An unexpected occurrence: discovery of the genus Cybaeopsis Strand, 1907 in Europe with the description of a new species from Italy (Arachnida, Araneae, Amaurobiidae)

We report on the unexpected finding of a new species of the genus Cybaeopsis Strand, 1907, C. lodovicii sp. nov. from the Northern Apennine Mountains in Italy. This is the first documented record of a Cybaeopsis species in Europe. Other currently known species of this genus have been previously recorded in North America, the Russian Far-East and Japan. The new species is illustrated and described based on both sexes. Another species from Portugal, Cybaeopsis theoblicki (Bosmans, 2021) comb. nov. , recently described in the genus Callobius Chamberlin, 1947, is hereby transferred to Cybaeopsis on the basis of morphological characters. An updated key to the European genera of Amaurobiidae is provided.


Introduction
Cybaeopsis Strand, 1907 is a small genus of cribellate spiders belonging to the family Amaurobiidae Thorell, 1870 currently numbering 10 species (WSC 2022). The majority of the known Cybaeopsis species (9 species) are endemic to North America (Leech 1972;WSC 2022). Among them, Cybaeopsis euopla (Bishop & Crosby, 1935) is the most broadly distributed species covering a wide area ranging from the territories of the Pacific Northwest and British Columbia on the Pacific coast to Quebec, Main and Nova Scotland in the east of the continent. Cybaeopsis macaria (Chamberlin, 1947), C. wabritaska (Leech, 1972), and C. spenceri (Leech, 1972) share a distribution covering the northwestern area of North America, from Alaska to the Pacific Northwest in the case of the former two species or limited to western Washington for the third one. Cybaeopsis armipotens (Bishop & Crosby, 1926), C. hoplites (Bishop & Crosby, 1926), C. hoplomacha (Bishop & Crosby, 1926), and C. pantopla (Bishop & Crosby, 1935) are distributed in the southeastern region of the United States, in some areas of North Carolina and along the Appalachian Mountains. The last known American species, C. tibialis (Emerton, 1888), is distributed over the northeastern part of North America, from New England to the easternmost part of Canada (Leech 1972). The only Cybaeopsis currently recorded outside the Nearctic realm is the type species of the genus C. typicus Strand, 1907. This species occurs in northeastern Asia, namely in the Sakhalin and the Kurile islands in the Russian Far-East (Marusik et al. 2012) and in the islands of Hokkaido and Eastern Honshu in Japan (Yaginuma 1987;Shinkai et al. 2022;WSC 2022). So far, no records of Cybaeopsis have been reported in other regions of the Palaearctic or in other zoogeographical realms. Little is also known about the ecology of the members of this genus. Apparently, these spiders live in humid and cool microhabitats in shadowed deciduous forests where they build cribellate lace-webs in the leaf litter or under stones and logs (Leech 1972;Paquin and Dupérré 2003).
While studying spider material collected with pitfall traps in beech forests in Northern Apennines, Italy, we found specimens of an unknown amaurobiid species. Surprisingly, a detailed morphological examination of the samples revealed them as belonging to an undocumented species of the genus Cybaeopsis. This finding represents the first record of Cybaeopsis in Italy and in the whole Western Palaearctic, far outside the supposed natural range of this genus. In addition, while checking information on Cybaeopsis, we realized that another closely related species, Callobius theoblicki Bosmans, 2021, has been recently found in Portugal but described as belonging to another genus (Bosmans 2021). The aim of this study is to revise and survey the taxonomy and geographic distribution of the genus Cybaeopsis in Europe, to describe the new species from Italy and to propose the transfer of Callobius theoblicki to Cybaeopsis.

Materials and methods
Spider samples were collected during surveys organized by the Museo Civico di Scienze Naturali "E. Caffi" of Bergamo (MSNBG) in the Northern Apennines. Specimens were sampled using pitfall traps with a preservative solution of vinegar and formalin, and preserved in 75% ethanol in the collections of the same institute. Specimens were examined using an Optika SZM stereomicroscope in the laboratories of the MSNBG. Photographs and measurements were taken at the Systematic Zoology Laboratory, Tokyo Metropolitan University, Japan (TMU) using a Canon EOS kiss X8i digital camera mounted on a Nikon SMZ 1270 stereomicroscope. Photographs were merged using Helicon Focus v.7 image stacking software (https://www.heliconsoft.com) and edited using Adobe Photoshop CC v.20.0.6 (https:// www.photoshop.com/). The left male palp is illustrated. Additional photos were taken using a Jeol JSM-6510LV Scanning Electron Microscope (SEM) at TMU. Female genitalia were dissected using a sharp needle and cleared with a 20% solution of KOH before being observed and illustrated with a Nikon Optiphot 2 microscope. All measurements are reported in millimeters. Legs' measurements are reported as follows: total length (femur, patella, tibia, metatarsus, tarsus). Terminology follows Marusik et al. (2012).
The samples used in this study are preserved in the following collections: AMNH = American Museum of Natural History, New York, USA (Curator: Lorenzo Prendini); MSNBG = Museo Civico di Scienze Naturali "E. Caffi" of Bergamo, Italy (Curator: Paolo Pantini).

Results
Key to the genera of Amaurobiidae in Europe (adapted from Nentwig et al. 2022) (Blackwall, 1846)). Females of Cybaeopsis can be distinguished from females of Callobius by the epigyne lacking a median lobe (vs. present) and by the shape of its lateral lobes (Ll), rectangular and extended laterally, with flat posterior margins (vs. lateral lobes extended antero-posteriorly with sharp or rounded posterior margin) (Fig. 4E cf. Leech 1972: figs 225). See also Leech (1972) (sub Callioplus Bishop & Crosby, 1935 for a detailed diagnosis of the genus. Description. Total length 2.5-5 (male), 3-6.5 (female). Carapace brown, dark brown or orange-yellowish with darker dorsal radiating striae, fovea clearly visible. Chelicerae frontally swollen. Eight eyes arranged into 2 rows of 4, AME the smallest. Legs uniformly brownish or brown-yellowish, darkened distally. Tarsi with 3 claws, scopula and claws tufts absent. Leg formula: IV, I, II, III. Opisthosoma brown-greyish or dark grey usually with lighter chevrons marks on the dorsal side, unmarked in some specimens. Cribellum undivided. Male palp with retrolateral tibial apophysis (RTA) distally bifurcated, dorsal tibial apophysis divided into several branches of different length (Da1-4), at least two branches (Da1-2) long and sharp. Median apophysis (Ma) sturdy. Prolateral and retrolateral tegular outgrowth (Pto and Rto) more or less developed and protruding from tegulum. Conductor (Co) wide. Embolus (Em) short and sturdy, ribbon-like. Epigyne divided into 2 lobes by a central septum, extended laterally, median lobe absent.

Cybaeopsis lodovicii
Female. Habitus as in Fig. 2F. Total length: 3.04. Carapace 1.35 long, 0.83 wide. Coloration as in male, chevrons on the opisthosoma more visible than in the male. Chelicera with 3 posterior and 5 anterior teeth. Eyes sizes and their interdistances: AME = 0.04, ALE = 0.1, PME = 0.07, PLE = 0.12, AME-ALE = 0.02, PME-PLE = 0.13. Length of legs segments (leg III missing): Leg spination as in Table 1. Calamistrum clearly visible, about 2/3 of metatarsus length. Other characters as in male. Epigyne as in Figs 2A-D, 3C. Epigynal plate divided into two lateral lobes (Ll) and a septum. Copulatory openings (Co) located in the antero-median inner part of lateral lobes. Internal pockets (Ip) of lateral lobes wide, comma-like, narrowing laterally, visible by transparency through tegument of epigyne. Copulatory ducts (Cd) short, comma-like, proximal traits parallel to each other in medial part of vulva and then diverging laterally. Spermathecae (Sp) small, separated from each other more than 4 times their diameter, located in anterior side of vulva.

Cybaeopsis theoblicki (Bosmans, 2021) comb. nov.
Callobius theoblicki Bosmans, 2021: 879, 32-41 (♂♀ Remarks. Cybaeopsis theoblicki shows the typical morphological characters of Cybaeopsis, in particular: a retrolateral tibial apophysis ending bifurcated, three dorsal apophyses in the male palpal tibia two of which elongated and sharp, epigyne lacking a median lobe, and lateral lobes of epigyne extended laterally with a flat posterior margin. All these characters can be easily observed in the photos illustrated in Bosmans (2021). The size range reported for the species (3.8-4.5 mm) further supports its affinity with the genus Cybaeopsis rather than Callobius. Based on these characters, the transfer of C. theoblicki to the genus Cybaeopsis is herein proposed.

Discussion and conclusions
Several new species belonging to the family Amaurobiidae have been described in Europe in recent years, from Northern Apennines in Italy (Amaurobius pesarinii Ballarin & Pantini, 2017), Minorca (A. minorca Barrientos & Febrer, 2018), the Caucasus mountains (A. caucasicus Marusik, Otto & Japoshvili, 2020), and Portugal (Cybaeopsis theoblicki (Bosmans, 2021)) (Nentwig et al. 2022). The majority of the known and newly described species are from Southern Europe and, in particular, from the Mediterranean region. This area represents a hotspot of spider diversity which is still scarcely explored. With this work we add one more genus and species to the European amaurobiid fauna, further increasing the diversity of this family in the Western Palaearctic. Currently, Amaurobiidae in Europe consists of 44 species belonging to 5 genera: Amaurobius C. L. Koch, 1837 (38 species), Arctobius Lehtinen, 1967 (1 species), Callobius Chamberlin, 1947 (2 species), Cybaeopsis Strand, 1907 (2 species), and Ovtchinnikovia Marusik, Kovblyuk & Ponomarev, 2010 (1 species) (Nentwig et al. 2022 and the present paper). The finding of Cybaeopsis in Southern Europe was unexpected, as the new localities are far from the previously known range of the genus and in an unforeseen environment. The updated distribution of Cybaeopsis indicates that the area of distribution of this genus is fragmented between three strongly disjunct areas: North America, North-Eastern Asia and South Europe (see Fig. 5G). This opens the door for new and challenging hypotheses about the origin and historical biogeography of these spiders, which warrant further exploration in the future. The rather uniform general morphology of copulatory organs and the disjunct distribution may suggest that this is a potential relict group once distributed in a wider area. A similar distribution is also shared by other genera of Amaurobiidae (e.g. Callobius, Amaurobius) or even other families (Y.M. Marusik & Z. Zhao, in litteris). Such results may suggest a common evolutionary history as a consequence of long-range dispersions or fragmentations of wider distributions related to ancient climatic and geological events. In addition, Cybaeopsis species have previously been considered to have rather frigophilic preferences, being often associated with shadowed, cool and humid environments (Paquin and Dupérré 2003). In this regard, regions at higher latitudes and localized habitats with relatively cool and uniform conditions throughout the year (e.g. vegetated narrow valleys) may have acted as a refuge for these spiders. Nevertheless, the new records in Portugal and Italy, in areas which are relatively warm and dry during the summer season, challenge this hypothesis. Such findings imply that our knowledge of the habitat preferences of Cybaeopsis is still incomplete and that this genus may have broader environmental tolerance than previously thought. Additional collections and studies on the European Cybaeopsis fauna and the comparison of these species with the North American and Eastern Asia congeners in the future may help to better define the ecology, distribution, evolutionary history and microhabitat preference of these spiders.