A key for the determination of European species of Eosentomon Berlese, 1909 (Protura, Eosentomata, Eosentomidae).

European species of Eosentomon are examined. A taxonomic key to identification of 61 Eosentomon species is provided based on body chaetotaxy, shape, and position of sensilla on the foretarsus and shape of sensilla on the maxillary palps. Biogeographically, 13 of the known European Eosentomon species are known only from their type localities.

Introduction

The proturan genus Berlese, 1909 has a worldwide distribution and contains approximately 310 described species (Szeptycki 2007, Bu and Yin 2007, Shrubovych and Szeptycki 2008, Nakamura and Likhitrakarn 2009, Nakamura 2010), of which 61 have been described from Europe (Szeptycki 2007, Shrubovych and Szeptycki 2008). PageBreakA key for the identification of European species was created by Nosek (1973) for 14 species, in which the author differentiated species into four groups according to the shape of female squama genitalis. This approach followed Tuxen (1960), who divided worldwide into 11 groups based on the squama genitalis. Szeptycki (1984, 1985a, 1985b, 1986) wrote a series of papers with keys to identification of four groups of Polish species, in which cephalic chaetotaxy was used for group separation (Szeptycki, 1986). Both Nosek and Szeptycki frequently used in their keys the shape of the female squama genitalis, which made identification of males and young stages impossible except by association. The present paper contains an identification key to European species based primarily on chaetotaxy, shape, and position of sensilla on the foretarsus and the shape of sensilla on the maxillary palpi.

Materials and methods

Type materials were examined of 31 species deposited in the collection of Prof. Szeptycki in the Institute of Systematics and Evolution of Animals PAS, eight species in the collection of J. Rusek in the Institute of Soil Biology BCCAS and one species deposited in the collection the State Museum of Natural History NASU. Information about the taxonomy of other species was taken from original descriptions or redescriptions of type materials in Tuxen (1964), Nosek (1973) and various other papers. Head chaetotaxy is labelled as in Szeptycki (1984), and body chaetotaxy is labeled according to Bernard (1990).

The geographical distribution of these species is given according to recent published data (Szeptycki 2007, Shrubovych 2010, Christian 2011, Galli et al. 2011, Blesić and Mitrovski-Bogdanović 2012, Shrubovych and Sterzyńska 2015, Shrubovych et al. 2015, Shrubovych and Fiera 2016). Each species was assigned to a major biogeographic region (Alpine, Boreal, Continental, Pannonian, Mediterranean, Macaronesian) according to the European Environment Commission (2017) Natura 2000 terminology of European biogeographic regions (see map in: https://www.eea.europa.eu/data-and-maps/figures/biogeographical-regions-in-europe-2).

Results and discussion

Taxonomic characters used in the key are present in juvenile stages as well as the adults. The shapes of the parts of the adult female squama genitalis may have great phylogenetic value and can serve as additional characters for identification of species. The characters used in the key, such as shape of maxillary palpi, chaetotaxy of the head, shape and position of sensilla on the foretarsus and position of seta P1a on tergite VII are stable from the second juvenile stage (larva I) (Nosek 1973, Szeptycki 1965b). All setae on the notal tergites and on the abdominal segments are present from the maturus junior stage (Imadaté 1965).

Analysis of the geographical distribution of European shows that nearly all species have been collected only in Europe, except for two ( and ) that have also been recorded from northern Africa. The majority of the species have been recorded only from Central Europe, probably due to many years of active work in this region by Josef Nosek, Josef Rusek and Andrzej Szeptycki. Sixteen species are known from Western Europe and only two species have been reported from Eastern Europe (Table 1). Nineteen species occur in Southern Europe and only two species have been noted from Northern Europe. If intensity of collection and study is correlated with number of recognized species then there are more species yet to be discovered in Europe. Thirteen of the 61 species are known only from their type localities: therefore, it is difficult to assert endemicity within such a poorly studied group of microarthropods. Nevertheless, two species could be endemics of the East Carpathians. The occurrence of has been confirmed in the Carpathian Mountains of Ukraine, Romania, Hungary (Shrubovych and Sterzyńska 2015, Shrubovych et al. 2015) and in the Slovakian Carpathians (unpublished data). Therefore, it can be considered an Eastern-Carpathian endemic (Table 1). The collection of in the lowlands of the Transcarpathian region is consistent with an earlier report that this species has a wide ecological plasticity and environmental distribution pattern, and can predominate in communities outside of mountain habitats in azonal habitats, such as floodplain forests (Sterzyńska et al. 2012). A similar situation exists with , which was collected in the Ukrainian and Slovakian Carpathians (Shrubovych and Sterzynska 2015, unpublished data) and has been considered an Eastern-Carpathian endemic (Shrubovych and Sterzynska 2017); however, in Poland this species was found outside of mountainous habitats.

Table 1.

Distribution pattern of species in European biogeographical regions.

Species	Countries	Biogeographical regions
E. armatum Stach, 1927	Nearly all of Europe	Continental-Pannonian-Mediterranean
E. bloszyki Szeptycki, 1985	Poland, Czech Republic, Luxembourg, Germany, Austria, Ukraine	Continental
E. boedvarssoni Nosek, 1973	Sweden	Boreal
E. bohemicum Rusek, 1966	Czech Republic, Poland	Continental
E. briophillum Szeptycki, 1986	Poland, type locality only	Continental
E. canarinum Szeptycki, 2004	Canary Islands	Macaronesian
E. carolae Condé, 1947	France, Spain	Mediterranean
E. carpaticum Szeptycki, 1985	Poland, Ukraine, Romania, Hungary, Slovakia	Alpine-Continental
E. cetium Szeptycki & Christian, 2000	Austria, type locality only	Continental
E. coiffaiti Condé, 1961	Minorca, Serbia	Macaronesian-Continental
E. condei da Cunha, 1950	Portugal, Spain	Mediterranean
E. delicatum Gisin, 1945	All Europe, North Africa	Alpine-Boreal-Continental-Pannonian-Mediterranean
E. denisi Condé, 1947	France, Spain	Mediterranean
E. enigmaticum Szeptycki, 1986	Poland, Ukraine, Romania, Slovakia	Alpine-Continental
E. fichteliense Rusek, 1988	Germany, type locality only	Continental
E. foliaceus Rusek, 1988	Germany, Poland	Continental
E. foroiuliense Torti & Nosek, 1984	Italy, type locality only	Continental
E. funkei Rusek, 1988	Germany, Luxembourg	Continental
E. gamae Aldaba, 1986	Portugal, type locality only	Mediterranean
E. germanicum Prell, 1912	Nearly all of Europe, Morocco	Alpine-Boreal-Continental-Mediterranean
E. gisini Nosek, 1967	Austria, Slovakia	Alpine
E. gramineum Szeptycki, 1986	Poland, Ukraine	Continental
E. kamenickiense Rusek, 1974	Czech Republic, type locality only	Continental
E. longisquamum Szeptycki, 1986	Poland, Austria	Continental
E. lusitanicum Aldaba, 1986	Portugal, type locality only	Mediterranean
E. luxembourgense Szeptycki, 2001	Luxembourg, Austria	Continental
E. mariae Szeptycki, 1986	Poland, Austria, Germany, Luxembourg, Ukraine	Continental
E. mirabile Szeptycki, 1984	Poland, Germany, Austria, Canary Islands, France, Ukraine	Continental-Macaronesian
E. mixtum Condé, 1945	France, Austria, Czech Republic, Germany, Slovakia, Madeira	Alpine-Continental-Macaronesian
E. noseki Tuxen, 1982	Macaronesia, Spain, Italy	Macaronesian-Mediterranean
E. occidentale Szeptycki, 1985	Poland	Continental
E. palustre Szeptycki & Sławska, 2000	Poland, type locality only	Continental
E. parvum Szeptycki, 1986	Austria, Poland	Continental
E. pastorale Szeptycki, 2001	Austria, Luxembourg	Continental
E. paucrum Szeptycki, 2001	Luxembourg	Continental
E. pinetorum Szeptycki, 1984	Austria, Czech Republic, Poland, Ukraine, Romania	Alpine-Continental
E. pinkyae Arbea-Polite, 1990	Spain, type locality only	Mediterranean
E. polonicum Szeptycki, 1985	Poland	Continental
E. posnaniense Szeptycki, 1986	Poland, Austria	Continental
E. pratense Rusek, 1973	Czech Republic, Poland, former Yugoslavia, Slovakia, Germany, Austria, Ukraine	Continental
E. rafalskii Szeptycki, 1985	Poland, Czech Republic, Germany	Continental
E. romanum Nosek, 1969	Italy	Mediterranean-Continental
E. rusekianum Stumpp & Szeptycki, 1989	Germany, Austria, Poland	Continental
E. scytha Shrubovych & Szeptycki, 2008	Ukraine, type locality only	Continental
E. semiarmatum Szeptycki, 1986	Balearic Islands, France, Germany, Poland, Ukraine, Romania	Mediterranean-Continental
E. sexsetosum Szeptycki, 1985	Luxembourg, Poland	Continental
E. silesiacum Szeptycki, 1985	Germany, Czech Republic, Poland, Luxembourg, Sweden	Boreal-Continental
E. silvaticum Szeptycki, 1986	Poland, Luxembourg, Romania	Alpine-Continental
E. solarzi Szeptycki, 1993	European part of Russia, type locality only	Continental
E. stachi Rusek, 1966	Austria, Luxembourg, Poland, Slovakia, Ukraine, Romania	Alpine - Continental
E. stompi Szeptycki & Weiner, 1993	Germany, Luxembourg	Continental
E. stumppi Rusek, 1988	Germany, Austria	Continental
E. sudeticum Szeptycki, 1985	Poland, Czech Republic	Continental
E. transitorium Berlese, 1909	all Europe	Alpine-Boreal-Continental-Pannonian-Mediterranean
E. ulinense Szeptycki, 1999	Poland	Continental
E. umbrosum Szeptycki, 2001	Luxembourg	Continental
E. vindobonense Szeptycki & Christian, 2000	Austria, type locality only	Continental
E. vulgare Szeptycki, 1984	Poland, Czech Republic, Germany, Austria, Luxembourg, Ukraine	Continental
E. wanda Szeptycki, 1985	Poland, type locality only	Continental
E. weinerae Szeptycki, 2001	Austria, Luxembourg	Continental
E. zodion Szeptycki, 1985	Poland, Ukraine	Continental

The existence of at least 61 European species, with only two of its species outside the continent (Mediterranean Africa), strongly suggests that the remaining continents must have many more species than are currently known from them. All of the world’s species have ranges restricted to a single continent, and most are apparently specialized to a particular biome or specialized habitat. Much more collecting needs to be done, even in Europe, for us to understand the diversity of these enigmatic hexapods.

1	Tergite VII with 2 A-setae (seta A4)	2
–	Tergite VII with greater number of A-setae	3
2	Tergite IV with 8 A-setae (A5 absent), foretarsal sensillum a clearly shorter than c (see Rusek 1974: figs 1, 2)	E. kamenickiense
–	Tergite IV with 10 A-setae (A5 present), foretarsal sensilla a and c equal in length (see Rusek 1973: figs 1, 2, 10)	E. pratense
3	Tergite VII with 4 A-setae (setae A4, A5)	4
–	Tergite VII with other number of A-setae	28
4	Tergite V with 8 A-setae (A3 absent)	5*
–	Tergite V with 10 A-setae (A3 present)	16
5	Head with aa and pa setal pairs	6
–	Head with one pair or without additional setae	11
Two species, E. denisi and E. condei, will key to couplet 5 but their cephalic chaetotaxy is unknown. Eosentomon denisi possesses eight A-setae on tergites V–VII, the female squama genitalis is of the “wheeleri” type (see Nosek 1973: 92–94, fig. 26 I), the foretarsus is 110 μm long. The other species, E. condei, has eight A-setae on tergites V–VI and six A-setae on tergite VII, and the foretarsus length is 80 μm (see Nosek 1973: 107–108).
6	Seta P1a at level of P2 on tergite VII (see Szeptycki 1985a: fig. 25; Szeptycki and Sławska 2000: fig. 19)	7
–	Seta P1a posterior to level of P2, extending past hind margin of tergite VII	10
7	Foretarsal sensillum d long, reaching base of t3 (Szeptycki 1985a: fig. 28; Szeptycki 2001: fig. 61)	8
–	Foretarsal sensillum d short, reaching base of α5 (see Szeptycki 2001: fig. 81; Szeptycki and Sławska 2000: fig. 10)	9
8	Foretarsal sensillum c’ long, base proximal to line α6 – δ5 (Szeptycki 1985a: fig. 27), length of foretarsus 100–105 μm	E. bloszyki
–	Foretarsal sensillum c’ short, base distal to line α6 – δ5 (Szeptycki 2001: fig. 60), length of foretarsus 80–85 μm	E. paucrum
9	Foretarsal sensillum t1 nearer to α3’ than to α3, rostral and subrostral setae equal in length (see Szeptycki 2001: figs 72, 85), length of foretarsus 105–115 μm	E. pastorale
–	Sensillum t1 midway between α3 and α3’, rostral setae shorter than subrostral setae (see Szeptycki and Sławska 2000: figs 2, 12), foretarsus 70–80 μm	E. palustre
10	Foretarsal sensillum c’ thick, proximal to line α6 – δ5 (see Nosek 1973: fig. 36B; Szeptycki 1985a: fig. 48), length of foretarsus 80–95 μm	E. stachi
–	Foretarsal sensillum c’ slender, on line α6 – δ5 (see Szeptycki 1985: fig. 85), length of foretarsus 95–100 μm	E. carpaticum
11	Head with pa setae only, foretarsal sensillum b’2 very long, foliaceous (see Rusek 1988: figs 1D, 2B), length of foretarsus 95 μm	E. foliaceus
–	Head without additional setae, foretarsal sensillum b’2 shorter, sensilliform	12
12	Notal seta P2a clearly longer than one-third the length of P3a; setae on tergite XI very short, one-sixth the length of those on tergite X (see Szeptycki 1985b: figs 48, 52, 56, 70)	13
–	Notal setae P2a one-third the length of P3a; setae on tergite XI half as long as setae on tergite X (see Szeptycki 1985b: figs 13, 17, 22, 34)	15
13	Tergite VI with 8 A-setae (A3 absent) (see Szeptycki 1985b: fig. 39; Szeptycki and Weiner 1993: fig. 12)	14
–	Tergite VI with 6 A-setae (A1, A3 absent) (see Szeptycki 1985b: fig. 57)	E. sexsetosum
14	Dorsal sensillum on maxillary palpus longer than lateral sensillum, rostral and subrostral setae subequal (see Szeptycki 1985b: fig. 46), length of foretarsus 100–110 μm E. occidentale	E. occidentale
–	Sensilla on maxillary palpus equal in length, rostral and subrostral setae subequal (see Szeptycki and Weiner 1993: fig. 5), length of foretarsus 85–100 μm	E. stompi
15	Tergite IV with 8 A-setae (A3 absent), dorsal sensillum on maxillary palpus longer than lateral sensillum (see Rusek 1966: fig. 7; Szeptycki 1985b: figs 4, 6)	E. bohemicum
–	Tergite IV with 10 A-setae, sensilla on maxillary palpus equal in length (see Szeptycki 1985: figs 23, 30)	E. polonicum
16	Tergite VI with 10 A-setae	17
–	Tergite VI with 8 A-setae	18
17	Foretarsal sensilla a and c short, sensillum f2 very short, one-fifth length of f1 (see Torti and Nosek 1984: fig. 1B), length of foretarsus 112 μm	E. foroiuliense
–	Foretarsal sensillum a longer than c, sensilla f1 and f2 nearly equal in length, female squama genitalis with small beak-like terminus (see Arbea-Polite 1990: figs 2a, 11), length of foretarsus 75–85 μm	E. pinkyae
18	Seta P1a at level of P2 on tergite VII (see Szeptycki 2001: figs 19, 20)	19
–	Seta P1a posterior to level of P2 on tergite VII	21
19	Foretarsal sensilla a and c equal in length, female squama genitalis of “romanum” type (see Nosek 1973: figs 38A, J, J’)	E. romanum
–	Foretarsal sensillum a clearly shorter than c, female squama genitalis of “transitorium” type (see Szeptycki 2001: fig. 17; Nosek 1973: fig. 33 I)	20
20	Foretarsal sensillum c’ proximal to base of α6 or to line α6 – δ5, broad (see Szeptycki 2001: figs 4, 12, 14), length of foretarsus 65–75 μm	E. luxembourgense
–	Foretarsal sensillum c’ to line α6 – δ5, slender (see Nosek 1973: fig. 33 A), length of foretarsus 90–100 μm	E. delicatum
21	Foretarsal sensillum c’ on line α6 – δ5	22
–	Foretarsal sensillum c’ proximal to line α6 – δ5	24
22	Foretarsal sensillum t1 nearer to α3’ than to α3, sensilla on maxillary palpus nearly equal in length (see Szeptycki 1985a: figs 102, 109)	E. wanda
–	Foretarsal sensillum t1 midway between α3 and α3’ or nearer to α3, dorsal sensillum on maxillary palpus clearly longer than lateral (see Szeptycki 1985a: figs 122, 125, Shrubovych and Szeptycki 2008: figs 5, 20)	23
23	Sensillum t1 midway between α3 and α3’, rostral and subrostral setae equal in length (Shrubovych and Szeptycki 2008: figs 4, 9)	E. scytha
–	Sensillum t1 much closer to α3 than to α3’, rostral setae slightly shorter than subrostral setae (see Szeptycki 1985a: figs 120, 125)	E. zodion
24	Head with aa and pa setae	25
–	Head with pa setae only (see Szeptycki 2001: fig. 26)	27
25	Sensilla on maxillary palpus thick, foretarsal sensillum a half the length of c (see Szeptycki 2004: figs 48, 51)	26
–	Sensilla on maxillary palps slender, foretarsal sensilla a and c nearly equal in length (see Szeptycki 1985a: figs 66, 71)	E. armatum
26	Dorsal sensillum on maxillary palpus clearly longer than lateral sensillum (see Szeptycki 2004: fig. 48), length of foretarsus 95–100 μm	E. noseki
–	Sensilla on maxillary palpus nearly equal in length (see Szeptycki 2004: fig. 26), length of foretarsus 70–80 μm	E. canarinum
27	Foretarsal sensillum c’ in half distance between α6 – δ4’, seta P2a on nota equal in length to P3a (see Szeptycki: figs 32, 37), length of foretarsus 65 μm	E. umbrosum
–	Foretarsal sensillum c’ closer to δ4’ than to α6, seta P2a shorter than P3a (see Rusek 1988: fig. 3B), length of foretarsus 75–85 μm	E. stumppi
28	Tergite VII with 10 A-setae (see Nosek 1973: fig. 31H)	E. boedvarssoni
–	Tergite VII with fewer A-setae	29
29	Tergite VII with 8 A-setae (A3 absent) (see Aldaba 1986: fig. 17)	30
–	Tergite VII with 6 A-setae (A1, A3 absent)	31
30	Sternites IX – X with 6 setae, female squama genitalis of “wheeleri” type (Nosek 1973: p. 95; Tuxen 1964: fig. 105)	E. carolae
–	Sternites IX – X with 4 setae, female squama genitalis of “transitorium” type (see Aldaba 1986: table 2, fig. 18)	E. gamae
31	Tergite VI with 10 A-setae	32
–	Tergite VI with 8 A-setae	57
32	Sternites IX – X with 4 setae	33
–	Sternites IX – X with 6 setae (sternite X with 4 setae in maturus junior)	48
33	Head with aa and pa setae (J. Rusek, pers. comm.; Arbea-Polite 1990: fig. 15a), seta P1a passing hind margin of tergite VII (see Nosek 1973: fig. 37H; Arbea-Polite 1990: fig. 7)	34
–	Head with pa setae or without additional setae	35
34	Foretarsal sensillum t1 midway between α3 and α3’, rostral seta evidently shorter than subrostral (see Nosek 1973: fig. 37B, C), length of foretarsus 86 μm	E. gisini
–	Foretarsal sensillum t1 near to α3’, rostral and subrostral setae equal in length (see Arbea-Polite 1990: fig. 2a, 24), length of foretarsus 77–86 μm	E. pinkyae
35	Head without additional setae	36
–	Head with pa setae	37
36	Basal seta D2 on hind leg about half the length of D1 (see Szeptycki 1985b: fig. 85)	E. rafalskii
–	Basal seta D2 on hind leg subequal with D1 (see Szeptycki 1985b: figs 108, 109)	E. silesiacum
37	Basal seta D2 on hind leg spine-like	38
–	Basal seta D2 on hind legs setiform	46
38	Seta P1a not reaching hind margin of tergite VII	39
–	Seta P1a extending past hind margin of tergite VII	42
39	Sensilla on maxillary palps short and equal in length (see Szeptycki 1986: fig. 73, Szeptycki and Christian 2000: fig. 3)	40
–	Maxillary sensilla long, lateral sensillum longer than dorsal	41
40	Notal setae P1 longer than P1a, foretarsal sensillum f1 spatuliform (see Szeptycki 1986a: figs 74, 81)	E. bryophilum
–	Notal setae P1 shorter than P1a, foretarsal sensillum f1 filiform (see Szeptycki and Christian 2000: figs 4, 10)	E. vindobonense
41	Length ratio of notal setae P1:P1a ≥1.5 (see Szeptycki 1986a: fig. 31)	E. enigmaticum
–	Length ratio of notal setae P1:P1a ≤1.3 (see Szeptycki 1986a: fig. 46)	E. gramineum
42	Sensilla on maxillary palpus nearly equal in length (see Szeptycki 1986: fig. 158; Szeptycki and Christian 2000: fig. 24)	43
–	Lateral sensillum of maxillary palpus much longer than dorsal sensillum (see Szeptycki 1986a: figs 107, 123, 138)	44
43	Notal setae P1a and P1 nearly equal in length (see Szeptycki 1986a: fig. 152), length of foretarsus 85–90 μm	E. longisquamum
–	Notal seta P1a shorter than P1 (Szeptycki and Christian 2000: fig. 28), length of foretarsus 100–115 μm	E. cetium
44	Seta P1a on tergites I – VI longer than P1, foretarsal sensillum t1 nearer to α3 than to α3’, sensillum t3 longer than c’, length of foretarsus less than 100 μm	45
–	Seta P1a on tergites I – VI equal in length or shorter than P1, foretarsal sensillum t1 midway between α3 and α3’ or slightly closer to a3’, sensillum t3 short, equal in length to c’, length of foretarsus 100–110 μm (see Szeptycki 1986a: figs 115, 116)	E. silvaticum
45	Tracheal camerae long, slender; foretarsal sensillum d long, reaching base of α6, length of foretarsus 90–100 μm (see Szeptycki 1986a: figs 125, 126, 130, 131)	E. semiarmatum
–	Tracheal camerae short, stocky; foretarsal sensillum d short, not reaching base of α5, length of foretarsus 75–85 μm (see Szeptycki 1986a: figs 140, 145)	E. parvum
46	Seta P1a at level P2 on tergite VII	47
–	Seta P1a slightly posterior to P2 and extending past hind margin of tergite VII (see Szeptycki 1986a: fig. 63)	E. posnaniense
47	Rostral seta thinner than subrostral seta (see Szeptycki 1986a: fig. 6), lateral sensillum on maxillary palpus longer than dorsal sensillum (see Nosek 1973: fig. 28C’; Szeptycki 1986a: fig. 7), foretarsal sensillum t1 nearer to α3 than to α3’(see Nosek 1973: fig. 28A; Szeptycki 1986a: fig. 20) or midway between α3 and α3’ (see Szeptycki 1986a: fig. 21)	E. transitorium
–	Rostral seta thicker than subrostral seta, sensilla on maxillary palpus nearly equal, foretarsal sensillum t1 nearer α3’ than α3 (see Szeptycki 1986a: figs 86, 100)	E. mariae
48	Seta P1a at level of P2 on tergite VII	49
–	Seta P1a posterior to level of P2 on tergite VII	52
49	Foretarsal sensillum f1 thickened apically, body length more than 1600 μm (see Nosek 1973: fig. 32A; Rusek 1988: p. 229)	E. mixtum
–	Foretarsal sensillum f1 not thickened apically, body length less than 1600 μm	50
50	Foretarsal sensillum f1 thick, thicker than sensillum a (see Aldaba 1986: fig. 5), body length less than 850 μm	E. lusitanicum
–	Foretarsal sensillum f1 thin (see Rusek 1988: fig. 8A), body length more than 1300 μm	51
51	Foretarsal sensillum t1 midway between α3 and α3’, sensillum f2 sensilliform (see Rusek 1988: fig. 8A, B), body length about 1460 μm	E. funkei
–	Foretarsal sensillum t1 nearer α3 than α3’, sensillum f2 spatuliform (see Nosek 1973: fig. 35A), body length about 1300 μm	E. coiffaiti
52	Head with both aa and pa setae	53
–	Head with aa or pa setae	54
53	Foretarsal sensillum a longer than half the length of c, sensillum f1 spatulate (see Szeptycki 1984: fig. 38)	E. mirabile
–	Foretarsal sensillum a shorter than half the length of c, sensillum f1 filiform (see Szeptycki 2001: figs 103, 105)	E. weinerae
54	Head with aa setae (see Stumpp and Szeptycki 1989: fig. 8)	E. rusekianum
–	Head with pa setae only	55
55	Lateral sensillum on maxillary palpus clearly longer than dorsal, spatulate dilation on foretarsal sensilla e and g short, about third of sensillum length, tracheal camerae long (see Szeptycki 1984: figs 7, 9, 11, 12)	E. vulgare
–	Sensilla on maxillary palps nearly equal in length, spatulate dilation on foretarsal sensilla e and g long, about half of sensillum length, tracheal camerae short and thickened (see Rusek 1988: fig. 6D; Szeptycki 1984: figs 20, 26, 27)	56
56	Foretarsal sensillum a about half of c length, lateral sensillum on maxillary palpus slightly shorter than dorsal (see Szeptycki 1986a: figs 20, 26)	E. pinetorum
–	Foretarsal sensillum a about equal in length to c, sensilla on maxillary palpus equal in length (see Rusek 1988: fig. 5A, 6D)	E. fichteliense
57	Sternites IX – X with 4 setae	58
–	Sternites IX – X with 6 setae, head with pa setae (see Nosek 1973: fig. 32F’; Szeptycki 1984: p. 200)	E. germanicum
58	Head without additional setae (Szeptycki 1985b: p. 532), length of foretarsus 100–110 μm	E. sudeticum
–	Head with pa setae, length of foretarsus ≤85µm	59
59	Head with both aa and pa setae (see Szeptycki 1999: fig. 1), length of foretarsus 80–85 μm	E. ulinense
–	Head with only pa setae (see Szeptycki 1993: fig. 43), length of foretarsus 70–80 μm	E. solarzi