Eotetranychus palatiensis, Gotoh & Arabuli, 2019

Gotoh, Tetsuo & Arabuli, Tea, 2019, New species of the genus Eotetranychus (Acari, Prostigmata, Tetranychidae) from Japan, Zootaxa 4555 (1), pp. 1-27 : 3-10

Eotetranychus palatiensis sp. nov.

[Japanese name: Kôkyo-akehadani]

( Figs 1–22 )

Diagnosis. Dorsocentral setae simple, acicular, longer than longitudinal intervals between their bases; striation pattern transverse on genital flap, pregenital striae irregular but can be more or less transverse (in pallidus species group as defined by Tuttle et al. (1976)). Peritreme with short distal hook. Tarsus I of female with 5 tactile setae and one solenidion proximal to duplex seta; tibia I of both sexes with 9 tactile setae; tibia II of both sexes with 8 tactile setae; femora IV of both sexes with 3 setae. Empodia I–II of male short, thick, bifid with each side bearing 3 distal teeth, median tooth strongest and longest. Aedeagus shaft linear, with dorsal and ventral margins of proximal part of shaft more or less parallel, shaft bending ventrally at a slight angle near middle of total aedeagal length, ventrally directed portion tapered to a narrow truncate tip. Egg with a short thin dorsal stipe on its center.

Description. Female (n=10, paratypes). Body greenish yellow. Length of body including gnathosoma 326– 433; gnathosoma 79–96 long; width of body 182–246.

Dorsum. Dorsal body setae long, linear, acicular; length of setae: v 2 47 –54; sc 1 78–88; sc 2 60–72; c 1 67–76; c 2 71–83; c 3 62–70; d 1 67–74; d 2 67–79; e 1 61–72; e 2 68–78; f 1 58–66; f 2 43–53; h 1 29–36. Dorsocentral opisthosomal setae long and thin, longer than distance between their bases, not set on tubercles ( Fig. 1 ). Prodorsum with longitudinal striation; hysterosomal striation transverse medially, oblique and longitudinal laterally ( Fig. 1 ); lobes on dorsal striae square shaped (truncate), usually broader than tall ( Figs 1, 2 ).

Gnathosoma. Stylophore rounded anteriorly with longitudinal striation dorsally. Peritreme with short distal hook ( Fig. 4 ). Terminal sensillum (spinneret) of palptarsus long, approximately three times as long as wide: 7.7–8.8 long and 2.2–3.1 wide; dorsal sensillum (solenidion) spindle shaped 4.5–5.8 long; eupathidia asymmetrical ul’’ζ longer than ul’ζ, 8.2–9.2 and 6.2–7.1 long, respectively ( Fig. 3 ).

Venter. Genital flap with transverse to weakly arched striae; striae on pregenital area irregular, which is typical striae of the pallidus species group as defined by Tuttle et al. (1976) ( Fig. 5 ), but striae can vary from rather transverse to oblique ( Fig. 6 ). Two pairs of ventrocaudal (h 2, h 3) setae and two pairs of pseudanal (ps 1, ps 2) setae present.

Legs. Leg I 185–214, leg II 155–170, leg III 170–181; leg IV 186–220 long (from trochanter to tarsus). Length of segments of leg I as follows: femur 60–67, genu 28–34, tibia 35–41, tarsus 58–63 long. Leg setal counts as follows ( Figs 8–11 ):

I 2 - 1 - 10 - 5 - 9 + (1) - 14 + (1) + 2 duplexes

II 2 - 1 - 7 - 5 - 8 - 13 + (1) + 1 duplex

III 1 - 1 - 4 - 4 - 6 - 10 + (1)

IV 1 - 1 - 4 - 4 - 7 - 10 + (1)

Tarsus I with 5 tactile setae and 1 solenidion proximal to proximal set of duplex setae; distal duplex solenidion of tarsus I longer than that of proximal duplex: 59–62 and 40–46 long, respectively; tactile setae of distal and proximal duplexes equal in length 13–15 ( Fig. 8 ). Tarsus II with 4 tactile setae and 1 solenidion proximal to duplex seta, one tactile seta near level of duplex seta; solenidion of duplex seta 30–33 long and tactile seta 10–11; tibia II with 8 tactile setae ( Fig. 9).

Empodia I–IV split into 3 pairs of ventrally directed hairs of equal size and length ( Figs 7–11 ).

Male (n=11, holotype and 10 paratypes). Body greenish yellow as female. Length of body including gnathosoma 261 (258–308); gnathosoma 76 (72–85) long; width of body 134 (130–152).

Dorsum. Dorsal body setae simple, acicular, longer than distance between bases of consecutive setae, length of setae: v 2 40 (36–42); sc 1 68 (68–72); sc 2 49 (47–52); c 1 59 (55–62); c 2 68 (65–71); c 3 52 (49–58); d 1 59 (49–59); d 2 66 (59–68); e 1 52 (47–55); e 2 62 (59–67); f 1 42 (35–45); f 2 24 (20–25); h 1 15 (14–16).

Gnathosoma. Peritreme as in female ( Fig. 4 ). Terminal sensillum of palptarsus long, approximately four times as long as wide: 7.7 (6.7–7.8) long and 1.8 (1.7–2.3) wide; dorsal sensillum (solenidion) spindle shaped 5.4 (4.6– 5.5) long; eupathidia asymmetrical ul’’ζ longer than ul’ζ, 7.7 (7.2–8.4) and 6.2 (4.9–6.7) long, respectively ( Fig. 12 ).

Legs. Leg I 179 (174–180); leg II 137 (133–139); leg III 143 (137–143); leg IV 170 (161–172) long (from trochanter to tarsus). Length of first leg segments as follows: femur 52 (42–54); genu 27 (23–29); tibia 31 (25–32); tarsus 55 (50–55) long. Leg setal count as follows ( Figs 14–17 ):

I 2 - 1 - 10 - 5 - 9 + (4) -13 + (3) + 2 duplexes

II 2 - 1 - 7 - 5 - 8 - 13 + (1) + 1 duplex

III 1 - 1 - 4 - 4 - 6 - 10 + (1)

IV 1 - 1 - 4 - 4 - 7 - 10 + (1)

Tarsus I with 4 tactile setae and 3 solenidia proximal to proximal set of duplex setae; distal duplex solenidion of tarsus I longer than that of proximal duplex: 47 (46–50) and 32 (28–32) long, respectively; tactile seta of distal and proximal duplexes equal in length 13.8 (12–14) ( Fig. 14 ). Tarsus II with 4 tactile setae and 1 solenidion proximal to duplex seta, one tactile seta near level of duplex seta; tarsus II solenidion of duplex seta 25 (24–28) long, tactile 9.7 (10–11); tibia II with 8 tactile setae ( Fig. 15 ).

Empodia I–II thick, with 3 pairs of teeth, middle pair strongest, ventral and dorsal digits slender and shorter ( Figs 13–15 ). Empodia III–IV split into 3 pairs of hairs as in female ( Figs 7 , 16–17 ).

Aedeagus. Shaft of aedeagus more or less linear, with dorsal and ventral margins of proximal part of shaft more or less parallel, shaft bent ventrally at a slight angle near middle of aedeagus, with ventrally directed distal portion nearly straight and narrowing to a truncate tip ( Figs 18–22 ). Measurements of aedeagus: dorsal margin (shaft/tip) 10.4 (10.4–12.5), ventral margin longer than dorsal (shaft/tip) 14.3 (13.6–16.5) length, width (broadest part of shaft) 2.6 (2.4–3.7).

Etymology. This species is named after the type locality, the Imperial Palace Estate.

Type series. Holotype: male (voucher specimen no. 0540), the Imperial Palace Estate (35°40’N 139°45’E), Chiyoda City, Tokyo, 6-VI-2011 (T. Gotoh leg.), on Morus australis Poiret (Moraceae) . Paratypes: 17 males and 16 females (voucher specimen no. 0540), data same as for holotype.

Remarks. Eotetranychus palatiensis sp. nov. belongs to the pallidus species group with transverse striae on the genital flap, and irregular striae in the pregenital area, however, the pattern of the pregenital area varies from irregular to transverse. The aedeagus of E. palatiensis sp. nov. is identical to another Japanese mite Eotetranychus boreus Ehara, 1969 (the pallidus species group) collected from apricot, Japanese apricot and plum ( Prunus spp., Rosaceae ). Some examined specimens of the new species also closely resemble E. boreus by the pattern of striation in the genital area of the female and other characters, but are distinguished in leg chaetotaxy: tibia II with seven, tibia III with five and tibia IV with five-six tactile setae in E. boreus , whilst E. palatiensis sp. nov. has eight, six and seven tactile setae (without any intraspecific variation observed), respectively. The aedeagus of E. palatiensis sp. nov. is morphologically close to two other species: Eotetranychus cornicola Ehara, 1989 (the willamettei species group), and Eotetranychus asiaticus Ehara, 1966 (the sexmaculatus species group), which are both described from Japan, on Cornus controversa Hemsley (Cornaceae) and Ficus erecta Thunberg (Moraceae) , respectively. The new species resembles E. cornicola by leg chaetotaxy, also some individuals of both species have identical striation in the female genital area, but E. palatiensis sp. nov. can be easily distinguished by the length of terminal sensillum (spinneret) on palptarsus of male, which is far smaller and conical in E. cornicola . Both sexes of the new species differ from E. cornicola by having a short hook on the peritremal ends (varies from simple bulb to golf-club shaped in E. cornicola ), and E. cornicola can be separated from the new species by the female empodium I which has a minute mediodorsal spur (absent in E. palatiensis sp. nov.). Eotetranychus palatiensis sp. nov. shares morphological characters with E. asiaticus , but differs in the shape of peritremal ends of both sexes and by the distinctive striation of the genital (longitudinal and oblique anteriorly) and pregenital area (longitudinal in E. asiaticus ) of female.

Eotetranychus palatiensis sp. nov. also resembles Eotetranychus talisiae ( Hirst, 1920) (the sexmaculatus species group) described from a glasshouse in England on Talisia princeps Oliver ( Sapindaceae ), which has an aedeagus of similar shape, and females are pale yellowish green. But both sexes of the new species differ from E. talisiae by having a longer spinneret on the palp, which is at least 2.5 times as long as wide, instead of less than 2 times longer than wide in E. talisiae . This is especially so of the spinneret of male E. talisiae which is extremely tiny.

Some acarologists consider that E. asiaticus is a junior synonym of Eotetranychus sexmaculatus ( Riley, 1890) , but nobody directly compares their morphology based on their slide preparations and their DNA sequence data yet. So, in the present work, E. asiaticus is treated as a valid species according to Ehara (1999), and this problem will be solved in the future.

Figures

FIGURES 1–2. Eotetranychus palatiensis sp. nov., 1. Female (dorsum), 2. Lobes on dorsal striation.

FIGURES 3–8. Eotetranychus palatiensis sp. nov., female—3. Distal segment of palpus, 4. Peritremes, 5–6. Genital flaps and pregenital areas, 7. Empodium I, 8. Leg I, left leg, adaxial view.

FIGURES 12–15. Eotetranychus palatiensis sp. nov., male—12. Distal segment of palpus, 13. Empodium I, 14. Leg I, left leg, adaxial view, 15. Leg II, left leg, adaxial view.

FIGURES 16–22. Eotetranychus palatiensis sp. nov., male—16. Leg III, left leg, adaxial view, 17. Leg IV, right leg, adaxial view, 18. Aedeagus (holotype), 19–22. Aedeagi (paratypes, four variations).