Eutetranychus orientalis (Klein)

Kamran, Muhammad, Khan, Eid Muhammad & Alatawi, Fahad Jaber, 2018, The spider mites of the genus Eutetranychus Banks (Acari, Trombidiformes, Tetranychidae) from Saudi Arabia: two new species, a re-description, and a key to the world species, ZooKeys 799, pp. 47-88 : 47

Eutetranychus orientalis (Klein) Figures 47, 48, 49

Anychus latus Klein, 1936: 3.

Eutetranychus orientalis (Klein): Baker and Pritchard 1960: 464−467.

Eutetranychus monodi Andre, 1954: 859.

Eutetranychus anneckei Meyer, 1974: 148−149.

Eutetranychus sudanicus Elbadry, 1970: 301−305.

Previous records from Saudi Arabia.

Martin 1972, Alatawi 2011.

Material examined.

Twenty seven females, Citrus sp., Education Farm, King Saud University, Riyadh, 24°44.253'N, 46°37.225'E, 01 Feb 02 Apr 2009, 26 Oct 01 Nov 2010, 14, 24 Apr 2011, leg. J Basahih, and T Martibi; one female, Citrus sp., Dariyah, Riyadh, 24°44.866'N, 46°34.624'E, 02 Feb 2009, leg. J Basahih; seven females, Vitis vinifera and Citrus sp., Ammaria, Riyadh, 24°49.194'N, 46°28.163'E, 12 Apr 2009, 10 Mar 2011, leg. W Negm; five females, Hayer, Riyadh, 24°23.611'N, 46°49.464'E, 28 Apr 2009, leg. J Basahih; two females, Rhodat ul Khoraim, Riyadh, 03, 9 May 2009, leg. J Basahih;, three females, Citrus sp., Waseel, Riyadh, 24°48.786'N, 46°31.180'E, 11 Oct 2009, 23 Apr 2010, leg. J Basahih; four females, Citrus sp., Juniperus sp., and Grasses under P. dactylifera , near students housing King Saud University, Riyadh, 24°43.484'N, 46°36.985'E, 20 Sep 2010, 28 Mar 2011, leg. J Basahih; eight females, P. dactylifera , Imam Muhammad Ibn Saud University, Riyadh, 24°48.759'N, 46°42.735'E, 13, 27 Dec 2010, 01, 25 Jan 25, 23 Mar 2011, leg. J Basahih; twelve females, Citrus sp., Nijran, 18 Apr 28 Sept 2011, leg. Jaid; six females, Citrus sp. Qassim, 26°00.612'N, 044°00.166'E, 26 May 2011, leg. J. Basihih and A. Majeed; two females, Acacia sp., and soil under P. dactylifera Al-Madina, 24°26.335'N, 39°36.866'E, 19 Jun 13 Oct 2011, leg. M Kamran and W Negm; eleven females, Datura sp., and Citrus sp., Wadi Namar, Riyadh, 24°34' 18.9N, 46°40' 40.4E, 14 Oct 2012, leg. M Kamran; two females, Nerium oleander , Dariyah, Riyadh, 24°44.866'N, 46°34.624'E, 5 Apr 2014, 18 Mar 2015 leg. M Kamran; two females, Tamarix sp. and Saccharum sp., Deesa valley, Tabuk, 27°36'049N, 36°25'785E, 17, 18 Oct 2015, leg. M Kamran; two females, P. dactylifora , Al-Sail Kabeer, Taif, 21°33.882'N, 040°18.048'E, 15 Oct 2016, leg. M Kamran and M Rehman; two females, Citrus sp., Khayber, 25°34.563'N, 39°19.375'E, 1 Nov 2016, leg. M Kamran and E M Khan; nine females, Citrus sp., Ziziphus sp., and Albizia sp., Al-Ula, 26°48.757'N, 37°58.241'E, 2 Nov 2016, leg. M Kamran and E M Khan; twenty five females, Citrus sp., Mangifera sp., P. dactylifera , Olea sp., Psidium sp., Azadirachta sp., and Ficus sp., Al-Ula, 26°39.923'N, 37°55.032'E. 3, 4, 5, 6, 7 May 2017, leg. E M Khan and M Rehman.

Discussion.

Variations within the different populations of Eutetranychus orientalis .

Morphological variations of Eutetranychus orientalis in 91 female specimens that were collected from 28 various host plants and 80 different localities in six regions of Saudi Arabia during 2009 to 2017 are shown in Figures 47A−H, 48, and 49. The lengths and shapes of dorsal body setae, striation patterns between setae d1 and e1, and chaetotaxy of leg segments including femora and tibiae have been presented in Table 1.

The most prominent variations within in E. orientalis populations are in the length and shape of dorsal setae. These variations including, dorsocentral setae length [c1 (10−51), d1 (12−50), e1 (14−41) and f1 (10−45)] and shape [oblanceolate, ovate, obovate, subspatulate and spatulate] (Figure 47A−H). Also, these setae were either very short far behind the bases of next consecutive setae (Figure 47B, D, E, G), reaching one third to half (Figure 47A, F) or almost extending to the bases of next consecutive setae (Figure 47C, F, H). Dorsal setae sc1, sc2, c2, c3, d2, e2, f2, and h1 were also varied in shape (oblanceolate, subspatulate, spatulate, slender), mostly among the specimens of different populations. The same variations in these dorsal setae have been recorded in populations of this species collected from different countries ( Baker and Pritchard 1960, Chaudhri et al. 1974, Meyer 1974, Meyer 1987, Khanjani et al. 2017).

Striations patterns between the dorsocentral setae d1 and e1 varied either forming “V” shaped pattern (n = 80; Figure 47A-E, G, H) or a longitudinal pattern (n = 11; Figure 47F) and varied even among the specimens of the same population. Similar variations in dorsal striation patterns have also been observed by Chaudhri et al. (1974), Meyer (1987), and Khanjani et al. (2017).

Moreover, all dorsal setae in E. orientalis collected in this study are set on tubercles; lateral setae are on prominent tubercles as compared to dorsocentral setae (c1, d1, and e1) which are mostly set on relatively smaller tubercles (n = 73). However, in some specimens setae c1, d1, and e1 are without distinct tubercles (n = 19) as shown in Figure 47D, G. This variation was observed even among the individuals of a single population collected in the current study. A similar variation has been illustrated by Chaudhri et al. (1974). However, E. orientalis dorsocentral setae c1, d1, and e1 were described and illustrated only on small tubercles ( Meyer 1987, Khanjani et al. 2017).

Our observations also showed that legs setal count was fixed in E. orientalis on coxae, trochanters, and genua I−IV (2−1−1−1, 1−1−1−1 and 5−5−2−2), respectively (see Table 1). Chaetotaxy on leg femora and tibiae were observed mostly as I−IV (8−6−3−1) and (9(1)−6−6−7), respectively. The differences in legs chaetotaxy of the specimens of E. orientalis belonging to the same and different populations were observed on femora I 7 (n = 3), 7/8 (n = 10); femora II 5/6 (n = 2), 6/7 (n = 2); femora III 3/4 (n = 10), 3 (n = 40); 4 (n = 23), 2/3 (n = 3); femora IV 1/2 (n = 8); on tibiae I 8/9 (1) (n = 7), 8 (1); tibia II 6/7 (n = 3); tibia III 6/5 (n = 2); tibia IV 7/6 setae (n = 2) in the current study, similar to the variations on femora and tibiae documented by Khanjani et al. (2017) in E. orientalis populations collected from Iran and Australia.

The spermathecal sacculus terminally varied from rounded to slightly pointed in some specimens of this study (Figures 48A, 49A). Also, the length of the spinneret on the palp tarsus varied from three to four times compared to its width. Similarly, Khanjani et al. (2017) reported that shape of spermathecal sacculus varied distally from rounded to pointed and that spinneret length also varied in E. orientalis . However, Meyer (1987) considered variations in shape of spermathecal sacculus (rounded or pointed distally) and length of spinneret (3 to 4 times as long as its width) as a method to differentiate E. fici Meyer from E. orientalis .

The morphological variations in E. orientalis have resulted in misidentifications and additions of new species in the genus Eutetranychus . Because some morphological variations have now been reported in E. orientalis , four species Anychus ricini Rahman & Sapra, 1940, E. monodi André, 1954, E. sudanicus El Badry, 1970, and E. annecki Meyer, 1974 were synonymized with E. orientalis by Meyer (1987) and Bolland et al. (1998).

Eutetranychus fici Meyer, reported from Africa, was separated from E. orientalis by the slightly longer dorsocentral setae, shape of spermathecal sacculus, and length of palp spinneret (Table 2; Meyer 1987). The three species E. pruni , E. ricinus , and E. sanaae reported from Yemen were differentiated from E. orientalis by variation in the number of setae on femora I and IV, shapes of dorsal setae, and striation pattern between setae d1 and e1 ( Smiley and Baker 1995). Eutetranychus phaseoli Nassar & Ghai, 1981 reported from India was separated from E. orientalis based on the difference in numbers of setae on femur I and distances between dorsal setae e1 and f1 (see also Table 2). The two species E. guangdongensis and E. xianensis , reported from China, were distinguished from E. orientalis and E. banksi , respectively, based only on differences in lengths of dorsal setae ( Ma and Yuan 1982) (Table 2). However, the leg chaetotaxy of these two species were mentioned in the original descriptions as being similar in E. orientalis ( Ma and Yuan 1982) (Table 2).

Because these seven species have been differentiated in their original descriptions by only one or more variable characters which have also been observed in E. orientalis populations ( Chaudhri et al. 1974, Meyer 1987, Khanjani et al. 2017) as well as this study (see Table. 2), these seven Eutetranychus species ( E. phaseoli , E. guangdongensis , E. xianensis , E. fici , E. pruni , E. ricinus , and E. sanaae ) are suggested as synonyms of E. orientalis in this study.