Euseius aridophilus Karmakar & Biswas, 2025

Euseius aridophilus Karmakar & Biswas sp. nov.

( Figures 1a–e View FIGURE 1 , 5a–h View FIGURE 5 )

Diagnosis. Dorsal shield strongly reticulated with marks of sigilla mostly on prodorsum and five pairs of solenostomes (gd2, gd5, gd6, gd8 and gd9); all dorsal setae smooth, short to medium in length, with pointed tip, except seta Z5 slightly barbed; setae j3 and s4 equal and seta Z5 the longest, setae r3 and R1 located on interscutal membrane; peritreme extending up to the level of seta j3; sternal shield sparsely striated, with three pairs of setae and posterior margin with an inconspicuous median lobe; ventrianal shield vase-shaped wider at anus level, with three pairs of pre-anal setae and one pair of large elliptical pre-anal solenostomes (gv3) situated posteriad to setae JV2; fixed digit of chelicera with six teeth clustered anteriorly, movable digit unidentate; calyx of spermatheca proximally wider adjacent to atrium, gradually narrowed and distally flared at the base of vesicle; atrium submerged within calyx; leg IV with three blunt, hyaline-tipped macrosetae each on genu, tibia and basitarsus; genu II and III each with a blunt macroseta.

Description

Female (n = 10).

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

Dorsum ( Figures1a View FIGURE 1 , 5a–c View FIGURE 5 ).Dorsal shield strongly reticulated medially,and striated antero-laterally forming elongated cells, with marks of sigilla mostly on prodorsum, 464 (455–472) long, 251 (242–258) wide at level of s4 setae and 239 (231–245) wide at S2 setal level, with irregular waist at level of R1 seta; with five pairs of solenostomes (gd2, gd5, 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 31 (29–33), j3 28 (26–29), j4 14 (13–14), j5 14 (13–15), j6 15 (15–17), J2 15 (14–16), J5 7 (6–7), z2 22 (21–23), z4 23 (21–23), z5 15 (15–17), Z1 18 (18–20), Z4 19 (18–20), Z5 68 (68–70), s4 28 (26–29), S2 21 (20–22), S4 26 (24–26), S5 28 (26–29), r3 15 (15–17), R1 15 (14–16). All setae smooth, short to medium in length, with pointed tip, except seta Z5 slightly barbed; seta j3 and s4 equal and seta Z5 the longest.

Peritreme ( Figures 1a View FIGURE 1 , 5a–b View FIGURE 5 ). Extending to the level of seta j3.

Venter ( Figure 1b View FIGURE 1 ). Sternal shield sparsely striated, rectangular, 75 (73–76) long and 90 (87–92) wide, with three pairs of setae and two pairs of lyrifissures; posterior margin with an inconspicuous median lobe; distances between ST1–ST1 54 (51–55), ST2–ST2 65 (62–66), ST3–ST3 75 (74–79), ST1–ST3 55 (52–56) and ST4 30 (28–31) on an inconspicuous metasternal plate. Genital shield broad at base and rounded posteriorly, narrower at genital opening with anterior irregular circular flap, with one pair of setae ST5 33 (31–34) long; distance between ST5–ST5 85 (82–85). Ventrianal shield vase-shaped, with anterior margin sub-angulate at ZV2 level, lateral margin slightly wavy and wider at level of anus; 100 (97–102) long, 55 (52–55) wide at level of ZV2 and 73 (71–75) at anus level, with three pairs of pre-anal setae: JV1 30 (28–30), JV2 28 (27–30), ZV2 25 (24–26). One pair of large elliptical pre-anal solenostomes (gv3) situated posteriad to setae JV2, distant 28 (26–29) from each other. Setae ZV2 located near lateral shield margin. Membrane surrounding the ventrianal shield with four pairs of setae: ZV1 25 (24–25), ZV3 15 (14–16), JV4 13 (12–14), and JV5 37 (35–38). One pair of metapodal plates, 21 (20–21) long at the level of posterior margin of genital shield.

Chelicera ( Figures 1c View FIGURE 1 , 5d View FIGURE 5 ). Fixed digit 30 (28–32) long with six small teeth clustered anteriorly to a distinct pilus dentilis; movable digit 25 (24–28) long, unidentate.

Spermatheca ( Figures 1d View FIGURE 1 , 5f–h View FIGURE 5 ). Calyx 13 (12–13) long, proximally, adjacent to atrium, gradually narrowed and distally flared at base of vesicle. Atrium conspicuous, submerged within calyx. Major duct flattened with obscured banding and minor duct distinctly visible.

Legs ( Figures 1e View FIGURE 1 , 5e View FIGURE 5 ). Leg IV with three blunt, hyaline-tipped macrosetae on genu, tibia and basitarsus. Length of macrosetae: SgeIV 46 (43–46), StiIV 32 (31–34) and StaIV 57 (54–58). Leg II–III each with single blunt macroseta on genu: SgeII 21 (20–21) and SgeIII 29 (28–30). Chaetotactic formula of Ge II: 1 2/0, 2/0 2 and Ge III: 1 2/1, 2/0 1. Length of leg I: 344 (335–350), leg II 289 (278–292), leg III 274 (268–281), and leg IV 351 (346–358).

Male. Unknown.

Type material. HOLOTYPE: Female (Acarol.lab/ BCKV /8917/2023) deposited in the National Zoological Collection, Zoological Survey of India, Kolkata, on Mexican cotton ( Gossypium hirsutum L.: Malvaceae ) at Pitchandikulam Forest (11°59’39” N 79°49’24” E, 15 m asl), 2 May 2023; GoogleMaps PARATYPES: 3 females (Acarol.lab/ BCKV /8949–8951/2023) on mango ( Mangifera indica L.: Anacardiaceae ) at Madurai (9°58’51” N 78°08’36” E, 130 m asl), 10 May 2023; GoogleMaps 6 females (Acarol.lab/ BCKV /8952‒8957/2023) on castor ( Ricinus communis L.: Euphorbiaceae ) at Ooty (11°23’19” N 76°41’22” E, 2240 m asl), 18 May 2023, Tamil Nadu, India. GoogleMaps

Other material examined. 4 females (Acarol.lab/ BCKV /9048–9051/2023) on papaya ( Carica papaya L.: Caricaceae ) at Ballowal Saunkhri, (31°05’58.7” N, 76°23’13.2” E, 300 m asl), 10 February 23, Punjab; GoogleMaps 4 females (Acarol.lab/ BCKV /9052‒9055/2023) on orchid tree ( Bauhinia variegata (L.) Benth.: Fabaceae ) at Ludhiana, (30°53’50” N 75°48’21” E, 224 m asl), 18 February 23, Punjab; GoogleMaps 2 females (Acarol.lab/ BCKV /9056–9057/2023) on Coorg orange (Citrus reticulata Blanco: Rutaceae ) at Madikeri, (12°25’20” N 75°44’42” E, 1050 m asl), 10 May 23, Karnataka; GoogleMaps 6 females (Acarol.lab/ BCKV /9058–9063/2023) on teak tree ( Tectona grandis L.f.: Lamiaceae ) at Bhitarkanika National Park, (20°43’20” N 86°52’08” E, 3 m asl), 06 June 23, Odisha; GoogleMaps 5 females (Acarol.lab/ BCKV /9064‒9068/2023) on silkworm mulberry ( Morus alba L.: Moraceae ) at Hazaribagh Wildlife Sanctuary, (24°07’28” N 85°26’19” E, 520 m asl), 08 July 23, Jharkhand; GoogleMaps 6 females (Acarol.lab/ BCKV /9069‒9073/2023) on burflower tree ( Neolamarckia cadamba (Roxb.) Bosser : Moraceae ) at Araku Valley, (18°19’06” N 82°53’25” E, 910 m asl), 08 July 23, Andhra Pradesh; GoogleMaps 5 females (Acarol.lab/ BCKV /9074‒9078/2023) on earpod wattle ( Acacia auriculiformis A.Cunn. ex Benth. : Fabaceae ) at Bankura, (23°06’29” N 87°04’27” E, 91 m asl), 24 August 23, West Bengal, India. GoogleMaps

Etymology. The specific name aridophilus refers to the occurrence of this species in arid dryland areas.

Differential diagnosis. The new species Euseius aridophilus is unique among all the species in the genus with the following combination of characters: strongly reticulated dorsal shield with five pairs of solenostomes (gd2, gd5, gd6, gd8 and gd9); all dorsal setae shorter, smooth, except seta Z5 barbed; and seta Z5 longest, setae r3 and R1 on interscutal membrane; peritreme extending up to j3; sternal shield sparsely striated, with posterior margin inconspicuous; vase-shaped ventrianal shield wider at anus level, with a pair of large elliptical pre-anal solenostomes (gv3) posteriad of JV2; movable digit of chelicerae unidentate; calyx of spermatheca proximally wider adjacent to atrium, gradually narrowed and atrium submerged within calyx; major duct banded obscurely; and leg IV with three blunt, hyaline-tipped macrosetae each on genu (SgeIV 43–46), tibia (StiIV 31–34) and basitarsus (StaIV 54–58).

The genus Euseius presently includes 241 species worldwide. The new species, E. aridophilus is close to E. alatus De Leon, 1966 ; E. bandispermathecae Pramanik & Karmakar, 2016 ; E. ceylonicus Moraes & Lopes, 2004 (in Moraes et al., 2004); E. citrifolius Denmark & Muma, 1970; E. dossei Pritchard & Baker, 1962 ; E. omentum Qayyum, Afzal &Ahmad, 2002 a ; E. plazo Ahmad, Yasmin & Chaudhri, 1987 ; E. relictus Chaudhri, Akbar & Rasool, 1979 ; E. sundarbanensis Karmakar & Bhowmik, 2018 ; and E. vulgaris ( Liang & Ke, 1983) . These species share characters like imbricated dorsal shield; dentitions in the fixed digit of chelicerae clustered apically, and peritreme not extending beyond seta j3. However, the new species E. aridophilus clearly differs from E. alatus , by sublateral seta R1 on interscutal membrane (R1 on dorsal shield in E. alatus ); peritreme extended up to seta j3 (peritreme extended between j3 and z 2 in E. alatus ); tip of leg IV macrosetae blunt (leg IV macrosetae bulbous in E. alatus ); and calyx of spermatheca short (12–13 vs. 25). Euseius aridophilus differs from E. bandispermathecae , by sublateral seta R1 on interscutal membrane (R1 on dorsal shield in E. bandispermathecae ); tip of leg IV macrosetae hyaline and not curved (leg IV macrosetae curved and not hyaline in E. bandispermathecae ); and calyx of spermatheca without sclerotised bands (calyx of spermatheca looped with sclerotised bands in E. bandispermathecae ). Euseius aridophilus differs from E. ceylonicus , by sublateral seta R1 on interscutal membrane (R1 on dorsal shield in E. ceylonicus ); and peritreme extended up to seta j3 (peritreme extended between j3 and z 2 in E. ceylonicus ). Euseius aridophilus differs from E. citrifolius , by longer prodorsal setae (j4 13–14 vs. 7, j6 15–17 vs. 8); shorter prodorsal seta (s4 26 –29 vs. 39); and tip of leg IV macrosetae blunt (leg IV macrosetae pointed in E. citrifolius ). Euseius aridophilus differs from E. dossei , by strongly reticulated dorsal shield (dorsal shield anterolaterally striated in E. dossei ); shorter prodorsal seta (z4 21–23 vs. 30); peritreme extended up to seta j3 (peritreme extended between j3 and z 2 in E. dossei ); shorter leg IV macrosetae on genu and basitarsus (SgeIV 43–46 vs. 57, StaIV 54–58 vs. 68); and calyx of spermatheca not trumpet-shaped (calyx of spermatheca trumpet-shaped in E. dossei ). Euseius aridophilus differs from E. omentum , by peritreme extended up to seta j3 (peritreme extended up to z 2 in E. omentum ); and tip of leg IV macrosetae blunt (leg IV macrosetae pointed in E. omentum ). Euseius aridophilus differs from E. plazo , by longer opisthosomal seta (Z5 68–70 vs. 57); shorter opisthosomal seta (s4 26 –29 vs. 9); peritreme extended up to seta j3 (peritreme extended up to z 2 in E. plazo ); and tip of leg IV macrosetae blunt (leg IV macrosetae pointed in E. plazo ). Euseius aridophilus differs from E. relictus , by longer opisthosomal seta (Z5 68–70 vs. 55); peritreme extended up to seta j3 (peritreme extended up to z 2 in E. relictus ); and tip of leg IV macrosetae blunt and not curved (leg IV macrosetae pointed and curved in E. relictus ). Euseius aridophilus differs from E. sundarbanensis , by longer prodorsal seta (j5 13–15 vs. 8, z5 15–17 vs. 8); peritreme extended up to seta j3 (peritreme extended between j3 and z 2 in E. sundarbanensis ); longer leg IV macroseta on genu (Sge IV 43–46 vs. 37); shorter leg IV macroseta on tibia (StiIV 31–34 vs. 43); tip of leg IV macrosetae blunt and not curved (macrosetae pointed and curved in E. sundarbanensis ); and calyx of spermatheca tubular (calyx of spermatheca fundibular in E. sundarbanensis ). Euseius aridophilus differs from E. vulgaris , by longer opisthosomal seta (Z5 68–70 vs. 56.5); entire dorsal shield reticulated (dorsal shield laterally striated, medially reticulated in E. vulgaris ); peritreme extended up to seta j3 (peritreme extended between j3 and z 2 in E. vulgaris ); tip of leg IV macrosetae blunt (macrosetae pointed in E. vulgaris ); and calyx of spermatheca tubular (calyx of spermatheca sausage-shaped in E. vulgaris ). These comparisons are summarised in Table 1 View TABLE 1 .

Remarks. Euseius aridophilus is widely distributed throughout the dryland tracts of Tamil Nadu, Andhra Pradesh, Karnataka, Jharkhand, Odisha, Punjab, and West Bengal, in association with many agri-horticultural crops and weeds infested with phytophagous mites and small sucking insects. It has been found to be one of the most abundant species of phytoseiid mites based on the large number of specimens collected during survey from those areas. It has been found mainly in arboreal habitats. It has been observed to feed on the oriental red mite Eutetranychus orientalis (Klein) in Bauhinia spp. along with thrips, scale insects and leaf hoppers, specifically during the flowering time in the dry tracts of Punjab. This species was also found in citrus, papaya and mulberry associated with the citrus red mite Panonychus citri (McGregor) and other spider mites ( Tetranychus sp. , Oligonychus sp. ), leaf hoppers and mealybugs.