Review of the genus Coccus Linnaeus from Korea, with description of a new species (Hemiptera, Coccomorpha, Coccidae)

Abstract The genus Coccus from Korea is reviewed, including a new species, C. ficicola sp. n., and a first record of C. malloti (Takahashi, 1956). The new species is characterized by a distinctive pattern of ventral tubular ducts on medial area of head and thorax, and submarginal area of abdomen. The adult female of Coccus ficicola sp. n. is described and illustrated, and a morphological comparison is given with congeners. Coccus malloti is redescribed and illustrated based on the adult female specimens from Korea. A key to the four species of Coccus known from Korea is provided with diagnoses and photographs.


Introduction
The genus Coccus Linnaeus, 1758, which is a species-rich group in the family Coccidae, comprises approximately 111 species worldwide (Hodgson 1994;García-Morales et al. 2016). This group is defined morphologically by the distribution of ventral tubular ducts, the shape of dorsal and marginal setae, and the presence of a tibio-tarsal articulatory sclerosis on each leg (Hodgson 1994); however, the molecular phylogeny using  1A-D) with a reticulated pattern of brown stripes and a longitudinal ridge medially on dorsum; dermal areolations present but small; dorsal tubercles present; dorsal tubular ducts sparse on submarginal area; dorsal setae with bluntly rounded apices; marginal setae usually with simple pointed apices; multilocular disc-pores usually with ten loculi; ventral tubular ducts with a narrow inner ductule, frequent on posterior region of the head, medial area of thorax, and inner submarginal area of abdomen; antennae each with eight segments; legs each with a tibio-tarsal sclerosis on the articulation.
Description. Adult female. Living appearance ( Fig. 1A-D). Body oval, flattened, or moderately convex. Young adult females yellowish to brownish, with a reticulated pattern of brown stripes except for a longitudinal ridge on mid dorsum. Older adult females becoming more convex and darker. Eggs not seen.
Dorsum. Derm membranous. Dermal areolations oval and small, each with a microduct. Dorsal tubercles normally convex, present on submarginal area, 4-6 in total on each side: two between apex of head and anterior stigmatic cleft, one or two between anterior and posterior stigmatic clefts, and one or two between posterior stigmatic cleft and anal cleft. Dorsal setae cylindrical, short, stout, blunt apically, each 6-9 μm long, moderately distributed on dorsum. Dorsal tubular ducts each with a developed outer ductule and a slender inner ductule with a developed terminal gland, sparsely present on submargin. Dorsal microducts evenly scattered over entire dorsum. Preopercular pores round and small, rather inconspicuous, 6-7 μm wide, set in a small group of approximately 6-15 in front of anal plates. Anal plates quadrate, 190-223 μm long, 160-203 μm wide, usually posterolateral margin slightly longer than anterolateral margin; anterolateral margin 119-144 μm long, posterolateral margin 130-154 μm long; each plate with four apical setae. Ano-genital fold with two pairs of anterior and three pairs of lateral margin setae. Anal ring with six long setae.
Etymology. Named after its host plant, Ficus benghalensis L. Host plant. Moraceae: Ficus benghalensis L. Comments. Coccus ficicola sp. n. is probably a non-endemic species because it occurs on an imported ornamental plant, Ficus benghalensis, which is widely cultivated in tropical areas (Starr et al. 2003). In order to know the exact origin of the new species, further investigations are needed.
Although the African species, C. africanus (Newstead) and C. alpinus De Lotto, are not included in the list of related taxa for morphological comparison, C. ficicola is  Diagnosis. Adult females in life ( Fig. 3A-F) highly variable in body color and pigment pattern, but usually dorsum pale yellowish to brownish, with black or brown spots; dermal areolations present; dorsal tubercles present; dorsal tubular ducts present or absent; dorsal setae with sharply pointed apices; marginal setae usually with pointed, bifid or fimbriate apices; multilocular disc-pores usually with ten loculi; ventral tubular ducts with a narrow inner ductule, few present around meso-and procoxa, and anal plates; antennae each 7-segmented; legs each with a tibio-tarsal articulatory sclerosis.    (Takahashi, 1956). A adult female on Ilex cornuta B adult female on Aphananthe aspera. ten loculi; ventral tubular ducts of three types: Type I with a broad inner ductule, densely present on posterior medial area of head; frequent on anterior medial area of prothorax, extending to inner submarginal area of thorax; and also sparsely scattered on inner submarginal area of abdomen; Type II with a narrow inner ductule and a large flower-shaped terminal gland, rarely present on inner submarginal area and posterior medial area of abdomen; Type III with a long filamentous inner ductule and a quite small terminal gland, moderately present on submarginal area between anal clefts and each posterior spiracular furrow; all types of ventral tubular ducts absent on medial area of meso-, metathorax and anterior abdomen, and submarginal area of head; antennae each eight segments; legs each with a tibio-tarsal sclerosis on the articulation. (Figs 4A-B). Body elongate oval, flattened, or slightly convex. Young adult females yellowish to dark brownish, with a reticulated pattern of brown or black stripes, getting darker at maturity. Eggs reddish in color, stored beneath venter.
Dorsum. Derm membranous. Dermal areolations oval and small, each with a microduct. Dorsal tubercles normally convex, present on submarginal area, 1-5 in total on each side: one or two between apex of head and anterior stigmatic cleft, zero to two between anterior and posterior stigmatic clefts, and zero or one between posterior stigmatic cleft and anal cleft. Dorsal setae sharply spinose, short, stout, each 6-9 μm long, moderately distributed on dorsum. Dorsal tubular ducts absent. Dorsal microducts evenly scattered over entire dorsum. Preopercular pores round and small, 3-5 μm wide, set in a small group of approximately 8 in front of anal plates. Anal plates quadrate, 217-249 μm long, 169-198 μm wide, each with slightly concaved posterolateral margin, usually posterolateral margin quite longer than anterolateral margin; anterolateral margin 123-143 μm long, posterolateral margin 150-169 μm long; each plate with four apical setae. Ano-genital fold with two pairs of anterior and three pairs of lateral margin setae. Anal ring with six long setae.
Venter. Derm membranous. Multilocular disc-pores 6-7 μm wide, each with 8-10 loculi, mostly with ten loculi, abundant around vulvar area; one or two transverse rows on each abdominal segments; and also small groups present laterad of each metacoxa and mesocoxa, but not observed around procoxa. Spiracular pores 4-5 μm wide, each with five loculi, in a narrow band 2-4 pores wide between each spiracle and stigmatic cleft. Ventral tubular ducts of three types: Type I each with 33-39 μm long, with a developed outer ductule and a moderately broad inner ductule, straight or slightly curved, with a flower-shaped terminal gland, densely present on posterior medial area of head; frequent on anterior medial area of prothorax, extending to inner submarginal area of thorax; and also sparsely scattered on inner submarginal area of abdomen; Type II each with 16-24 μm long, with a narrow inner ductule and a large flower-shaped terminal gland, rarely present on inner submarginal area and posterior medial area of abdomen; Type III each with 15-24 μm long, with a long filamentous inner ductule and a quite small terminal gland, moderately present on submarginal area between anal clefts and each posterior spiracular furrow; all types of ventral tubular ducts absent on medial area of meso-and metathorax and anterior abdomen, and submarginal area of head. Ventral microducts present on entire venter, especially frequent on sub- Figure 5. Coccus malloti (Takahashi, 1956), adult female. A dorsal microduct B dorsal tubercle C dermal areolations D dorsal seta E stigmatic spines F marginal seta G anal plates H preopercular pore I multilocular disc-pores J ventral tubular duct (Type II) K leg L ventral tubular duct (Type III) M ventral tubular ducts (Type I) N ventral seta O spiracular pore P ventral microduct Q antenna. Scale bars: 200 μm (K, Q); 100μm (G); 50 μm (C, E); others = 10 μm. margin. Ventral setae with three pairs of long pregenital setae; approximately three or four pairs of long and short setae between antennae; other setae sharply spinose, each 5-10 μm long, sparsely distributed over entire venter. Legs well developed, each with a tibio-tarsal articulation and an articulatory sclerosis; total length of each metathoracic leg 614-769 μm long: each coxa 141-189 μm long, trochanter+femer 209-257 μm long, tibia+tarsus 243-311 μm long, claw 17-24 μm long. Tarsal digitules thinner and longer than claw digitules. Spiracles normal, mostly posterior peritreme broader than anterior: anterior peritremes each 37-52 μm wide, posterior peritremes each 45-61 μm wide. Antenna 8-segmented, each 339-399 μm long. Clypeolabral shield 138-157 μm wide.
Distribution. Only known from Japan (Takahashi 1956); first record for Korea. Comments. The above description based on Korean specimens agrees well with that of Takahashi (1956), except that variation in the number of dorsal tubercles and marginal setae, and exact distributions of each type of ventral tubular ducts are newly provided in this study. Coccus malloti probably has intermediate morphological characters between the tribes Coccini and Pulvinariini. However, the woolly test, known as ovisac and one of the typical characters of the Pulvinariini, is not observed in the species. In addition, some slide-mounted specimens of C. malloti contain eggs and nymphs in their body, which indirectly indicates that they would not produce an ovisac for oviposition. Although Coccus malloti would be retained in the tribe Coccini, it needs to be reviewed with its type materials to clarify the exact generic position of the species. Diagnosis. Adult females in life (Fig. 6A-B) greenish or greyish, with light or dark yellow mottling; dermal areolations present; dorsal tubercles absent; dorsal tubular ducts absent; dorsal setae with sharply pointed apices; marginal setae with simple pointed or spatulate apices; multilocular disc-pores usually with 6-10 loculi; ventral tubular ducts with a narrow inner ductule, few present on submaginal area of posterior abdomen; antennae each 8-segmented; legs without tibio-tarsal articulatory scleroses.

Discussion
Recently, Lin et al. (2017) described Coccus praetermissus Lin & Tanaka, which could be confused with a cosmopolitan species, Coccus hesperidum Linnaeus, 1758, based on morphological and molecular evidences. They pointed out that a morphological difference exists between the adult females of two genetically distinct species, the shape of dorsal setae, although molecular data (COI) should be used for exact identification. The adult female of Coccus praetermissus has dorsal setae with bluntly rounded apices, whereas those of C. hesperidum have sharply pointed tips. Coccus ficicola sp. n. is close to C. praetermissus in having the former type of dorsal setae, but differs in the distributional pattern of ventral tubular ducts, which is a reliable and constant character in each species within the genus Coccus. The ventral tubular ducts of Coccus ficicola are present on medial area of head, pro-and mesothorax, and submarginal area of abdomen, whereas C. praetermissus has the structures on medial area of mesothorax only.
Under the morphological comparison with congeners, we conclude that Coccus ficicola sp. n. is a distinct species which is a morphologically differentiated lineage. The distinctive pattern of ventral tubular ducts seems to be an autapomorphic feature of Coccus ficicola because it shows uniqueness in the comparison of morphological characters. In order to clarify the phylogenetic relationships of a new species within the genus Coccus, molecular analysis employing mitochondrial and nuclear loci are required.
de Investigación Agropecuaria, Corpoica, Colombia) and Dr. Yen P. Lin (School of Biological Sciences, The University of Queensland, Brisbane, Australia) for the useful comments. In addition, we thank Dr. H. Tanaka (Ehime University, Ehime, Japan) for comparing our samples with Japanese samples.