Terminology

Phytoseiid mites are about 300-600 µm in length and whitish to light brown in color (Chant 1985; Krantz & Walter 2009). Body of phytoseiid mite can be divided into two parts, gnathosoma and idiosoma. Gnathosoma is the structure located in the front end of mite. It comprises of a pair of pedipalps, a pair of chelicerae, and the subcapitulum, and also a pair of spermatodactyl in adult males. The functions of gnathosoma are sensation, predation, and feeding, and in male, copulation (Chant 1985).

Idiosoma is the major body part includes all parts behind gnathosoma. It comprises four pairs of legs and also dorsal shield and ventral shields. Besides, the female spermatheca is located between the coxa III and coxa IV of adult female.

Phytoseiid mites are sexual dimorphic. Nevertheless, the earlier researchers always described just adult female, rarely studied about male (but some species are opposite, Amblyseius californicus was described by male (McGregor 1954). One reason for this is

the numbers of male are relatively fewer. Another reason is some researchers considered the male are of little taxonomic importance (Tseng 1983). In fact, there are differences between the two sexes of phytoseiid mites. Adult males are relative smaller, with shorter dorsal setae, a fused sterno-genital shield, a copulatory organ, spermatodactyl, growing side-armed to the moveable digit of chelicerae, and the genital orifice opened on the anterior margin of the sterno-genital shield. The taxonomic characters of Phytoseiidae are as follows:

1. Gnathosoma (Fig. 4):

a. Pedipalp (Fig. 4): The pedipalp is divided into 6 segments, coxa, trochanter, femur, genus, tibia, and tarsus. There is a bifurcate seta on the end of tarsus. It is used to sense and assist to detect diets.

b. Chelicera (Fig. 4, 8): Movable digit and fixed digit comprise chelicera. The inner part of digits (fixed digits and movable digits) with teeth; the number of teeth is an important characters. Fixed digit usually has one pilus dentilus. The chelicerae are used to grasp and capture prey.

c. Spermatodactyl (Fig. 8): The spermatodactyl arises from the membranous junction of the movable digit of the male chelicera. It consists of shaft and foot. The foot consists of the heel, the actual foot, the toe, and thorn or hook-like structure which projects laterally from the foot (Beard 2001). This structure is introducing spermatophore into female. It may have different shapes, foot-shaped, horseshoe-shaped, L-shaped, penile shaped, rod-shaped, T-shaped, U-shaped and wand-shaped. This character is not species specific but group specific (Prasad 2013). Chant and McMurtry (2007) considered this character has little taxonomic value due to homoplasy (except genus Graminaseius and Neoseiulus).

2. Idiosoma:

a. Dorsal shield (Fig. 4): The sclerotization of dorsal shield is varied among species.

Its surface may be smooth, reticulated, or rugose. There are some solenostomes and lyrifissures on dorsal shield.

b. Dorsal setation (Fig. 3): Dorsal setae were considered as an important character in Phytoseiidae for a long time, this character could reflect the evolutionary history of Phytoseiidae (Chant & Yoshida-Shaul 1992). However, many different setation systems were applied by different acarologists in the past. Until now, J-Z-S-R system was accepted by most acarologists. In this study, we will describe all species by this system, and also provided comparison among different systems in following paragraph. Fig. 3 shows the hypothetical holotrichous setation of the dorsal shield in the family Phytoseiidae. It provides all dorsal setae known to occur in this family, though there is no known species has this full complement of setae. In taxonomic studies, dorsal setation is of greater value than ventral setation; due to few studies discuss the ventral setation.

c. Dorsal setation pattern:

The dorsal setation pattern is divided to two parts, previous one for podosomal setae, and latter one for opithosomal setae. For example, 10A:9B means 10 setae on podosoma, 9 setae on opithosoma; besides, A, B (or C, D) means more than one pattern in the same number of setae (Chant & Yoshida-Shaul 1989b).

d. Solenostomes and lyrifissures (Fig. 4): Solenostomes (pores) and lyrifissures (poroids) were ignored before because of difficulty of examination. Since some phytoseiid researchers discuss (Hirschmann (1960); Athias-Henriot (1969b; 1970;

1975)), these naming system of these pores were developed. Solenostomes (pores) is defined as the external opening of a gland or gland-like internal structure. They were named by Athias-Henriot (1975) as follows: gd1, gd2, gd4, gd5, gd6, gd8 and gd9.

Beard (2001) proposed an adenotaxy on genus Neoseiulus. Solenostomes gd3 are located on the peritremal shield while solenostomes gd7 are absent in the Phytoseiidae.

The shapes of the solenostomes can be crateriform, crescent, or punctiform. Lyrifissures is defined as a cuticular proprioreceptor structure (Walter 2005) or just as sense organ.

Under light microscopy, these may look like a round pit (cupule) in soft cuticle, or or a slit in hard cuticle.

e. Ventral setation (Fig. 5, 6): Fourteen pairs of setae and a single post-anal seta are known to occur on the ventral surface of the idiosoma of adult Phytoseiidae.

f. Ventral setation pattern: st1 to st5 are fixed setae, and also JV1, JV5, ZV2 also fixed, the formula only focus on present/absent variable setae (JV2, JV3, JV4, ZV1, ZV3). For example: JV3,4: ZV-1,3, which means this species lacks the JV3, JV4, ZV1, ZV3. JV:ZV means none of the variable setae absent (Chant & Yoshida-Shual 1991).

f. Sternal shield (Fig. 5): The sternal shield is located behind the tritosternum, in between coxae I-II, with 3 pairs of setae (st1, st2, st3), two pairs of pores (pst1, pst2), sometimes, posterior margin reduced, t3 off the shield. The shape of sternal shield and ratio of length and width are used to distinguish species. Besides, posterior margin of sternal shield is also important for identification (e.g. straight, with rounded median lobe, with median projection). Male have 5 pairs of sternal setae on sternogenital shield.

g. Metasternal shield (Fig. 5): A pair of metasternal shields are postero-lateral to sternal shield, may absent in some species, with 1 pair of setae (st4) and 1 pair of lyrifissures (pst3). Metasternal shield sometimes is absent.

h. Genital shield (Fig. 5): The genital shield located behind metasternal shield, with genital opening in the front end, and one pair of setae (st5).

i. Ventrianal shield (Fig. 5, 6): The ventrianal shield is behind the genital shield, and is formed by the fusion of ventral shield and anal shield. Only few species retained

the two separate shields (e.g. Chanteius separatus), or only anal shield (e.g. Honduriella maxima). The shape of ventrianal shield, level of reticulation, pre-anal setae are important to identification of species or different genera (Prasad, 2013). The shape of ventrianal shield is variable among species, such as triangle, rectangle, pentagonal, or vase-shaped. The extent of the sclerotization of ventrianal shield is also used to diagnose species, for example, ventrianal shield of Gynaseius liturivorus with unclear margin. Ventrianal shield bears four pairs of pre-anal setae (JV1, JV2, JV3, ZV2), one pair of para-anal setae (Pa) and one post-anal seta (Pst). Four pairs of setae (ZV1, ZV3, JV4, JV5) are set on the membranous integument surround the ventrianal shield.

j. Metapodal plate (Fig. 5): Behind coxa IV and lateral to anterior part of ventrianal shield, there may have 1 or 2 small plates, primary plate and secondary plate, on each side.

k. Peritreme (Fig. 4, 5): The peritreme is a furrow-shape elongation of stigma extend forward up to the level of seta j1, or shorter in some species. It is enveloped by peritremal shield which may extend to the posterior end of coxa IV. Usually, one pairs of solenostomes (gd3) and one pairs of lyrifurres (id3) on preitremal shield.

l. Spermetheca (Fig. 5, 7): Spermatheca locates between the coxa III and IV of adult female. The spermatheca consists of five sections, including vesicle, calyx, atrium, minor and major ducts (Beard 2001). Besides, neck, cannot be found in some species, is the connection between the calyx and the atrium. Most North American acarologists suggest the calyx substitute to cervix, and care should be taken not to confuse this term or structure with the term neck (cervix) as used by European acarologists for the connection between the calyx. The calyx is a sclerotized structure, and the shape is variable, such as tubular, bowl-shaped, bell-shaped, U-shaped etc. The atrium may be small or large, incorporated into the base of the calyx; bifurcate at the junction with

major duct; ring-like; separate from calyx and major duct.

3. Leg (Fig. 4): Adult phytoseiids have 4 pairs of legs, and consist of 7 segments, coxa, trochanter, femur, genu, tibia, tarsus, and apotele. Leg I is longer with the tarsal segment well-endowed with sensory setae and sensillae, and is usually hold up to wavering, functioning as antenna, not for walking. Leg chaetotaxy is followed by Evans (1963). In the study, the segments of leg are described respectively. Coxa is described the coxal formula in the ventral view. In addition, the segments are illustrated and described the chaetotactic formula, including femur, genu, tibia and basitarsus.

a. Macroseta (Fig. 4): The macroseta is a longer and stronger seta on Legs, the present and length of macroseta, especially on leg IV (genus, tibia, tarsus), are important characters for distinguishing species. Beard (2001) provided a clear definition of macrosetae “describe a seta (usually on the legs) that is obviously morphologically differentiated fromthough not always longer than, the other setae (normally thin, setaceous) on the same body part”.

FIGURE 4. Dorsal view of adult female phytoseiids.

FIGURE 5. Ventral view of adult female phytoseiids.

FIGURE 6. Ventral view of adult male phytoseiids.

FIGURE 7. Spermatheca of phytoseiids.

FIGURE 8. Chelicera and spermatodactyl of phytoseiids.