Phytoseius tixierae Kreiter, 2020

Kreiter, Serge, Bopp, Marie-Charlotte, Douin, Martial, Nguyen, Duc Tung & Wyckhuys, Kris, 2020, Phytoseiidae of Vietnam (Acari: Mesostigmata) with description of a new species, Acarologia 60 (1), pp. 75-110 : 99-104

Phytoseius tixierae Kreiter n. sp.

Zoobank: 7B2DE1ED-FE36-488E-87B2-969ADBB09507

Figs. 4 a – d , 5 a – b , 6 a – c

Diagnose — Phytoseius tixierae Kreiter n. sp. lacks setae J2 and R1 and consequently belongs to the horridus species group. This species is unique by the following characters: z2 and Z4 smooth, s6 only slightly serrated, setae j4, j5, j6, J5 also smooth, setae s6, Z4 and Z5 subequal, s6 being the longest seta, four macrosetae on leg IV spatulate, SgeIV being the shortest and StiIV being the longest, with StIV and SttIV being intermediate and subequal, setae j1 and j3 almost equal, setae JV5 very short, <20, peritreme reaching the level of setae j1.

Description of the adult female of Phytoseius tixierae Kreiter n. sp.

n = 4 ( Figs. 4 a – b , Figs. 5 a – b ) (in bold, average measurements)

Dorsum — ( Fig. 4a ) Dorsal shield rugose 271 (250 – 280) long and 130 (125 – 140) wide, smooth, with no visible solenostome, 8 pairs of poorly visible poroids, 14 pairs of dorsal setae and one pair of sub-lateral setae on the dorsal shield: j1 23 (21 – 23), j3 18 (15 – 23), j4 10 (10 – 11), j5 10 (10 – 11), j6 11 (10 – 13), J5 9 (8 – 9), z2 12 (10 – 13), z3 20 (18 – 25), z4 19 (18 – 23), z5 12 (9 – 13), Z4 57 (48 – 63), Z5 53 (48 – 55), s4 44 (43 – 45), s6 59 (55 – 63), r3 30 (28 – 30). Setae z2, j4, j5, j6, z5 and Z4 smooth, setae s6 very slightly serrated at the distal third of setae, setae j1, j3, z3, z4, r3, s4 and Z5 serrated.

Peritreme — ( Fig. 4a ) Extending to the level of setae j1.

Venter — ( Fig. 4b ) All shields smooth.

Sternal shield with three pairs of setae and two pairs of lyrifissures; one pair of sternal setae on metasternal shields with a pair of pores; posterior margin straight. Distances between st1-st1 46 (43 – 50), st2-st2 53 (50 – 55), st3-st3 59 (43 – 68), st1-st3 58 (55 – 60), st4-st4 62 (50 – 75). Genital shield length 101 (98 – 105), st5-St5 56 (50 – 60), width at the level of the posterior corners ot the genital shield 80 (78 – 82).

One pair of narrow metapodal shields 24 (20 – 28) long and 2 wide.

Ventrianal shield with three pairs of preanal setae JV (1, JV2 and ZV2) and a pair of pores. Membrane surrounding ventrianal shield with two pairs of setae ZV (3 and JV5), and no visible poroids in our specimens; ventrianal shield 92 (85 – 98) long, 51 (50 – 53) wide at level of anterior corners (ZV2), and 44 (43 – 45) wide at level of anus.

JV5 short, 19 (15 – 20) long, and serrated.

Chelicera — Chelicerae not clearly visible and therefore not drawn. Fixed digit 17 (14 – 20) long with apparently 2 teeth; and movable digit 18 (15 – 20) long with apparently 1 tooth.

Spermatheca — ( Fig. 5a ) Spermatheca with calyx pocular ( Denmark and Evans 2011), 10 long and 5 wide, and a small atrium. Ductus minor not visible but large ductus major well visible in all specimens.

Legs — ( Fig. 5b ) Four macrosetae on leg IV, all spatulate: SgeIV 10, StiIV 39 (38 – 40), StIV 21 (20 – 23), SttIV 19 (18 – 20). Genu II with 7 setae and Genu III with 6 setae, chaetotactic formula of genu II: 2-2/0, 2/0-1; genu III: 1-2/0, 2/0-1.

Description of the adult male of Phytoseius tixierae Kreiter n. sp.

n = 1 ( Figs 6 a – c )

Dorsum — ( Fig. 6a ) Dorsal shield rugose 200 long and 113 wide, with no visible solenostome. The dorsal shield bears 14 pairs of dorsal setae and 1 pair of sub-lateral setae situated on the dorsal shield: j1 20, j3 16, j4 10, j5 8, j6 9, J5 6, z2 10, z3 18, z4 18, z5 10, Z4 30, Z5 28, s4 35, s6 35, r3 25. Setae z2, j4, j5, j6, z5 and Z4 smooth, setae s6 very slightly serrated, setae j1, j3, z3, z4, r3, s4 and Z5 serrated, like in the female.

Peritreme — ( Fig. 6a ) Extending to the level of setae j1.

Venter — ( Fig. 6b ) Sternal shield smooth. Distances between st1 – st1 43, st2 – st2 48, st3 – st3 50, st1 – st5 90, st4 – st4 43, st5 – st5 35. Ventrianal shield with three pairs of pre-anal setae, JV1, JV2 and ZV2. Pre-anal pores absent. Membrane surrounding ventrianal shield with one pair of setae JV5; ventrianal shield 75 long, 90 wide at anterior corners and 50 wide at level of paranal setae. Short setae JV5 serrated, 10 long.

Chelicera – Fixed digit 15 long, with 2 teeth visible and movable digit 15 long with 1 tooth visible. Spermatodactyl circumflex accent shaped, shaft ( Fig. 6c ) 11, toe 9.

Legs — Legs IV with four spatulate macrosetae like in the female: SgeIV 5, StiIV 10, StIV 15, SttIV 15. Chaetotactic formula of genu II and III similar to that of females.

Specimens examined — Muoi in P4 experimental plot (aasl 66 m, lat. 21°54’41” N, long. 104°38’7” E), 1 ♀ + 1 ♂, 12/05/2017 and in P12-P13 plots (aasl 66 m, lat. 21°54’50” N, long. 104°38’45” E), 3 ♀♀ on Bambusodae sp. ( Poaceae ).

Type material — The holotype female, 3 paratype females, and 1 paratype male on 3 slides deposited in CBGP, in Montpellier SupAgro Acarology collection, France.

Etymology — The name “ tixierae ” refers to our colleague Professor-Dr Marie-Stéphane Tixier (Montpellier SupAgro) to whom this species is dedicated for her huge contribution to the knowledge of mites and especially to the taxonomy of Phytoseiidae and her great assistance with this paper.

Remarks — Measurements of specimens collected during this study are provided in table 14 for females and for the single male and compared with measurements obtained from specimens of the closest described species.

Females of Phytoseius tixierae Kreiter n. sp. ( Table 14) resembles that of P. huaxiensis Xin, Liang and Ke but differs in having s6 only slightly serrated, shorter s4, s6, Z4, Z5 and JV5. It also resembles P. indicus Bhattacharyya but differs in having s6 only slightly serrated, shorter s4, s6, Z4, JV5, Z4 not serrated but z4 serrated and longer. It is also related to P. kazusanus Ehara but differs in having s6 only slightly serrated, z4 serrated, longer Z5, JV5 and StIV and Z4 not serrated. It is also very close to P. longchuanensis Wu but differs from this species by having longer setae except s4 and Z4, s6 only slightly serrated, z4 serrated, longer JV5 and 4 macrosetae on the leg IV instead of zero. It is also very similar to P. rimandoi Corpuz but differs from this species in having shorter s6, Z4 smooth. Finally, the closest species is P. nudus Wu and Li but the new species differs from this species in having z4 strongly serrated (only slightly serrated in the former), and the dorsal shield rugose (smooth in the former).

Males of Phytoseius tixierae Kreiter n. sp. ( Table 14) also resembles to the males of P. huaxiensis and P. kazusanus that are the only species for which males have been described. But males of the new species differ from males of the former species in having s6 only slightly serrated, and shorter s4, s6, z3, Z4, Z5 and JV5. Males of the new species differ from males of P. kazusanus in having s6 only slightly serrated, shorter Z4, Z5 and JV5, z4 serrated and longer and Z4 not serrated.

Figures

Figure 4 Female of Phytoseius tixieraeKreiter n. sp.. a – Dorsal shield and peritreme; b – Ventral shields.

Figure 5 Female of Phytoseius tixieraeKreiter n. sp.. a – Insemination apparatus; b – Genu, tibia and basitarsus of the leg IV.

Figure 6 Male of Phytoseius tixieraeKreiter n. sp.. a – Dorsal shield and peritreme; b – Ventral shields; c – Spermatodactyl.