Cheilosia crassiseta LOEW , 1859

Żóralski, Robert, 2020, Cheilosia crassiseta Loew, 1859 (Diptera: Syrphidae) from the Polish Tatra Mountains, Dipteron (Oxford, England) 36 (4), pp. 26-32 : 27-30

Cheilosia crassiseta LOEW, 1859 ( FIG. 1.)

MATERIAL. Tatra Mountains , Czerwone Wierchy, 1920-2120 m a.s.l., 26 VI 1956, 2♂♂ 2♀♀, leg. B. PISARSKI, coll. MIZ PAS .

DIAGNOSTIC FEATURES (IMAGINES). A series of four tiny (6 – 6.5 mm) specimens bearing the same handwritten label, fitted the original detailed description by LOEW (1859) of C. crassiseta . They differ from all other Taeniochilosia specimens present in revisions of BECKER (1889, 1894), BARKALOV & STÅHLS (1997) and CLAUSSEN & VAN DE WEYER (2004). Two male specimens collected by B. PISARSKI are almost identical to each other, only difference being that one of them has the 3 rd segment of the antennae completely black, whereas the second has a slightly reddish posterior corner. Among other diagnostic features they have black, slightly hairy arista tightened from the middle of its length, 3 rd segment of antennae a bit rectangular but with rounded corners, two- sized (long black and short white) pubescence on thorax and pubescent posterior anepisternum. They have the dorsal part of the thorax without any visible pubescence markings. Two female specimens, however, show some differences from each other in the thorax pilosity (presence versus

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absence of a few longer black bristles among short light hairs), the hue of the 3 rd segment of antennae (falling into red in posterior half versus completely black), pubescence of sternites II- IV (equally pubescent comparing to 1 st segment as opposed to more shiny than that), black hairs on scutellum (present versus absent), shape of the facial knob (small and elongated versus more broader and massive), but are identical in all other characters and body size, including characteristic depressed and parted outwards hairs on the tergites III and IV as described by LOEW (1859) and visualized by CLAUSSEN & VAN DE WEYER (2004). Interpretation used here is they are both in the scope of intraspecific variability of one species. Variations in some diagnostic features of C. crassiseta are reported in literature since the original description, e.g., “ ♂, the rounded third segment [of antenna] sometimes reddish- brown” ( LOEW 1859); “ ♂ and ♀, sometimes has red- brown antennae, a variety that is designated as such in Loew's collection.” ( BECKER 1889); “ ♂ and ♀, third antennal segment small, rectangular with rounded corners, brownish to blackish, sometimes with lower posterior corner reddish” ( BARKALOV & STÅHLS 1997); “ ♀, scutellum margin with a few short black bristles or without” ( BARKALOV & STÅHLS 1997). A side effect of that variability is that females of C. crassiseta were placed three times in the determination key of BARKALOV & STÅHLS (1997) that was modeled after the key of BECKER (1894).

DISTRIBUTION. Known localities of Cheilosia crassiseta are in the high mountains of Austria, Croatia, Czech Republic, Germany, Italy, Montenegro, Poland, Romania, Slovakia, Slovenia and Switzerland ( LOEW 1859; VUJIĆ 1996; BARKALOV & STÅHLS 1997; DUNK 1999; SOMMAGGIO 2010; VAN STEENIS et al. 2013; VAN STEENIS et al. 2015).

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NOTES ON THE BIOLOGY. Not much is known about the biology of Cheilosia crassiseta , except the fact that the imago is reported almost exclusively from high mountains in Europe and it lives on the alpine grasslands and hilltops ( VAN STEENIS et al. 2015). The host plant is still unknown, however based on analysis of a limited set of potential hosts in the plant communities endemic to the Tatra Mountains occurring on moist gravel and granite screes of the mountain (1800-2400 m a.s.l.), and the fact that larvae of related C. pubera were described as narrowly monophagous from Geum rivale L. (STUKE & CARTENSTER 2002), one can set a hypothesis that larvae of C. crassiseta develop in lower parts of creeping avens Geum reptans L., the distribution of which is only high altitudes and extends from the Alps to the Carpathians, the Illyric mountains and Macedonia ( PLUESS & STOCKLIN 2004), perfectly matching the known distribution of C. crassiseta , or in alpine avens Geum montanum L., which has a similar and slightly broader distribution.

NOTES ON THE LOCATION IN POLAND. Czerwone Wierchy in Tatra Mountains is a massif consisting of four hills in a row: Ciemniak – 2096 m, Krzesanica – 2122 m, Małołączniak – 2096 m and Kopa Kondracka – 2005 m, divided by three passes: Mułowa – 2067 m, Litworowa – 2037 m, Małołącka – 1924 m, located at a border between Poland and Slovakia. The name “Czerwony Wierchy” (eng. Red Peaks) comes from the red- brown color of their slopes, which is given to them by a plant Juncus trifudus L., which turns red in autumn, or sometimes in the middle of summer ( FIG. 2) .

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SUMMARY

The Diptera of the higher parts of the Polish part of the Tatra Mountains are poorly recognized and probably there are still species new to the Polish fauna and new to science to be found here ( KLASA & PALACZYK 2010). Considering the endemic character of the plant communities of the subalpine and alpine layers it would be especially interesting to recognize the endemic phytophagous fauna associated to those herbs. In case of Syrphidae , there was practically no research done in the highest parts of Polish Tatra since field trips of NOWICKI (1867, 1868), LOEW (1870), BOBEK (1890) and MALSKI (1959). The unavailability of some of areas, unpredictable weather, as well as a short flight periods of imagines of Syrphidae , make any systematic field research on Syrphidae in the area difficult. Nowadays it is also an area highly protected by the Tatra National Park and proper permits for research are required. In this context every piece of information on the biology of these animals is valuable.

Specimens published in this work and found in MIZ PAS collection are rather accidental findings of prof. BOHDAN PISARSKI (1928-1992), collected at the beginning of the series of his expeditions on Hymenoptera. His visit in Tatra Mountains around the date of finding of C. crassiseta can be confirmed with a date of another Syrphidae specimen ( Sphaerophoria ) present in the material sections of BAŃKOWSKA (1964). B. PISARSKI was an entomologist specializing in myrmecology ( CZECHOWSKI 1994), employed for 43 years in Institute of Zoology of Polish Academy of Science and in the years 1982-1992 was director of the institute ( TROJAN & KAZUBSKI 1993; TROJAN 1994). He was also the second husband of PROF. REGINA BAŃKOWSKA-PISARSKA (1930-2017), a known Polish syrphidologist.

Taeniochilosia is overall difficult subgenus in Cheilosia and most of the older literature information about it still requires verification, by careful examination of the historical material deposited in museums. Two species in the subgenus Taeniochilosia require further revision the most (in the sense of their real distribution in Poland, if any): Cheilosia antiqua (MEIGEN, 1822) and Cheilosia sahlbergi BECKER, 1894 , because those names were used historically for specimens of a few species being recognized nowadays.