Rhaucus Simon, 1879

Pinzón-M, Conchita & Pinto-Da-Rocha, Ricardo, 2024, Two new species of Rhaucus Simon, 1879 reveal putative synapomorphies related to the microstructural morphology of male genitalia (Opiliones: Cosmetidae), Zootaxa 5555 (1), pp. 35-56 : 37-38

Rhaucus Simon, 1879

Rhaucus Simon, 1879: 213

Emended diagnosis: Species of the genus Rhaucus can be diagnosed among Metergininae by the following combination of characters: A dorsal scutum α-shaped, shared with species of the genera Arucillus , Erginulus , Rhaucoides , Rhauculanus , and Rhauculus (β-shaped in Meterginus and Poecilaemula , oval-shaped in Trinimontius ). Ornamentation on area III among species of Rhaucus may present acuminate tubercles as in Erginulus , Meterginus , Rhaucoides , Rhauculanus , and Rhauculus ; dome-shaped tubercles as in Poecilaemula or mammiliform tubercles occurring only within Rhaucus , whereas Arucillus and Trinimontius are unarmed on area III and instead present strong ornamentation on area IV. The Ti of the pedipalp can be spoon-shaped (oval and dorsally well projected, see Fig. 4A–B in García & Kury, 2017), a feature that occurs in species of Erginulus , Poecilaemula , Rhaucoides , and Rhauculus ; some species of Rhaucus present Ti elongated almost sub-rectangular (laterally projected and not well projected dorsally, see Figs. 3I and 6H ), similar to Meterginus . Chelicerae with basal segment with outstanding ectal projections, as in Poecilaemula , Rhaucoides , Rhauculus , and Rhauculanus , but differing from these genera by the presence of a meso-apical projection (see Figs. 3B and 6A ). Ectal projections of the basal segment of the chelicerae are absent in Erginulus , Meterginus , and Trinimontius . Clavi inguines are multi-tuberculated in Rhaucus , being absent in Erginulus , Meterginus , Poecilaemula , and Rhaucoides , and being a single tubercle in Arucillus , Rhauculanus , and Rhauculus . Male Cx IV bears a multi-capitate apical apophysis, present in Rhaucoides and Rhauculus , and is a single triangular apophysis in Erginulus and Meterginus . Fe III and IV are curved and granulated in almost all genera of Metergininae including Rhaucus , except in Poecilaemula which are straight and smooth, and Rhaucoides with sub-straight Fe III and IV. Ornamentation of Fe and Ti III and IV presents ventral rows of tubercles of variable size in Rhaucus and Rhaucoides , differing from Erginulus , Meterginus , and Rhauculanus , where only leg IV is armed. The genital morphology in Rhaucus presents a short VP covered by microsetae T4 on the lateral fields, not reaching the medial field, as well as in Arucillus , Meterginus , Rhaucoides , and Erginulus . Rhaucus can be differentiated from Arucillus by the spoon-shaped or finger-shaped dorsal process of the glans, being sub-triangular in Arucillus ; from Rhaucoides by the absence of a ventro-basal protuberance (see Fig. 5c in Medrano et al., 2022); and in general, Rhaucus differs from all remaining Metergininae by the presence of Ventral MS E and B, which are volcano-shaped and/or areolate, being areolate on MS B.

Species included: Rhaucus artifex sp. nov.; R. florezi Garcia & Kury, 2017 ; R. gaiterus sp. nov.; R. marmoratus (Roewer, 1912) comb. nov.; R. papilionaceus (Simon, 1879) ; R. quinquelineatus Simon, 1879 ; R. robustus (Mello-Leitão, 1941) ; R. serratus (Roewer, 1912) comb. nov.; R. serripes (Simon, 1879) ; R. trilineatus (Sørensen, 1932) [by implication], and R. vulneratus Simon, 1879 (type species).

Figures

FIGURE 3. Rhaucus artifex sp. nov. A–J: Male holotype (MUSENUV-Ar-2618).A. Habitus, dorsal view; B. Right chelicera, dorsal view; C. Right hand of chelicera, anterior view; D. Right leg, Pa, dorsal view; E. Left leg I, tarsomeres, mesal view; F–H. Left leg IV: F. Ti, ventral view; G. Fe, ventral view; H. Fe, dorsal view; I–J. Left pedipalp: I. Tro, Fe, Pa, Ti, Ta, Dorsal view; J. Same, Mesal view. Scales: 1 mm.

FIGURE 4. Rhaucus artifex sp. nov. A–F. Male holotype (MUSENUV-Ar-2618). Penis. A. Dorsal view; B. Ventral view; C. Lateral view; D. VP, detail of MS E, rigth side, ventral view; E. Lateral view; F. VP, detail of MS E, ventral view, left side. Scales: A–C, F: 0.05 mm; D,F: 0.025 mm.

FIGURE 5. Rhaucus gaiterus sp. nov. A–D: Male holotype (MUSENUV-Ar 2620).A. Habitus, dorsal view; B. Habitus, lateral view; C. Prosoma, dorsal view; D. Cx IV, lateral view.

FIGURE 6. Rhaucus gaiterus sp. nov. A–I: Male holotype (MUSENUV-Ar-2620).A. Habitus, dorsal view; B. Left chelicera, mesal view; C. Left leg I, tarsomeres, retrolateral view; D. Left Fe III, dorsal view. E–F: Right Fe IV, E. Ventral view; F. Prolateral view. G–H. Left pedipalp, G. Fe and Pa, mesal view; H. Ti and Ta, ventral view. I. Right pedipalp, Tr, Fe, Pa, Ti, and Ta, ectal view. Scales: 1 mm.