Myrmecologische Nachrichten 8 257 - 262 Wien, September 2006 Formica lusatica SEIFERT, 1997 (Hymenoptera: Formicidae), an ant species new to Finland, with notes on its biology and the description of males Wojciech CZECHOWSKI & Alexander RADCHENKO Abstract A taxonomically problematic ant species from southernmost Finland, so far determined as Formica rufibarbis FABRICIUS, 1793 or / and F. cunicularia LATREILLE, 1798, is identified as Formica lusatica SEIFERT, 1997. This is the first report of this species from Finland. Aspects of the biology of F. lusatica under the local conditions, and especially its relations with Formica sanguinea LATREILLE, 1798, are presented and the description of its males is given. Key words: Ants, Formica lusatica, Formica sanguinea, fauna, taxonomy, description of male, ecology, social para- sitism, Finland. Prof. Dr. Wojciech Czechowski (contact author), Prof. Dr. Alexander Radchenko, Museum and Institute of Zoology, Polish Academy of Sciences, 64 Wilcza Str., 00-679, Warsaw, Poland. E-mail: [email protected]; [email protected]. kiev.ua Introduction Until recently, two species of the Formica rufibarbis com- given by SEIFERT (1996) in the key. Together with this plex were recorded in Finland: F. rufibarbis FABRICIUS, report, we describe the males of F. lusatica and briefly 1793 (COLLINGWOOD 1979) and F. cunicularia LATREILLE, compare them with the males of F. cunicularia and F. rufi- 1798 (ALBRECHT 1993), both reported only from the south- barbis. The aim of the study was also to describe elements ern part of the country (approximately to latitude 62° N). of biology of F. lusatica, especially the nature of its rela- The main morphological differences between F. rufibarbis tionships with Formica sanguinea LATREILLE, 1798, as and F. cunicularia, two sympatric sibling species, are the the ants of the F. rufibarbis complex are potential slave characters of standing pilosity on the alitrunk and petiole, species for the latter. and the colouration of the workers. Formica rufibarbis is generally more hairy: setae on the alitrunk are more abun- Material and methods dant and long, and those on the petiolar scale (seen in pro- Formica lusatica was found in Tvärminne village and its file) are directed backward and forward; the alitrunk is vicinity on Hanko Peninsula, the southernmost part of usually totally reddish, sometimes with variable amounts Finland (59º 50' N, 23º 15' E). A few nests of this species, of dark. The alitrunk of F. cunicularia, usually with vast originally recognized as (atypical) F. rufibarbis, were seen dark patches on the sides, has at most a few setae and very every year from 1996 till 2005 in a local complex of sand often is completely hairless; there are usually no setae on dunes when myrmecological studies, mainly on interspe- the petiolar scale or, if some setae are present, they are di- cific social-parasitic and competitive relations, were carried rected upward or slightly forward (for details see DLUSSKY out there (see, e.g., CZECHOWSKI & ROTKIEWICZ 1997, 1967, BERNARD 1968, KUTTER 1977, COLLINGWOOD 1979, CZECHOWSKI 1999, 2000, 2001, CZECHOWSKI & VEPSÄ- SEIFERT 1996, CZECHOWSKI & al. 2002, RADCHENKO & LÄINEN 2001). Earlier, the same ant species, also recog- al. 2004). nized as F. rufibarbis, was reported from the Tvärminne ALBRECHT (1993), in his short report on the occurrence dunes by GALLÉ (1991). Earlier still (in the late seven- of F. cunicularia in Finland, insisted that all previous re- ties), these Tvärminne ants were determined both as F. cords of F. rufibarbis for this country need to be re-exam- rufibarbis and F. cunicularia (B. Pisarski & K. Vepsälä- ined, as some of them might pertain to F. cunicularia. This inen unpubl.). unclear situation of these two species already reported from The dune colonies of F. lusatica were observed par- Finland is in fact even more complicated with our obser- ticularly with the aim of studying their relations with F. vation of a third sibling species there, the rather recently sanguinea, a facultative slave-maker, which was a very described F. lusatica SEIFERT, 1997. It differs from both, common ant species in that habitat. Every year these ob- F. rufibarbis and F. cunicularia, in the character of pilo- servations were carried out during 2 - 3 weeks, starting in sity, in having a relatively longer antennal scape, and a gen- late June or early July, i.e., in the period of raiding activity erally bigger, more robust body. From F. cunicularia it of F. sanguinea (each time including its very beginning). additionally differs in having a lighter alitrunk and in head Besides observations of natural situations, an experimental colouration; for details see SEIFERT (1997). colony of F. sanguinea was artificially founded in the vic- SEIFERT (1997) did not include F. lusatica sexual forms inity of two F. lusatica nests in 2003 to provoke a con- in his description of the species and comparison of sexuals flict between the species. of F. lusatica with those of so far known sibling species. In the years 2003 - 2005, the investigation of F. lusa- Only a brief morphological characterization of gynes of tica was expanded to include other neighbouring habitats. F. lusatica (under the name F. glauca RUZSKY, 1896) was In total, nearly 20 F. lusatica nests were localized. Nest Stefan-Schödl-Gedenkband / Stefan Schödl Memorial Volume samples, including sexuals if present, were taken from most of them. The species was identified based on SEI- FERT's (1997) description of workers and, in the case of gynes, on SEIFERT's (1996) key (where F. lusatica is re- ferred to as F. glauca). In the latter case, the most useful discriminating features of F. lusatica, F. cunicularia and F. rufibarbis appeared to be the number of standing setae on the alitrunk and pigmentation of the alitrunk. Thirty males taken as pupae from three nests on the meadow and reared in the laboratory in 2004 were sub- jected to morphological examination, using the following morphometrics and indices: HL maximum length of head in dorsal view, measured in a straight line from the anteriormost point of clypeus Fig. 1: Meadow at Tvärminne populated by F. lusatica to the mid-point of the occipital margin. (photo: W. Czechowski). HW maximum width of head in dorsal view behind eyes. SL maximum straight-line length of antennal scape from its articulation with condylar bulb to the prox- imal edge of scape. AL diagonal length of alitrunk in profile, measured from anterodorsal point of alitrunk to posterior margin of metapleural lobe. CI cephalic index: HL / HW. SI scape index: SL / HL. AI alitrunk index: AL / AH. Results 1. Habitats and mode of nesting In the study area, F. lusatica was most abundant on a dry, sporadically mowed country meadow (Fig. 1), where c. 10 nests were found in an area of approximately 0.5 ha. Apart from the ubiquitous F. fusca LINNAEUS, 1758, and F. poly- Fig. 2: Part of the meadow at Tvärminne with biggest ctena FÖRSTER, 1850, a visitor from a nearby forest, F. colonies of F. lusatica along the right side of the sandy lusatica was the main representative of the genus Formica route (photo: W. Czechowski). L. there. There were also sporadic small colonies of F. ex- secta NYLANDER, 1846, and F. sanguinea. Most F. lusa- tica nests were found in the driest part of the meadow with Calamagrostis epigeios (L.) ROTH as the prevalent grass species. The largest colonies were found along a sandy road cutting across the meadow, in a thin marginal band of herbaceous vegetation (Fig. 2). The nests had a number of nest holes and were 40 - 50 cm in diameter. The earth mounds were irregular, rather flat (at most sev- eral centimeters in height) (Fig. 3). The F. lusatica colo- nies were all seen only in that one meadow (in two parts separated by a gravelly road; to be seen on the right in Fig. 1) with no nests found in the surrounding meadows despite apparently similar habitat conditions. Five other colonies of F. lusatica (including one incip- ient colony) were found in the habitat of the sand dunes with some early stands of pine (for a habitat description Fig. 3: Nest of F. lusatica in the meadow at Tvärminne see GALLÉ 1991 and CZECHOWSKI & al. 2005). These (photo: W. Czechowski). colonies nested in two complexes (I and II; Figs. 6, 7), about 300 m apart, in open localities near the southern slope of the dunes and along the northern edge of a pine forest below the dune, several metres away from the for- by flat embankments of elevated sand (Fig. 5). The nest est edge. The sand there was partly covered with a layer area of the largest colony, including two groups of nest of lichens and low moss, somewhere else with sparse cov- holes, was approximately 60 cm in diameter. erage of Carex arenaria L., Festuca ovina L. or Calama- A third habitat where F. lusatica occurred was the grav- grostis epigeios (Fig. 4). The F. lusatica nests in this hab- elly side of an asphalt road. One nest was found there in itat generally resembled nests of F. cinerea MAYR, 1853, the village of Tvärminne (on the same side as the dune com- the dominant Formica species on the Tvärminne dunes, plex), with more nests occurring farther on (K. Vepsälä- with single nest holes or groups of nest holes, surrounded inen, pers. comm.). 258 Fig. 6: Map of the observed complex I of nests of F. lusa- tica (colonies FL-I and FL-II) and F. sanguinea (FS) in the sandy dune habitat (see the text and also Fig. 2 in CZE- Fig. 4: Habitat of F. lusatica in the sandy dunes at Tvär- CHOWSKI & VEPSÄLÄINEN 2001). minne; situation of the F. lusatica (FL-IV) and F.