Amblyseius largoensis (Muma)

Fang, Xiao-Duan, Nguyen, Van-Liem, Ouyang, Ge-Cheng & Wu, Wei-Nan, 2020, Survey of phytoseiid mites (Acari: Mesostigmata, Phytoseiidae) in citrus orchards and a key for Amblyseiinae in Vietnam, Acarologia 60 (2), pp. 254-267 : 257-261

Amblyseius largoensis (Muma)

( Figs. 2 a – e , 3 a – c )

Amblyseiopsis largoensis Muma 1955: 266 ; Garman 1958: 76.

Typhlodromus (Amblyseius) largoensis, Chant 1959: 96 .

Amblyseius largoensis, Ehara 1959: 293 ; De Leon 1966: 90, 1967: 23; Muma & Denmark 1970: 69; Wu 1980: 41; Schicha 1981: 105; McMurtry & Moraes 1984: 29; Chen et al. 1984: 332; Moraes et al. 1986: 17, 2000: 239, 2004a: 143, 2004b: 33; Denmark & Muma 1989: 55; Wu & Lan 1989: 449; Wu et al. 1997: 39; Gondim Jr & Moraes 2001: 72; Chant & McMurtry 2004: 208, 2007: 78; Zannou et al. 2007: 16; Ferragut et al. 2011: 40; Oliveira et al. 2012: 4; Nguyen & Dao 2019.

Amblyseius (Amblyseialus) largoensis, Muma 1961: 287 .

Amblyseius magnoliae, Denmark & Evans 2011: 69 .

Typhlodromus largoensis, Hirschmann 1962 .

Amblyseius (Amblyseius) largoensis, Ehara 1966 ; Ehara & Bhandhufalck 1977: 67; Denmark & Evans 2011: 69.

Amblyseius amtalaensis, Gupta 1977: 53 ; 1986: 51.

Amblyseius neolargoensis, Van der Merwe 1965:59 ; Chant et al. 1978: 1347.

Amblyseius sakalava, Blommers 1976: 96 ; Ueckermann & Loot 1988: 70.

Description — Female (n = 25)

Dorsum — Idiosomal setal pattern: 10A: 9B/JV-3: ZV. Dorsal shield ( Fig. 2a ) mostly smooth except anteriorly striated. Dorsal shield 355 (341–376) long and 224 (212–253) wide, distances between setae j1- J5 338 (326–364) and s4-s4 194 (181–213), shield nearly oval, slightly constricted at level of R1. Setae r3 and R1 on soft membranous cuticle laterad dorsal shield, r3 at level of between z4 and s4, R1 at level of shield incisions. All setae smooth. With six pairs of solenostomes (gd1, gd4, gd5, gd6, gd8, gd9) on dorsal shield. Length of setae: j1 36 (30–40), j3 51 (41–59), j4 6 (4–8), j5 5 (3–6), j6 7 (4–10), J2 9 (6–12), J5 9 (6–12), z2 11 (8–14), z4 9 (7–13), z5 6 (4–8), Z1 10 (6–14), Z4 98 (89–105), Z5 277 (243–296), s4 95 (86–103), S2 13 (9–16), S4 12 (9–16), S5 11 (8–15), r3 12 (10–16), R1 10 (7–14).

Venter — ( Fig. 2b ). Ventral setae smooth. Sternal shield with sparse striation, anterior margin convex, posterior margin straight, 80 (72–90) long, 77 (68–82) wide, with three pairs of setae st1 34 (29–39), st2 31 (27–34), st3 30 (26–33), and two pairs of lyrifissures (pst1-pst2), distance between st1-st3 63 (57–67) and st2-st2 68 (60–73). Metasternal platelets drop-shaped, each with one metasternal seta, st4 29 (26–34) and one lyrifissure (pst3). Genital shield smooth, with one pair of thin genital setae st5 27 (23–33), distance between st5-st5 74 (68–81); one pair of associated poroids on soft cuticle near posterior corners of shield. Ventrianal shield vase-shaped, 109 (99–117) long, 48 (45–53) wide at level of ZV2, 72 (64–84) wide at level of anus, with three pairs of thin pre-anal setae JV1 20 (15–23), JV2 17 (15–20), ZV2 15 (12–18); Pa 18 (15–21), Pst 18 (14–21) long. Pre-anal pores crescentic, posteromediad to JV2, distance between pores 26 (23–28). Opisthogastric soft cuticle with four pairs of setae, ZV1 17 (14–21), ZV3 10 (8–13), JV4 10 (6–13), JV5 64 (53–74) long. All ventral setae thin, except JV5, thicker. Two pairs of metapodal platelets, primary platelets 23(18–27) long, 4 (3–6) wide, secondary ones 13 (9–16) long, 2 (1–4) wide.

Peritremes — Peritremes extending anteriorly between j1.

Chelicerae — ( Fig. 2c ). Fixed digit 32 (29–35) long, with nine teeth and pilus dentilis, movable digit 29 (26–31) long, with three teeth.

Spermatheca — ( Fig. 2d ). Calyx of spermatheca tubular, 21 (18–24) long, 4 (2–5) wide at the opening; atrium 4 (2–5) long, 4 (3–5) wide, massive atrium as wide as cervix, connected with calyx; major duct broad, short, directly attached to atrium, and minor duct visible.

et

Legs — Genua formula for leg I 0 – 1/2, 2/2– 2, leg II 0 – 1/2, 1/1 – 2, leg III 2 – 2/1, 1/1 – 0, leg IV 2 – 2/1, 0/1 – 1. Genua I-III each with one macroseta, Sge I 41 (37–45), Sge II 38 (32–41), Sge III 50 (42–55). Leg III with one macroseta on tibia, Sti III 41 (35–45). Leg IV ( Fig. 2e ) with three long-whipped macrosetae on genu, tibia and basitarsus, Sge IV 128 (111–138), Sti IV 101 (91–113) and St IV 65 (56–73).

Male — (n=7)

Dorsum — ( Fig. 3a ). Idiosomal setal pattern: 10A: 9B/JV-3: ZV. Dorsal shield mostly smooth except anteriorly striated, same as on female, 271 (264–291) long and 184 (173–201) wide at level of setae s4, shield nearly oval, nineteen pairs of dorsal setae, all smooth. Same adenotaxy and poroidotaxy as in females. Length of setae: j1 29 (24–31), j3 47 (42–50), j4 6 (4–7), j5 5 (4–6), j6 6 (5–8), J2 8 (7–9), J5 7 (5–8), z2 9 (7–11), z4 9 (7–10), z5 5 (4–7), Z1 9 (6–10), Z4 73 (65–81), Z5 215 (194–236), s4 79 (75–82), S2 11 (8–13), S4 10 (9–11), S5 10 (9–11), r3 11 (9–13), R1 8 (7–10).

Venter — ( Fig. 3b ). Ventral setae smooth. Sternogenital shield smooth, 131 (125–143) long, wider 81 (77–87) between coxae II–III than at posterior corners 41 (38–44). Five pairs of sterogenital setae (st1–st5), st1 27 (24–30), st2 23 (21–24), st3 22 (20–26), st4 21 (19–24), st5 22 (19–24), and three pairs of lyrifissures (pst1-pst3). Chaetotaxy of genua similar to female. Ventrianal shield subtriangular, 111 (106–116) long, 155 (147–161) wide at level anterior corners; transversally striated; striation on anterior part of the shield more obvious, with three pairs of thin pre-anal setae JV1 17 (14–20), JV2 15 (13–17), ZV2 13 (11–17); Pa 14 (11–17), Pst 17 (15–18) long. Preanal pores crescentic, posteromedian to JV2, distance between pores 19 (18–21). Opisthogastric soft cuticle with one pairs of setae, JV5 37 (33–40) long.

Peritremes — Peritremes extending to between j1. Peritrematal shield fused with dorsal shield.

Chelicerae and spermatodactyl — ( Fig. 3c ). Cheliceral dentition not discernible in the examined specimens. Fixed digit 22 (20–23) long, movable digit 20 (18–22) long. Spermatodactyl L-shaped; shaft 16 (15–18), foot 8 (7–10) long.

Legs — Chaetotaxy of genua similar to female. Macrosetae on genu I 31 (29–35), genu II 31 (30–33), genu III 37 (35–40), tibia III 35 (32–38), genu IV 81 (78–85), tibia IV 69 (65–72), tarsus IV 56 (52–59).

Specimens examined – 9 ♀♀, Chau Thanh district, Ben Tre Province (accession no. BT-0121, BT-0130, BT-0140, BT-0180, BT-0250, BT-0260, BT-0270, BT-0281, BT-0282), on Citrus reticulata × sinensis, 10 IV 2018, Fang X.D. coll. ; 2 ♂♂ (accession no. BT-0122, BT-0160) same locality, host, date and collector ; 16 ♀♀, Phong Dien district , Can Tho Province (accession no. CT-0301, CT-0302, CT-0321, CT-0322, CT-0341, CT-0342, CT-0350, CT-0360, CT-0371, CT-0372, CT-0401, CT-0402, CT-0430, CT-0441, CT-0450, CT-0481), and 2 ♂♂ (accession no. CT-0442, CT-0482), 12 IV 2018, same host and collector ; 4 ♀♀, Cao Lanh district , Dong Thap Province (accession no. DT-0490, DT-0500, DT-0521, DT-0540) and 3 ♂♂ (accession no. DT-0522, DT-0532, DT-0550), 13 IV 2018, same host and collector.

Previous Records — Nearctic, Neotropical, Oriental, Australasian, Ethiopian, West Palaearctic and East Palaearctic, almost including all biogeographic realms except Antarctica ( Hernandes et al. 2011).

Remarks — This species is very similar to A. herbicolus ( Chant, 1959) and A. eharai Amitai and Swirski, 1981 , but having differences in sternal shield with weak sclerotization and posterior margin straight, and calyx of spermatheca tubular. This species prefers high humidity environment, and it is the dominant species of brushes in Hainan islands in China. This species is important natural enemies of agriculture and forestry pest mites ( Wu et al. 2009). In this survey, A. largoensis was found the dominant native species in surveyed citrus orchards in Vietnam.

Figures

Figure 2 Female of Amblyseius largoensis. a – Dorsal shield; b – Ventral idiosoma; c – Chelicera; d – Spermatheca; e – Leg IV, genu-basitarsus.

Figure 3 Male of Amblyseius largoensis. a – Dorsal idiosoma; b – Ventral idiosoma; c – Spermatodactyl.