Arctoseius semiscissus (Berlese)

Rueda-Ramírez, Diana, Varela, Amanda & De Moraes, Gilberto J., 2016, Soil mites of the families Ascidae, Blattisociidae and Melicharidae (Acari: Mesostigmata) from mountainous areas of Colombia, Zootaxa 4127 (3), pp. 493-514 : 494-495

Arctoseius semiscissus (Berlese)

Laelaps (Iphis) semiscissus Berlese, 1892: 7 .

Arctoseius bispinatus Weis-Fogh, 1948: 255 (first synonymised by Bernhard, 1963: 151). Arctoseius bicuspidatus Willmann, 1949: 355 (first synonymised by Halliday et al., 1998: 16). Arctoseius (Arctoseiulus) semiscissus .— Willmann, 1949: 357.

Arctoseius limburgensis Nesbitt, 1954: 20 (first synonymised by Halliday et al., 1998: 16).

Arctoseius sellnicki Karg, 1962: 45 (first synonymised by Bernhard, 1963: 151). Laelaps semiscissus .— Hirschmann, 1962: 48.

Morphology (female, eight specimens measured).

Gnathosoma. Fixed cheliceral digit 30 (29–30) long, with four teeth and setiform pilus dentilis; movable digit 31 (30–33), with two teeth; anterior region of epistome with two subequal, pointed, smooth projections.

Dorsal idiosoma. Dorsal shield smooth, entire, with lateral incisions at line of fusion between podonotal and opisthonotal shields; 392 (345–422) long and 203 (177–224) wide, with 31 pairs of setae. Unsclerotised cuticle with ten pairs of setae (s 2, r 2– r 5, R 1– R 5). Setal measurements: j 1 23 (19–25), j 2 33 (30–35), j 3 40 (37–43), j 4 35 (33–36), j 5 31 (27–35), j 6 32 (28–35), J 1 32 (31–32), J 2 32 (30–34), J 3 35 (35–35), J 4 34 (33–36), J 5 12 (11–12), z 1 16 (15–17), z 2 44 (40–49), z 3 44 (40–50), z 4 44 (41–49), z 5 35 (30–37), z 6 35 (31–39), Z 1 39 (34–43), Z 2 42 (38–45), Z 3 46 (42–49), Z 4 53 (50–57), Z 5 57 (54–60), s 1 27 (24–33), s 2 24 (23–25), s 3 48 (42–50), s 4 49 (45–52), s 5 47 (44–52), s 6 46 (42–49), S 1 44 (40–47), S 2 45 (41–49), S 3 44 (40–47), S 5 50 (46–55), r 2 30 (27–32), r 3 37 (31–40), r 4 31 (28–35), r 5 32 (28–35), R 1 30 (26–35), R 2 29 (25–32), R 3 28 (24–30), R 4 27 (22–31), R 5 29 (24– 32); setae aciculate and smooth.

Ventral idiosoma. Base of tritosternum 18 (17–18) long and 13 (12–13) wide proximally; laciniae 58 (54–62), separated for about 90% of their total length, pilose. Presternal plates large, consolidated with sternal shield, lineate and bearing st 1. Sternal shield smooth; 84 (78–95) long and 71 (65–77) wide at the widest level, with two pairs of setae and three pairs of lyrifissures; setae st 1 29 (25–31), st 2 27 (25–30), st 3 24 (22–26), st 4 20 (18–22). Distances st 1 –st 3 79 (75–84), st 2 –st 2 63 (60–65). Genital shield punctate; 96 (85–100) long and 47 (40–55) wide at the widest level; seta st 5 20 (18–21); distance st 5 –st 5 54 (49–59). One pair of ovoid metapodal plates. Anal shield small, ovate, weakly reticulate; 75 (70–78) long and 74 (66–80) wide, bearing only circumanal setae; para-anal setae 21 (20–23), post-anal 39 (36–40); anus 20 (19–21) long. Unsclerotised cuticle around anal shield with eight pairs of setae (Jv 1 –Jv 5, Zv 1, Zv 2 and Zv 5). Endopodal and exopodal plates indistinct. Peritrematic plate narrow, abutting but not fused anteriorly with dorsal shield at level of z1 and extending posteriorly as a narrow strip behind coxa IV. Peritreme extending anteriorly to the median level of coxa II (level of s 3). Setal measurements: Jv 1 22 (20–25), Jv 2 24 (22–26), Jv 3 24 (20–25), Jv 4 22 (20–23), Jv 5 40 (37–43), Zv 1 19 (15–21), Zv 2 22 (18–26), Zv 4 29 (27–32), Zv 5 31 (26–35); setae aciculate and smooth.

Legs. Setation: genua I–IV: 12, 10, 7, 7; tibiae I–IV: 12, 9, 7, 6.

Material examined. Six and two females, respectively, from soil of the fragment of Andean forest ( pH 3.6– 4.4; organic matter 45%; humidity 60–73%; soil temperature 10–11°C), and of the grassland ( pH 5.2; organic matter 57%; humidity 57%; soil temperature 13°C) in August and October, 2010.

Remarks. This species was originally described from Italy. The specimens examined are larger than reported by Kalúz & Fenďa (2005) in a complementary description based on mites collected in Slovakia (340 long and 151 wide). Concurrently, the setae are also longer, especially J 5 (5 µ, in Slovakian specimens). Of the 18 specimens collected, eight were fixed by the gnathosoma to an adult Sciaridae (Diptera) . This, as well as other species of this genus, have been reported phoretically on adult flies of that family and as predators of sciarid eggs and larvae ( Binns 1972, 1974; Dmoch 1995 cited by Rudzińska 1998; Gerson et al. 2003).