The genus Paraplonobia Wainstein and Neopetrobia Wainstein (Acari, Trombidiformes, Tetranychidae) from Saudi Arabia: new species, new records and key to the world species of Paraplonobia

Abstract The two tetranychid genera Paraplonobia Wainstein and Neopetrobia Wainstein (Trombidiformes: Tetranychidae) are reported for the first time from Saudi Arabia. Three new species Paraplonobia (Anaplonobia) arabica Mirza & Alatawi, sp. n., Paraplonobia (Anaplonobia) haloxylonia Alatawi & Mirza, sp. n. and Paraplonobia (Anaplonobia) tabukensis Kamran & Alatawi, sp. n. are described and illustrated based on adult females, collected from Prosopis juliflora (SW.) Dc. (Fabaceae) and Haloxylon salicornicum Bunge (Amaranthaceae) from two different regions of Saudi Arabia. Neopetrobia mcgregori (Pritchard and Baker) is redescribed and illustrated based on female collected from Cynodon dactylon L. (Poaceae).The diagnostic morphological features including leg chaetotaxy of all known species of the subgenus Anaplonobia is tabulated. A key to the world species of the genus Paraplonobia is also provided.

The genus Paraplonobia includes 32 species to date, which are widely distributed throughout the world. The subgenera Anaplonobia, Paraplonobia, and Brachynychus include 22, nine and one species, respectively (Baker and Tuttle 1972, Meyer 1987, Migeon and Flechtmann 2004.
The subgenera Anaplonobia and Paraplonobia have a coxal setal formula of 2-2-1-1 while the subgenus Brachynychus has a coxal setal formula of 4-3-2-2. The subgenus Anaplonobia differs from Paraplonobia by having anastomosed peritremes while the later has simple peritremes (Gutierrez 1985. The genus Neopetrobia also belongs to the tribe Hystrichonychini and morphologically closely resembles the genus Paraplonobia except for the fourth pair of dorsocentral setae f 1 which are widely spaced as compared to setae c 1, while f 1 setae are normally spaced as c 1 in Paraplonobia (Meyer 1987). The genus Neopetrobia has been categorized into three subgenera; Neopetrobia, Reckia Wainstein and Langella Wainstein (Gutierrez 1985). The subgenus Neopetrobia is different from other two subgenera by having integument without tuberculate or reticulate pattern and rounded or spindle shaped dorsal setae and includes ten species to date   (Ugarov & Nikolskii), and T. urticae (Koch) (Martin 1972, Alatawi 2011. The genus Paraplonobia is poorly known from Arabian peninsula. Previously, two species P. (A.) harteni Meyer and P. (P.) dactyloni Smiley & Baker were reported from Yemen (Meyer 1996;Smiley and Baker 1995).
Two genera, Paraplonobia and Neopetrobia, are reported upon for the first time from Saudi Arabia with three new species: Paraplonobia (Anaplonobia) arabica sp. n., P. (A.) haloxylonia sp. n. and P. (A.) tabukensis sp. n. which are described and illustrated based on adult females. The male of P. (A.) haloxylonia sp. n. is also described and illustrated. Neopetrobia mcgregori (Pritchard & Baker) is redescribed and illustrated based on female.

Materials and methods
The mite specimens were collected by shaking the plant parts, especially leaves, onto a white sheet of paper. Mites found moving on paper were collected with the help of a camel hairbrush and preserved in small vials containing 70% ethanol. Preserved mite specimens were observed under a stereomicroscope (SZX10, Olympus, Tokyo, Japan) and mounted on glass slides in Hoyer's medium. The mounted specimens were examined under phase contrast microscope (DM2500, Leica, Wetzlar, Germany). Different body parts were pictured using an auto montage software system (Syncroscopy, Cambridge, UK), then drawn with Adobe Illustrator (Adobe System Inc., San Jose, CA, USA). All measurements are in micrometers. The terminology used in this paper follows that of Lindquist (1985). All type specimens were deposited at Acarology Laboratory, Department of Plant Protection, College of Food and Agricultural Sciences, King Saud University except one each of female and male paratypes of Paraplonobia (Anaplonobia) haloxylonia sp. n., female paratype each of P. (A.) arabica sp. n., and P. (A.) tabukensis sp. n., with Accession numbers, OSAL 0115769, OSAL 00115768, OSAL 0110333 and OSAL 0110332 respectively, that were deposited at Ohio State University Acarology Laboratory (OSAL), USA.
Peritremes anastomosed, coxal setal formula 2-2-1-1. The subgenus Anaplonobia includes 22 species (Migeon and Flechtmann 2004). The species of the subgenus Anaplonobia can be grouped into two categories: 1) Eight species with dorsal body setae slightly shorter/as long as or longer than distances to the bases of consecutive setae (Tables 1 and 2), second group with dorsal body setae distinctly shorter than distances between their bases, contains 17 species including three new species (P. (A.) arabica sp. n., P. (A.) haloxylonia sp. n., and P. (A.) tabukensis sp. n.) reported in this study (Table 1, 2).
Shape of setae (spatulate, subspatulate, lanceolate or setiform), comparative length of setae with respect to the distance of setae next behind, shape of peritremes (compact anastomose, branched or weakly anastomosed), propodosomal shield (pebbled, lobbed, with longitudinal/transverse striations), hysterosoma (medially with closely/ widely spaced striations), comparative length of leg I with respect to body length (shorter/longer) and leg chaetotaxy are the major diagnostic characters vary among/ within the species of subgenus Anaplonobia (Table 1, 2).
Most species of the subgenus Anaplonobia have been reported from USA, Mexico, South Africa and Pakistan and collected mostly from three host plants families Asteraceaea, Fabaceae and Poaceae   (Table 1).
The specimens of new species P. (A.) arabica sp. n., collected from Prosopis juliflora from three different regions (Riyadh, Tabuk, and Jazan) of Saudi Arabia, are morphologically similar except for some variations in setal counts on Tibia II and Tarsus I-II-III. ( Table 2). The variations in the setal count of leg I-II-IV (Tibia and Tarsus) in P. (A.) prosopis had been found also in the description made by Tuttle and Baker (1964) from USA and Toroitich and Ueckermann (2009) from Kenya (Table 2). However, in some other species of the subgenus Anaplonobia, setal variations on genua, tibiae and tarsi have been found among the different specimens collected from the same host and location within the same species. i.e. genua I (8-9) in P. (A.) candicans, tibia I (12-13) and tarsus II (12-13) of P. (A.) glebulanta, and tarsus III (12-13) of P. (A.) theroni (Table 2).
Diagnosis. Dorsal body setae subspatulate, serrate, expanded distally and distinctly shorter to the distances of setae next in line, first pair of dorsocentral setae c1 reaching 2/3 to the distance of setae d1, setae c1 almost 1.5 times widely spaced than setae f1, setae e 2 , f 1 , f 2 and h 1 set on small tubercles, dorsal hysterosomal striations widely spaced, propodosoma medially with longitudinal broken striations, stylophore with a  small mediocephalic emargination, peritremes branched tube like compact anastomosing, leg I shorter than body length.
Male. Not in collection. Etymology. The specific epithet is derived from the region "Arabia" from where type specimens were collected. Diagnosis. Dorsal setae lanceolate, densely serrate, not set on tubercles and distinctly shorter to the distances of setae next behind, dorsocentral setae (c1, d1 and e1) almost 1/3 to the distance of setae next behind, propodosoma medially with weak, longitudinal irregular striations, hysterosoma with transverse and closely spacedstriations medially, stylophore slightly notched anteriorly, peritremes anastomosed distally, with few long thread like branches, and hysterosomal striations closely spaced, leg I shorter than body.
Etymology. The specific epithet is derived after the host plant, Haloxylon salicornicum from which some type specimens were collected.
Male. Not in collection. Etymology. The specific epithet is derived from the region of Saudi Arabia, Tabuk, from where it was collected.
True claws pad like, each bearing a pair of tenant hairs; empodial pad longer than true claws, bearing a row of tenant hairs, distally not coalescent; dorsum with 3 pairs of prodorsal setae which are short and spindle shaped or spatulate; setal tubercles small or nonexistent; fourth pair of dorsocentral setae (f 1 ) widely spaced, not normal as c 1 ; peritremes anastomosing distally.