Eusarcus didactylus, Hara & Pinto-Da-Rocha, 2010

Hara, Marcos Ryotaro & Pinto-Da-Rocha, Ricardo, 2010, Systematic review and cladistic analysis of the genus Eusarcus Perty 1833 (Arachnida, Opiliones, Gonyleptidae) 2698, Zootaxa 2698, pp. 1-136 : 51-53

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.