Xysticus albomaculatus

Rainer Breitling, Tobias Bauer, Arno Grabolle, Pierre Oger, Paolo Pantini, Johan Van Keer, Walter P. Pfliegler, Elke JantsCher & Jan Dolanský, 2016, East meets West: on the true identity of Cheiracanthium rupestre and Xysticus albomaculatus (AraChnida: Araneae: EutiChuridae, Thomisidae), Arachnologische Mitteilungen 52, pp. 38-49 : 44-46

The case of Xysticus albomaculatus

Material examined

sub X. albomaculatus : GERMANY: 1♂, Conweiler, Straubenhardt near Pforzheim, “Birnbaumrinde [pear tree bark]”, 19 August 1981, coll. J. Wunderlich. AUSTRIA: 2♀♀ (1 epigyne missing), Lower Austria near Purgstall, Ressl, leg., J. Wunderlich coll. SLOVAKIA: 1♂ 3 juv. Szomotor, HNHM Chyzer coll. 1187 (syntypes). Uncertain locality (HUNGARYȓ) 1♀ B.-Lellc.(ȓ), Szombathy det., HNHM.

sub B. baudueri : FRANCE: 1♀, 2subad. ♂♂ “Sos [Lot-et- Garonne]” MNHN 1467.2156 (syntypes) [an adult male in the same tube is B. υersicolor s. str.; it was probably collected in Contis or Mimizan, Landes, as indicated by a second label]. 1♀ “Saint Saud [Dordogne] (aout 1918!) écorce de châtaignier [chestnut bark]”, MNHN Simon coll. 1467.25464 (designated as “lectotype” of B. baudueri by Déjean & Ledoux 2013, but not a syntype and therefore invalid). 2♂♂ Forêt de Grésigne (Tarn), pitfall traps, 1999, H. Brustel leg., MNHN Ledoux coll. JV.10.898. 1♀ “Berrias (Ardêche) Montchamp, 7/8/04”, MNHN Ledoux coll. NOE 10.898-16.921.

Comparative material

Bassaniana decorata (Karsch, 1879) : JAPAN 2♀♀, 3♂, 7 juv. Yokohama (syntypes of Coriarachne japonica Simon, 1886 ), MNHN Simon coll. 1467.7346.

Bassaniana utahensis ( Gertsch, 1932) : UNITED STA- TES: 1♀, 1♂ New York, Banks leg., T.A. Bowling det. Nov. 1973, MNHN Simon coll. 1467.4. 9♀♀, 3♂♂, 1sub♂ “Mass. N. Carol. Georg. Colora.”, T.A. Bowling det. Nov. 1973, MNHN Simon coll. 1467.688. 2♀♀, 4♂♂ “Am. sept. pacif.” (= Pacific North America) T.A. Bowling det. Nov. 1973, MNHN Simon coll. 1467.17106.

Bassaniana υersicolor (Keyserling, 1880): UNITED STA- TES 16♀♀, 9♂♂ “Mass. N. Carol. Georg. Colora.”, T.A. Bowling det. Nov. 1973, MNHN Simon coll. 1467.688.

Coriarachne brunneipes Banks, 1893 : UNITED STATES: 1♀, 1sub♂ “Mass. N. Carol. Georg. Colora.”, T.A. Bowling det. Nov. 1973, MNHN Simon coll. 1467.688. 1♀, 1♂ Washington, Banks leg. “Type!”, MNHN Simon coll. 1467.3.

Xysticus albomaculatus was first described in 1891 on the basis of very few (“perpauca”) male and female specimens from Sátoraljaújhely (Hungary) and the sands at Szomotor (= Somotor, Slovakia) (Kulczyński in Chyzer & Kulczyński 1891). Other specimens were reported in a later volume of the same work from Pozsony (= Bratislava, Slovakia) and Pápa (Hungary) ( Chyzer & Kulczyński 1897), and a single male was found a few years later by Bösenberg (1902) on the Großer Feldberg, Taunus, Hesse, Germany; but afterwards it took more than 60 years before the next reliable records were published, from Aiud, Romania (13.V.1962, Fuhn & Niculescu-Burlacu 1969), Pforzheim, Germany (19.VIII.1981) and Purgstall, Austria (both Wunderlich 1982). Based on this material, Jantscher (2001) re-described the species in detail in her unpublished doctoral thesis.

Even the original description of X. albomaculatus was uncertain about its generic placement, noting an affinity with Ozyptila , and Jantscher (2001) cites personal communications by Logunov and Marusik, indicating that the species probably belongs to a new genus, with additional representatives in Siberia. A closer examination shows, however, that X. albomaculatus with respect to its cryptic mottled habitus, tree bark habitat and the basic structure of the copulatory organs is very similar to species currently placed in the genus Bassaniana , which has commonly found representatives in East Asia and North America.

In Europe the genus Bassaniana is represented by a single species from France, which has been just as rarely reported as X. albomaculatus : Bassaniana baudueri ( Simon, 1877) , was first described (as Oxyptila baudueri ) on the basis of subadult males and a “young female” from Sos, Lot-et-Garonne, France. Another female was found in 1918 in Saint-Saud, Dordogne, together with its egg sac under the bark of a chestnut tree. Simon (1903) transferred the species from Coriarachne (where he apparently had placed it in the meantime) to Xysticus , together with several other species currently placed in Bassaniana . The new records were published in Simon (1932, publ. posthumously). In this work, the taxonomic situation is considerably confounded by the inclusion of an illustration of a supposed B. baudueri female from Spain, which actually belongs to Xysticus cribratus ( Déjean & Ledoux 2013) . Moreover, in addition to the records of B. baudueri (again sub Oxyptila baudueri ), the work also contains a single record of a male B. υersicolor (sub Coriarachne υersicolor) from Mimizan or Contis, Landes, which is considered an accidental introduction. At a later stage, someone (Simon himself?) considered this specimen to belong to B. baudueri , and it is currently found in the same vial in Simon’s collection as the original type material of the latter. However, the structure of the pedipalp, with a long, thin, straight embolus indicates that Simon was actually correct in assuming that this male belongs to B. υersicolor s. str. Mimizan was a major American army base, housing engineering corps members working in the Landes forest around the town ( Fenneman 1930), and together with the neighbouring seaside village Contis was a popular tourist location in the interwar years, both of which could explain the introduction, especially as B. υersicolor is a common spi- der often found in synanthropic habitats in North America ( Kaston 1948).

Déjean & Ledoux (2013) were the first to report the rediscovery of B. baudueri after an interval of almost 80 years, reporting the species to be widespread in forest locations across southern France. They considered baudueri a subspecies of the North American B. υersicolor, and also downgraded B. utahensis and (tentatively) B. decorata (from Japan) to subspecific status. It is true that all these species are very similar in their (rather variable) habitus, as well as in their genitalia, and difficult to distinguish with confidence. Probable hybrids between B. υersicolor and B. utahensis have been reported as occurring regularly in part of the overlapping range of the two species (Dondale & Redner 1978), and even the material in the Simon collection that was re-identified by T. A. Bowling during his revision of the genus ( Bowling & Sauer 1975) seems to contain misidentified specimens. Nevertheless, B. baudueri seems to differ consistently in subtle details of the genitalia of both males and females, sufficiently to justify re-elevation to species rank, in addition to the zoogeographical implausibility of spider subspecies occurring on separated continents. In the female, the epigynal septum in B. baudueri is broader and less distinct than in the related species, lacking the deeply notched posterior margin, which is particularly prominent in B. decorata , but also clearly expressed in the North American species; in the male, the embolus is more Scale bar = 0.2 mm

robust (not long and thin, as in B. υersicolor), very gradually tapering towards the tip, which is clearly curved outwards (not straight, as in B utahensis ; Dondale & Redner 1978: fig. 439). These characters are shared by all European specimens, including the material reported previously as X. albomaculatus from Central Europe¸ and we therefore consider Xysticus albomaculatus a junior synonym of Bassaniana baudueri (stat. nov., syn. nov.).

Both X. albomaculatus and its senior synonym B. baudueri have been characterized in detail before, both in the original descriptions and in the more recent work of Jantscher (2001) and Déjean & Ledoux (2013). Here we only provide an abbreviated description and illustration of the diagnostic characters. Bassaniana baudueri is a typical member of the genus Bassaniana , with a variable cryptic mottled pattern of white, brown and black blotches, on legs and body (habitus photos are provided in Wunderlich 1982 and Déjean & Ledoux 2013). It has rather thick, club-shaped spines on the body (but not on the clypeus), in contrast to the thin, pointed spines of Xysticus s. str. Total length: ♂♂ 3.8–4.5 mm, ♀♀ 5.0–5.6 mm. Prosoma length: ♂♂ 1.9–2.2 mm, ♀♀ 2.3–2.6 mm. In the male palpus ( Figs 8-9 ), the retrolateral tibial apophysis carries a short straight tooth that is clearly visible in ventral and dorsal view and readily distinguishes the species from similar European spiders in Xysticus or Ozyptila . The embolus emerges at the distal end of bulbus, is strong and with its tip distally bent outwards retrolaterally in an almost 90̊ angle, different from B. υersicolor and other American species in the genus.

The female epigyne ( Figs 10-11 ) is characterized by a very indistinct light septum, without a distinct posterior margin (different from B. decorata and the American species). The poor definition of the epigynal structures might be the reason why Simon (1877) considered his type a “young” (not full sclerotizedȓ) female. The width and shape of the septum are variable, but always broader than in the other species of the genus.

46 R. Breitling, T. Bauer, A. Grabolle, P.Oger, P.Pantini, J. Van Keer, W. P. Pfliegler, E. Jantscher & J. Dolanský As discussed above, the generic placement of B. baudueri has been unclear since its first description, with suggested affinities to Ozyptila , Xysticus and Coriarachne . The same holds true for the remaining Bassaniana species, which were treated as a distinct (unnamed) species group in Xysticus by Simon (1903) and partly united in their own genus (Platyxysticus) by Gertsch (1932), who later (1939, 1953) synonymized this genus with Coriarachne C.L. Koch, 1837 , but maintained two distinct species groups, corresponding to the species currently placed in Coriarachne ( brunneipes group) and Bassaniana (υersicolor group). Finally, the species were placed in Bassaniana Strand, 1928 (type species: Bassania aemula O. Pickard- Cambridge, 1898 = B. υersicolor) in its current sense by Ono (1985, 1988). Subsequently, Lehtinen proposed downgrading Bassaniana to a subgroup “lower than subgenus” of Coriarachne , implying (erroneously) that Ono’s separation of the two genera was based only on irrelevant differences in body shape (flattened vs. not quite so flattened), and Dondale (2009) suggested that at least the North American species of Bassaniana be placed in Coriarachne , arguing that the separation was based solely on “equivocal differences in microhabitat”. These arguments do not seem particularly convincing: both Bassaniana and Coriarachne s. str. are very homogenous and probably monophyletic assemblages. Of the two outliers, C. nigrostriata Simon, 1886 , from Vietnam (holotype subadult female and additional adult male in MNHN, examined) is probably misplaced in this genus and might possibly belong in or near to Demogenes Simon, 1895 , an unrevised genus (or group of genera) of coriarachnine-like spiders that includes some of the dominant ground-living thomisids in the Oriental region and Melanesia and resembles C. nigrostriata in its habitus and the structure of the pedipalp ( Lehtinen 2004, Marusik et al. 2005). And B. ora Seo, 1992 , from Korea is clearly very close to (and in all probability a junior synonym of) C. fulυipes according to the illustrations of the pedipalp provided by Seo and in Namkung (2003) (compare, e.g., figs. 2 and 3 in Seo 1992, to figs. 60 and 61 in Ono 1988). In contrast, the evidence for uniting the two groups in a single Coriarachne s. lat. seems to be based entirely on adaptive characters, in particular the flattened body, associated with the shared tree trunk habitat. It is certainly possible that Xysticus or Ozyptila are paraphyletic with respect to Bassaniana and/ or Coriarachne s. str., but resolving their exact relationships will require a broader study of the entire Coriarachnini (sensu Ono 1988), preferably using a total evidence approach including molecular genetic characters. Until such a study becomes available, we conservatively maintain the generic placement of baudueri in Bassaniana , following the latest version of the World Spider Catalog (2016).

In a curious twist, Déjean & Ledoux (2013) had suggested that Simon’s first description of O. baudueri was incomplete, as it did not include information on the genitalia, and that the correct publication date should be 1932. This change was not widely accepted, but if it were correct, O. baudueri would be a junior synonym of X. albomaculatus . However, even if the 1877 description does not include the details that Déjean & Ledoux would have liked to see, it constitutes a perfectly valid description, providing a plethora of supposedly diagnostic details, and even the type material is still available. The change in publication date is therefore not justified, and the associated assignment of a lectotype collected in 1918 is invalid, as this specimen was not a part of the original type series (ICZN art. 74.2).

The known distribution of Bassaniana baudueri as defined here extends from northern Portugal ( Cardoso et al. 2008, sub B. υersicolor, two specimens from a Mediterranean oak forest in Mata da Albergaria, Peneda-Gerês National Park (PNPG), at an altitude of 600 to 700 m) and the western coast of France, via Germany, Austria, Hungary, Slovakia to Central Romania. Considering that its relatives in North America are widespread, common and often found in rather large numbers in synanthropic habitats (see, e.g., Shinkai 2006 and Kaston 1948), it will be interesting to see if the number of records of B. baudueri will increase throughout Europe in the coming years. New records might also fill the apparent gap between the eastern and western populations.

Figures

Fig. 8: Pedipalp (ventral view) of Bassaniana baudueri: a. from the original description of X. albomaculatus (Kulczyński in Chyzer & Kulczyński 1891: Tab. IIIı fig. 33 b) ı b. from a German specimen (Jantscher 2001: Tab. 3 a) ı and C. a French specimen (figure from Déjean & Ledoux 2013: fig. 10 Bı by Jean-Claude Ledouxı courtesy of Sylvain Déjean)

Fig. 9: Pedipalp (retrolateral view) of Bassaniana baudueri ı based on a German specimen (Jantscher 2001: Tab. 3 b).

Fig. 10: Epigyne of Bassaniana baudueri: a. from the original description of X. albomaculatus (Kulczyński in Chyzer & Kulczyński 1891: Tab. IIIı fig. 33 a) ı b. from an Austrian specimen (Jantscher 2001: Tab. 3 c) ı and C. a French specimen (figure from Déjean & Ledoux 2013: fig. 10 Aı by Jean-Claude Ledouxı courtesy of Sylvain Déjean)

Fig. 11: Internal view of the cleared epigyne of Bassaniana baudueri (Austrian specimenı Jantscher 2001: Tab. 3 d)