(Figs. 1–3)
Material examined. Holotype: Female, USA, Delaware, Walter S. Carpenter Jr. State Park (White Clay Creek), near Newark, mixed deciduous forest near nature trail, understorey of Aruncus and Polygonatum ferns, litter moist to very moist, 15 July 1984, J. Rafalski coll. Paratypes: 3 females and 2 males, same data as holotype. Holotype deposited in the Zoologische Staatssamlung Munich, paratypes in the Department of Animal Morphology, Poznań University.
Description. Female
Dorsum (Fig. 1). Length 440–485 µm, width 355–400 µm, (holotype length 485 µm, width 390 µm). Podonotum with reticulated sculpture. Opisthonotum with a tile-like sculpture in upper corners, remainder of opisthonotum reticulated with large refracting pits surrounded by connecting lines. Opisthonotum in the region of setae Z 1 -Z 3 and I 1 -I 3 with a bright oval field. Posterodorsal cavities large and well sclerotized, oriented transverse to the body axis.
Dorsal setae. Podonotal setae i 1 plumose (Fig. 3 a), i 2 finely barbed, remaining setae of row “i” short and smooth. Podonotal row “z” with two pairs of short smooth setae. Row “s” with six pairs of short smooth setae. Marginal setae r 1 short and smooth, r 2 finely barbed, remaining setae of row “r” long and feathered with hyaline tips. Opisthonotal setae I 1 -I 5 short and finely barbed (Fig. 3 c), I 6 long, pilose, with hyaline tip, 125 µm apart (Fig. 3 e). Z 1 -Z 2 short and smooth, Z 3 similar to I 1 -I 5. Z 4 long and pilose with hyaline tip, almost half of its length projecting beyond margin of opisthonotum. Z 5 short and smooth. Bases of setae I 6 and Z 5 very close together. S 1 short and smooth, S 2 -S 4 similar in shape to I 6. Seta S 2 with almost half of its length projecting beyond margin of opisthonotum. Marginal setae of row R short and smooth (Fig. 3 b). Lengths of opisthonotal setae and longitudinal distances between them as in Table 1.
Pores. Podonotal pores po 1 lie outside the line connecting setae s 1 - i 3; po 2 lie on the line connecting setae s 3 - i 5; pores po 3 lie on the line s 5 -z 2, near s 5. Opisthonotal pores Po 1 lie antero-antaxial to the bases of setae Z 1; Po 2 lie outside the line connecting S 1 and Z 2; Po 3 lie inside the line connecting setae Z 3 -Z 4, separated from seta Z 4 by twice the diameter of Po 3. Pores Po 4 lie on the margin of the opisthonotum, postero-paraxial to the insertion of setae S 4.
Venter (Fig. 2). Chaetotaxy and shape of peritrematal shield typical for genus Zercon. Setae p 1 short and barbed, p 2 long and plumose, with hyaline ending. Adgenital shields present. Ventri-anal shield with 11 pairs of setae and an unpaired postanal setae, two pairs of setae on the anterior margin of the shield.
Epistome as in Fig. 3 f.
. Zercon rafaljanus Female, dorsum.
S 1 (S 2) - 16 Z 1 - 16 I 1 - 16 48 45 42 S 2 (S 3) - 42 Z 2 - 16 I 2 - 16 62 40 40 S 3 (S 4) - 48 Z 3 - 18 I 3 - 18 72 62 42 S 4 (S 5) - 54 Z 4 - 54 I 4 - 18 72 42 Z 5 (JV 5) - 16 I 5 - 20 62 I 6 (Z 5) - 54
Male
Length 340 µm, width 265–270 µm, chaetotaxy, pores and sculpture similar to those of female. Etymology. This species is named in honour of Prof. Dr. Jan Rafalski, the founder of the Polish school of acarology. Notes. The new species belongs to the group of Zercon species that have two pairs of setae on the anterior margin of the ventri-anal shield, and with setae I 6 and Z 5 in close proximity. Zercon rafaljanus is most similar to Z. canadensis Halašková, 1977 and Z. fenestralis Evans, 1955. It differs from these species in the length and morphology of setae I 5, Z 3 and s 3, as shown in Table 2.
CZESŁAW BŁASZAK & IZA ŁANIECKA Department of Animal Morphology, A. Mickiewicz University, Umultowska 89, 61-614 Pozna ú, Poland. E-mail: blaszak@amu.edu.pl