Euseius dwakiensis, Kar & Karmakar, 2021

Kar, Anamika & Karmakar, Krishna, 2021, Description of eleven new species of phytoseiid mites (Acari: Mesostigmata) from Meghalaya state, north eastern India, Zootaxa 5068 (3), pp. 301-354 : 316-318

Euseius dwakiensis sp. nov.

( Figs 16–20 ; 70–74)

Female (n=6). Diagnosis. The new species is characterised by dorsum strongly reticulated, seta R1 on the dorsal shield, waist region irregular, ventrianal shield vase-shaped, fixed digit of chelicerae with five anterior teeth, with pilus dentilis, spermatheca with a cap-like structure on calyx, narrow at the base of vesicle, leg IV with three macrosetae with rounded tips.

Dorsum ( Figs 16 ; 70). Dorsal shield 328 (326–330) long and 230 (229–232) wide, strongly reticulated, with sigillum mostly on prodorsal area, prodorsum wide, irregular lateral margin at waist region with five pairs of pores (gd2, gd5, gd6, gd8 and gd9); 18 pairs of setae on dorsal shield and one pair of setae on unsclerotised cuticle: j1 33 (30–33), j3 24 (23–25), j4 10 (10–11), j5 10 (10–12), j6 13 (12–14), J2 14 (13–15), J5 4 (3–5), z2 19 (18–20), z4 21 (20–23), z5 14 (13–15), Z1 14 (13–15), Z4 19 (18–20), Z5 60 (60–63), s4 28 (25–29), S2 20 (19–20), S4 23 (23–25), S5 29 (28–31), r3 14 (13–15), R1 14 (13–15). All setae smooth, setae j1, j3 and s4 long, seta Z5 longest, all other setae medium to small.

Peritreme ( Fig. 16 ; 70). Extending to the level near about the base j3.

Venter ( Figs 17 ; 71). The sternal shield rectangular, posterior margin of sternal shield with a distinct loop. Sternal shield 62 (60–63) long and 77 (74–78) wide at the level of setae st1-st3 and st3-st3 respectively, with three pairs of setae and two pairs of poroids; one pair of setae (st4) on unsclerotised membrane 16 (15–18) long with conspicuous poroids on distinct metasternal plate. Distances between st2-st2 60 (58–60), st5-st5 71 (70–73). Two pairs of metapodal shields present. Primary inguinal sigilla 23 (23–25) long and 4 (3–5) wide, secondary ones 6 (5–8). Genital shield smooth, broad at base and narrow at genital opening with irregular circular flap touching sternal loop anteriorly. Ventrianal shield vase-shaped, smooth, 90 (89–92) long, 40 (40–43) wide at level of ZV2 and 65 (65–67) wide at anus level with three pairs of pre-anal setae, JV1 18 (17–20), JV2 22 (20–23), ZV2 18 (18–20) and one pair of large elliptical pre-anal pores gv3 28 (27–30) apart below JV2. Membrane surrounding ventrianal shield with four pairs of setae ZV1 18 (17–20), ZV3 9 (8–10), JV4 9 (8–10) and JV5 31 (30–33); seta JV5 long and smooth.

Chelicera ( Figs 18 ; 74). Fixed digit 25 (23–25) long with five anterior teeth and distinct pilus dentilis, movable digit 22 (20–23) long with a single tooth.

Spermatheca ( Figs. 19 ; 72). Calyx elongated 22 (19–23) long with cap like structure. Distal part of calyx narrow towards the vesicle with divergent arms. Atrium incorporated at the base of calyx, major and minor duct distinctly visible.

Legs ( Figs 20 ; 73). The macrosetae on genu, tibia and tarsus of leg IV with bulbous tips, of following lengths: genu 48 (46–49), tibia 35 (33–36) and tarsus 68 (65–69). Chaetotactic formula of genu II 1 2/1. 1/1 1 and genu III 1 1/1. 2/1 1. Length of leg I 375 (373–376), leg II 255 (253–256), leg III 278 (276–280) and leg IV 354 (351–355).

Type specimens. Holotype: female (Acarol.lab/ BCKV/8381 /20) collected from Carambola, ( Averrhoa carambola L.), at Dwaki: 25°131"N, 91°58'16"E, 520m AMSL, West Jaintia Hills , Meghalaya on 2 nd May , 2019; deposited in the NZC, Zoological Survey of India, Kolkata. Five paratype females (Acarol.lab/ BCKV/8382-8383 /2019) with same collection data as holotype deposited in the Acarological laboratory, Department of Entomology , BCKV, Mohanpur, Nadia, West Bengal, India.

Etymology. The specific name dwakiensis refers to the type locality “Dwaki” from where this new species was collected.

Remarks. The new species, Euseius dwakiensis is different from all the members of Euseius by having its spermatheca with cap or flap-like structure at atrium. However, the species is close to E. coccosocius Ghai & Menon, 1967 ; E. elinae Schicha, 1977a ; E. victoriensis Schicha, 1977 ; by the similar pattern of dorsum and ventral plates.

The new species differs from these close species by the position of dorsal seta R1, number of teeth in fixed and movable digit of chelicerae, leg macrosetae and spermatheca. All the differences between new species and close species are presented in Table 5 .

Figures

FIGURES 16–20. Euseius dwakiensis (female). 16. Dorsal view of idiosoma; 17. Ventral view of idiosoma; 18. Chelicera; 19. Spermatheca; 20. Genu, tibia and basitarsus of leg IV.