Eutimesius Roewer, 1913

Villarreal, Osvaldo, Ahumada-C., Daniela & Navas-S., Gabriel R., 2024, Exploring the diversity of Eutimesius Roewer, 1913: new species and records from Colombia and Venezuela (Opiliones, Gonyleptoidea, Stygnidae), Zoosystematics and Evolution 100 (3), pp. 803-820 : 803-820

Genus Eutimesius Roewer, 1913

Included species.

Eutimesius albicinctus ( Roewer, 1915) ; Eutimesius aroa sp. nov.; Eutimesius canoabo sp. nov.; Eutimesius ephippiatus ( Roewer, 1915) ; Eutimesius guaichia sp. nov.; Eutimesius ornatus (Rower, 1943) ; Eutimesius punctatatus ( Roewer, 1913) ; Eutimesius simoni Roewer, 1913 .

Diagnosis.

Heterostygninae with white, dry spot on the dorsal scutum. Carapace with interocular monticle or spine, and scutal area III with two acute paramedian spines. Genital “ bauplan ” as Heterostygninae , LP with distal cleft, and long basal “ neck. ” MS - B ventrally positioned (Fig. 1 ) when compared to Innoxius .

Distribution

(Fig. 2 ). So far, species of the genus (except the Amazonic E. simoni ) are primarily known to be distributed in the Andes, specifically in the Cordillera Oriental of Colombia ( WWF ecoregion, Cordillera Oriental montane forests, NT 0118; and Northern Andean páramo, NT 1006) and in the Cordillera de Mérida of Venezuela ( WWF ecoregion, Venezuelan Andes montane forests, NT 0175). The records of Eutimesius aroa sp. nov., Eutimesius canoabo sp. nov., and Eutimesius guaichia sp. nov. represent the first occurrences of the genus — considered until now an Andean component — in the Venezuelan Coastal Range ( WWF ecoregion, Cordillera de la Costa montane forests, NT 0117) and the first records outside the Cordillera de Mérida in this country. Records of Heterostygninae in the Coast Range refer primarily to the genera Stygnoplus Simon, 1879 , and Stenostygnellus Roewer, 1913 .

Natural history

(Fig. 3 ). Opiliones exhibit diverse microhabitat preferences within forest ecosystems. Within the family Stygnidae , species demonstrate foraging locations within the understory, utilizing both arboreal substrates such as tree trunks and ground-level leaf litter. Villarreal et al. (2019 b) documented E. punctatus utilizing the upper vegetation, such as small trees and shrubs, positioned well above the forest floor at heights of 1.5–3 meters, for foraging and oviposition. Additionally, at least one species of Stenostygnellus has been reported to deposit its eggs between the leaf and stem of certain palms ( Villarreal and Machado 2011). The three species described here were consistently collected at heights between 1.5 and 2 meters above ground, exclusively within shrubby vegetation or small trees. A preference for microhabitat was suggested for species within this genus ( Villarreal et al. 2019 b).

The altitudinal range occupied by species of this genus is extensive, ranging from low elevations in the Amazon to heights reaching 3,050 meters in the Venezuelan Andes. However, the majority of species are found above 1,000 meters, typically in cloud forest habitats. Only E. simoni has been recorded in lowland areas between 70 and 110 meters in altitude, which is characteristic of the Amazonian region. E. ephippiatus occurs at the foothills of the Andes between 500 and 1,000 meters. All other species occur above 1,000 meters in altitude. The highest altitude record corresponds to a single female from Táchira state in Venezuela, misidentified as E. ornatus ( Pinto-da-Rocha 1997), reaching 3,050 m.

Figures

Figure 1. Eutimesius sp., male (IAvH 3000054 - undescribed species from Norte de Santander, Colombia), showing the genital bauplan in the genus. Penis: A. Ventral view; B, E. Lateral views; C. Dorsal view; D. Apical view; F. MS - A, detail in lateral view. Abbreviations: GSt = gland, stylus; LP = lamina parva; Ma = malleus; MS = macrosetae of penis.

Figure 2. Map showing the distribution of Eutimesius.

Figure 3. Schematic diagram illustrating the known altitudinal range for species of Eutimesius, their biogeographic area of occurrence, the country, and the microhabitat used if known.