Euseius spontaneum, Kar & Karmakar, 2022

Kar, Anamika & Karmakar, Krishna, 2022, Seven new species of phytoseiid mites (Acari: Mesostigmata) from Tripura, northeastern India, Zootaxa 5120 (2), pp. 213-241 : 217-220

Euseius spontaneum sp. nov.

( Figs 6–10 , 41–44 )

Diagnosis. The new species is characterised by having the dorsum strongly reticulated; lateral margin at waist region irregular; R1 on the dorsal shield; peritreme extends extends up to base of j3; all ventral shields smooth, fixed digit of chelicerae with six distinct teeth and a pilus dentilis; spermatheca unique tubular, constricted at base of vesicle; leg IV with three macrosetae with blunt tips.

Description

Female (n=8). Dorsum ( Fig. 6 ). Dorsal shield 298 (296–299) long and 198 (195–197) wide, strongly reticulated, with sigilla mostly on prodorsal area, prodorsum wide, irregular lateral margin at waist region with five pairs of solenostomes (gd2, gd5, gd6, gd8 and gd9); 18 pairs of setae on dorsal shield and one pair of setae on unsclerotised cuticle: j1 30 (28–30), j3 17 (15–18), j4 8 (7–9), j5 8 (7–9), j6 8 (7–9), J2 5 (3–6), J5 7 (5–7), z2 10 (9–11), z4 10 (9–12), z5 8 (7–9), Z1 8 (7–9), Z4 16 (15–18), Z5 56 (55–58), s4 20 (19–23), S2 19 (18–20), S4 22 (20–23), S5 26 (25–28), r3 13 (12–14), R1 10 (9–12). Seta R1 present on the dorsal shield. All setae smooth, setae j1, j3, Z4, Z5, s4, S2, S4 and S5 long, seta Z5 longest, all other setae medium to small.

Peritreme ( Fig. 6 ). Extending up to base of j3.

Venter ( Fig. 7 ). Sternal shield square shaped, posterior margin of sternal shield with loop at the posterior margin of sternal shield. Sternal shield 54 (53–56) long and 80 (79–82) 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) 25 (24–26) long and conspicuous poroids on distinct metasternal platelets. Distances between st2–st2 75 (72–76), st5–st5 70 (70–73). Two pairs of metapodal platelets present. Primary metapodal platelet 25 (23–26) long and 3 (3–4) wide, secondary metapodal platelet 10 (9–10). 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 98 (97–101) long, 46 (46–49) wide at level of ZV2 and 68 (65–68) wide at anus level with three pairs of pre-anal setae, JV1 18 (16–19), JV2 20 (17–20), ZV2 22 (19–22) and one pair of large elliptical pre-anal pores gv3 just below JV2 29 (28–31) apart. Membrane surrounding ventrianal shield with four pairs of setae ZV1 13 (12–14), ZV3 8 (8–10), JV4 8 (8–10) and JV5 33 (32–35); seta JV5 long and smooth.

Chelicera ( Fig. 8 ) Fixed digit 22 (21–24) long with six teeth clubbed anteriorly and distinct pilus dentilis, movable digit 20 (20–21) long with one tooth.

Spermatheca ( Fig. 9 ). Calyx elongated 26 (24–27) and tubular, distinctly constricted at the distal part of calyx thereafter flared and gradually tapered at the proximal part towards the atrium with conspicuous major and minor duct. Arms of the calyx formed a funnel shaped appearance.

Legs ( Fig. 10 ). The genu, tibia and tarsus of leg IV with blunt hyaline tip macrosetae of following lengths: genu 40 (39–42), tibia 33 (32–34) and tarsus 58 (57–59). Chaetotactic formula of genu II 1 2/1 1/1 1 and genu III 1 2/1 0/2 1. Length of leg I 338 (332–340), leg II 275 (273–276), leg III 262 (260–265) and leg IV 325 (324–330). Leg III and leg II having macrosetae, Genu III 31 (29–32); genu II 18 (16–20).

Type specimens. Holotype: female (Acarol.lab/ BCKV/8590 /2021) collected from Kash grass ( Saccharum spontaneum ), at Mungiakami, Atharamura hill: 23°53'19"N, 91°44'0"E, 118m AMSL, Tripura, on 28 th August , 2019 and deposited in the NZC, Zoological Survey of India, Kolkata ; 3 paratype females (Acarol.lab/ BCKV/8591 /2021) with same collection data as holotype; 4 paratype females (Acarol.lab/ BCKV/8592 /2021) collected from unidentified shrub with same collection data as holotype; deposited in the Acarological laboratory, Department of Entomology , BCKV, Mohanpur, Nadia, West Bengal, India.

Etymology. The specific name sponateum refers to the species name of the host plant, Saccharum spontaneum or Kash grass from which the type species was collected.

Remarks. The new species is distinguished from all other species under the genus Euseius by its spermatheca, where calyx is tubular, distinctly constricted at the base of vesicle, flared distally and gradually tapered towards the atrium with conspicuous major and minor duct. This new species is also different from all the Euseius species described and reported from India ( Kar & Karmakar, 2021b) but close to E. neococciniae Gupta, 1978 ; E. dowdi ( Schicha, 1993 in Schicha &O’Dowd, 1993); E. lasalasi Denmark & Evans, 1998 in Denmark et al., 1999; E. inouei ( Ehara & Moraes, 1998) , by having similar type of spermatheca. However, the new species differs from these close species by the dorsal shield reticulated versus smooth, length of dorsal setae (long versus short), lateral margin of dorsal shield (regular versus irregular), position of seta R1 (on the shield versus off the shield), number of teeth in fixed and movable digit of chelicera and leg macrosetae variable. All the differences between the new species and its close species are presented in Table 2 .

Figures

FIGURES 6–10. Euseius spontanieum (female). 6. Dorsal view of idiosoma; 7. Ventral view of idiosoma; 8. Chelicera; 9. Spermatheca; 10. Genu, tibia and basitarsus of leg IV.

FIGURES 36–44. 36–40. Euseius tripuraensis (female). 36. Dorsal view of idiosoma; 37. Ventral view with ventrianal shield; 38. Spermatheca; 39. Genu, tibia and basitarsus of leg IV; 40. Chelicera; 41–44. Euseius spontanieum (female). 41. Dorsal view of idiosoma; 42. Genu, tibia and basitarsus of leg IV; 43. Chelicera; 44. Spermatheca.