A New Record and Description of a New Species of the Genus Thrips, with an Updated Key to Species from Iran

An illustrated key is provided to distinguish the 26 species of the genus Thrips L. (Thripidae: Thripinae) recorded from Iran. Thrips alavii Mirab-balou, Tong & Chen, sp. n. is described and illustrated. Thrips alliorum (Priesner) is newly recorded for the fauna of Iran. A checklist is provided for all recorded species in this genus from Iran, with information on the geographical distribution for each species.


Introduction
Thrips L. (Thripidae: Thripinae) is the largest genus in the Thysanoptera subfamily Thripinae, with about 280 described species in the world. Most species of Thrips are flowerliving, although a few appear to breed mainly on leaves (Mound and Ng 2009), and several species play an important role in the pollination of crops. For example, T. hawaiiensis (Morgan) is an effective pollinator for oil and banana palms in the pacific region, and T. imagines Bagnall and T. obscuratus (Crawford) in Australia and New Zealand (Kirk 1984). Several species of Thrips are considered crop pests in various parts of the world, such as T. angusticeps Uzel, T. flavus Schrank, T. hawaiiensis (Morgan), T. meridionalis Priesner, and T. tabaci Lindeman (Moritz et al. 2001). The latter species is well known as the most important pest of onion crops, greenhouses and ornamental plants in Iran (Khanjani & Mirab-balou 2005 a,b;Mirab-balou et al. 2008Mirab-balou et al. , 2009Mirab-balou et al. , 2012, and it is a carrier of some Tospovirus diseases on ornamental plants, especially in Tehran and Markazi provinces (Ghotbi et al. 2003). Recently, transmission of an isolate of Tomato spotted wilt virus on cineraria (Senecio sp.) by T. tabaci has been confirmed in Fars province, Iran (Rasoulpour and Izadpanah 2003).
Currently, 26 species of the genus Thrips have been recorded in Iran (Bhatti et al. 2009). A key to 72 species of Thrips is available in zur Strassen 's book (2003), and is useful for the study of Iranian thrips. The objective of our present paper is to provide an illustrated identification key to all 26 species known from Iran, including one new species, and one new record for the fauna of this country. In addition, some important characteristics shared by Iranian species of Thrips are listed in Table 1; a checklist is provided for all recorded species in this genus from Iran, with information on geographical distribution for each species (Table 2). Deciding the true host plant of Thysanoptera species is difficult, because plants on which adults are found are not always the same as those on which larvae can develop. Nevertheless, thrips-associated plants in Iran are listed in Table 3.

Materials and Methods
Thrips specimens were collected from different sites in Iran during 2007-2011. The method for preparing and mounting thrips on slides follows Mirab-balou & Chen (2010). All descriptions, measurements, and photos were made with a Leica DM IRB microscope, with a Leica Image 1000 system. All specimens were deposited in the Institute of Insect Sciences,

Genus Thrips L.
All members of the genus Thrips lack ocellar setae pair I on the head, and they all have paired ctenidia on abdominal tergite VIII, posteromesad to the spiracles. Other characteristics, such as number of antennal segments and setae on the forewing veins, and number of discal setae on the sternites, vary between species (Palmer 1992;Nakahara 1994;Mound and Masumoto 2005;Mirabbalou and Chen 2011). See Bhatti (1980) and Mound & Masumoto (2005) for generic characteristics, and the list of its synonyms.
Among Iranian species of the genus Thrips, T. tabaci (commonly known as onion thrips or tobacco thrips) is widely distributed. This polyphagous species is particularly abundant in warm, dry sites, especially where onion, its preferred host, is grown. It is a major pest of glasshouse crops, such as cucumber, sweet pepper, chrysanthemum, and many bedding plants in Iran ). Taxonomically, T. tabaci is principally characterized by rows of ciliate microtrichia on the sides of abdominal tergites II-VII, 4-7 distal setae on the first vein of the forewing, three lateral marginal setae on abdominal tergite II, and narrow transversely elongate pore plates on sternites III-V (males only). Another species, T. major Uzel, is characterized by having rows of ciliate microtrichia on the sides of abdominal tergites II-VII, similar to T. tabaci, but it can be distinguished from the latter by the following characters: tergite VIII with comb present laterally, forewing first vein with three distal setae, and tergite IX with two pairs of campaniform sensilla. Males of this species are very rare; we found less than ten males, but more than a thousand females.
Although T. iranicus and T. pistaciae have been recorded in Iran (Bhatti et al. 2009), little information on these two species is available. Dyadechko (1977) listed several characteristics for these two species as follows: (1) antennal segment V much shorter than IV in both species; (2) forewing first vein with 6-8 distal setae in T. pistaciae, and 3 distal setae in T. iranicus; (3) antennal segments I-III brownish yellow in T. pistaciae, but segments I and IV dark in T. iranicus; (4) abdominal tergite VIII without comb on posterior margin in T. pistaciae.

Measurements
Head. The head was 1.5 times as wide as it was long (Figure 1). The cheeks were convex, with two pairs of ocellar setae; pair III was situated outside of the ocellar triangle, and without sculpture between ocelli. Ocellar setae pair III was situated outside of ocellar triangle, behind the front ocellus. Postocular setae I & III were a little longer than others ( Figure 1). The antennal was 8-segmented, with forked sense cones on antennal segments III & IV (Figure 30). Segment VI was longer than others. Antennal segments I to VIII had a length/width as follows: 0.94, 1.65, 2.66, 2.62, 2.25, 3.6, 1.5 and 2.
Thorax. The pronotum was 1.6 times as wide as it was long, (Figure 8); two pairs of long posteroangular setae were present; posterior margin with three pairs of setae; at least 30-33 discal setae were present. Mesonotum with median setae far from the posterior margin; metanotum longitudinally striate (but a little more broadly striate than T. vulgatissimus), MCS was absent; median pair of setae were situated at the anterior margin. Mesofurca with spinula. Forewings first vein with three setae on the distal half, second vein with complete row of setae (Figure 7).
Abdomen. Abdominal tergites II-VIII without sculpture medially, and the median setae were small and wide apart; tergite II with 3 lateral marginal setae; tergites V-VIII with paired ctenidia laterally, on VIII posteromesad to spiracle; the comb on the posterior margin of tergite VIII was complete and long ( Figure 24); pleurotergites with discal setae (Figure 13); tergite IX with two pairs of campaniform sensilla; tergite X with median slit at apex; sternites II-VII with discal setae arranged in one row (Figure 42), II with one, and III-VII with 9-11 discal setae; sternite II with two pairs of posteromarginal setae, III-VII with 3 pais; setae S1 on sternite VII arising just in front of margin. The ovipositor was well developed.

Male. Unknown.
Remarks. This new species is similar to T.
vulgatissimus, but it is readily distinguished from the latter by the following characters: MCS absent (vs. present in T. vulgatissimus); metanotal median setae situated at anterior margine (vs. far behind anterior margin in T. vulgatissimus); abdominal sternites II-VII with discal setae that arranged in single row (vs. arranged in irregular double row in T. vulgatissimus). It is also distinguished from T. alliorum by the following character states: metanotal median setae situated near anterior margin (vs. behind anterior margin in T. alliorum); abdominal tergite VIII with complete comb on posterior margin (vs. may appear absent or represented by a few microtrichia laterally in T. alliorum); head broader than length, and postocular setae arranged in one row (vs. head elongate, and median postocular setae situated far behind rest of row in T. alliorum).
Etymology. This species is named in honor of Eng. Jalil Alavi of the Agricultural & Natural Resources Research Center of Khorasan-e-Shomali province, Bojnourd-Iran.