Euseius fascae, 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 : 313-316

Euseius fascae sp. nov.

( Figs 11–15 ; 66–69 )

Female (n=13). Diagnosis. The species is distinguished by having the dorsum strongly reticulated, lateral margin at waist region irregular, peritreme extends near about the bases of j3, dorsum with five pairs of pores, all ventral shields smooth, fixed digit of chelicerae with three distinct anterior teeth and a pilus dentilis, spermatheca tubular, annulated at the distal part of calyx, leg IV with three pointed macrosetae.

Dorsum ( Figs 11 ; 66 ). Dorsal shield 298 (296–299) long and 198 (195–200) 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); 17 pairs of setae on dorsal shield and two pairs of setae on unsclerotised cuticle: j1 28 (28–30), j3 28 (28–29), j4 15 (13–15), j5 15 (13–15), j6 15 (13–15), J2 15 (13–15), J5 5 (5–7), z2 22 (20–23), z4 22 (20–23), z5 15 (13–15), Z1 15 (13–15), Z4 20 (18–20), Z5 58 (57–60), s4 30 (28–30), S2 23 (20–23), S4 23 (20–23), S5 30 (28–30), r3 16 (16–18), R1 13 (13–15). All setae smooth, seta Z5 slightly serrated, setae j1, j3 and s4 long, seta Z5 longest, all other setae medium to small.

Peritreme ( Figs 11 ; 66 ). Extending near about the bases of j3.

Venter ( Figs 12 ; 69 ). Sternal shield rectangular, posterior margin forms a distinct loop. Sternal shield ornamented with lateral stripes, 53 (53–55) long and 72 (70–74) wide at 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 18 (18–20) long and conspicuous poroids on distinct metasternal plate. Distances between st2-st2 61 (60–63), st5-st5 70 (70–73). Two pairs of metapodal shields present. Primary inguinal sigilla 18 (17–20) long and 3 (3–4) wide, secondary ones 4 (3–5). Genital shield smooth, broad at base and narrow at genital opening with irregular circular flap touching sternal loop anteriorly. Ventrianal shield smooth, slightly sclerotised at anterior part 88 (85–88) long, 46 (44–47) wide at level of ZV2 and 66 (65–68) wide at anus level with three pairs of pre-anal setae, JV1 17 (16–18), JV2 18 (17–20), ZV2 18 (18–20) and one pair of large elliptical pre-anal pores gv3 26 (25–28) apart below JV2. Membrane surrounding ventrianal shield with four pairs of setae ZV1 16 (15–18), ZV3 8 (8–10), JV4 10 (10–12) and JV5 30 (30–33); seta JV5 long and smooth.

Chelicera ( Fig. 13 ). Fixed digit 24 (23–25) long with three anterior teeth and distinct pilus dentilis, movable digit 20 (20–21) long with two teeth.

Spermatheca ( Figs 14 ; 68 ). Calyx tubular, elongated 16 (15–18) long, annulated distally, narrow at middle and gradually widening thereafter towards conspicuous atrium, minor duct and major duct visible.

Leg ( Figs 15 ; 67 ). The genu, tibia and tarsus of leg IV with pointed macrosetae of following lengths: genu 30 (30–32), tibia 30 (28–30) and tarsus 50 (48–50). Chaetotactic formula of genu II 1 2/1. 1/1 1 and genu III 1 2/1. 1/1 1. Length of leg I 310 (310–314), leg II 275 (273–276), leg III 250 (248–250) and leg IV 329 (325–330).

Type specimens. Holotype: female (Acarol.lab/ BCKV/8376 /20) collected from needlewood tree ( Schima wallichii Dc. Korth ), at Barapani: 25°40'52"N, 91°54'41"E, 973m, AMSL, Ri-Bhoi , Meghalaya on 3 rd May , 2019; deposited in the NZC, Zoological Survey of India, Kolkata. 12 paratype females (Acarol.lab/ BCKV/8377–8380 /2019) with same collection data as holotype and deposited in the Acarological laboratory, Department of Entomology , BCKV, Mohanpur, Nadia, West Bengal, India.

Etymology. The specific name fascae refers to the unique annuli present at the basal part of calyx of the new species.

Remarks. The new species Euseius fascae is different from all the species in the genus Euseius by having unique type of spermatheca, calyx annulated basally and flared at atrium. It is close to E. insanus ( Khan & Chaudhri, 1969) ; E. bandispermathecae Pramanik & Karmakar, 2016 and E. astrictus Karmakar & Bhowmik, 2018 by having same pattern of ventral plates and annulation or constriction in calyx. However, this new species differs from the close species by dorsal setae, lateral margin of waist region, position of R1, denticles in chelicerae, macrosetae on leg IV, tip of macrosetae and shape or annulation pattern of spermatheca. All the differences between the new species and close species are presented in Table 4 .

Figures

FIGURES 11–15. Euseius fascae (female). 11. Dorsal view of idiosoma; 12. Ventral view of idiosoma; 13. Chelicera; 14. Spermatheca; 15. Genu, tibia and basitarsus of leg IV.

FIGURES 66–69. Euseius fascae (female). 66. Dorsal view of idiosoma; 67. Genu, tibia and basitarsus of leg IV; 68. Spermatheca; 69. Ventrianal shield; 70–74. Euseius dwakiensis (female). 70. Dorsal view of idiosoma; 71. Ventrianal shield; 72. Spermatheca; 73. Genu, tibia and basitarsus of leg IV; 74. Chelicera.