Euseius tamilicus Karmakar & Biswas, 2025

Euseius tamilicus Karmakar & Biswas sp. nov.

( Figures 3a–e View FIGURE 3 , 6f–h View FIGURE 6 )

Diagnosis. Dorsal shield sparsely striated laterally with marks of sigilla mostly on prodorsum and six pairs of solenostomes (gd1, gd2, gd4, gd6, gd8 and gd9); all dorsal setae smooth, short to medium in length, except setae j1 and Z5; setae r3 and R1 located on interscutal membrane; peritreme extending anteriorly up to level of seta z2; sternal shield smooth with three pairs of setae, posterior margin with an inconspicuous lobe; ventrianal shield with anterior margin rounded and indented laterally with three pairs of pre-anal setae and one pair of large elliptical pre-anal solenostomes (gv3) situated postero-mediad of setae JV2 and JV5 smooth; fixed digit of chelicera with six teeth and movable digit unidentate; calyx of spermatheca elongate, tubular; atrium submerged within proximal end of calyx; major duct flattened and minor duct distinctly elongated crossing vesicle; leg IV with three smooth, pointed macrosetae on genu, tibia and basitarsus; genu II and III each with a thick, pointed macroseta.

Description

Female (n = 6).

Idiosomal setal pattern 10A:9B/ JV -3: ZV.

Dorsum ( Figure 3a View FIGURE 3 ). Dorsal shield sparsely striated laterally, with marks of sigilla mostly on prodorsum, 366 (358– 372) long, 216 (208–220) wide at level of seta s4 and 242 (236–248) at level of S2, with prominent waist at level below R1; with six pairs of solenostomes (gd1, gd2, gd4, gd6, gd8 and gd9); seventeen pairs of setae on the dorsal shield and two pairs of sublateral setae (r3, R1) on the interscutal membrane: j1 35 (32–36), j3 18 (16–19), j4 9 (8– 10), j5 9 (8–10), j6 11 (9–12), J2 11 (10–13), J5 9 (8–10), z2 15 (13–15), z4 15 (14–16), z5 10 (9–11), Z1 13 (11–13), Z4 16 (14–16), Z5 52 (48–53), s4 27 (25–27), S2 18 (16–18), S4 18 (18–20), S5 19 (17–19), r3 14 (14–16), R1 13 (11–13). All setae smooth, short to medium in length, except setae j1 and Z5 which are long, seta Z5 longest.

Peritreme ( Figure 3a View FIGURE 3 ). Extending anteriorly up to level of seta z2.

Venter ( Figure 3b View FIGURE 3 ). All shields smooth. Sternal shield rectangular, 82 (80–84) long and 90 (87–91) wide, with three pairs of setae and two pairs of lyrifissures; posterior margin hardly distinguishable with an inconspicuous median lobe; distances between ST1–ST1 54 (52–55), ST2–ST2 61 (58–62), ST3–ST3 67 (65–68), ST1–ST3 63 (61–65) and seta ST4 30 (28–31) on a metasternal plate. Genital shield broad at base, narrow at genital opening with anterior irregular circular flap, with one pair of setae ST5 32 (29–32) long; distance between ST5–ST5 75 (72–76). Ventrianal shield elongated with anterior margin rounded and indented laterally; 116 (110–117) long, 54 (51–55) wide at ZV2 and 69 (66–70) at level of anus, with three pairs of pre-anal setae: JV1 26 (25–27), JV2 24 (24–26), ZV2 29 (27–30). One pair of large elliptical pre-anal solenostomes (gv3) situated postero-mediad of setae JV2, distant 20 (18–20) from each other. Setae ZV2 located on anterolateral shield margin. Membrane surrounding ventrianal shield with four pairs of setae: ZV1 20 (18–20), ZV3 16 (15–16), JV4 16 (14–16), and JV5 28 (26–28). One pair of comma-shaped metapodal plates, 14 (13–15) long at level of seta ZV1.

Chelicera ( Figures 3c View FIGURE 3 , 6g View FIGURE 6 ). Fixed digit 25 (24–27) long with six teeth and a distinct pilus dentilis, movable digit 23 (22–26) long, unidentate.

Spermatheca ( Figures 3d View FIGURE 3 , 6h View FIGURE 6 ). Calyx elongated, tubular 18 (18–20) long flared at the base of vesicle; atrium submerged within proximal end of calyx. Major duct flattened and minor duct distinctly elongated.

Legs ( Figures 3e View FIGURE 3 , 6f View FIGURE 6 ). Leg IV with three smooth pointed macrosetae genu, tibia and basitarsus. Length of macrosetae: SgeIV 33 (30–33), StiIV 39 (36–39) and StaIV 64 (62–65). Leg II–III each with single macroseta on genu: SgeII 15 (14–16) and genu SgeIII 21 (20–22). Chaetotactic formula of Ge II: 1 2/0, 2/0 2 and Ge III: 1 2/1, 2/0 1. Length of leg I: 355 (348–359), leg II 276 (268–280), leg III 269 (262–272), and leg IV 367 (364–375).

Male. Unknown.

Type material. HOLOTYPE: Female (Acarol.lab/ BCKV /8916/2023) deposited in the NZC, Zoological Survey of India, Kolkata, on neem ( Azadirachta indica A.Juss. : Meliaceae ) at Pallavaram Forest (12°58’12” N 80°09’44” E, 50 m asl), 14 May 2023; PARATYPES: 5 females (Acarol.lab/ BCKV /8923‒8927/2023) on tamarind ( Tamarindus indica L.: Fabaceae ) at Coimbatore (11°02’30” N 76°58’01” E, 427 m asl), 21 June 2023, Tamil Nadu, India.

Etymology. The specific name tamilicus refers to Tamil Nadu, India from where the specimens were collected.

Differential diagnosis. The new species, Euseius tamilicus is unique among all the species in the genus with the following combination of characters: sparsely striated dorsal shield laterally with six pairs of solenostomes (gd1, gd2, gd4, gd6, gd8 and gd9); all dorsal setae smooth, shorter, except setae j1 and Z5; setae r3 and R1 on interscutal membrane; peritreme extending anteriorly up to z2; posterior margin of sternal shield with an inconspicuous lobe; anterior margin of ventrianal shield rounded and indented laterally with one pair of large elliptical pre-anal solenostomes (gv3) situated postero-mediad of setae JV2; movable digit unidentate; calyx of spermatheca elongate 18–20, tubular; atrium submerged within calyx; and leg IV with three smooth, pointed macrosetae on genu (SgeIV 30–33), tibia (StiIV 36–39) and basitarsus (SbtIV 62–65).

The new species is close to E. neomagucii Ueckermann, Moraes & Oliveira, 2001 (in Moraes et al., 2001); E. notabilis Qayyum, Afzal & Ahmad, 2002 ; and E. suplebius ( Wu & Li, 1984) ; by sharing characters like dorsal shield setation; sublateral setae (r3, R1) on interscutal membrane; peritreme not crossing bases of seta j3; and pointed leg IV macrosetae. However, the new species E. tamilicus clearly differs from E. neomagucii by longer prodorsal seta j1 (32–36 vs. 25); shorter opisthosomal seta s4 (25–27 vs. 54); opisthosomal dorsal shield smooth (opisthosoma striated laterally in E. neomagucii ); peritreme extending anteriorly up to level of seta z2 (peritreme extending up to seta z 2 in E. neomagucii ); seta JV1 migrated downwards from ventrianal shield margin (seta JV1 on anterior shield margin in E. neomagucii ); and calyx of spermatheca uniformly tubular (calyx of spermatheca proximally wider in E. neomagucii ). The new species Euseius tamilicus differs from E. notabilis by shorter prodorsal setae (j3 16–19 vs. 40, z2 13–15 vs. 30, z4 14–16 vs. 33); dorsal shield anterolaterally striated (dorsal shield strongly reticulated in E. notabilis ); peritreme extending anteriorly up to level of seta z2 (peritreme extending between bases of setae j3 and z 2 in E. notabilis ); and shorter caudoventral seta JV5 (26–28 vs. 43). And the new species Euseius tamilicus differs from E. suplebius by shorter prodorsal setae (j4 8–10 vs. 18, j5 8–10 vs. 18, z4 14–16 vs. 25); opisthosomal dorsal shield smooth (opisthosoma striated laterally in E. suplebius ); peritreme extending anteriorly up to level of seta z2 (peritreme extending between bases of setae j3 and z 2 in E. suplebius ); and calyx of spermatheca tubular (calyx of spermatheca bell-shaped in E. suplebius ). These comparisons are summarised in Table 3 View TABLE 3 .