Cheiracanthium rupestre

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 : 38-44

The case of Cheiracanthium rupestre

Material examined

sub C. rupestre : BULGARIA: 1♀, 2 juv., Kranevo near Varna, forest edge, ca. 150 m a.s.l., 9.–11.VIII.2005, Dolanský leg. et coll. 1♀, Stranbaka mts., Vitanovo nature reserve, 28.–30.VIII.2000, S. Petrov leg., J. Dolanský coll. 1♂, 10.–14. VII.1977, NMP, J. Buchar leg. et coll. P6d-41/2012/C2331. 3 juv., Bosnek, ca. 1100 m a.s.l., 13. VIII. 2009, J. Dolanský leg. et coll. 6 juv. (1♀, 1♂ kept to adult stage under laboratory conditions), Bosnek, 13. X. 2010, J. Dolanský leg. et coll.

HUNGARY: 1♀, Várpalota, HNHM Araneae-2198, Chyzer coll. 1187. 2♀♀ Várpalota IZ Kulczyński coll. (photographs examined). 1♀, Szentendrei-sziget (Szentendre Island), north of Budapest, under bark on dead wood, end of May 2009, K. Pfeiffer leg., A. Grabolle coll. 1♂, Nadap, Meleghegy, oak forest, 15.VI.1951, HNHM, Kakassné leg. SLOVAKIA: 1♀, Čachtice, 19.VI.1978, J. Svatoň leg. et coll.

sub C. macedonicum : BULGARIA: 1♀, between Yakoruda between Yakoruda and Mekhomiya and Mekhomiya, NMN- HS, holotype.

sub C. striolatum : ITALY: 2♂♂, Firenze, Marradi, Badia Valle 430 m a.s.l., 25.VI.2003, A. Usvelli leg., MCSN. Sicily 1♀, Ragusa, Giarratana, fiume Irminio, 500 m a.s.l., 19.V.1995, P. Pantini, M. Valle leg., MCSN.

Comparative material

C. striolatum : FRANCE: 4♀♀, 1♂ “Pyr[énnés] Or[ientales] Prats de Mollo”, MNHN Simon coll. 1791. 1♂ Bonne Anse dunes, near La Coubre, Charente-Maritime “mainly un- der rock rose” MMUE Duffey coll. G7512. 1♀, Balcons de la Mescla near Draguignan, bushy area, ca 800 m a.s.l., 25. IV.2009, J. Dolanský leg. et coll. PORTUGAL: 1♀, Picotino, 21.II.2001, P. Cardoso leg. et coll. PMC0390b, pitfall. 1♂, Tó, 21.II.2001, P. Cardoso leg. et coll. PMC0390c, pitfall. 1♀, Fonte d’Aldeia, 7.III.2001, P. Cardoso leg. et coll. PMC0390d, pitfall. 1♀, Fonte d’Aldeia, 13.VI.2001, P. Cardoso leg. et coll. PMC0390g, pitfall. 1♀, Algozinho, 21.III.2001, P. Cardoso leg. et coll. PMC0390e, pitfall. 1♀, Algozinho, 4. IV. 2001, P. Cardoso leg. et coll. PMC0390f, pitfall. 1♂, Mogadouro, 8.II.2001, P. Cardoso leg. et coll. PMC0248B. 1♀, 1♂, Picote, 21.VI.2001, P. Cardoso leg. et coll. PMC0248c, pitfall. 1♂, Bruçó, 3.X.2001, P. Cardoso leg. et coll. PMC0248d, pitfall. 1♂, Picote, 14.XI.2001, P. Cardoso leg. et coll. PMC0248e, pitfall. 1♂, Mértola, 27.V.2003, P. Cardoso leg. et coll. 5358. 1♂, Limas, 18.VI.2003, P. Cardoso leg. et coll. 5475, pitfall. 4♀♀, 2♂♂, 5 juv., Picote, 31.V.2001, P. Cardoso leg. et coll. PMC0390a, swept. 1♀, 1 juv., Praia da Bordeira near Lagos, 12.IV.2005, M. Řezáč leg., J. Dolanský coll. 1♀, Mértola, Corredoura, valley of Guadiana river, 8.XI.2005, M. Řezáč leg., J. Dolanský coll. 1♀ Barca d’Alva near Mogadouro, 10.X.2007, M. Řezáč leg., J. Dolanský coll. 1 juv., Ribeira Limas, 1.VII.2007, S. Pekár leg., J. Dolanský coll. 1 juv., Golega near Torres Novas, 2.X.2007, M. Řezáč leg., J. Dolanský coll. 1♂, Palao near Mogadouro, 4.X.2007, M. Řezáč leg., J. Dolanský coll. 1♂, Fonte de Aldeia near Mogadouro, 5.X.2007, M. Řezáč leg., J. Dolanský coll. 1♀, Faro, Murração, 17.IV.2013, R. Bosmans leg. et coll. 1♀, 1♂, Lagoa de Obidos, in pine litter, 20. IV. 2013, R. Bosmans leg. et coll. 1♀, Belmeque, bushy area, 300 m a.s.l., 38̊2’45”N, 7̊22’59”W, 28.III.2013, J. Dolanský leg. et coll. 1♀, Mértola, bushy area, 50 m a.s.l., 37̊38’5”N, 7̊40’13”W, 30.III.2013, J. Dolanský leg. et coll. 1♀, Barranco do Velho, 30.III.2013, J. Dolanský leg. et coll. 15♀♀, southern Portugal, 3.–7.IV.2008, M. Řezáč et S. Korenko leg., J. Dolanský coll. SPAIN 1♂, Fabero, 1.V.2012, F. Šťáhlavský leg., J. Dolanský coll. 1♀, Málaga, Mijas, stones in pine forest, 19.XII.1997, R. Bosmans leg. et coll. Mallorca 14 juv. (3♀♀, 4♂♂ kept to adult stage under laboratory conditions), Badia Gran, bushy area, VI. 2008, J. Dolanský leg. et coll. ITALY 1♀, Livorno, Isola di Capraia, 20.V.1992 C. Berera leg. MCSN. Sardinia 1♀, SMF Roewer coll. RII/13643. FRANCE: Corsica 1♀, Vivario, Col de Sorba (1320m), 26.V.1995, under stones in Larix forest, J. & K.

Van Keer leg. et coll. CJVK 1506. 1♀, Solenzara, 28.V.1999, in a Juncus field, CJVK. 1♀, Asco, 23.IX.2013, under a stone along rocks, CJVK. 1♂ Zonza, 28.V.1999, under stones in Corsican pine forest, CJVK. 1♂, Mausoleo, rivière Tartagine, 1100 m a.s.l., light trap, 30.V.2000, E. Bertuetti et al. leg., MCSN. 2♀♀, Mausoleo, rivière Tartagine, 1100 m a.s.l., light trap, 1.VIII.2000 Giomi F., Salmini B. leg. MCSN. 3♀♀, Olmi Cappella, affluent rivière Tartagine, 840 m a.s.l., light trap, 30.V.2000, E. Bertuetti et al. leg., MCSN. 5♀♀, 3♂♂, Asco, rivière Stranciacone, 1800 m a.s.l., light trap, 1.VI.2000, E. Bertuetti et al. leg., MCSN. ALGERIA: 1♀, 2♂♂, Wilaya de Tissemsilt, Theniet el Had, clearing in cedar forest, 1750 m a.s.l., 23.III.1988, R. Bosmans leg. et coll. 2♀♀, 1♂, Wilaya de Bouira, Massif du Djurdjura, Tigounatine, 1460 m a.s.l., cedar forest, 6.X.1987–1.IV.1988, R. Bosmans leg. et coll. MO- ROCCO: 1♀, 1♂, Tiznit, Mirlef, litter and stones, near the sea, 25 m a.s.l., R. Bosmans leg. et coll. Uncertain locality (“gall. m., hisp., alg.”= Southern FRANCE, SPAIN, ALGERIA) 28♀♀, 16♂♂, MNHN Simon coll. 1796.1867 (probably including syntypes). No locality. 2♀♀, 1♂ MNHN Simon coll. 1803.13468.

C. sp. near striolatum : ALGERIA: 2♀♀ Tlemcen, MNHN Simon coll. 1804.13299. 1♂, Djelfa, Djebel Djellal, 17. VIII. 1990, R. Bosmans leg. et coll. MOROCCO 2♀♀, 1♂ “Mogador, La Escaleza” (= Essaouria, Marrakesh), MNHN Simon coll., 1803.13648. 1♀ “Maroc: entre Mazagan [= El Jadida] et Oualidia (J. Théodoridès leg.)”, J. Denis det., MNHN, Simon coll., 1803. TUNISIA: 2♀♀, 1♂ Djerba, MNHN Simon coll. 1804.12462.

Cheiracanthium rupestre was first described by Herman (1879) based on a single female found under a stone in a stony ditch close to Majláth (Diósgyőr, Miskolc, Hungary). It was redescribed by Chyzer & Kulczyński (1897), who not only discussed both sexes in their determination keys, but also provided the first description of the presumptive male of the species, based on a single specimen, the palp of which they illustrated. They considered the species much rarer (“multo rarius”) than C. effossum , which itself is one of the rarely found species of the genus. Another record, from “Pajsarjeva jama”, a cave in central Slovenia, was contributed by Kratochvíl (1934), without further details. The male, but not the female, was later redescribed with detailed illustrations by Cleopatra Oltean (1973), which were later republished (under her married name) in her monograph on the Romanian Clubionidae s. lat. ( Sterghiu 1985). The species is said by Sterghiu to be adult in May in Romania, where a single male was found in low vegetation on a roadside in Băneasa, on the northern edge of Bucharest. Since then, the species has been reported very rarely and usually on the basis of single male individuals from a few additional countries: Slovakia (various locations, Gajdoš et al. 1999, 2009), Austria (1 male collected in a xerothermophilic downy oak forest on a south-facing mountainside between 400 and 500 m, Kanzelkogel, Graz, Styria, Horak 1987), Macedonia (4 male specimens collected in July 1998 at elevations between 1300 and 1800 m on Šar Mountain, Komnenov 2002), and Bulgaria (Slavyanka Mountain, Naumova 2009). A female specimen from Bosnek in the Vitosha Mountains, Bulgaria (and now in the Dolanský collection), was illustrated by Kůrka et al. (2015).

Herman’s type material could not be found in the collection of the Hungarian Natural History Museum (HNHM) and is in all probability lost. It was also not found in the Natural History Museum Vienna (NHMW), the Museum & Institute of Zoology, Polish Academy of Sciences, Warsaw (IZ), or the Zoological Museum of the National University of Lviv (LNU), where parts of the Kulczyński collection are held. However, a single female specimen labelled as C. rupestre is still available in Chyzer’s collection in Budapest and two further females in the Kulczyński collection in Warsaw. Examination of this material showed that C. rupestre , as understood by Chyzer, is identical to C. macedonicum Drensky, 1921 , a species described on the basis of a female specimen collected between Yakoruda and Mekhomiya (= Razlog, Bulgaria), and later also reported as occurring relatively rarely on Babuna Mountain close to Abdi Han and between Resen and Ohrid (Macedonia; Drensky 1929, 1936) ( Figs 1-2 ). However, a specimen from Ohrid labelled as C. macedonicum in the Drensky collection in the NMNHS turned out to be a male C. montanum (JD vid.). Deltshev & Blagoev (1997) reported C. macedonicum from submediterranean to montane coni- ferous altitudes on Pirin Mountain (Bulgaria) and Deltshev et al. (2013) found it on Galichitsa Mountain in Macedonia. The records of C. rupestre from Macedonia ( Komnenov 2002) and Bulgaria ( Naumova 2009) already imply the synonymy established here. The synonymy between C. macedonicum and C. rupestre sensu Chyzer & Kulczyński (1897) auct. is further supported by the examination of male and female specimens collected together in Bosnek (100 km north of Razlog, the type locality of C. macedonicum ). This confirmed that Chyzer’s female is indeed correctly matched to the male that was illustrated by Chyzer & Kulczyński (1897), Oltean (1973) and Sterghiu (1985). The genital structures in both sexes are quite distinct and set the species apart from all other Cheiracanthium species in Eastern Europe.

One slight complication arises, however, from the fact that Herman’s type material of C. rupestre could not be traced anywhere, and his original figure of the epigyne shows little similarity to that of C. rupestre as it has been understood since the times of Chyzer & Kulczyński (1897), even when we assume that the intraspecific variability is very high ( Figs 1-2 ). The Hungarian text of the original description, but not its German translation in the same work, describes the epigyne as follows: “The epigyne is very characteristic: there is one pinhead-like brown little sphere on each side of a deeply incised leathery arch.” This matches the figure very well, so that a printer’s or illustrator’s error can be excluded. The “pinhead” structures do not seem to be compatible with the epigynal structure of the specimens that are currently assigned to C. rupestre , and the remainder of the illustrated details in the figure also show no resemblance to the distinct patterns seen in, e.g., Chyzer’s specimen. There is no indication of the “deeply incised arch” illustrated by Herman in the epigyne of any European Cheiracanthium species. The “pinheads” could represent mating plugs, which are known in other Cheiracanthium species, such as C. furculatum Karsch, 1879 ( Bayer 2014) and C. mildei L. Koch, 1864 ( Bryant 1952) , but if Herman’s specimen belonged to the same species Chyzer’s material, the anterio-lateral position of the plugs would be inexplicable. Moreover, while several females of the closely related C. striolatum in Simon’s collection had broken emboli lodged in their epigyne, none of the specimens examined had a mating plug. We considered the possibility of assigning a neotype for C. rupestre , to stabilize the interpretation of this name, but decided that in view of the major discrepancies between Herman’s illustration and the current concept of the species, it would be impossible to select a neotype specimen that fulfils the condition of ICZN art. 75.3.5. “that the neotype is consistent with what is known of the former name-bearing type from the original description and from other sources”. Instead, we consider C. rupestre as a nomen dubium, possibly based on a malformed individual. The valid name for the species described and illustrated in Chyzer & Kulczyński (1897), Oltean (1973) and Sterghiu (1985) thus becomes Cheiracanthium macedonicum Drensky 1921 , and all records of C. rupestre (except that in the original description) should be referred to this species.

Considering the descriptions published after Herman’s work and the genitalia of Chyzer’s specimen, both male and female C. macedonicum appear to be very similar to C. striolatum , a species described in 1878 by Simon from a wide range of localities in southern and western mainland France and Corsica, where it was found on low plants. The females were reportedly found with their egg sacs under stones in April. Although the first description already indicated that this species is not rare and can be quite common in suitable habitats, it was relatively rarely reported; and following its inclusion in Simon (1932), which added records from Algeria, Spain and Portugal and also provided the first illustration of the male and female genitalia, the species was not redescribed by modern authors for a long time. Numerous records are known from the Iberian Peninsula, where the species is widespread ( Cardoso & Morano 2010). The first illustrated record since Simon (1932) was published only in 2014, based on a female collected under dried leaves along a road margin in Malaga, Spain ( Lecigne 2014). Lecigne also reported a single female from a dune in Saint-Cyprien, Pyrénées-Orientales, France. Grill et al. (2005) reported the species from Sardinia/Italy and Barrientos et al. (2015) reported and illustrated the species from the Parc Natural del Montseny, Catalonia, Spain, providing the first modern illustrations of both sexes.

The similarity between C. macedonicum and C. striolatum had already been noted by Deltshev (2003), who had examined the female holotype of C. macedonicum in Drensky’s collection and concluded that this species is close to C. striolatum Simon, 1878 , to which it should be thoroughly compared. We have carried out this thorough comparison, based on a large number of specimens from the range of both species (see Material examined, above).

In contrast to the first impression based on published illustrations of the genitalia, C. macedonicum and C. striolatum cannot be reliably differentiated based on the genitalia in either sex. The female genitalia are extremely variable in morphology, with specimens matching the published illustrations of either C. striolatum or C. macedonicum , and morphological intermediates between these, even within a single population ( Figs 3-4 ).

In the male, the tegular (median) apophysis is often distinctly bent in specimens of C. striolatum ( Fig. 5 , specimen from mainland France), but this trait is highly variable and specimens with an almost straight apophysis can be found as well, as is typical for C. macedonicum .

The hind margin of the cheliceral groove carries 4 teeth in typical C. striolatum , compared to 2 teeth in C. macedonicum ; however, the cheliceral dentition can sometimes vary between the left and right side of the same animal and is difficult to assess reliably. Given that cheliceral dentition has turned out to be unreliable in distinguishing other closely related spiders (e.g., the notorious species pair Drassodes cupreus / lapidosus, Bolzern & Hänggi 2006 ), it seems unsuitable to distinguish the two species.

The most reliable feature to distinguish the two species is the opisthosomal pattern: male and female specimens from Western Europe have a distinct reddish heart mark, followed by a series of red chevrons ( Figs 6 a, 6b). These marks remain distinct and clearly visible even in specimens that have been stored in alcohol for around 100 years in Simon’s collection. In specimens from Eastern Europe, any indication of this pattern is usually absent ( Figs 6 c, 6d). Traces of the chevrons can rarely be seen in male specimens, but the heart mark is always pale and the pattern is never distinct in females. Thus, while some extreme specimens of the two species can be similar in their colouration, there is no overlap in the pattern seen in specimens of the two forms. The difference in opisthosomal pattern is already clearly established in the juveniles, which have distinct markings in C. striolatum but not in C. macedonicum , as seen in laboratory-reared specimens. Comparable cases of consistent differences in colouration in geographically vicariant populations of widespread spider species seem to be very rare. One example is seen in Carrhotus xanthogramma (Latreille, 1819) : here, male specimens in the Far East consistently show a black longitudinal line on the opisthosoma, which is missing in European specimens (RB unpubl. observation), while the genitalia are indistinguishable ( Prószyński 1973). However, even here, the unusual amphi-Eurasian distribution of the species ( Logunov & Marusik 2001) indicates that perhaps the Asian population is a separate species, Carrhotus crinitus (Karsch, 1879) , which is currently considered a synonym of C. xanthogramma . Another relevant case is provided by the sister species Clubiona υegeta Simon, 1918, and C. geneυensis L. Koch, 1866, which are more reliably distinguished based on their abdominal pattern and colouration than based on their genitalia ( Helsdingen 1979, Oger unpubl. observation).

Simon (1932) mentioned that the characteristic pattern is sometimes lacking in C. striolatum , but this may be due to the inclusion of material from North Africa; examination of the African material in his collection indicates that some populations of C. striolatum -like specimens occurring there have a unicolourous opisthosoma. Given the lack of genital diagnostic characters, it is not quite clear if these North African specimens belong to C. macedonicum or to a closely related third species, as would be more plausible zoogeographically. Given the apparently highly conservative morphology, it would seem necessary to assess the extent of gene flow between all taxa in this very distinct group using the tools of molecular genetics, with a focus on North Africa and the possible contact areas in the Iberian Peninsula, Italy and Slovenia. For Italy, only C. striolatum has been reported in the literature ( Caporiacco 1949, Pesarini 2003; another record, from the Laguna Veneta, Caporiacco 1950, is doubtful, according to Hansen 2007, as it is based on a juvenile specimen). However, examination of specimens in the collection of the Museo Civico di Scienze Naturali “E. Caffi”, Bergamo, revealed that specimens from the Italian mainland and Sicily lacked the striped opisthosomal pattern and should for now be considered as belonging to C. macedonicum . The most recent checklist of Slovenian spiders reports both C. macedonicum (sub C. rupestre ) and C. striolatum from that country, based on literature data ( Kostanjšek & Kuntner 2015). A molecular genetic analysis would be the most suitable tool to define the precise boundary between C. macedonicum and C. striolatum , and to determine if sympatric populations or hybrid forms occur in the contact zone.

For now, we refrain from describing the African specimens as a separate species, but consider C. striolatum and C. macedonicum as closely related, but distinct species, reliably defined by the differences in opisthosomal pattern only. In view of the stable differences in pattern over a large geographic area ( Fig. 7 ) and long period of time, we consider this hypothesis more likely than the alternative that the two taxa are actually representatives of a single widespread and variable species. Future research may allow a more confident decision in favour of one or the other hypothesis, but for now the treatment as two separate species is not only justified by the available evidence, but is also the more conservative approach, minimizing the number of changes in nomenclature and maximizing the information content of future faunistic records.

There is no clear indication for an ecological separation of the two species yet, but it is noteworthy that records of C. macedonicum come predominantly from montane localities, often in grassy habitats within forests or along forest edges, while there is a reported preference of C. striolatum for coastal dune habitats in France. In the Iberian Peninsula, however, records of C. striolatum are widespread at altitudes from sea level to 1900 m ( Morano et al. 2014).

Figures

Fig. 1: Illustration of the epigyne of a. C. rupestre in Herman’s original description; Herman 1879: Tab. VIIı fig. 158); b. of C. macedonicum in Drensky’s original description; Drensky 1921: Tab. Iı fig. 14) ı and C. of C. striolatum in Arachnides de France; Simon 1932: fig. 1361). The epigyne of C. rupestre is structurally quite different. In contrastı the epigynes of the other two taxa represent the extremes of a continuum in external appearanceı and both forms and their intermediates can be found within a single population.

Fig. 2: Epigyne of a. “ C. rupestre ” in Chyzer’s collection in HMNHı b. C. macedonicum (holotypeı Drensky collection in NMNHS) ı and C. C. striolatum (possible syntypeı Simon collection in MNHN)

Fig. 3: a., b. External view of the epigyne of two specimens of C. striolatum from Corsica representing the macedonicum type of external appearance. Cleared epigyne of the latter specimenı in C. ventral and d. dorsal view. Scale bars = 0.2 mm

Fig. 4: Cleared epigyne of C. macedonicum from Szentendre Islandı north of Budapestı Hungary in a., b. ventral and C., d. dorsal viewı photos (aı c.) and schematic drawing (bı d). Scale bars = 0.2 mm

Fig. 5: Ventral view of the pedipalp a., b. of two specimens of C. macedonicum from Bulgaria and three specimens of C. striolatum C. from Portugalı d.  mainland France and e. Corsica

Fig. 6: Habitus of a. female and b. male C. macedonicum ı and C. female and d. male C. striolatum

Fig 7: Distribution of Cheiracanthium striolatum (circles) and C. macedonicum (squares) ı superimposed on a map of climate types according to Köppen (Peel et al. 2007). Black symbols indicate examined specimensı open symbols are based on literature records. For clarityı records from closely adjacent locations are indicated by a single symbol.