanter IV prolateral process.   
 Description: Male (holotype): Dorsum (Fig. 12A,B): Measurements: SL 5.15; SMW 4.50; femur I 2.25; II 4.35; III 3.45; IV 4.00. Median paracheliceral projection smaller than PAM. Ocularium close to anterior scutal margin; high, with 2 blunts spines, 28 tubercles. Carapace with 51 scattered tubercles. Scutal area I with 45–50 scattered tubercles on each side; II with 87; III with 104 and a median spine long, almost straight, curved up and backwards, surpassing posterior margin of dorsal scutum; IV with 44 tubercles. Posterior margin of dorsal scutum and free tergites II–III with an irregular row of tubercles and another regular one of 12 and 21, 6 and 15, 5 and 11 tubercles, respectively; free tergite I with a row of 21 tubercles. Anal operculum with 28 tubercles.   
Venter: Coxa I with 28–37 tubercles, median and distal ones largest; II with 40–57 tubercles increasing in size distally; III–IV densely and irregularly tuberculate.  
Chelicera: Segment I smooth.  
Pedipalpus: Trochanter dorsally inflated, with 1 tubercle. Femur dorsally with 3 irregular tubercles; ventrally with 1 large pointed basal tubercle, 1 small one. Tibial setation: Prolateral IiIi, retrolateral Iii/IiIi. Tarsal setation: Prolateral IIi, retrolateral IiIi.  
Legs (Fig. 12C–I): Coxa IV densely tuberculate, with 1 oblique prolateral apical apophysis, this conical, long, blunt, curved posteriad and slightly ventrad, with 1 rectangular projection on retrolateral margin. Trochanters I–IV with scattered tubercles; I–III with large retrolateral tubercles; I–II with 1 large ventro-basal tubercle; IV prolaterally with 1 cylindrical and flattened median process, this apically bifurcated into a fingershaped projection slightly curved anteriad; basally with a small, blunt, slightly conical apophysis; retrolaterally with 1 large pointed subasal tubercle, 1 median and 1 large apical tubercle. Femur I with reduced PDS, RDS, two ventral irregular rows of slightly enlarged tubercles; II–III with reduced PDS, large RDS; III sinuous, ventrally with two irregular rows of tubercles increasing in size distally, prolateral ones enlarged, pointed, 1 blunt prolateral apical spine, 1 large retrolateral apical tubercle; IV sinuous, with medium PDS, large RDS; a prolateral and retrolateral row of enlarged tubercles; ventrally with 2 rows of tubercles, prolateral ones enlarged, increasing in size distally, becoming pointed (3 large), 2 apical spines. Patella IV ventrally with enlarged tubercles. Tibia III ventrally with two irregular rows of pointed tubercles increasing in size subapically, retrolateral ones enlarged; IV with enlarged tubercles, increasing in size dorso-ventrally, 1 retrolateral apical spine, ventrally with two irregular rows of tubercles increasing in size distally, 2 apical spines. Metatarsus IV with tubercles decreasing in size and amount distally. Tarsal segmentation: 6, 9, 6, 6.  
Penis (Fig. 43C,D): Stylus smooth, apex swollen, curved ventrad; without trichomes and angular medioventral projection. Ventral process of glans absent. Ventral plate trapezoidal, with a transversal median groove; with 1 ventro-distal pair of small setae, 3–4 dorsal pairs of long, straight, thin distal setae; 1 pair of short, straight median setae; 4–5 pairs of straight, thick basal setae, basalmost pair small, far from others and placed on trunk.  
Coloration: Dark brown; light brown on tarsi III and IV.  
 Female (paratype; IBSP 2187): Dorsum: Measurements: SL 5.20; SMW 4.50; femur I 2.00; II 4.00; III 3.20; IV 3.80. Median paracheliceral projection of similar-size as PAM. Free tergite I with an irregular row of 19 tubercles, a regular row of 19; II with 5 scattered and a regular row of 17; III with an irregular row of 9, and a regular row of 16 tubercles. Pedipalpus: Tibial setation: Prolateral Iii/IiIi, retrolateral IiIii/IIii. Legs: Coxa II with 2–3 retrolateral tubercles, 1 next to prolateral apophysis; IV densely tuberculate, with 1 oblique prolateral apical apophysis, this conical, short, pointed, curved backwards, surpassing posterior margin of this segment. Trochanter IV with scattered tubercles, retrolaterally with 1 subasal tubercle, 1 slightly enlarged median tubercle, 1 large apical tubercle. Femur III ventrally with two irregular rows of tubercles increasing in size distally, 1 small, blunt prolateral apical spine; IV with prolateral and retrolateral rows of similar-sized tubercles, ventrally with 2 rows of tubercles, prolateral ones increasing in size distally, 1 blunt prolateral apical spine, 1 large retrolateral apical tubercle. Tibia III ventrally with two irregular rows of tubercles, retrolateral ones enlarged; IV only with rows of similar-sized tubercles. Metatarsus IV unarmed. Tarsal segmentation: 6, 8, 6, 6.   
 Variation in female (n=2): Measurements: SL 5.00–5.20; SMW 4.40–4.50; femur I 1.90–2.00; II 3.70– 4.00; III 2.90–3.20; IV 3.70–3.80. Ocularium with 2 spines separated or fused at the base. Pedipalpus: Tibial setation: Prolateral IiIi/IIi/Iii, retrolateral IiIii/Iiii/IiIi.   
 Type locality: Brazil, Rio de Janeiro, Teresópolis, Parque Nacional Serra dos Órgãos.   
 Geographical distribution (Fig. 50A): Known only from the type locality.
description: Published as part of Hara, Marcos Ryotaro & Pinto-Da-Rocha, Ricardo, 2010, Systematic review and cladistic analysis of the genus Eusarcus Perty 1833 (Arachnida, Opiliones, Gonyleptidae) 2698, pp. 1-136 in Zootaxa 2698 on pages 51-53