Myrmica karavajevi

M. karavajevi is probably the most widespread of the workerless Myrmica social parasites. It is nowhere common, and usually myrmecologists can find one or two infested colonies and no more, despite repeated searching.

Identification
Radchenko and Elmes (2010) - A member of the karavajevi species group that has clear affinities with Myrmica lemasnei and Myrmica cagnianti.

Distribution
S. England to Ukraine, Czechoslovakia to Finland (Collingwood 1979).

Distribution based on Regional Taxon Lists
Palaearctic Region: Austria, Belarus, Belgium, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Iberian Peninsula, Italy, Norway, Poland, Romania, Russian Federation, Spain, Sweden, Switzerland, Ukraine, United Kingdom of Great Britain and Northern Ireland.

Biology
Radchenko and Elmes (2003) - It is catholic in its choice of host species and is perhaps a generalist social parasite specialising on species from the scabrinodis-group of Myrmica. Arnoldi (1930, 1933) found it with Myrmica scabrinodis; in England its host was Myrmica sabuleti; Elmes found it with M. scabrinodis in France; in Poland host species was Myrmica gallienii (Pisarski 1962 noted as host species M. rugulosa, misidentification, material examined); in Finland it hosts appear to be M. scabrinodis and Myrmica lonae while we found M. karavajevi near St. Petersburg in a nest of M. lonae. Similarly, the host worker on the same pin as a S. winterae queen (GENEVA) was Myrmica gallienii (although determined as M. ruginodis by Kutter). One common feature is that all its hosts live in warm but relatively wet places in marshes, meadows and forest glades. The host colony of M. sabuleti from England lived in rather cool damp conditions, which begs the question whether a cryptic ecomorph of M. sabuleti, with biology similar to M. zonae, exists in England (Elmes, unpublished).

Radchenko and Elmes (2010) - Jansen et al. (2010) based on a molecular phylogenetic study showed that M. karavajevi belongs to the same clade (scabrinodis-group) as its recorded hosts, but it appears to have had a common ancestor with its host species a long time ago. Thus it obeys Emery's rule in a loose sort of way: its multiple host use could be explained either by a sudden switch to more generalist behaviour after the extinction of its first host species or by its tracking of daughter species evolved from the original host species (Savolainen and Vepsalainen 2003). The great age of M. karavajevi and its relationship to its host species, illustrated by Jansen et al. (2010), suggests that the latter is more probable.

Collingwood (1979) - This ant has been recorded sometimes in large numbers and sometimes as one or two individuals in nests of various Myrmica host species including Myrmica rugulosa, Myrmica scabrinodis and Myrmica sabuleti. A colony in Dorset, England, was observed for over 4 years during which time alate queens and males of the parasite were present each season together with workers and worker brood of the host, indicating that egg laying queens of both parasite and Myrmica host were surviving together in the same nest. In Norway 2 dealate queens were caught in pitfall traps in July 1974 suggesting that after mating, fertilised queens wander over the ground in search of a colony of the host species.

Castes
A workerless inquline.

Nomenclature

 *  karavajevi. Symbiomyrma karavajevi Arnol'di, 1930c: 269, figs. 1-4 (q.m.) UKRAINE. [Also described as new by Arnol'di, 1933a: 41.] Combination in Symbiomyrma: Seifert, 1994: 15; Seifert, 1996b: 236; in Sifolinia: Samsinak, 1964: 156; in Myrmica: Bolton, 1988a: 4; Radchenko & Elmes, 2003a: 231. Senior synonym of pechi: Samsinak, 1964: 156; of faniensis, winterae: Seifert, 1994: 15. See also: Kutter, 1973c: 256 (misspelled as karawajewi); Collingwood, 1979: 58; Radchenko & Elmes, 2003a: 231; Radchenko & Elmes, 2010: 163.
 * pechi. Sifolinia pechi Samsinak, 1957: 167, 2 figs. (q.) CZECHOSLOVAKIA. Pisarski, 1962: 367 (m.). Junior synonym of karavajevi: Samsinak, 1964: 156.
 * faniensis. Myrmica faniensis Boven, 1970a: 127, figs. 1, 2 (q.) BELGIUM. Junior synonym of karavajevi: Seifert, 1994: 15. See also: Kutter, 1973c: 256; Boven, 1977: 114; Bolton, 1988a: 4.
 * winterae. Sifolinia winterae Kutter, 1973c: 263, figs. 1, 2, 8, 9, 13-15 (q.m.) SWITZERLAND. Combination in Myrmica: Bolton, 1988a: 4. Junior synonym of karavajevi: Seifert, 1994: 15.

Queen
(n=31): HL 0.78-0.89; HW 0.73-0 .84; SL 0.71-0.80; AL 1.16-1.44 mm; FI 0.42-0.49; FLI 1.03-1.07; SI1 0.83-0.92; SI2 0.89-1.00; PPI 0.55-0.62; ESLI 0.26-0.33; males (n=12): HL 0.66-0.79; HW 0.65-0.73; SL 0.63-0.79; AL 1.14-1.28 mm; SI1 0.91-1.01; SI2 0.97-1.10; PPI 0.54-0.63; ESLI 0.09-0.16.

Etymology
Radchenko and Elmes (2010) - this species was dedicated to the famous Ukrainian myrmecologist Prof. Vladimir Afanasievich Karawajew.