Eusarcus geometricus 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 geometricus

description: Eusarcus geometricus sp. n.   
(Figs. 17, 44A,B, 51)  
 Type material: BRAZIL. Rio de Janeiro: Teresópolis (Parque Nacional Serra dos Órgãos), A.P.L. Giupponi & R.L.C. Baptista leg., 27.i.2001, ma holotype, 1 ma, 2 fe & 1 im paratypes (MNRJ 4480); idem, 1 ma & 2 fe paratypes (MZSP); idem, R. Pinto-da-Rocha & A.B. Kury leg., 5.viii.1989, 1 ma & 1 fe paratypes (MHNC 6589); idem, A.P.L. Giupponi & A. Pires leg., 1–2.xi.1998, 1 ma & 1 fe paratypes (MNRJ 5736).   
 Diagnosis: E. geometricus resembles E. incus, E. pusillus, E. nigrimaculatus, E. acrophthalmus, E. alpinus e E. didactylus because of the cylindrical prolateral median process on male trochanter IV and because forms of the generally large body size, and can be distinguished by: The ocularium with similar-sized tubercles; rectangular projection on the retrolateral margin of the prolateral apical apophysis of coxa IV and the shape of the cylindrical prolateral median process of male trochanter IV: Prolateral distal edge of apex with cylindrical projection, retrolateral distal edge of apex with conical blunt projection; basally with a small pyramidal apophysis. Penis without ventral process of glans (unusual within the genus) and similar to that of E. nigrimaculatus.   
 Etymology: The name, an adjective, refers to the prolateral apophyses on the male trochanter IV that resemble geometrical forms, such as pyramids, cylinders and cones.   
 Description: Male (holotype; MNRJ 4480): Dorsum (Fig. 17A,B): Measurements: SL 5.10; SMW 4.30; femur I 2.25; II 4.55; III 3.55; IV 4.45. Median paracheliceral projection larger than PAM. Ocularium far from anterior scutal margin; with 15 tubercles. Carapace with 20 scattered tubercles. Scutal area I with 24–25 scattered tubercles on each side; II with 42; III with 57 and a median spine long, almost straight, strongly pointing backwards, surpassing posterior margin of dorsal scutum; IV with 28 tubercles. Posterior margin of dorsal scutum and free tergites I–III with a row of 20, 16, 13, 11 tubercles, respectively. Anal operculum with 17 tubercles.   
Venter: Coxa I with 25–26 tubercles, median and distal ones largest; II with 36–38, increasing in size distally; III–IV densely and irregularly tuberculate.  
Chelicera: Segment I with 3 tubercles.  
Pedipalpus: Trochanter dorsally inflated, with 2 tubercles. Femur dorsally with 3 aligned tubercles, 6–7 apical small ones; ventrally with 1 large pointed basal tubercle, 2 small scattered ones. Tibial setation: Prolateral IiIi, retrolateral IiIi/iIi. Tarsal setation: Prolateral IIi, retrolateral IiIi.  
Legs (Fig. 17C–I): Coxa II with 3 tubercles on retrolateral margin; 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, prolateral edge of its apex with cylindrical projection; retrolateral edge of apex with conical, blunt projection; basally with 1 small pyramidal apophysis; retrolaterally with 1 large pointed median tubercle, 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; II with two ventral rows of tubercles increasing in size distally; III sinuous, ventrally with two irregular rows of tubercles increasing in size distally, prolateral ones enlarged, 1 blunt prolateral apical spine, 1 large retrolateral apical tubercle; IV sinuous, with medium PDS, large RDS; prolateral and retrolateral rows of enlarged, pointed tubercles; ventrally with 2 rows of tubercles, prolateral ones enlarged and increasing in size distally, 2 apical spines. Tibia III with 2 irregular ventral rows of pointed tubercles increasing in size subapically (3 large); IV with 2 lateral apical spines, prolateral one smaller, ventrally with 2 rows of enlarged tubercles increasing in size distally, 2 apical spines. Metatarsi III– IV with tubercles decreasing in size and amount distally. Tarsal segmentation: 6, 8–9, 6, 6.  
Penis (Fig. 44A,B): Stylus smooth, apex swollen, curved ventrad; without medio-ventral trichomes and angular medio-ventral projection. Ventral process of glans absent. Ventral plate covering only basal third of glans; with 2 pairs of short, straight distal setae, 1 dorsal pair of small distal setae, 1 pair of short, straight median setae, 2 pairs of ventral subapical tubercles; 3–4 pairs of long, straight basal setae, basalmost pair far from others and placed on trunk of penis.  
Coloration: Generally dark brown; brown on grooves, pedipalps, chelicerae, median portions of femora, tibiae, metatarsi. Light brown on tarsi.  
 Female (paratype; MNRJ 4480): Dorsum: Measurements: SL 4.75; SMW 3.60; femur I 1.85; II 3.95; III 3.10; IV 3.90. Posterior margin of dorsal scutum with 10 scattered tubercles and an irregular row of 21 tubercles. Free tergites I–III with an irregular row of 20, 13, 14 tubercles, respectively. Pedipalpus: Tibial setation: Prolateral IiIi, retrolateral iiIi. Legs: Coxa IV densely tuberculate, with 1 oblique prolateral apical apophysis, this conical, short, blunt, curved backwards, surpassing posterior margin of this segment. Trochanter III with scattered tubercles, retrolateral ones enlarged, 1 retrolateral apical standing out; IV with scattered tubercles, with 1 large pointed retrolateral apical tubercle. Femur I ventrally with rows of similarsized tubercles; III ventrally with two irregular rows of tubercles slightly increasing in size distally, prolateral ones enlarged, 1 small, blunt prolateral apical spine, 1 large retrolateral apical tubercle; IV with prolateral and retrolateral rows of similar-sized tubercles; ventrally with 2 rows of tubercles, prolateral ones enlarged and increasing in size distally, 2 small blunt apical spines. Patella IV ventrally with enlarged tubercles; tibia III only with rows of similar-sized tubercles; IV with two irregular rows of enlarged tubercles slightly increasing in size distally, 2 large apical tubercles. Metatarsus III unarmed. Tarsal segmentation: 6, 7–8, 6, 6.   
 Variation in males (n=5): Measurements: SL 4.30–5.20; SMW 3.50–4.40; femur I 1.90–2.25; II 4.00– 4.55; III 3.00–3.55; IV 3.90–4.45. Pedipalpus: Tibial setation: Retrolateral IiIi/IIi/iIi. Femur I reduced or small RDS; II–III with reduced or small PDS.   
 Variation in females (n=6): Measurements: SL 4.70–5.10; SMW 3.60–4.00; femur I 1.70–2.00; II 3.40– 4.20; III 2.50–3.30; IV 3.30–4.30. Pedipalpus: Tibial setation: Prolateral IiIi, retrolateral iiIi/iIi.   
 Type locality: Brazil, Rio de Janeiro, Teresópolis, Parque Nacional Serra dos Órgãos.   
 Geographical distribution (Fig. 51): 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 63-65