Okeseius unisetatus, 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 : 323

Okeseius unisetatus sp. nov.

( Figs 26–30 ; 79–84)

Female (n=3). Diagnosis. The new species is characterised by strongly reticulated dorsum, all setae including J5 and S5 thick and serrated, arising from distinct tubercles, a small depression present on lateral margin of dorsal shield at level r3, distinct notch present at below level of R1, posterior margin of sternal shield concave, ventrianal shield vase-shaped, only one pair of elongated, inwardly curved metapodal shields, fixed digit of chelicerae with seven teeth including pilus dentilis, leg IV with three distinct rod-like macrosetae, all the dorsal setae are rod-like while all the ventral are pointed. All these characters make the species different from all the ten species under this subgroup.

Dorsum ( Figs 26 ; 79–80). Dorsal shield 308 (307–310) long and 175 (174–176) wide, strongly reticulated, with five pairs of pores (gd2, gd5, gd6, gd8 and gd9); 16 pairs of setae on dorsal shield and one pair of setae on unsclerotised cuticle: j1 25 (24–26), j3 21 (20–23), j4 15 (15–17), j5 15 (15–17), j6 26 (25–27), J5 6 (5–7), z2 25 (24–26), z4 25 (24–26), z5 19 (18–20), Z1 32 (31–33), Z4 47 (46–49), Z5 47 (46–48), s4 28 (27–29), S2 36 (35–38), S5 19 (18–21), r3 25 (24–26), R1 26 (25–28). All setae serrated, only seta j3 weakly serrated.

Peritreme ( Figs 26 ; 79–80). Extended beyond the bases of j1.

Venter ( Figs 27 ; 81). All shields are smooth. Sternal shield is longer than width, posterior margin concave. Sternal shield 64 (62–65) long and 62 (61–63) 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 metasternal plate on unsclerotised membrane at the margin of genital flap 16 (15–18) long with a conspicucous poroid on metasternal plate. Distances between st2-st2 44 (42–48), st5-st5 57 (56–60). Genital shield smooth, broad at base and narrow at genital opening with irregular circular flap and almost straight posteriorly. One pair of elongated narrow inwardly curved metapodal shields present 39 (37–40) long. Ventrianal shield smooth, pentagonal 113 (110–115) long, 50 (48–50) wide at level of ZV2 and 58 (56–59) wide at anus level with three pairs of pre-anal setae, JV1 12 (11–14), JV2 8 (7–10), ZV2 9 (8–10) and one pair of pre-anal pores 18 (17–19) apart closely placed on longitudinal line below JV2. Membrane surrounding ventrianal shield with four pairs of setae ZV1 12 (11–13), ZV3 9 (8–10), JV4 11 (10–12) and JV5 32 (31–33); the latter one is long and serrated.

Chelicera ( Figs 28 ; 83). Fixed digit 18 (17–20) long with six teeth and a distinct pilus dentilis, movable digit 16 (15–17) long with single tooth.

Spermatheca ( Figs 29 ; 84). Calyx short 4 (3–5) long with conspicuous atrium, minor duct and major duct visible.

Legs ( Figs 30 ; 82). The genu, tibia and tarsus of leg IV with macrosetae of blunt tips, of following lengths: genu 11 (10–12), tibia 16 (15–17) and tarsus 19 (17–20). All the dorsal setae have blunt tips while the ventral and lateral have pointed tips. Chaetotactic formula of genu II 1 2/1. 1/1 1 and genu III 1 1/1. 2/1 1. Length of leg I 280 (280–284), leg II 250 (246–250), leg III 235 (235–238) and leg IV 342 (341–345).

Type specimens. Holotype: female (Acarol.lab/ BCKV /8389/20) collected from Litchi , ( Litchi chinensis Sonn. ) at Dwaki: 25°13'1"N, 91°58'16"E, 520m AMSL, West Jaintia Hills, Meghalaya on 2 May 2019; and deposited in the NZC, Zoological Survey of India, Kolkata , two paratype females (Acarol.lab/ BCKV /8389–8390/2019) with same collection data as holotype deposited in the Acarological laboratory, Department of Entomology, BCKV, Mohanpur, Nadia, West Bengal, India.

Etymology. The specific name unisetatus refers to the uniform serration pattern of dorsal setae of new species.

Remarks. The new species is close to O. subtropicus Ehara,1967b , O. merenoi Schicha, 1987 ; O. eharai Liang & Ke, 1982 ; O. sikkimensis Gupta, 1986 ; O. yazuliensis Gupta, 1986 and O. himalayana Gupta, 1986 by having similar type of heavily sculptured dorsum, depression at the level r3, and rod-like shape of leg macrosetae. However, the new species differs from these close species by the length of dorsal setae, serration pattern of dorsal setae, denticles of chelicerae, number of metapodal shields, number of rod-like setae in leg IV and shape of spermatheca. In O. subtropicus all dorsal setae serrated except J5, with a distinct notch at level between R1 and S5; fixed digit of chelicerae with three teeth; metapodal shields fused, very long, about 130 long. The new species also differs from O. merenoi by all setae serrated except J5 and S5; setae j6, S5 and R1 shorter than the new species; fixed digit of chelicerae with two teeth; two pairs of metapodal shield while in new species all dorsal setae are serrated, fixed digit with six teeth and with single metapodal shield. In new species j1 longer and s4 shorter, all dorsal setae serrated, fixed digit of chelicerae with six teeth while in O. himalayana j1 shorter and s4 longer, J5 smooth, fixed digit of chelicerae with three teeth. All the differences between the new species and its close species are presented in Table 7.

Figures

FIGURES 26–30. Okiseius unisetatus (female). 26. Dorsal view of idiosoma; 27. Ventral view of idiosoma; 28. Chelicera; 29. Spermatheca; 30. Genu, tibia and basitarsus of leg IV.