November 8–9, 2017, Brno, Czech Republic 24 years
LIFE STRATEGIES OF JUMPING SPIDERS (ARANEAE: SALTICIDAE) OF GENUS PELLENES – A POSSIBLE EXPLANATION OF THE UNUSUAL SOCIABILITY
KRISTINA STEMPAKOVA, VLADIMIR HULA Department of Zoology, Fisheries, Hydrobiology and Apiculture Mendel University in Brno Zemedelska 1, 613 00 Brno CZECH REPUBLIC [email protected]
Abstract: The unusual sub social behaviour of spiders of the genus Pellenes spp. has not yet been reliably explained. In our study, we infer that relatively common gregarious wintering in one land snail shell (especially for species Pellenes tripunctatus and Pellenes nigrociliatus) can be conditioned by the collective maturing of offspring in shells which are hanging on vegetation. Observation was carried out on two steppe locations. Altogether, eight shells (Caucasotachea vindobonensis) hanging on vegetation were found. In each of these shells have been discovered one female of spider species Pellenes tripunctatus. This is an interesting finding because this way of caring for offspring has not yet been confirmed for this species (only old records of Pellenes nigrociliatus). In the course of our research, we also found the use of another species of gastropods Helicigona lapicida by spider Pellenes tripunctatus, which was never reported before. Key Words: Araneae, Salticidae, shells, Pellenes tripunctatus, sociability, breeding of offspring
INTRODUCTION Spiders represent the most abundant group of invertebrates using empty land snail shells. As the shells are primarily occupied during the period when the air temperature begins to decrease, shells are mentioned mainly in connection with the overwintering of spiders. Besides of overwintering, empty shells are used also as a hiding place or for reproduction. Spiders there also create specific nests for establishment of next generation (mainly family Salticidae). Shells offer advantageous microclimate which ensures protection during hot summer days or protection from various predators (Moreno- Rueda et al. 2008). The most common inhabitant (in terms of overwintering) is the Salticidae family with specific species of Pellenes tripunctatus (Walckenaer, 1802), P. nigrociliatus (Simon, 1875) and Sitticus penicillatus (Simon, 1875), as reported by several authors (Horn 1980, Bauchhenss 1995, Szinetár et al. 1998, Bellmann 1999, Moreno-Rueda et al. 2008, Hula et al. 2009, Michálková 2012, Niedobová et al. 2013, Štempáková 2014, Štempáková 2016). The most occupied are the shells of Xerolenta obvia (Menke, 1828), Caucasotachea vindobonensis (Férussac, 1821), Helicigona lapicida (Linnaeus, 1758), Arianta arbustorum (Linnaeus, 1758), Zebrina detrita (O. F. Miller, 1774) or less occupied shells of larger species of gastropod – Helix pomatia (Linnaeus, 1758). In addition, for some spider species there is a strong affinity to certain species of gastropods (Mikulska 1961, Horn 1980, Szinetár et al. 1998, Hula et al. 2009, Niedobová et al. 2013, Štempáková 2016). The strongest and most frequently mentioned is the affinity of P. nigrociliatus to the shells of X. obvia. It confirmed that Pellenes nigrociliatus use these shells for reproduction and breeding of offspring. Spiders hang up empty shells by spider web on stalks of grass. Then will create a nest for establishment of a new generation inside the shell (Mikulska 1961). After hatching cubs, the female will ensure the protection of their offspring. The young spiders remain in the shells until they are able to reproduction (Horn 1980). Probably similar strategies are also used by P. tripunctatus, but in the
742 November 8–9, 2017, Brno, Czech Republic 24 years case of the shell of the gastropod C. vindobonensis. Pellenes tripunctatus use this shell for hibernation very often and even was confirmed also affinity to the mentioned shell (Hula et al. 2009, Niedobová et al. 2013), but in the case of an unusual life strategy in the form of hanging shells, there are almost no records. It is possible to mention the case when this behaviour was observed and slightly different from species P. nigrociliatus. The breeding and protection of offspring were ensured by both female and male [(Horn 1980) cited by (Braun 1956)]. This statement, respectively this form of relatively weaker sub sociability can explain a gregarious overwintering of predatory species within a single shell.
MATERIAL AND METHODS The survey took place on June 13, 2017 and June 14, 2017 at pre-selected sites. The first site (visited on June 13, 2017, about 400 m southeast of the protected area – Malhotky) is a step, lighted locality with low and sparse vegetation and calcareous subsoil. This site was selected for a large number of empty shells, confirmed from earlier records. A slightly different site is protected area – Švařec, which was visited on June 14, 2017. It is an acidic environment with the admixture of calcareous rocks of anthropogenic origin, also with the presence of sparse and low vegetation. After arriving at the site, a survey of the area were starting and then the searching for the individual shells hanging on the vegetation was carried out. When we found a shell, photo-documentation took place and the individual shells were collected. The recording of environmental conditions was also carried out. Determination of spiders and detection of all available information related to this life strategy were carried out in the laboratory.
RESULTS AND DISCUSSION Altogether, eight shells hanging on vegetation were found. At the first site (a locality next to the Malhotky site), six shells of C. vindobonensis were found. At the second locality Švařec, two shells of C. vindobonensis were found. One female (without offspring) of P. tripunctatus was present in each shell, which contradicts the theory that the male remains with the female (Braun 1956). Young spiders inside the hanging shells create for a period of time a group in which individuals are relatively tolerated to each other. In the case of P. nigrociliatus, the young individuals leave the shell after the first molting (Mikulska 1961). It is likely that a certain affinity or form of sociability is formed between the individuals during this period. It is possible that a group of these young spiders living together in shells can influence to a certain extent by the subsequent gregarious overwintering, which is very noticeable for P. tripunctatus. Regarding to group overwintering, total of six adults individuals of P. tripunctatus were recorded in one shells (Štempáková 2016). This is an interesting phenomenon, because no form of social behaviour is mentioned in connection with the Salticidae family. These are typical predators that attack each other (Buskirsk 1981, Herberstein 2011). It is interesting that the species P. tripunctatus also uses the shells of H. lapicida, as it was seen on the Švařec site. At the recent time, the overwintering of this species is associated with shells of C. vindobonensis (Hula et al. 2009, Niedobová et al. 2013, Štempáková 2016). There are records which are also confirmed by wintering in the shells of Xerolenta sp. (Bellmann 1992) or Z. detrita (Bauchhenns 1995). The issue of coexistence of spider offspring in shells or group overwintering in shells enriches previously acquired knowledge of life and unusual life strategies of these species. By continuing with similar research, we may supplement or refute the previously unsubstantiated facts as well as the previously unknown conditions leading to the formation of these unusual groups.
743 November 8–9, 2017, Brno, Czech Republic 24 years
Figure 1 Red dot – site near the Malhotky locality. Green dot – Švařec site
Figure 2 Caucasotachea vindobonensis inhabited Figure 3 Caucasotachea vindobonensis inhabited by Pellenes tripunctatus (locality near the by Pellenes tripunctatus (locality Švařec) Malhotky)
Figure 4 Helicigona lapicida inhabited by Pellenes tripunctatus (locality Švařec)
744 November 8–9, 2017, Brno, Czech Republic 24 years
CONCLUSION The results brought interesting insights into the behaviour of Pellenes tripunctatus and the unexplained form of social behaviour of these predatory species. The detected coexistence of the individual young spiders in the hanging shells has probably an impact on the formation of groups within the gregarious overwintering. Interestingly, there is also evidence that P. tripunctatus uses Helicigona lapicida shells. In general, shells are important refuges for various, very often rarely or endangered species of invertebrates.
ACKNOWLEDGEMENTS The research was financially supported by the grant IGA FA MENDELU No. IP_8/2017.
REFERENCES Bauchhenss, E. 1995. Überwinternde Spinnen aus Schneckenhäusern. Arachnologische Mitteilungen, 9: 5760. Bellmann, H. 1992. Spinnen beobachten, bestimmen. 1st ed., Augsburg: Naturbuch Verlag. Bellmann, H. 1999. Zur Nutzung leerer Schneckenhäuser durch Arthropoden. Verhandlungen der Gesellschaft für Ökologie, 29: 169172. Braun, R. 1956. Zur Spinnenfauna von Mainz und Umgebung, mit besonderer Berücksichtigung des Gonsenheimer Waldes und Sandes. Jahrbücher des Nassauischen Vereins für Naturkunde, 92: 5079. Buskirsk, R.E. 1981. Sociality in Arachnida. In Social Insect, Vol. II. Georgia: Academic Press, pp. 281367. Herberstein, M.E. 2011. Spider behaviour: flexibility and versatility. 1st ed., New York: Cambridge University Press. Horn, H. 1980. Die Bedeutung leerer Schneckengehäuse für die Überwinterung und das Brutverhalten von Pellenes nigrociliatus L. Koch, 1874 in Steppenrasenformationen (Araneae: Salticidae). Beiträge zur naturkundlichen Forschung in Südwestdeutschland, 39: 167175. Hula, V., Niedobová, J., Košulič, O. 2009. Overwintering of spiders in land-snail shells in South Moravia (Czech Republic). Acta Musei Moraviae, Scientiae Biologicae (Brno), 94: 112. Michálková, M. 2012. Bezobratlí přezimující v ulitách suchozemských měkkýšů v okolí Štramberku. Diploma thesis, Mendel University in Brno. Mikulska, I. 1961. Parental care in a rare spiders Pellenes nigrociliatus (L. Koch) var. bilunulata Simon. Nature, 190(4773): 365366. Moreno-Rueda, G., Marfil-Daza, C., Ortiz-Sanchez, F.J., Melic, A. 2008. Weather and the use of empty gastropod shells by arthropods. Annales de la Société entomologique de France (N.S.), 44(3): 373377. Niedobová, J., Hula, V., Košulič, O. 2013. Prázdné ulity plžů a tajemství, která skrývají. Živa, 61(1): 26–28. Szinetár, Cs., Gál, Zs., Eichardt, J. 1998. Spiders in snail shells in different Hungarian habitats. Miscellanea Zoologica Hungarica, 12: 6775. Štempáková, K. 2014. Bezstavovce prezimujúce v ulitách suchozemských mäkkýšov v širšom okolí Vranova nad Topľou (Slovensko). Bachelor thesis, Mendel University in Brno. Štempáková, K. 2016. Vplyv prostredia a hospodárenia na prezimovanie pavúkov v ulitách suchozemských mäkkýšov. Diploma thesis, Mendel University in Brno.
745