New records of Acritas bilineatus Sørensen, 1932 (Arachnida, Opiliones, Cosmetidae) in Venezuela

Acritas bilineatus Sørensen, 1932, is reported for the first time in lowlands (llanos) and Andean slopes from Barinas, Táchira, and Yaracuy states in Venezuela, increasing its range extension 350 km southwest from its known distribution. Photographs of habitus, variations of dorsal scutum blots, leg IV armature, and scanning electron microscopy (SEM) of the penis are provided.


Introduction
The Neotropical family Cosmetidae C.L. Koch, 1839 is the second most diverse in the suborder Laniatores, with about 126 genera and 719 species (Kury 2013).Acritas bilineatus Sørensen, 1932, the only species of Acritas Sørensen, 1932, is hitherto known to inhabit the northern lowlands of Venezuela, in Carabobo and Lara states (Kury 2003).Sørensen, in the posthumous work finished and edited by Henriksen (1932), described this species and offered drawings of the posterior portion of the abdomen, including the anal operculum of some males showing intraspecific variability, a simplified dorsal view of femur IV of the male and the tip of the penis (Henriksen 1932: 325, figs 20-22).Posteriorly, González-Sponga (1992) made a re-description of the species adding drawings of a male, including dorsal habitus, pedipalpus, chelicera, tarsus of leg I, and a lateral view of the tip of the penis (González-Sponga 1992: 3, figs 1-7).In a recent revision of cosmetid material from Venezuela, we found some specimens of A. bilineatus that correspond to new records of the species.In this manuscript we present some photographs of the habitus of A. bilineatus, different views of leg IV, and complementary SEM photographs of the male penis, showing details overlooked by Henriksen (1932) and González-Sponga (1992).Additionally, a map with the distribution of the species is presented.

Methods
The examined material is deposited in CAULA (Colección de Arácnidos de la Universidad de los Andes, Mérida, Venezuela; curators: Nestor Sanchez and Antonio De Ascenção).Geographic coordinates (in decimal NOTES ON GEOGRAPHIC DISTRIBUTION degrees, WGS84) were obtained using Google Maps and placed between square brackets to indicate that they are estimates.The distribution map was made with Quantum GIS 2.2.0 software.Colored shapes refer to WWF Terrestrial Eco-regions of the World (Olson et al. 2001).Scanning electron microscopy (SEM) was carried out with a JEOL JSM-6390LV at the Center for Scanning Electron Microscopy of Museu Nacional-Universidade Federal do Rio de Janeiro (MN-UFRJ, Brazil).Photographs of the specimens were taken using a Sony Cybershot DSC-V1 camera.The multiple images at different focal planes were combined with Combine ZP Suite software (Hadley 2015) and were posteriorly edited in Photoshop CC 2014 software.Color descriptions use the standard names of the 267 Color Centroids of the NBS/IBCC Color System (Jaffer 2017) following Kury (2012).Drawings were made using Inkscape 0.91 software.The morphological terminology follows Kury and Medrano (2016) for dorsal scutum terms; Kury and Villarreal (2015) and Medrano and Kury (2016) for macrosetae; and Kury (2016)  Acritas bilineatus Sørensen in Henriksen 1932: 325, figs 20-22;Mello-Leitão 1933c: 113;González-Sponga 1992: 3, figs 1-7;Kury 2003: 37. Type material.Zoological Museum, University of Copenhagen (ZMUC), 5 males and 2 females syntypes, not examined.
Remarks.The examined material matches with the description given by Sørensen in Henriksen (1932) and González-Sponga (1992)

Distribution and habitat.
Acritas bilineatus is distributed in dry and montane forests of lowlands (eastern plains called llanos), Andean slopes from Barinas, Lara and Táchira and lowlands of Yaracuy and Carabobo states in the La Costa Range in Venezuela (Fig. 1).This species was collected in a wide variety of microhabits such as Legs I-III unarmed, straight (Fig. 2A).Leg IV dorsally and ventrally with some tubercles from trochanter to tibia (Fig. 3D, E).Femur IV curved in retrolateral view, with a row of 8 separated tubercles, the 2 basal lower than third and fourth, the others decreasing in size distally (Fig. 3F).
Tibia IV in retrolateral view with a row of 6 tubercles (Fig. 3F).Tarsi I-II with 1 smooth claw; tarsi III-IV with 2 subparallel smooth claws and tarsal process (Fig. 3G).Male genitalia (Fig. 4).VP of penis subrectangular with concave distal border; VP with 2 apical MS C curved and laterally inserted; 2 MS D, the most distal (D1) large and straight following the same lateral row as MS C and the other (D2) smaller, inserted dorso-laterally on the mid third of VP (Fig. 4A, B, D); 2 MS A straight and laterally inserted, near to D2 (Fig. 4B); VP with 2 lateral, elongated, dense patches of type 4 microsetae (Fig. 4C) but separated by a longitudinal space (Fig. 4B); 2 small MS E volcano-shaped in the ventral face (Fig. 4B); 1 small MS B volcano-shaped inserted laterally in the base of the VP (Fig. 4D).Glans mostly smooth; stylus long falciform, tip with wattle barbels, without process (Fig. 4A, B).

Sexual dimorphism. Male chelicerae not hypertelic.
Females differ from males by having slender armature in leg IV, posterior margin of DS wider, and by lacking a tubercle in anal operculum (Fig. 5).We did not detect differences in size of this tubercle among the collected males.

Discussion
The previously known records of Acritas bilineatus suggest a distribution restricted to the northern Caribbean  coast on the southern slopes of La Costa Range (including the Sierra de Aroa) and northern slopes of the Andes of Venezuela, from 200 to 1200 m above sea level (a.s.l.) (Kury 2003).However, the new records show that this species occupies several ecoregions in its range including montane forests of the La Costa and Andes ridges (Cordillera La Costa montane forests ecoregion, Venezuelan Andes montane forests, and Cordillera Oriental montane forests) and dry forests of the Llanos plain (Apure-Villavicencio dry forests), indicating a widespread distribution in Venezuela (Fig. 1).
The widespread distribution of selected species of harvestmen has been addressed in some recent works, but only from Argentina (Acosta and Vergara 2013 for Gryne orensis (Sørensen, 1879); Vergara and Acosta 2015 for Discocyrtus dilatatus Sørensen, 1884).Both works show 2 interesting patterns: 1) overlapping distribution areas of 2 harvestmen species belonging to different families and 2) disjunct areas with the same species.In the case of A. bilineatus, González-Sponga (1992) thought that the type locality of the species (San Esteban, Carabobo State), as stated by Sørensen in Henriksen (1932), is questionable and could be result of wrong label data because he made expeditions to the type locality and was unable to obtain specimens from this area.However, we have recorded individuals of this species in the Yaracuy State, 75 km west of San Esteban, in the same ecoregion (Fig. 1).So, we do not question the type locality until new expeditions to this area are done.
The localities where A. bilineatus is recorded for the first time display climatic characteristics (24-27 °C and 1300-2400 mm of precipitation) and vegetation related with semideciduous forests or premontane forests sharing similar characteristics, influenced by the trade winds in much of its extension, which occupy the area near the Andean piedmont, beginning at the eastern base of the Andean Cordillera in the states Apure, Táchira, Barinas, and continuing in a west-east direction to the region of contact with the piedmont of the Cordillera de la Costa, near San Carlos, Cojedes State.This vegetation formed a large jungle spot of about 500 km long by 60 km wide, defining a large dry forest unit, which has now lost 80% of its area as a result of deforestation and establishment of agricultural activities (which even extend to the southwest in Colombia, Departments of Meta and Casanare) (Guevara et al. 2011).This mosaic of vegetation (typical grass plains and montane and dry forests mixed) supports the presence of the species in Barinas and Táchira states, 350 km at southwest of the type locality, close to the border with Colombia (Fig. 1).
Additionally, the occurrence of this species is linked to the presence of forests with these characteristics because they represent a biological and biogeographic corridor between the bioregions associated to the Caribbean and those related to the lower portions of the Andes and forests of Amazonian influence (Guevara et al. 2011).On the other hand, this species is able to exploit environments at higher elevation, being found in rain forests up to 1200 m in height as pointed out by González-Sponga (1992).In fact, the wide altitude range of A. bilineatus seems not to be uncommon between harvestmen.Medrano and Kury (2017: fig. 33) showed that the cosmetid Eulibitia scalaris (Sørensen in Henriksen, 1932) is distributed in 3 different ecoregions in Colombia, encompassing altitude ranges between 1584 to 3000 m a.s.l.(Medrano and Kury 2017: 41).In Venezuela this situation is also evidenced in the cosmetid Cynortula venezuelensis Roewer, 1915, whose distribution in the state Merida (Venezuela) covers an altitudinal range between 1500 and 3000 m a.s.l.(unpublished data).
Acritas bilineatus was found in sympatry with other species of harvestmen of the genus Cynorta Koch, 1839 (Cosmetidae), Stygnus Perty, 1833 (Stygnidae), and some specimens of Manaosbiidae and Sclerosomatidae (Gagrellinae).These accompanying species were recorded in all the new localities reported in this study, indicating that they follow the same pattern of wide distribution described for A. bilineatus and constituting other evidence that breaks down the marked endemism of the species of Venezuelan harvestmen postulated by González-Sponga (1992).
Intraspecific variation of DS blots pattern are common in cosmetids from the same locality or from different localities (e.g.Kury andBarros 2014, Medrano andKury 2017) and A. bilineatus is not the exception.The 2 yellow longitudinal blots of the DS exhibit variation between specimens, always beginning at the ozopores level but sometimes ending at the area III level (from Barinas) or reaching the posterior border of DS and fusing to the posterior blot (from Táchira) (Fig. 3A).
Finally, the SEM images of the penis show the stylus apex with a wattle and the type 4 ms distributed at lateral margins of the VP (Fig. 4), as seen in Taito (Kury and Barros 2014) and Platymessa (Medrano and Kury 2016), characteristics considered informative for taxonomy of Gonyleptoidea (Kury andVillarreal 2015, Kury 2016) and that were not showed in the descriptions/drawings of Sørensen in Henriksen, 1932 andGonzález-Sponga (1992).We hope that this information will be useful for further research in cosmetid systematics.

Figure 1 .
Figure 1.Map showing the distribution of Acritas bilineatus in Venezuela.The colored areas represent the WWF (World Wildlife Fund) ecoregions.Dots represent new records and stars represent previous records.