Eotetranychus fraxini

Migeon, Alain, Malagnini, Valeria, Navajas, Maria & Duso, Carlo, 2007, Notes on the genus Eotetranychus (Acari: Tetranychidae) in Italy and France with a redescription of Eotetranychus fraxini Reck, new record for Italy and Western Europe, Zootaxa 1509, pp. 51-60 : 55-59

publication ID

https://doi.org/ 10.5281/zenodo.177227

DOI

https://doi.org/10.5281/zenodo.5686912

persistent identifier

https://treatment.plazi.org/id/038987E8-852E-C50F-66F8-FF26FED1FE05

treatment provided by

Plazi

scientific name

Eotetranychus fraxini
status

 

Redescription of Eotetranychus fraxini

Reck (1948a) described a new Schizotetranychus , and classified it into the subgenus Eotetranychus . Although the original description from Reck was rather imprecise, the provided shape of the aedeagus and the peritreme allowed us to identify our specimens from northern Italy as E. fraxini . This species is here redescribed, including all the measurements and morphological characters currently used

Schizotetranychus (Eotetranychus) fraxini ( Reck, 1948a) : 448, figures 2 and 11; ( Reck, 1948b): 374, figures 6, 17 and 31.

Schizotetranychus fraxini Reck 1948 : ( Bagdasarian, 1957): 124, figure 54; ( Reck, 1959): 56, figure 82; ( Ripka et al., 1993): 562.

Diagnosis. Eotetranychus fraxini can be distinguished from other Eotetranychus species by considering the shape of the male aedeagus and the short tarsus I.

Female (Figs 1 and 3)

Four specimens where measured and the results are presented in Table 2 View TABLE 2 .

Idiosoma (Fig. 1A): Length 248 μm, width 156 μm.

Gnathosoma: Palptarsus spinneret about three times as long as broad, sensilium shorter than the nearby setae (Fig. 1D). Peritreme bulbous distally (Fig. 1C). Stylophore rounded anteriorly.

Dorsum: Dorsal striae with minute lobes about as long as wide, longitudinal on prodorsum and transverse on opisthosoma. All body setae linear, lanceolate. Dorsal setae extending beyond the base of next row (Fig. 1A). The measurements of the dorsal setae are given in table 2.

Venter: Ventral striae transverse. Genital flap with transverse striae, area anterior to genital flap with transverse striae (Fig. 1B).

Legs: Empodia split into two claw-like structures, each one split near the middle into three pairs of hairs (Fig. 1E). Tarsus I short, about 2–2.5 time long as wide, distal duplex setae with sensory seta about 4.5 times longer than tactile seta ( Fig. 3 View FIGURE 3 A). Chaetotaxy as follows (numbers of setae refer to tactile setae; sensory setae are given in parentheses and duplexes setae – 1 sensory coupled with 1 tactile – counted separately) – coxa, trochanter, femur, genu, tibia, tarsus:

I: 2, 1, 10, 5, 8 + (2), 13 + (2) + 2 duplexes ( Fig. 3 View FIGURE 3 A)

II: 2, 1, 7, 5, 8, 13 + (1) + 1 duplex ( Fig. 3 View FIGURE 3 B)

III: 1, 2, 4, 4, 6, 10

IV: 1, 1, 4, 4, 7, 10

Male ( Figs 2 View FIGURE 2 and 4 View FIGURE 4 )

Four specimens where measured and the results are presented in Table 2 View TABLE 2 . Some measurements could not be taken on all the specimens, because the male was laterally oriented, which is essential to examine the aedeagus.

Males are slightly smaller than females.

Idiosoma: Length 232 μm, width 108 μm.

Gnathosoma: Palptarsus spinneret about four times as long as broad, sensilium about as long as the nearby setae ( Fig. 2 View FIGURE 2 A). Peritreme bulbous distally. Stylophore rounded anteriorly.

Dorsum: Striae as for the female. Setae as for the female. Measurements are given in table 2.

Venter: All striae transverse as for the female.

Legs: Empodia I split into two claw-like structures, each one with a central spur and two smaller ones ( Fig. 2 View FIGURE 2 C). Empodia II to IV with three pairs of hairs like as in female ( Fig. 2 View FIGURE 2 D). Tarsus I short, about 2 –2.5 time long as wide, distal duplex setae with sensory seta about 5.3 times longer than tactile seta ( Fig. 4 View FIGURE 4 A). Chaetotaxy as follows (numbers of setae refer to tactile setae, sensory setae are given in parentheses): I: 2, 1, 10, 5, 8 + (3), 13 + (3) + 2 duplex ( Fig. 4 View FIGURE 4 A)

Material examined. Colli-Euganei, Rocca Pendice (Padova), Italia, on Fraxinus ornus (Oleaceae) , 10 July 2001, 3 males and 3 females, 5 October 2001, 2 males and 2 females, V. Malagnini leg. . Previous records. Georgia (Tbilissi) and Hungary (Ujlak) respectively on Fraxinus excelsior and Fraxinus sp. .

Remarks. Reck (1948a) recorded a total of 18 setae on male tarsus I, 14 on male tarsus II and 10 on male tibia I. We detected instead 20, 16 and 11 respectively on our specimens. This variation could be due to the lack of one or two proximal ventral setae on tarsus I, as observed on some of the specimens studied here. Eotetranychus fraxini is characterised by a female genital flap with transverse striae, which is typical of the willamettei group of the genus Eotetranychus . It also possesses eight tactile setae on the female tibia II like the species of the tiliarium group. The most characteristic feature for both male and female is the shortness of the tarsus I, having length/width values of 2–2.5 instead of 3–3.5 for most of the species.

The discovery of this species in Northern Italy, suggests a wider distribution of E. fraxini from Georgia to Western Europe, which could match to the distribution of the host plant genus, which includes the entire Holarctic region.

TABLE 2. Measurements of Eotetranychus fraxini Reck, habitus, dorsal setae and distances between the base of the dorsal setae (all values are in μm).

  Female (n=4)   Male  
  Mean Minimum Maximum Mean Minimum Maximum Number
Idiosoma:        
length 248 230 260 232 220 250 4
width 156 140 190 108 105 110 2
Dorsal setae:        
v2 48 44 52 35 33 36 3
sc1 84 81 88 68 66 69 3
sc2 55 50 64 44 41 46 3
c1 69 68 71 55 50 60 3
d1 72 70 74 57 55 58 3
e1 70 65 76 50 49 50 3
f1 68 61 75 46 42 50 3
h1 52 46 60 26 26 26 3
c2 74 71 78 55 55 55 3
d2 72 69 76 61 60 61 3
e2 73 70 78 52 52 52 2
f2 51 39 63 36 33 38 3
c3 61 53 71 43 43 43 2
Distances:        
v2–h1 227 218 232 158 155 160 3
sc2–sc2 131 127 140 54 - - 1
c1–c1 46 40 49 47 - - 1

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Prostigmata

Family

Tetranychidae

Genus

Eotetranychus

Loc

Eotetranychus fraxini

Migeon, Alain, Malagnini, Valeria, Navajas, Maria & Duso, Carlo 2007
2007
Loc

Schizotetranychus fraxini

Reck 1948
1948
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