Tetranychus (Tetranychus) occultaspina, Naing, Htar Htar, Chandrapatya, Angsumarn, Navajas, Maria & Auger, Philippe, 2014

Naing, Htar Htar, Chandrapatya, Angsumarn, Navajas, Maria & Auger, Philippe, 2014, New species and new records of Tetranychidae (Acarina, Prostigmata) from Thailand, Zootaxa 3802 (2), pp. 257-275 : 263-269

Tetranychus (Tetranychus) occultaspina sp. nov. Naing & Auger

( Figures 15–32 )

Type-specimens. Holotype (male), 5 male and 7 female paratypes on 13 preparations from Ipomoea aquatica Forssk , ( Convolvulaceae ), Kasetsart University campus, Khet Bangkhen, Bangkok, Thailand, 05/08/2011, Leg. H. H. Naing. Holotype, 3 male and 5 female paratypes deposited in the Insect museum of Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand; 2 males and 2 females deposited in the collection of the CBGP, coll. Auger-Migeon N° 1821–1824, 34988 Montferrier-sur-Lez, France.

Diagnosis. This species is a Tetranychus sensu stricto assigned into the ninth group as defined by Flechtmann and Knihinicki (2002). Females bear four tactile setae proximal to the proximal pair of duplex setae and the female empodia are without a dorsomedian spur. Among Tetranychus (T.) belonging to this group, this species is distinctive by the shape of the aedeagus which has a shaft slightly upturned ending in a knob whose axis forms an acute angle with the shaft’s axis.

Description. Male: Holotype (415 µm long including gnathosoma). Five paratypes measured, 400–425 µm long, (including gnathosoma).

Dorsum. Dorsal body setae long, linear lanceolate, well surpassing in length distance between consecutive bases (length of holotype and variations of 5 paratypes): v 2 48 (48–53); sc 1 105 (99–107); sc 2 69 (69–74); c 1 93 (91–100); c 2 94 (78–96); c 3 81 (77–82); d 1 94 (87–94); d 2 95 (91–95); e 1 87 (82–86); e 2 89 (89–93); f 1 63 (56–69); f 2 45 (43–48); h 1 26 (23–27). Dorsal striae without lobes.

Gnathosoma. Palptarsus terminal sensillum about 2.5 times as long as broad, 5.5–6 µm long, 2.3–2.6 µm wide. Peritreme hooked distally.

Venter. Ventral striae without lobes.

Legs. Empodium I bifid, each side composed of one claw-like digit. Large mediodorsal spur present, about three-quarters length of empodium, difficult to see in perfect lateral view because concealed by empodial claws. Empodia II, III and IV without dorsal spurs and with three pairs of proximoventral hairs. Leg setal counts as follows:

I 2 − 1 − 10 [9] − 5 − 9 + (4) – 13 + (3) + 2 duplexes; II 2 − 1 – 6 – 5 – 7 − 13 + (1) + 1 duplex; III 1 − 1 − 4 − 4 – 6 – 9 + (1);

IV 1 − 1 − 4 − 4 – 7 − 10 + (1).

Aedeagus. Aedeagus shaft gradually narrows distally, slightly upturned. Neck short and wide, aedeagal knob axis forming an acute angle about 50° with shaft axis (range 43° – 52°, 5 males measured). Knob large 4.2 (3.9–4.3 µm), on average 1.7 times neck width 2.9 (2.1–2.9 µm), asymmetrical with poorly developed posterior rounded projection and well-developed anterior rounded projection anterodorsally directed. Knob dorsal margin undulate.

Female: 5 females measured. Idiosoma: length 505–544 µm (including gnathosoma), width 334–342 µm.

Dorsum. Dorsal body setae lanceolate, longer than distances between bases of consecutive setae (variations of 5 paratypes): v 2 60 –74; sc 1 138–156; sc 2 104–114; c 1 134–148; c 2 126–142; c 3 118–126; d 1 134–152; d 2 132–142; e 1 126–134; e 2 130–142; f 1 112–120; f 2 96–100; h 1 42–46. Propodosomal striation longitudinal with rounded and oblong lobes becoming triangularly rounded and triangular near dorsohysterosomal setae. Hysterosomal striation transverse except between setae e 1- e 1 and f 1- f 1 (longitudinal) bases forming diamond-shaped pattern between these setae, with lobes triangular, as tall as broad to taller than broad.

Gnathosoma. Palptarsus spinneret about one and a half as long as broad. Peritreme hooked distally.

Venter. Ventral striation with rounded lobes, broader than tall, few oblong lobes also present. Area immediately anterior to genital flap with broken longitudinal striation, becoming dotted striation medially. Genital flap with transverse slightly arched striae. One pair of ventrocaudal (h 3) and two pairs of pseudanal setae (ps 1-2) present.

Legs. Empodia I–IV bear three pairs of proximoventral hairs and no spur was observed. Leg setal counts as follows:

I 2 − 1 − 10 − 5 − 9 + (1–3) – 13 + (1–3) + 2 duplexes; II 2 − 1 – 6 – 5 – 7 − 13 + (1) + 1 duplex; III 1 − 1 − 4 − 4 – 6 – 9 + (1);

IV 1 − 1 − 4 − 4 – 7 − 10 [9–11] + (1).

Tarsus I with four tactile setae and up to two additional solenidia proximal to proximal duplex setae. One solenidion at or near proximal duplex level. Tibia I with up to three solenidia instead of one as usually observed in this group.

Etymology. The species designation, “ occultaspina ”, is taken from Latin adjective and noun meaning hidden spine, and refers to the spur of male empodium I which is difficult to see when the empodium is observed in a perfect lateral view.

Biological observations. The adult females are red in colour to dark red, darkening with age and produce silk. The adult males are yellowish brown and the eggs are pale amber in colour turning into dark orange/brownish-red before hatching.

Remarks. Among the Tetranychus of the 9th group defined by Flechtmann and Knihinicki (2002) (including ungrouped species that bear four tactile setae proximal to the proximal duplex setae on tarsus I), the aedeagus of T. occultaspina is quite close to those of Tetranychus bellottii Flechtmann , Tetranychus neocaledonicus André , Tetranychus puschelii Meyer , Tetranychus afrindicus Nassar & Ghai , Tetranychus papayae Nassar & Ghai and Tetranychus ismaili Yusof & Zhang. Tetranychus occultaspina can be distinguished from T. bellottii by its anterior aedeagal angulation which is rounded vs. acute in T. bellottii and by the angle formed between the knob’s axis and the shaft’s axis, which is greater in T. occultaspina . The aedeagus of T. occultaspina differs from those of T.

neocaledonicus and T. puschelii by the shape of its aedeagal knob which is more flattened with a dorsal margin not indented but undulated. It can be separated from T. afrindicus and T. papayae according to the shape of its aedeagal anterior projection which is rounded whereas it is angulate in the two others species and by the angle formed between the knob axis and the shaft’s axis. In T. ismaili aedeagal projections are acute whereas rounded in T. occultaspina .

Additional solenidia are sometimes present on tibia I and tarsus I of T. occultaspina : one to two on tarsus I (proximal to the proximal duplex) and one to two on tibia I. This unusual chaetotaxy is not specific to T. occultaspina . Indeed, hypertrichous forms have already been reported in some strains of Tetranychus species belonging to the 9th group ( Auger et al. 2013). It is known to occur in the two colour forms (green and red) of Tetranychus urticae Koch and also in Tetranychus gloveri Banks (e. g. McGregor (1950); Boudreaux (1956, 1958); Zhang & Jacobson (2000)).

Figures

FIGURES 15 – 16. Tetranychus (T.) occultaspina sp. nov., female. 15, dorsal aspect; 16, triangular lobes on dorsal striae.

FIGURES 17 – 22. Tetranychus (T.) occultaspina sp. nov., male. 17, tarsus and tibia I; 18, tarsus and tibia II; 19, empodium I in a perfect lateral view; 20, 21, empodium I not in a full lateral view; 22, empodia II – IV.

FIGURES 23 – 25. Tetranychus (T.) occultaspina sp. nov., male. 23, peritreme; 24, palptarsus; 25, aedeagi (variations).

FIGURES 26 – 28. Tetranychus (T.) occultaspina sp. nov., female. 26, tarsus and tibia I; 27, tarsus and tibia II; 28, empodium.

FIGURES 29 – 32. Tetranychus (T.) occultaspina sp. nov., female. 29, flap and anterogenital area; 30, lobes on ventral striation; 31, palptarsus; 32, peritreme.