Nabiseius arabicus, Negm & Alatawi, 2013

Negm, Mohamed Waleed & Alatawi, Fahad Jabr, 2013, First record of Otopheidomenidae Treat, 1955 (Acari: Mesostigmata) in Saudi Arabia, with description of Nabiseius arabicus sp. nov., Turkish Journal of Zoology 37 (2), pp. 184-187 : 185-187

Nabiseius duplicisetus Chant and Lindquist, 1965: 516 . Nabiseius arabicus sp. nov. Negm and Alatawi

Nabiseius arabicus sp. nov. can be distinguished from other known species of Nabiseius by the following combination of characters: 2 pairs of metasternal setae on integument; 2 pairs of poroids on sternal shield; dorsal shield entire and incised mediolaterally; 4 longitudinal platelets present between genital and ventrianal shields; and 2 pairs of elongate metapodal shields.

Description

Female ( Figures 1–6 ) (n = 5).

Dorsal idiosoma ( Figure 1 ). Dorsal shield entire, 270 (258–282) long and 126 (118–135) wide, rounded posteriorly, deeply incised mediolaterally, with some scattered muscle marks, bearing 17 pairs of simple setae, j1: 5 (4–5); j3: 9 (8–10); j4: 5 (5–6); j5: 7 (6–8); j6: 7 (7–8); J2: 5; J5: 3 (3–4); z2: 10 (8–12); z3: 5 (4–5); z4: 8 (8–9); z5: 8; Z3: 7 (6–7); Z5: 5 (5–6); s4: 5; s6: 6 (5–7); S2: 6 (5–6); S5: 4 (4–5), with 1 pair of lateral setae, r3: 6 (6–7), on striate lateral integument.

Ventral idiosoma ( Figure 2). Tritosternum large, with wide base 15 (14–16) and elongate stem 75 (72–78), normal in shape, biramous, with a pair of slender laciniae. Sternal shield smooth, 65 (61–69) long, 50 (44–56) wide at widest point, bearing 2 pairs of setae on shield edges, ST1: 17 (16–18), ST2: 18 (17–18), and 2 pairs of poroids. Two pairs of metasternal setae, ST3: 18 (16–20), ST4: 15 (14–15) inserted in the integument and lying posterior and lateral to sternal shield. Metasternal shields absent. Genital shield smooth, 94 (87–101) long along midline, 48 (46–50) wide at level of setae ST5, bearing 1 pair of setae, ST5: 15 (15–16), on lateral edges of shield, with rounded membranous anterior margin, shield concavesided medially and quite straight posteriorly. Two pairs of

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narrow and elongate metapodal plates present; primary 25 (23–27) long, accessory 8 (8–9) long. Four longitudinal platelets present between genital and ventrianal shields. Ventrianal shield 67 (64–70) long and 52 (50–54) wide, slightly concave anteriorly, solenostomes absent, with 2 pairs of pre-anal setae, ZV2: 14 (14–15), JV1: 10 (9–10), anus ventral in position, with 1 pair of para-anal setae 12 (11–12) and a post-anal seta 8 (7–8). Two pairs of opisthogastric setae, ZV3: 10 (9–11), JV4: 11 (11–12), inserted on the striated integument posterior to coxa IV. Peritreme ( Figure 5 ): short, 46 (41–51) long, reaching only to the anterior edge of coxae III. Spermatheca ( Figure 3 ): 32 (29–35) long, of phytoseiid type, cervix sac-like with irregular shape, atrium incorporated with cervix, major duct narrow and opening near posterior corner of coxa III and anterior corner of coxa IV.

Gnathosoma . Chelicera ( Figure 4), movable digit edentate, 14 (13–15) long, fixed digit 12 (11–12) long, with 1 tooth and a hyaline sheath distally, pilus dentilis absent. Palp setae of trochanter, femur, genu, and tibia, respectively, 1–4–5–6.

Legs. Number of setae on legs I–IV: coxa 2–1–1–1; trochanter 4–3–4–4; femur 11–8–5–5; genu 9–6–6–6; tibia 8–7–7–5

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Male: Unknown.

Eggs (n = 1, inside female opisthosoma) ( Figure 6) ovoid, 145 long, 100 wide.

Type material. Holotype female, 14 paratype females, on aerial part of Bermuda grass, Cynodon dactylon L. ( Poaceae ) in a date palm orchard, 24°48′N, 46°42′E, 645 m, Riyadh, Saudi Arabia, 12.VII.2011, coll. Mohamed W. Negm. Holotype and paratypes were deposited at the King Saud Museum of Arthropods ( KSMA). All paratypes have the same data as the holotype.

Etymology: The specific epithet arabicus refers to the Arabian Peninsula.

Remarks: According to Zhang (1995), the new species was assigned to the subfamily Treatiinae because of the following characters: dorsal idiosoma with more than 15 setae, ventrianal shield with 7 setae, tritosternum normally developed, spermathecal system of a phytoseiid type and well developed, genua IV fewer than 8 setae, and tibiae IV fewer than 7 setae. Only 3 species of Nabiseius were described: N. duplicisetus , a parasite of an unidentified nabid bug ( Hemiptera : Nabidae ) from Chile ( Chant and Lindquist, 1965); N. rivnayae , found on Tamarix sp. ( Tamaricaceae ) near the Dead Sea in Israel ( Amitai and Swirski, 1980); and N. melinae , found beneath wings of Creontiades sp. ( Hemiptera : Miridae ) in Australia ( Halliday, 1994). However, N. arabicus sp. nov. individuals were collected from Cynodon dactylon in association with thrips ( Insecta: Thysanoptera). In his description and illustrations of N. melinae, Halliday (1994) showed the dorsal idiosoma with 2 shields, while Zhang (1995) distinguished the genus Nabiseius as having only 1 dorsal shield.

Key to species of Nabiseius (adult female)

1- Dorsal shield entire; genital setae present .................... 2 - Dorsal shield divided; genital setae absent .....................

....................................................... melinae Halliday, 1994 2- Anus terminal; 1 pair of metapodal plates ...... ...............

.............................. duplicisetus Chant & Lindquist, 1965 - Anus ventral; 2 pairs of metapodal plates ..................... 3

Figures

Figure 1. Nabiseius arabicus sp. nov. Negm and Alatawi, female, dorsal idiosoma.

Figure 3. Nabiseius arabicus sp. nov. Negm and Alatawi, female, spermatheca.

Figure 5. Nabiseius arabicus sp. nov. Negm and Alatawi, female, peritreme.