Tetranychus salicornicus, Alatawi & Kamran, 2018

Alatawi, Fahad Jaber & Kamran, Muhammad, 2018, Spider mites (Acari: Tetranychidae) of Saudi Arabia: two new species, new records and a key to all known species, Journal of Natural History 52 (7 - 8), pp. 429-455 : 439-445

Tetranychus salicornicus sp. nov.

( Figures 13 −24)

Diagnosis (based on male and female)

Male: Aedeagus with curved neck, head forming 40° angle with main shaft and posteriorly hooked downward. Female: Dorsomedial striation on hysterosoma tranverse; the striations on pre-genital area irregular, transverse-oblique and complete.

Description ( Figures 13 –24)

Adult female (n = 29). Measurement of holotype followed by paratypes (in parentheses).

Dorsum ( Figure 13 ). Length of body including gnathosoma 425 (417 – 431), excluding gnathosoma 315 (310 – 317), maximum width (at the level of setae c) 236 (229 – 239). Prodorsum entirely with longitudinal striations; hysterosomal striations transverse medially; oblique longitudinal laterally; striations between e 1 and f 1 transverse. All dorsal striations without lobes. All dorsal setae setiform, serrate, not on tubercles; length of dorsal setae: v 2 63 (60 – 65), sc 1 110 (105 – 111), sc 2 69 (68 – 74), c 1 94 (90 – 96), c 2 94 (90 – 96), c 3 82 (78 – 84), d 1 88 (83 – 90), d 2 94 (88 – 95), e 1 82 (82 – 86), e 2 85 (83 – 88), f 1 94 (90 – 99), f 2 77 (76 – 80), h 1 32 (30 – 32). Distance between dorsal setae: v 2 –v 2 54 (50 – 57), v 2 –sc 1 22 (20 – 24), sc 1 –sc 2 57 (55 – 62), sc 1 –sc 1 72 (70 – 77), sc 2 –sc 2 180 (175 – 185), c 1 –c 1 79 (79 – 86), c 1 –c 2 32 (30 – 34), c 2 –c 3 57 (55 – 59), c 2 –c 2 140 (135 – 140), c 3 –c 3 230 (225 – 235), d 1 –d 1 76 (70 – 78), d 1 –d 2 41 (40 – 45), d 2 –d 2 150 (145 – 155), c 1 –d 1 38 (35 – 39), c 3 –d 2 57 (56 – 63), e 1 –e 1 47 (47 – 54), e 1 –e 2 50 (49 – 55), e 2 –d 2 60 (60 – 66), e 2 –e 2 130 (125 – 135), f 1 –f 1 38 (36 – 40), f 2 –f 2 88 (85 – 95), f 1 –f 2 32 (30 – 34), f 1 –d 1 91 (89 – 95), h 1 –h 1 22 (20 – 24).

Venter (Figure 14). Striations on ventral idiosoma between coxae transverse and simple, pregenital striations complete transverse and oblique. Subcapitular setae, m 47 (44 – 48), m–m 44 (44 – 46). Length of and distances between intercoxal setae: 1a 47 (47 – 55), 1a–1a 32 (30 – 34), 3a 47 (45 – 50), 3a–3a 66 (66 – 70), 4a 53 (50 – 57), 4a–4a 47 (47 – 55); length of coxal setae 1b 52 (49 – 55), 1c 57 (55 – 59), 2b 57 (52 – 59), 2c 73 (72 – 80), 3b 85 (77 – 85), 4b 50 (45 – 50); aggenital setae ag 50 (45 – 50), ag–ag 88 (85 – 91); genital setae two pairs g 1 34 (30 – 34), g 2 35 (30 – 35), g 1 –g 1 28 (27 – 30), g 2 –g 2 66 (64 – 67), g 1 –g 2 25 (24 – 27); anal setae two pairs ps 1 22 (21 – 22), ps 2 20 (20 – 21), ps 1 –ps 1 37 (35 – 38), ps 2 –ps 2 43 (37 – 43); para-anal setae h 3 41 (36 – 42), h 3 –h 3 91 (88 – 93).

Gnathosoma (Figures 15–16). Stylophore rounded anteriorly with longitudinal striations dorsally. Peritreme hooked distally; palpfemur with one seta dPFe 38 (37 – 39), palpgenu with one seta, l’’PGe 27 (25 – 28), palptibia with three setae dPTi 23 (20 – 22), l’ PTi 20 (20 – 213) l’’PTi 10 (9 – 10) and a tibial claw; Palptarsus 12 long, 9 wide, longer than wide, with three simple setae a 8 (8 – 9), b 8 (8), c 11 (10 – 11), two blunt-tipped eupathidia, a spinneret (6.5 long, 3.5 wide) and one solenidion 4 (4).

Legs ( Figures 17 –20). Length of legs I – IV (with coxae) 267 (255 – 270), 205 (200 – 210), 214 (210 – 219), 236 (230 – 245), respectively. Number of setae and solenidia (in parentheses) on legs I – IV: coxae 2 – 2 – 1 – 1, trochanters 1 – 1 – 1 – 1, femora 10 – 6 – 4 – 4, genua 5 – 5 – 4 – 4, tibiae 9(1) – 7 – 6 – 7, tarsi I with 10 tactile setae, two sets of duplex setae, three eupathidia and one solenidion (four tactile setae proximal to proximal set of duplex setae, two tactile setae and solenidion almost in line with proximal set of duplex setae); tarsi II with nine tactile setae, one set of duplex setae, three eupathidia and one solenidion; tarsi III and IV each with nine tactile setae and one solenidion. Empodia split into three pairs of hairs and with a dorsal spur ( Figure 17 (a)).

Male. (n = 5; Figures 21 – 24).

Dorsum. Dorsal setae same as in female, not set on tubercles.

Aedeagus. Main shaft 8.5 (8.5 – 9) long, 3.80 (3.5 – 4) wide, maximum length of neck 1.75 (1.60 – 1.75), maximum width 0.95, head of aedeagus with a posterior projection 1.10 long, apically hooked downward, axis of head forming 40° angle with the shaft (Figures 21, 21(a)).

18. leg II; 19. leg III; 20. leg IV

Legs. Tarsus I with two sets of duplex setae, 10 tactile setae, three eupathidia and three solenidia, tarsus II with one set of duplex setae, eight tactile setae, three eupathidia and one solenidion, empodia split distally and with a prominent dorsal spur (Figures 23, 24).

Etymology. The specific epithet ‘salicornicus’ is derived from the species name of the host plant “ Haloxylon salicornicum ”.

Remarks. The armenychus species group in the genus Tetranychus Dufour is characterised by entirely transverse dorsocentral hysterosomal striations ( Flechtmann and Knihinicki 2002). Currently, this group includes only seven species: T. armeniaca Bagdasarian , T. cobrensis Baker and Tuttle , T. iraniensis Mahdavi et al. , T. graminae Flechtmann , T. mcdanieli McGregor , T. pacificus McGregor and T. rhagodiae Miller ( Flechtmann and Knihinicki 2002; Flechtmann and Navia 2007; Mahdavi et al. 2013). The new species T. salicornicus sp. nov. closely resembles T. pacificus and T. mcdanieli because all three species have a similar angled aedeagus with long posterior projection of head. The new species differs from the males of T. pacificus and T. mcdanieli by posterior projection of aedeagus head strongly turned downward distally vs not turned downward distally, tapered and straight, length of posterior projection almost equal to or slightly longer than the width of aedeagus neck vs posterior projection 2 – 2.5 times longer than the width of aedeagus neck; and from the female of the new species by its pregenital area with complete transverse and oblique striae vs irregular, sparse medially and incomplete/vague in T. pacificus or broken longitudinal in T. mcdanieli . The new species also differs from females of T. pacificus by dorsal striations without lobes vs with lobes in T. pacificus .

Type material

Holotype female and 17 paratypes (15 females, two males), Salsola imbricata , ( Amaranthaceae ), College of Food and Agriculture Sciences, King Saud University , Riyadh, 24°43 ʹ 30.687N, 46°36 ʹ 30.404E, 11 December 2014; paratypes: (nine females, three males), Haloxylon salicornicum, Salbookh Road , near Dariyah , Riyadh, SA, 24° 50.57′N, 46°33.149′E, 21 September 12 October 2012; three females, H. salicornicum , Makkah road near police checkpost, Riyadh, 24º31 52.97N, 46º26 27.44E, 18 October 2012; all collected by M. Kamran.

Key to the species of the armenychus species group Wainstein in the genus Tetranychus Dufour (males)

1. Posterior projection of aedeagi long, reaching well beyond the bend of the neck ................................................................................................................................................. 2

− Posterior projection of aedeagi very small or absent.............................................................. 4

2. Posterior projection hooked apically downward, length of posterior projection almost equal to or slightly longer than width of aedeagus neck ( Figure 25 (h)...... ....................................................................................................................... T. salicornicus sp. nov.

− Posterior projection not hooked apically downward, almost straight, length of posterior projection almost 2 – 2.5 times width of aedeagus neck ......................................................... 3

3. Aedeagus strongly sigmoid in shape, posterior projection long tapering strongly distally, without anterior projection/knob (male) ( Figure 25 (f)), dorsal striations with lobes (female).................................................................................................................... T. mcdanielli McGregor

− Aedeagus not sigmoid, angular, with large tapered posterior projection, anterior projection very small (male) ( Figure 25 (g)), dorsal striations with lobes (female)........... ................................................................................................................................. T. pacificus Mcgregor

4. Aedeagal neck with anterior or posterior angulations, aedeagus with head slightly to much wider than the neck................................................................................................................... 5

− Aedeagus almost rounded at tip with no defined head and neck ( Figure 25 (e))........... ............................................................................................. T. iraniensis Mahdavi and Ueckermann

5. Aedeagal neck/knob with minute anterior and posterior angulations, head slightly wider than the neck ( Figure 25 (c)).................... .................... T. cobrensus Baker and Tuttle

6. Aedeagus without prominent posterior projection .................................................................. 7

− Aedeagus with prominent tapered posterior projection ( Figure 25 (d))............................... ...................................................................................................................................... T. rhagodiae Miller

7. Aedeagal neck almost at right angle with the shaft; aedeagus head dorsally flat ( Figure 25 (a))...................................................................................... T. armeniaca Bagdasarian

− Aedeagal neck forming an obtuse angle with the shaft; aedeagus head rounded posterodorsally ( Figure 25 (b)).............................................................. T. graminae Flechtmann

Figures

Figure 13. Tetranychus salicornicus sp. nov., female, dorsum.

Figure 25. Shape of aedeagi of different species belonging to armanychus species group:(a) Tetranychus armeniaca Bagdasarian (reproduced from Bagdasarian 1954); (b) T. graminae Flechtmann (reproduced from Flechtmann and Navia 2007); (c) T. cobrensus Baker and Tuttle (reproduced from Baker and Tuttle 1972); (d) T. rhagodiae Miller (reproduced from Miller 1966); (e) T. iraniensis Mahdavi and Ueckermann (reproduced from Mahdavi et al. 2013); (f) T. mcdanieli McGregor; G. T. pacificus McGregor (reproduced from Seeman and Beard 2011); (h). T. salicornicus sp. nov. (The scale bar applies to T. salicornicus n. sp., T. pacifus and mcdanieli (the latter reproduced from Seeman and Beard 2011), but not to other aedeagi since their earlier descriptions did not indicate the scale).

Figures 17, 17a, 18, 19, 20. Tetranychus salicornicus sp. nov., female, 17. leg I; 17(a) empodium of leg I;.