Zercon C. L. Koch, 1836

Urhan, Raşit & Karaca, Mehmet, 2023, Contributions to the Zerconidae (Acari: Mesostigmata) fauna of Dilek Peninsula-Büyük Menderes Delta National Park, Türkiye, Acarological Studies 5 (1), pp. 21-33 : 21-30

Genus Zercon C. L. Koch, 1836

Type species: Zercon triangularis C. L. Koch, 1836

Peritremal shields terminate in blunt end at the posterior part of coxae IV, with 2 types of setae: r1 short and smooth, r3 long and feathered or spiny. There is a distinctive gap between the peritremal shield and the edge of the podonotum with weak sclerotization. Adgenital shields present, with 2–5 opening valves. Opisthonotum with 7 or 8 pairs of marginal setae (S1 + R1 – R6 or S1 + R1 – R7 ). Anterior margin of the ventrianal shield with 1 pair (seta JV1 present, seta ZV1 absent) or 2 pairs (setae JV1 and ZV1 present) of setae (Urhan et al. 2020) .

Table 1. Average lengths of opisthonotal setae and the distances between their bases in J, Z, and S rows of Zercon andrei (deutonymphs).

Key to Zercon species in the Dilek Peninsula-Büyük Menderes Delta National Park

1 Anterior margin of ventrianal shield with 2 setae (setae JV1 present, setae ZV1 absent) ........................................ 2

1′ Anterior margin of ventrianal shield with 4 setae (setae JV1 and ZV1 present) ...................................................... 5

2 Opisthonotal seta S4 reaching to margin or beyond of opisthonotum ................................................................ 3

2′ Opisthonotal seta S4 not reaching to margin of opisthonotum ...................................... Z. colligans Berlese, 1920

3 All marginal setae on opisthonotum (S1 and R setae) finely barbed with hyaline endings ................................... 4

3′ All marginal setae on opisthonotum (S1 and R setae) short, smooth and needle-like ..... Z. huseyini Urhan, 2008

4 Opisthonotal setae J5, Z4 and S4 not reaching to margin of opisthonotum .... Z. plumatopilus Athias-Henriot, 1961

4′ Opisthonotal setae J5, Z4 and S4 reaching to margin or beyond of opisthonotum ............ Z. cretensis UJvári, 2008

5 Opisthonotal seta J2 short, smooth and needle-like ...... 6

5′ Opisthonotal seta J2 finely barbed with hyaline ending .................................................... Z. kallimci Urhan, 2010

6 Opisthonotal seta S4 reaching to beyond of opisthonotum................................................................................. 7

6′ Opisthonotal seta S4 not reaching to margin of opisthonotum .............................................. Z. dilekensis sp. nov.

7 Opisthonotal seta S3 with hyaline ending .................... 8

7′ Opisthonotal seta S3 without hyaline ending ................ .............................................. Z. denizliensis Urhan, 2011

8 Opisthonotal setae J3–5 not reaching the bases of the following setae ................................ Z. andrei Sellnick, 1958

8′ Opisthonotal setae J3–5 reaching the bases of the following setae ........... Z. turcicus Urhan and Ayyıldız, 1994

Altitude preferences of Zercon species in the study area

All materials for the Zercon species were collected from suitable forestland areas at the altitude from 0 to 1000 m a.s.l. All sampling areas were divided according to 50 meters elevation ranges. After identification processes in the laboratory, the altitudinal distribution results of the Zercon species were marked in Table 5 .

According to Table 5 , Z. plumatopilus and Z. turcicus occur only at middle altitudes (350–550 m a.s.l.), Z. dilekensis sp. nov. and Z. huseyini occur only at higher altitudes (850– 950 m a.s.l.). On the other hand, since Z. colligans (0–950 m a.s.l.) and Z. kallimcii (150–900 m a.s.l.) showed a wide range of occurrences. The remaining species have no clear preference in terms of altitudinal ranges.

Habitat preferences of Zercon species in the study area

Samplings for Zercon species were carried out in 97 different localities and the following 22 habitat types, mostly tree species, were noted: carob tree ( Ceratonia siliqua ), common hawthorn ( Crataegus monogyna ), juniper ( Juniperus sp. ), mastic tree ( Pistacia lentiscus ), moss (unspecified), oaks ( Quercus spp. ), oleaster-leafed pear ( Pyrus elaeagrifolia ), olive ( Olea europaea ), pines ( Pinus spp. ), holy bramble ( Rubus sanctus ), sage-leaved rock-rose ( Cistus salviifolius ), shrub ( Daphne gnidioides ), strawberry trees ( Arbutus spp. ), sycamore ( Platanus orientalis ), thorn ( Paliurus spina-christi ) and thorny burnet ( Sarcopoterium spinosum ). Habitat preferences of Zercon species were marked in Table 6 .

Table 8 show that Z. colligans and Z. kallimcii were found in samples from 18 and 11 different habitat types, respectively. On the other hand, Z. huseyini was found only in the habitat of Greek strawberry tree ( Arbutus andrachne ), Z. dilekensis sp. nov. was found only in the habitats of oleaster-leafed pear ( Pyrus elaeagrifolia ) and Turkish oak ( Quercus cerris ), Z. turcicus was found only in the habitats of thorn ( Paliurus spina-christi ) and holly oak ( Quercus ilex ). The most species-rich habitats are: Sage-leaved rock-rose (6 spp.), black pine (5 spp.) and holly oak (5 spp.). In contrast to these rich habitats, specimens of single Zercon species were found in the following habitats: Strawberry tree, carob tree, common hawthorn, shrub, juniper, mastic tree, sycamore, and holm oak.