Discocyrtanus Roewer, 1929

Kury, Adriano B. & Carvalho, Rafael N., 2016, Revalidation of the Brazilian genus Discocyrtanus, with description of two new species (Opiliones: Gonyleptidae: Pachylinae), Zootaxa 4111 (2), pp. 126-144 : 127-128

Discocyrtanus Roewer, 1929 , revalidated

Discocyrtanus Roewer, 1929: 250 ; Mello-Leitão 1932: 199 [junior subjective synonym of Discocyrtus Holmberg, 1878 , by B. Soares (1944); type species: Discocyrtanus goyazius Roewer, 1929 , by monotypy].

Etymology. The formation of this name is simply a variation of Discocyrtus . Gender masculine.

Diagnosis. Dorsal scutum on males widest more posteriorly than that of females, with laterals of area II curved backwards displacing area III. Ocularium moderately elevated (ca. 2x eye diameter), armed with a pair of extremely high (ca. 3.5x eye diameter) acuminate parallel or divergent spines ( Figs 3 a, d, g, j, m). Femur and tibia III of males unarmed and not incrassate ( Figs 1 d–e). Posterior border of coxa IV of males in situ not reaching posterior border of dorsal scutum ( Figs 5 a, 10a). Coxa IV of males prodorsal distal apophysis thick falciform, moderately elongate, with small accessory blunt branch ( Figs 5 a–b, 10a–b); females only have a small acuminate tubercle. Trochanter IV of males elongate (twice longer than wide), armed with robust and curved prodorsal distal apophysis ( Figs 5 a, 10a). Fe IV of males ( Figs 5 d–g, 10d–g) covered with diverse rows of tubercles and/or spines and sometimes more intensely sigmoid (females always have femur IV only slightly arched). Each species has differently located stronger spines on femur IV. All species have a row of 6 to 18 prolateral spatulate spines on distal half ( Figs 2 a–e). Ventral plate of penis (VP) sharply divided into two regions: distal part rectangular, proximal part elliptical. Ventral surface of VP entirely covered with microsetae ( Figs 7 c, 8c). All macrosetae inserted on lateral of VP ( Figs 7 b, 8a): A1–A3, cylindrical, thick, acuminate, forming a triangle on basal third of VP; B inserted ventrally, proximal to A3; C1–C3 slender, only moderately elongate, forming a tight row on the distal part of VP; D1 small, midway between C3 and A1. Glans sac short, arising from middle bulge on podium, not extended as a dorsal process ( Figs 7 a, 8d). Stylus ( Figs 9 e, 11f) stout, strongly flattened and curved to ventral, with dorsal ditch, without any processes. Apex of stylus densely spiny, projected as a pair of curved horns, also densely spiny ( Figs 6 f, 9g).

Remarks. As no significant differences have been found among the male genitalia, no individual descriptions are made of them.

Included species. Discocyrtanus bugre sp. nov., Discocyrtanus goyazius Roewer, 1929 , Discocyrtanus oliverioi ( H. Soares, 1945) comb. nov., Discocyrtanus pertenuis (Mello-Leitão, 1935) comb. nov. and Discocyrtanus tocantinensis sp. nov.

Distribution. Brazil, states of Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, São Paulo and Tocantins. Paraguay, without further locality data ( Fig. 4 ).

Figures

FIGURE 1. Discocyrtanus spp. Living specimens. a – b. Discocyrtanus pertenuis comb. nov., males and females, from Belo Horizonte, Brazil. c – e. Discocyrtanus bugre sp. nov., one female, two males, from Chapada dos Guimarães, Mato Grosso, Brazil. Photos a – b, courtesy Pedro Martins (UFMG). Photos c – e by A. B. Kury.

FIGURE 2. Species of Discocyrtanus, left Fe IV of males, dorsal view. Images taken under ultraviolet (black light) and artificially colorized to enhance details of sculpture: a. Discocyrtanus bugre (MNRJ 4345); b. Discocyrtanus goyazius (MNRJ- HS 1022); c. Discocyrtanus oliverioi (MNRJ 13389); d. Discocyrtanus pertenuis (MNRJ 2179); e. Discocyrtanus tocantinensis (MNRJ 19084).

FIGURE 3. Discocyrtanus spp., some external diagnostic features for ♂ specimens. Respectively: ocularium, frontal view; armature of scutal area III, posterior view and trochanter IV, prodistal view: a – c. Discocyrtanus bugre sp. nov.; d – f. Discocyrtanus goyazius; g – i. Discocyrtanus oliverioi comb. nov.; j – l. Discocyrtanus pertenuis comb. nov.; m – o. Discocyrtanus tocantinensis sp. nov.

FIGURE 4. Central South America showing distribution of the five species of Discocyrtanus as defined here. Colored areas in the background are WWF ecoregions.

FIGURE 5. Discocyrtanus bugre sp. nov., ♂ holotype (MNRJ 2400): a. Habitus, dorsal view; b. Same, lateral view; c. Ocularium, frontal view; d. Right femur IV, dorsal view; e. Same, retrolateral view; f. Same, ventral view; g. Same, prolateral view. Scale bars = 1 mm.

FIGURE 6. Discocyrtanus bugre sp. nov., ♂ paratype (MNRJ 4913), penis, distal part: a. Dorsal view; b. Lateral view; c. Same, detail; d. Ventral view; e. Detail of ventral plate and glans, dorsal view; f. Stylus, dorso-lateral view. Scale bars = 200 µm (a); 100 µm (b, d, e); 50 µm (c); 20 µm (f).

FIGURE 7. Discocyrtanus goyazius, ♂ (MNRJ 1022), penis, distal part: a. Ventral view; b. Lateral view; c. Dorsal view.

FIGURE 9. Discocyrtanus pertenuis comb. nov., ♂ (MNRJ 4698), penis, distal part: a. Lateral view; b. Same, detail; c. Ventral view; d. Dorsal view; e. Stylus, latero-ventral view; f. Stylus, dorsal view; g. Apex od stylus, ventral view. Scale bars = 200 µm (a); 100 µm (b, c); 50 µm (d); 20 µm (e, f); 10 µm (g).