Spilococcus pacificus ( Borchsenius 1949 )

Tanaka, Hirotaka & Kamitani, Satoshi, 2022, Review ofthegenus CrisicoccusFerris (Hemiptera: Coccomorpha: Pseudococcidae) in Japan with description of a new species, and the identity of a South Korean mealybug misidentified as Crisicoccus matsumotoi (Shiraiwa 1935), Zootaxa 5209 (5), pp. 555-572 : 568-570

Spilococcus pacificus ( Borchsenius 1949)

Pseudococcus pacificus Borchsenius 1949: 119 .

Paracoccus betulae Borchsenius & Kozarzhevskaya 1966 (synonymy by Danzig 1980: 158).

Spilococcus pacificus ( Borchsenius 1949) ; Danzig 1980: 158 (change of combination); Ben-Dov 1994: 491; Suh 2020: 2.

Atrococcus pacificus ( Borchsenius 1949) ; Tang 1992: 228 (change of combination); Danzig & Gavrilov-Zimin 2015: 270.

Crisicoccus matsumotoi ( Shiraiwa 1935) ; Paik 1978: 186; Paik 2000: 64; Kwon et al. 2003: 403; Suh 2020: 2 (misidentifications).

Material examined. South Korea: Busan, on Acer palmatum , 20.v.2001, no collector indicated, 1 adult female mounted singly ( APQA) ; Gunwi ( GB) , on Pyrus ussuriensis , 13.ix.2012, coll. Suh, S.J., 2 adult females mounted on a slide ( APQA) .

Updated description

Appearance in life. Body orange in life ( Danzig & Gavrilov-Zimin 2015).

Slide-mounted adult female ( Fig. 7 ) (n = 3): Body elongate oval, 2.7–3.3 mm long and 1.4–1.6 mm wide; derm membranous; segmentation recognizable, but not well developed. Anal lobes well developed; dorsal surface of each lobe with a slightly sclerotized area; ventral surface with well-developed anal lobe bar and long apical seta, 208–271 µm long. Antenna 360–450 µm long, with 8 segments and many flagellate setae; subapical segment with 1 fleshy seta and apical segment with 3 fleshy setae. Eyespots present on margin, not associated with discoidal pores. Legs well developed, with many flagellate setae; hind leg measurements (in µm): trochanter + femur 260–338 long; hind tibia + tarsus 280–395; claw 34–40, without a denticle. Ratio of lengths of hind tibia + tarsus to trochanter + femur about 1: 1.01–1.17; ratio of lengths of hind tibia to tarsus 1: 1.55–2.17. Paired setose tarsal digitules present, subequal in length to the minutely knobbed claw digitules. Hind coxa with translucent pores on both surfaces; hind tibia with or without translucent pores on posterior surface; hind trochanter, femur and tarsus without translucent pores. Labium 165–186 µm long, usually same length as clypeolabral shield. Circulus usually quadrate, located between abdominal segment III and IV, 68–170 µm long and 87–125 µm wide. Ostioles present, each with inner edges of lips weakly sclerotized; anterior ostioles each with a total for both lips of 16–29 trilocular pores and 3–5 setae; each posterior ostiole with a total for both lips of 19–49 trilocular pores and 2–5 setae. Anal ring 86–98 µm wide, bearing 6 setae, each seta 110–140 µm long. Cerarii numbering 6–8 pairs, all present on abdominal segments. Anal lobe cerarii (C 18) mostly each containing 2 conical cerarian setae, each seta 12–21 µm long and about 4–7 µm wide at base, 4–7 auxiliary setae and a concentration of trilocular pores. Penultimate cerarii (C 17) each containing 2 conical setae, no auxiliary setae and some trilocular pores. Cerarii situated further forward generally each with 2 conical setae and usually a few trilocular pores.

Dorsum. Setae flagellate, each 8–45 µm long, distributed segmentally; longest setae present on head. Trilocular pores each 3–4 µm wide, evenly distributed. Oral collar tubular ducts absent. A few oral rim tubular ducts present on submarginal to medial areas of head, thoracic and abdominal segments. Discoidal pores each about 2–3 µm wide, sparsely distributed.

Venter. Setae relatively long and flagellate, each 18–136 µm long; setae on head longest. Multilocular disc pores, each 6–9 µm wide, present in medial areas of abdominal segments IV‒IX; a few also present on head and thoracic segments, arranged in 1 to 3 rows on posterior areas of abdominal segments VI–VII but arranged randomly on abdominal segments VIII and IX. Trilocular pores, each same size as those on dorsum, evenly distributed. Oral collar tubular ducts of 2 sizes present: (i) large-type ducts, each about 3–4 µm in diameter, mostly wider than a trilocular pore, present on marginal to submarginal areas of all abdominal segments and anterior of thorax; and (ii) small-type ducts, each about 1–2 μm in diameter, present on medial areas of abdominal segments IV–VII, forming transverse bands across most posterior abdominal segments. Discoidal pores, each about 1–2 µm wide, sparsely distributed.

Host plants in South Korea. Moraceae : Broussonetia kazinoki ( Paik 1978; Suh 2020), Rosaceae : Malus pumila (Kwon et al. 2003; Suh 2020), Pyrus pyrifolia var. cultiva ( Kwon & Han 2003; Suh 2020), P. ussuriensis (Rosaceae) (Kwon et al. 2003; Suh 2020); and Sapindaceae : Acer palmatum ( Paik 1978; Suh 2020).

Remarks. In South Korea, this species was first reported as “ C. matsumotoi ” by Paik (1978) and later by Paik (2000), Kwon et al. (2003), and Suh (2020). However, the morphology of the Korean specimens examined in this study, which were identified by South Korean mealybug experts Suh, S.J. and Park, M.J. as “ C. matsumotoi ” is quite different from that of the species currently regarded as C. matsumotoi (= Crisicoccus seruratus ) in Japan, the native country of the type specimen. The Korean material could be identified as a member of the genus Spilococcus , namely S. pacificus . The true C. matsumotoi (= C. seruratus ) is a well-known significant pest of fruit crops in Japan ( Kawai 1980; 2003) and, based on our investigation, is probably absent from South Korea. Thus, this rectification of the misidentifications will be beneficial to agriculture and international plant quarantine. Where mentioned above, Suh (2020) just cited an earlier paper by South Korean researchers; she was not responsible for the misidentifications.

In this study, we could not check all the specimens of C. matsumotoi that were used by the South Korean researchers; possibly a few of them could be the true C. matsumotoi (= C. serruratus ) from South Korea. However, the morphological characteristics of the Korean specimens we examined in this study are consistent with those of “ C. matsumotoi ” in the key provided by Kwon et al. (2003), such as having some oral rim tubular ducts on the dorsum. We now consider that most or all specimens reported as “ C. matsumotoi ” from South Korea are consistent with S. pacificus . We also believe that the specimens used by other researchers should be re-examined in the future, especially as Suh (2020) cited Kwon & Han (2003) as having recorded S. pacificus on Acer palmatum in Korea, whereas Kwon et al. (2003) mentioned “ C. matsumotoi ” on the same host plant.

All the Korean specimens examined in this study have oral-rim tubular ducts on the dorsum and anal lobe bars on the ventral surfaces of the anal lobes. According to Kaydan & Szita (2017), the species should be transferred either to the genus Maconellicoccus Ezzat or to Paracoccus Ezzat & McConnell (probably, to the genus Paracoccus with minor generic diagnostic modifications); however, in the present study, none of the type specimens were examined so the species is left in Spilococcus for now.

Figures

FIGURE 7. Spilococcus pacificus (Borchsenius 1949), adult female collected in Gunwi, South Korea in 2012. ALC, anal lobe cerarius; ANT, antenna; DP, discoidal pore; LG, hind tibia, tarsus and claw; MP, multilocular disc pore; OCD I, large type oral collar duct; OCD II, small type oral collar duct; ORD, oral rim tubular duct; PLC, penultimate cerarius (C17); TP, trilocular pore. Scale bars: 200 µm for ANT and LG; 50 µm for ALC and PLC; 10 µm for others.