A new species of Coccus (Hemiptera, Coccoidea, Coccidae) from China

Abstract A new species of soft scale, Coccus multisetus Wang & Feng, sp. n. is described and illustrated from Yunnan, China. A key to adult females of all Coccusknown from China is provided.


Introduction
The Coccidae or soft scales (Hemiptera: Sternorrhyncha: Coccoidea) is the third largest family of the Coccoidea after the Diaspididae (armored scales) and the Pseudococcidae (mealybugs) (Ben-Dov et al. 2012). Soft scales are widespread throughout the world and many of them are important pests on agricultural and horticultural crops and ornamental plantings (Henderson and Hodgson 2005), such as Ceroplastes rubens Maskell, C. japonicus Green and Didesmococcus koreanus Borchsenius. Nonetheless, some species are very beneficial to man, such as Ericerus pela (Chavannes), whose wax provides an important raw material for many industries (Tang 1991).
Coccus is the oldest genus within the Coccidae (Avasthi and Shafee 1991). The genus was proposed by Linnaeus in 1758, with Coccus hesperidum Linnaeus as its type species, and belongs to the tribe Coccini, subfamily Coccinae (Hodgson 1994). Coccus is a very large genus present in all zoogeographical regions (Hodgson 1994) but is in urgent need of revision. Hitherto, coccidologists have listed about 94 species in this genus (Williams and Ben-Dov 2009, Martin and Lau 2011, Ben-Dov et al. 2012, of which 10 have been recorded from China (Takahashi 1932, Tao et al. 1983, Tang 1991, Martin and Lau 2011. Moreover, some Coccus species are pests of horticultural and ornamental plants in China (Yang 1982).
In this paper, we describe and illustrate the adult female of a new species, Coccus multisetus Wang & Feng, sp. n. This new species shares certain characteristics with C. formicarii (Green), which has previously been placed in Taiwansaissetia Tao et al., 1983, but that genus has now been synonymised with Coccus (Lin et al. in press). A key is provided for separation of the 11 species of Coccus currently known from China.

Materials and methods
The specimens were all immersed in 75% ethanol, and then prepared and mounted mainly according to the method of Hodgson and Henderson (2000). The terminology used in the description is mainly that of Hodgson (1994). Characters were examined under a Nikon compound microscope. An Olympus BH-2 stereoscopic microscope was used for drawing. The illustrations show adult female specimens, with the dorsum depicted on the left side and the venter on the right side, with enlargements of important characters shown around the main illustration. All measurements were made using the software NIT-Elements D and were given in micrometers (µm) or millimeters (mm). creasing in thickness during ageing. Dorsal setae setose, spinose, clavate or cylindrical. Dorsal tubular ducts and dorsal submarginal tubercles present or absent. Preopercular pores present or absent, varying in number and shape. Anal plates together quadrate. Anal ring with 6 or 8 setae. Margin. Marginal setae simple to branched; stigmatic clefts deep or shallow, each with 2-8 stigmatic spines. Venter. Antennae 2-8 segmented. Legs well developed or reduced; with or without a tibio-tarsal articulatory sclerosis. Spiracular disc-pores with 5 loculi. Pregenital disc-pores mainly with 10 loculi, present around anal opening, or extending anteriorly, even as far as head. Ventral tubular ducts present or absent; when present located medially, or forming a sparse or dense submarginal band. Dorsum. Derm membranous, with cell-like clear areas. Dorsal setae setose, slender, each 16-30 µm long, with well-developed basal sockets, sparsely distributed over dorsum but absent from median area. Dorsal pores circular, each with a dark rim and about 1-2 µm in diameter, sparsely distributed on dorsum. Dorsal microducts, each with a very short outer ductule and a normal inner filamentous ductule, present in each cell-like area. Dorsal tubular ducts and dorsal submarginal tubercles absent. Preopercular pores, each 3-4 µm in diameter, present in an elongate group anterior to anal plates. Anal plates each broadly triangular, 152-169 µm long, 90-98 µm wide; anterior and posterior margins subequal in length, outer angle nearly a right-angle; each plate with 6 or 7 apical or subapical setae, each 9-16 µm long. Ano-genital fold with 2 pairs of long setae, each 45-60 µm long, present along anterior margin plus 3 pairs of setae, each 28-40 µm long, along each lateral margin. Anal ring subcircular, with 2 or 3 rows of translucent pores and 6 anal ring setae.
Distribution. China (Yunnan). Etymology. The species epithet multisetus refers to the many setae on the dorsal surface of the anal plates.
Comments. Adult females of C. multisetus are superficially similar to those of C. formicarii (Green), which also had been collected in the nests of ants on Mangifera indica. The new species and C. formicarii (data from Hodgson, 1994, as Taiwansaissetia formicarii) share some distinct characteristics: 1) presence of setose dorsal setae; 2) lack of a tibio-tarsal articulatory sclerosis; 3) pregenital disc-pores restricted to around anal opening, and 4) lack of dorsal tubular ducts and submarginal tubercles. These distinct characteristics of the two species differ from those of typical Coccus, and might be due to their myrmecophilous habit and adaptation to living inside ant nests (Lin et al. in press).
However, C. multisetus can be distinguished by the possession of the following features (character states of C. formicarii in brackets): 1) 2 pairs of pregenital setae present (3 pairs); 2) 6 or 7 apical or subapical setae on each plate (3 or 4); 3) a submarginal band of ventral tubular ducts (absent); 4) dorsal setae nearly absent on median area (present), and 5) absence of a denticle on the claw (present). Although Hodgson (1994), when studying slide-mounted specimens considered to be T. formicarii, found their morphology to be rather variable, he noted none of the differences mentioned here, other than the presence of the denticle on the claw. It is thus considered that C. multisetus is an undescribed species which may be close to C. formicarii.