A new species of Octaspidiotus (Hemiptera, Diaspididae) from China

Abstract Adult females of a new species of armored scale insect, Octaspidiotus shanghaiensis sp. n. are described and illustrated from specimens collected in China. A key is provided for the all described species of Octaspidiotus.


Introduction
Scale insects (Hemiptera: Coccoidea) are sap-sucking parasites which are small (generally less than 5 mm) and cryptic in their habitats (Gullan 1997), with at least 30 families and approximately 8000 species (García et al. 2016). Containing more than 2500 described species, Diaspididae is the largest species-rich family in the Coccoidea (García et al. 2016). Adult diaspidid females are sessile and permanently reside on their host plants (Gullan 1997). Adult females have the complete loss of the legs, the reduction of the antennae to a single segment and the modification of the abdomen into a specialized pygidium for forming the test, and these characteristics are the primary recognition features for these insects (Andersen 2010;Balachowsky 1948). Armored scale insects are important agricultural pests and have colonized a diverse set of plant species. They are distributed on every continent except Antarctica (Andersen 2010).
Although the family classification is controversial, the Aspidiotinae and the Diaspidinae are the two major subfamilies. The genus Octaspidiotus was established as a member of the former subfamily by MacGillivray (1921), with Aspidiotus subrubescens Maskell as its type species. However, two species that he transferred from Aspidiotus are not now included in this genus. Since then, many additional species were described and added to Octaspidiotus by other authors (Borchsenius 1966;Tang 1984;Tang and Chu 1983;Takagi 1984). Takagi (1984) showed that O. corticoides (Green) was not a member of Octaspidiotus because the distinguishing characteristics were invalid. Currently, this genus is comprised of 14 valid species, eight of which are known to occur in China (García et al. 2015;Tang 1984;Takagi 1984). There are only two species recorded from Oceania, the other 12 species being distributed throughout East Asia.
Recently, one new species of Octaspidiotus was discovered from China. It was described and illustrated in this paper, bringing the number of recognized species in the genus to 15, of which nine species are recorded from China. A key to all known species of Octaspidiotus is provided.

Materials and methods
In this paper, the terminology described by Henderson (2011) has been used. This publication also includes illustrations for most of the species treated herein. All measurements are presented in micrometers (μm). Measurements were made using NIT-Elements D tools.
The abbreviations L 1 , L 2 and L 3 are short for the median, second, and third pygidial lobes, respectively.
All specimens have been deposited in the Entomological Museum, Northwest A & F University, Yangling, Shaanxi, China (NWAFU).
Generic diagnosis. Adult female. Body is oval to rounded; derm membranous except pygidium. Cephalothorax. Antennae with 1 seta. No trilocular pores associated to the spiracles. Pygidium. With 3-4 pairs of lobes, never bilobed. Median lobes (L 1 ) well-developed, with notches on both margins or only present on the outer margin. Second lobes (L 2 ) smaller than L 1 , with notches on both laterals or only present on the outer lateral. Third lobes (L 3 ) similar to L 2 . Fourth lobes (L 4 ) small and pointed apically, only present in O. subrubescens. Marginal setae occurring on dorsal bases of L 2 and L 3 , lanceolate, broadened and flattened. Plates are well-developed, fimbriate on the outer margin in most species, occurring laterally and even extended to the abdominal segment IV. Paraphyses absent on pygidial margin. Ducts. Dorsum has one-barred type macroducts, that are aligned in some species. Ventral microducts are scattered. Anal opening is toward the apex of the pygidium, more or less elongate. Vulvar opening situated anterior to anal opening. Perivulvar pores are quinquelocular, present or absent, if present, in four groups.
Remarks. This genus is very close to Aspidiotus Bouché, 1833 and Oceanaspidiotus Takagi, 1984 in terms of pygidial lobes and pygidium, but can be distinguished by the form of the dorsal marginal setae occurring on L1 and L2 which are lanceolate, broadened and flattened, while these setae in the other two genera are simply thickened.  Figure 5). The pygidium has three pairs of lobes: L 1 are well-developed, a small mesal notch is present on or near the apex, and a relative larger notch is present on or near the apex of the outer margin. L 1 is 6.7-7.2μm wide and the distance of two lobes of L 1 is 1.5-2.1μm wide. Median lobes separated by a space 0.2-0.3 times the width of L 1 . L 2 smaller than L 1 , with one notch on the outer margin. L 3 similar to L 2 , but smaller. Lanceolate setae on L 2 and L 3 shorter than these lobes themselves. Plates (Figure 5 and 7) one pair of pointed plates between L 1 , not extending to the apex of the lobe; 2 pairs of plates between L 1 and L 2 , apically fringed with few fine bifurcated; with 3 pairs of plates similar in size and shape between L 2 and L 3 ; with 6-7 pairs of plates lateral to L3. Ducts (Figure 4 and 5). Dorsal macroducts 1-barred-shaped. No marginal macroduct between median lobes. One marginal macroduct between L 1 and L 2 , two between L 2 and L 3 , and 3-4 present between L3. Dorsal submarginal macroducts about the same size as marginal macroducts which are 30-35 μm long. Total dorsal macroducts on dorsum in submarginal and marginal areas of pygidium on each side of body 32-44 (44 in holotype). Dorsal macroducts on abdomen segment IV shorter than on pygidium, with 5-6 macroducts on margin Remarks. This species is similar to O. cymbidii Tang, 1984 in the body shape and the pygidial lobes, but can be distinguished by the following characters (those for O. cymbidii in parentheses): 1) without marginal macroduct on abdomen segment III (with 3-4); 2) the three plates between L 2 and L 3 all equally shaped (the third plate is narrower than the first and the second plates); 3) L 1 is separated by a space 0.2-0.3 times the width of each median lobe (by a space 0.5 times the width of each L 1 ); 4) without marginal macroducts between L 1 (present).

Key to the adult females Octaspidiotus
With notches on both margins of L 3 ; both second and third plates between L 2 and L 3 narrower than first plates between L 2 and L 3 . With notches on outer margin of L 2 and L 3 ; with no more than 7 plates occurring on the outer side of L 3 ..