Euseius alstoniae ( Gupta, 1975 )

Bhowmik, Sagarika & Karmakar, Krishna, 2021, Five new species and re-description of eight species belonging to the family Phytoseiidae (Acari: Mesostigmata) from West Bengal, India, Zootaxa 4975 (3), pp. 401-450 : 402-406

Euseius alstoniae ( Gupta, 1975)

Amblyseius alstoniae Gupta, 1975: 31 .

Amblyseius (Euseius) alstoniae . — Gupta, 1985.

Euseius alstoniae . — Chant & McMurtry, 2005c: 187.

( Figs 1–7 , 82–83 )

Female (n =10).

Dorsum ( Fig. 1 ). Dorsal shield 328 (320–335) long and 230 (225–235) wide, striated laterally and reticulated dorsomedially, with five pairs of solenostomes (gd2, gd4, gd6, gd8 and gd9;) and 19 pairs of dorsal setae including two pairs of sublateral setae: j1 32 (31–33), j3 37 (35–38), j4 16 (15–17), j5 15 (13–16), j6 27 (25–28), J2 27 (26–28), J5 6 (5–7), z2 32 (30–33), z4 41 (40–42), z5 15 (13–17), Z1 22 (21–23), Z4 30 (27–32), Z5 64 (63–65), s4 54 (53–55), S2 27 (25–28), S4 24 (22–25), S5 29 (28–30), r3 17 (17–18), R 1 12 (12–13). All setae smooth and short to medium in length, except j3, z4, s4 and Z5 setae are longer than other dorsal setae and Z5 is the longest.

Peritreme ( Fig. 1 ). Extending up to the level of seta z2.

Venter ( Fig. 2 ). All shields smooth. Sternal shield 65 (61–68) long and 80 (74–84) wide at level of setae ST1– ST3 and ST3–ST3 respectively, with three pairs of setae and two pairs of lyrifissures; one pair of setae (ST4) on the membrane; posterior margin inconspicuous. Distances between ST2–ST2 67 (63–71) and ST5–ST5 79 (77–80). Two pairs of metapodal shields, primary shield 29 (28–30) long and secondary shield 17 (15–18) long. Ventrianal shield 105 (100–110) long, 53 (50–55) wide at level of ZV2 setae and 72 (70–74) wide at level of anus; with three pairs of pre-anal setae, JV1, JV2 and ZV2, and one pair of large elliptical pre-anal pores. Membrane surrounding ventrianal shield with four pairs of setae ZV1, ZV3, JV4 and JV5, the latter 32 (31–33) long smooth.

Chelicera ( Fig. 3 ). Fixed digit 24 (24–25) long, with three teeth and a distinct pilus dentilis; movable digit 24 (24–25) long, without teeth.

Spermatheca ( Fig. 4 ). Calyx elongated, tubular 38 (36–40) long, flared at the base of vesicle. Atrium with distinct major and minor duct.

Legs ( Fig. 5 ). Legs IV with three smooth macrosetae with pointed tips: SgeIV 54 (51–57), StiIV 41 (39–43), StIV 73 (70–75). Chaetotactic formula of genu II: 2 2/0, 2/0 1; genu III: 1 2/1, 2/0 1. Length of leg I: 413 (400–425), leg II: 334 (325–343), leg III: 344 (332–355), leg IV: 465 (455–475).

Male (n =7) A lightly sclerotised mite with 19 pairs of dorsal setae. Idiosomal setal pattern: 10A:9B/ JV –3,4: ZV –1,3.

Dorsum. Dorsal shield 237 (235–238) long and 167 (165–168) wide, with lateral lines and reticulated in the dorsomedian region; with five pairs of solenostomes (gd2, gd4, gd6, gd8 and gd9); 19 pairs of setae on the dorsal shield: j1 22 (22–23), j3 21 (20–22), j4 13 (11–15), j5 11 (9–12), j6 14 (12–16), J2 14 (12–16), J5 4 (4–5), z2 19 (18–20), z4 26 (24–27), z5 9 (8–10), Z1 13 (10–15), Z4 15 (13–17), Z5 36 (33–38), s4 37 (33–40), S2 18 (15–20), S4 15 (13–17), S5 17 (15–19), r3 14 (13–15), R1 10 (9–11). All setae smooth and short to medium in length, j3, z4, s4 and Z5 longer, Z5 longest.

Peritreme. Extending up to the level of seta z2.

Venter ( Fig. 6 ). Sternogenital shield with a few lateral lines, ventrianal shield striated. Sternogenital shield with five pairs of setae and three pairs of distinguishable lyrifissures. Ventrianal shield 110 (108–111) long, 111 (110–112) wide at level of ZV2 setae and 68 (65–69) wide at level of anus; with three pairs of pre-anal setae, JV1, JV2 and ZV2 arranged in a tangential line and one pair of large elliptical pre-anal pores. Membrane surrounding ventrianal shield with one pair of setae JV5; the latter 18 (16–20) long and smooth.

Chelicera ( Fig. 7 ). Spermatodactyl foot-shaped, shaft 14 (14–15) long and foot 4 (4–5) long.

Legs. Legs IV with three smooth macrosetae, pointed distally and of the following lengths: SgeIV 36 (33–38), StiIV 26 (22–30), StIV 49 (48–50). Chaetotactic formula of genu II and genu III are identical to the female. Length of leg I: 316 (313–318), leg II: 258 (255–260), leg III: 263 (255–270) and leg IV: 333 (328–338).

Specimens examined. Two female specimens (Acar.lab/ BCKV /8307/2018) collected from China rose, Hibiscus sp. (Malvaceae) at Jhargram: 22°27’47” N, 87°0’45” E, 81 m above mean sea level, Paschim Medinipur, West Bengal on 30 March 2018. Voucher slides of these two female specimens have been deposited in the National Zoological Collection (NZC), Zoological Survey of India, Kolkata with same collection data as above. Two female specimens (Acar.lab/ BCKV /8308/2018) collected from Paper flower, Bougainvillea glabra (Nyctaginaceae) , two female specimens (Acar.lab/ BCKV /8309/2018) collected from Cashew, Anacardium occidentale (Anacardiaceae) , three female specimens (Acar.lab/ BCKV /8310–8311/2018) collected from Champak, Magnolia champaca (Magnoliaceae) , three female specimens (Acar.lab/ BCKV /8312–8313/2018) collected from Cassia , Cassia tora (Leguminosae) and five female specimens (Acar.lab/ BCKV /8314–8315/2018) collected from Yellow oleander, Cascabela thevetia (Apocynaceae) with same collection data as the above mentioned female specimen. One female specimen (Acar.lab/ BCKV /8316/2018) collected from Chalta, Dillenia indica (Dilleniaceae) and one female specimen (Acar. lab/ BCKV /8317/2018) collected from unknown weed, at Mukutmanipur: 22°57’25.18” N, 86°47’30.84” E, 300 m above mean sea level, Bankura, West Bengal on 3 April 2018. Five male specimens (Acar.lab/ BCKV /8318– 8322/2018) collected from Star fruit, Averrhoa carambola (Oxalidaceae) at Mondouri: 22° 56’ 32”N, 88° 30’ 51”E, 9 m above mean sea level, Nadia, West Bengal on 21 June 2016. Two male specimens (Acar.lab/ BCKV /8316/2018) collected from Chalta, Dillenia indica (Dilleniaceae) and one male specimen (Acar.lab/ BCKV /8317/2018) collected from weed, at Mukutmanipur: 22°57’25.18” N, 86°47’30.84” E, 300 m above mean sea level, Bankura, West Bengal on 3 April 2018. Voucher slides of these three male specimens have been deposited in the National Zoological Collection (NZC), Zoological Survey of India, Kolkata with same collection data as above.

Distribution. Asia: India: Arunachal Pradesh ( Gupta, 1987b); Bihar ( Gupta & Nahar, 1981); Delhi ( Dhooria, 1982); Gujarat ( Gupta, 1977b); Kerala ( Haneef & Sadanandan, 2013); ( Sadanandan, 2011); Madhya Pradesh (Gupta, 1986); Orissa ( Gupta, 1978b); Punjab ( Dhooria, 1990; Gupta, 1977b); Rajasthan ( Gupta, 1977b); Tamil Nadu ( Gupta, 1978a); Uttar Pradesh ( Dhooria, 1983); West Bengal ( Gupta, 1975, 1992).

Remarks. There is no difference in the dorsal setal meseaurement and in the setae of leg IV of our specimens compared with the original description ( Table 1 ). However the dorsal shield is described as smooth in the original description while in the present species it is laterally striated and reticulated dorsomedially.

Ecological Notes. This species is widely distributed throughout the state of West Bengal and it is associated with many agri-horticultural and weed plants. It has been noted to feed on many spider mites and eriophyid mites species and hence can be utilised for biological control of pest mites and small sucking insects.

Figures

FIGURES 1–7. Euseius alstoniae. 1. Female, dorsal idiosoma; 2. Female, ventral idiosoma; 3. Female, chelicera; 4. Female, spermatheca; 5. Female, genu, tibia and basitarsus IV; 6. Male, ventral idiosoma; 7. Male, chelicera.

FIGURES 82–92. 82. Euseius alstoniae, female, leg IV; 83. Euseius alstoniae, female, spermatheca; 84. Paraphytoseius orientalis, female, leg IV; 85. Paraphytoseius orientalis, female, chelicera; 86. Paraphytoseius orientalis, female, spermatheca. 87. Amblyseiulella heveae, female, leg IV; 88. Amblyseiulella heveae, female, chelicera; 89. Gynaeseius ricini, female, leg IV; 90. Gynaeseius ricini, female, chelicera; 91. Gynaeseius ricini, female, spermatheca; 92. Gynaeseius ricini, female, chelicera.

Tables

Table 1. Measurements Euseius alstoniae collected in this study compared with those of the holotype. Abbreviations: Dsl: Dorsal shield length, Dsw: Dorsal shield width, Vs: Ventrianal shield length, Vsw: Ventrianal shield width. Holotype data from Gupta (1986).

	female		male
Characters	India (n = 10)	Holotype	India (n = 8)	Paratype
	(present study)	India (n = 1)	(present study)	India (n = 1)
Dsl	328 (320–335)	–	237 (235–238)	–
Dsw s4	230 (225–235)	–	167 (165–168)	–
j1	32 (31–33)	25–28	22 (22–23)
j3	37 (35–38)	28–33	21 (20–22)
j4	16 (15–17)	8–13	13 (11–15)
j5	15 (13–16)	8–13	11 (9–12)
j6	27 (25–28)	26–31	14 (12–16)
J2	27 (26–28)	26–31	14 (12–16)
J5	6 (5–7)	5–6	4 (4–5)
r3	17 (17–18)	15–18	14 (13–15)	Dorsal chaetotaxy
R1	12 (12–13)	15–18	10 (9–11)	similar to female
s4	54 (53–55)	48–56	37 (33–40)
S2	27 (25–28)	26–31	18 (15–20)
S4	24 (22–25)	18–22	15 (13–17)
S5	29 (28–30)	28–34	17 (15–19)
z2	32 (30–33)	26–28	19 (18–20)
z4	41 (40–42)	31–38	26 (24–27)
z5	15 (13–17)	18–19	9 (8–10)
Z1	22 (21–23)	20–22	13 (10–15)
Z4	30 (27–32)	27–29	15 (13–17)
Z5	64 (63–65)	56–63	36 (33–38)
ST2–ST2	67 (63–71)	–	–	–
ST3–ST3	80 (74–84)	–	–	–
ST1–ST3	65 (61–68)	–	–	–
ST5–ST5	79 (77–80)	–	–	–
Vsl	105 (100–110)	90	110 (108–111)	–
Vsw ZV2	53 (50–55)	–	111 (110–112)	–
Vsw anus	72 (70–74)	78	68 (65–69)	–
JV5	32 (31–33)	44	18 (16–20)	–
SgeIV	54 (51–57)	48–52	36 (33–38)	18–21
StiIV	41 (39–43)	32–36	26 (22–30)	18–34
StIV	73 (70–75)	67–76	49 (48–50)	22–50
Calyx length	38 (36–40)	–	NA	–
Fixed digit length	24 (24–25)	–	–	–
No teeth fixed digit	3	2–3	–	–
Movable digit length	24 (24–25)	–	–	–
No teeth movable digit	0	0	–	–
Spermatodactyl shaft	NA	NA	14 (14–15)	–
Spermatodactyl toe	NA	NA	4 (4–5)	–
Primary metapodal plate length	29 (28–30)	–	NA	–
Secondary metapodal plate length	17 (15–18)	–	NA	–

Table 1. Measurements Euseius alstoniae collected in this study compared with those of the holotype. Abbreviations: Dsl: Dorsal shield length, Dsw: Dorsal shield width, Vs: Ventrianal shield length, Vsw: Ventrianal shield width. Holotype data from Gupta (1986).