Chileseius australis Ferragut n. sp. (Figures 1–10) Diagnosis. Female dorsal shield strongly sclerotised and reticulated. Dorsal setal pattern 11B:10B with presence of seta J4 and absence of Z3. Nineteen pairs of thick dorsal setae. Setae S2 (sometimes), S4, S5, J4, J5, Z4 and Z5 (always) serrated and set on tubercles; the remaining smooth. Seven pairs of dorsal solenostomes. Peritremes extend forward to bases of j1. Sternal shield with three pairs of setae; posterior margin straight. Ventrianal shield pentagonal, with three pairs of setae and pre-anal pores punctiform and widely separated. Calyx of spermatheca shallow bowl-shaped. Cheliceral fixed digit with seven teeth, movable bidentate. Genu II with seven setae. Three macrosetae on leg IV, being msge and msti similar in length and msta longer. Male ventrianal shield with six pairs of pre-anal setae and pre-anal pores. Spermatodactyl L-shaped with a lateral projection. FEMALE (Figures 1–5) (nine females measured). Dorsal surface. Dorsal shield 435 (400–435) long, 242 (220–249) wide, well sclerotised and delicately reticulated throughout. Nineteen pairs of thick and acute setae, being S2 (occasionally), S4, S5, J4, J5, Z4 and Z5 serrated. Setae r3 and R1 on lateral integument. Setae on the opisthoscutum inserted on tubercles. Seta j1 26 (25– 29), j3 22 (22–25), j4 15 (15–19), j5 16 (16–18), j6 18 (18–21), J2 26 (26–32), J4 30 (24–32), J5 16 (16–23), z2 25 (23–27), z4 24 (19–26), z5 18 (18–28), z6 21 (21–25), Z1 29 (27–36), Z4 49 (44–52), Z5 66 (60–70), s4 27 (27–31), S2 40 (37–44), S4 40 (37–47), S5 43 (35–47), r3 27 (25–29), R1 27 (25–28). Seven pairs of solenostomes (gd1, gd2, gd4, gd5, gd6, gd8, gd9); gd1 anterolaterad to j3, gd5 posteromediad to z5, gd9 anteromediad to S5, closer to S5 than to Z5. Poroids is1 and idl2 prominent and located on the margin of dorsal shield. Peritremes fully developed, reaching setae j1. Ventral surface. Sternal shield quadrate, with three pairs of setae. Distance st1–st3 72 (69–72), distance st2–st2 70 (69–73). Seta st4 on metasternal platelets. Posterior margin of shield straight. Genital shield 95 (83–97) wide. Ventrianal shield pentagonal, with anterior angles right, 148 (129–148) long, 119 (110–121) wide at level of ZV2, 119 (109–119) wide at level of preanus (immediately anterior to anus). Surface striated and with two lateral areas of muscle attachments on the posterior margin, at the level of anus. Three pairs of pre-anal setae; pre-anal (gv3) pores punctiform and widely separated 59 (39–59). Distance between pores gv3 broader than distance between setae JV2. Platelets spga elongated and located on the anterior angles of the shield. Four pairs of setae around the shield, JV5 47 (37–47). A pair of large pores associated with JV5. Chelicerae. Fixed digit with seven teeth; movable digit with two teeth. Insemination apparatus. Calyx shallow bowl-shaped. Major duct broad, decreasing in thickness toward the atrium. Legs. Genu II with seven setae; chaetotactic formula 2–2/0, 2/0–1. Macrosetae on leg IV short, thick and blunt to knobbed. Macrosetae on genu 25 (22–26), tibia 26 (25–27) and basitarsus IV 40 (34–40). MALE (Figures 6–8) (four males measured). Dorsal surface. Dorsal shield 326 (323–330) long, 219 (210–227) wide, weakly reticulated. Twenty-one pairs of thick and blunt setae, S4, S5, J4, Z4 and Z5 serrated. Setae on the opisthoscutum inserted on tubercles. Seta j1 23 (22–24), j3 20 (20–21), j4 14 (13–15), j5 14 (12–15), j6 16 (16–17), J2 21 (20–22), J4 20 (19–22), J5 15 (14–16), z2 19 (17–21), z4 20 (19–20), z5 15 (14–15), z6 15 (14–17), Z1 22 (20–24), Z4 35 (34–37), Z5 46 (45–47), s4 23 (21–25), S2 29 (27–32), S4 30 (29–30), S5 29 (27–30), r3 21 (20–22), R1 20 (18–22). Seven pairs of solenostomes. Peritremes extend to bases of setae j1 or between j1 and j3. Ventral surface. Ventrianal shield striated, 137 (135–138) long, 188 (185–194) wide, with six pairs of pre-anal setae; pre-anal pores punctiform and widely separated. Chelicerae. Fixed digit with three teeth; movable digit unidentate. Spermatodactyl L-shaped with a lateral projection. Legs. One macroseta on basitarsus IV 31 (30–31). Macrosetae on genu and tibia IV undifferentiated. DEUTONYMPH (Figures 9–10) (five deutonymphs measured). Dorsal shield weakly sclerotised, with lateral incisions at level of R1. 346 (332–357) long, 162 (154–168) wide at level of setae z4. Nineteen pairs of setae as in female, S2, S4, S5, Z4, Z5, J4 and J5 serrated. Seta j1 24 (22–24), j3 23 (22–23), j4 14 (13–15), j5 14 (13–15), j6 18 (16–19), J2 23 (20–24), J4 27 (25–28), J5 18 (16–18), z2 19 (17– 20), z4 19 (19–20), z5 12 (11–12), z6 18 (17–20), Z1 22 (20–24), Z4 42 (39–44), Z5 44 (42–47), s4 25 (24–25), S2 31 (29–32), S4 32 (30–35), S5 42 (39–44), r3 22 (20–22), R1 21 (20–22), JV5 24 (22–25). Seven pairs of dorsal solenostomes, distance between ventral solenostomes gv3 34 (31–36). Lateral cuticle with two setae, r3 and R1. Peritreme shorter than in females, reaching seta z2. Two distinct macrosetae on genu IV 28 (27–29) and tarsus IV 32 (30–35); macroseta on tibia IV not differentiated. Type material. One female holotype, eight female paratypes, four male paratypes and five deutonymph paratypes on Tepualia stipularis (Hooker et Arnott) Griseb. (Mirtaceae). Near Ushuaia (Argentina); 54º 50'51" S, 68º 29'19" W; 18 m asl. 10 January 2013. Holotype and some paratypes were deposited at Museo Nacional de Ciencias Naturales, Madrid, Spain (MNCN). Reference number of holotype: MNCN 20.02/17377; 1 paratype female MNCN 20.02/17378. Etymology. The specific name australis means "southern" or "austral" and refers to the occurrence of the species in the southernmost part of the Earth with arboreal vegetation. Comments. Chileseius belongs to the tribe Neoseiulini and is the unique genus in the family Phytoseiidae containing three species with three different idiosomal setal patterns: Ch. camposi 11B:11A/JV–3:ZV with 36 pairs of setae, Ch. australis sp. nov. 11B:10C/JV3:ZV, with 35 pairs of setae and Ch. paracamposi 11B:9B/JV3:ZV, with 34 pairs of setae. Table 1 summarizes the main morphological features to distinguish species within the genus Chileseius. The new species appears to be most closely related to Ch. camposi on the basis of sharing the presence of J4, a similar spermathecal apparatus, ratio Z4 / Z5 and wide distance between pores gv3.

Published as part of Ferragut, Francisco & Navia, Denise, 2015, Phytoseiid mites (Acari: Phytoseiidae) from Patagonia and Tierra del Fuego, pp. 525-550 in Zootaxa 3990 (4) on pages 527-530, DOI: 10.11646/zootaxa.3990.4.3, http://zenodo.org/record/240688