Phenacoccus miruku Tanaka & Choi, 2022

Tanaka, Hirotaka, Sasaki, Daisuke, Choi, Jinyeong, Husnik, Filip & Kamitani, Satoshi, 2022, Two new species of mealybugs (Hemiptera: Coccomorpha: Pseudococcidae) from Japan, Zootaxa 5168 (3), pp. 306-318 : 313-316

Phenacoccus miruku Tanaka & Choi sp. nov.

(Japanese common name: Miroku-kona-kaigaramushi)

Material examined. Holotype: JAPAN, / Okinawa prefecture, / Okinawa Is. Ogimi-son, / on Bidens pilosa / var. radiata , / 26.vi.2021, / coll. J. Choi; adult female mounted singly ( ELKU) . Paratypes: same data as for holotype; 13 adult females mounted singly (6 ELKU, 7 EUMJ). Paratype used for molecular phylogenetic analysis: same data as for holotype; 1 adult female (1 ELKU, Genbank Accession No. ON533756 for COI, ON527953 for 18S, ON527955 for 28S D2).

Description (n = 15). Live adult female: Body elongate oval, yellowish, with a thin layer of white powdery wax, very short lateral filaments around entire body margin, and caudal filaments slightly longer and thicker than lateral filaments. At the oviposition stage, the adult female produces a rather loose ovisac of fine wax filaments and lays eggs in it ( Fig. 4 ).

Slide-mounted adult female ( Fig. 5 ): Body elongate oval, 1.8 (1.5–2.1) mm long and 1.0 (0.8–1.2) mm wide; derm membranous; segmentation not well developed. Anal lobes evident but not prominent, dorsal and ventral surfaces of each lobe without sclerotised areas and ventral surface with long apical seta, 150 (105–180) µm long. Antenna 327 (304–387) µm long, with 8 or 9 segments (usually 9) and many flagellate setae; subapical segment with 1 fleshy seta and apical segment with 2 (0–3) fleshy setae. Eyes present on margin. Legs well-developed, with many flagellate setae; hind trochanter + femur 243–252 (205–269) µm long, hind tibia + tarsus 310–318 (268–331) µm long; claw 24–30 (22–33) µm long, with a denticle. Ratio of lengths of hind tibia + tarsus: trochanter + femur 1: 1.3 (1.2–1.3); ratio of lengths of hind tibia to tarsus 1: 2.4–2.6 (1.8–2.6). Paired setose tarsal digitules present (most of them partially broken in examined specimens), subequal in length to slightly knobbed claw digitules. Hind legs without translucent pores. Labium about 146 (108–146) µm long, shorter than clypeus. Circulus present or absent, if present located in posterior part of abdominal segment III, 24 (4–51) µm long and 33 (6–122) µm wide. Ostioles present, each with inner edges of lips weakly sclerotised; anterior ostioles each with a total of 16 or 17 (6–23) trilocular pores and 3 or 4 (0–5) setae on both lips; each posterior ostiole with a total of 23–29 (6–35) trilocular pores and 2 or 3 (0–5) setae on both lips. Anal ring 72 (63–88) µm wide, bearing 6 (4–6) setae, each seta 100–112 (74–128) µm long. Cerarii numbering 18 (17 or 18) pairs. Anal lobe cerarii mostly each containing 2 slender conical setae, each seta 14 (8–15) µm long and about 3 (2–5) µm wide at base, also 0 or 1 (0–3) auxiliary setae and a concentration of trilocular pores. Penultimate cerarii each containing 2 slender conical setae but without auxiliary setae. Cerarii situated further forward mostly each with 2 (1–4) conical slender setae only, those cerarii containing 4 slender conical setae mostly located on head.

Dorsum. Setae conical to lanceolate, each 3–13 (2–15) µm long, distributed evenly. Trilocular pores, each 3–4 µm wide, evenly distributed. Oral collar tubular ducts of 1 size, each about 2–4 µm in diameter, present on marginal areas of each abdominal segment, and rarely present on marginal areas of head and thoracic segments. Discoidal pores, each 1–2 µm wide, sparsely distributed. Multilocular disc pores each 6–9 µm wide, present on marginal areas of abdominal segments as follows: segment I, 0 (0); II, 0 (0); III, 0 (0 or 1); IV, 0 (0–2); V, 0 (0–3); VI, 0 (0–3); VII, 0 (0–2); and VIII, 0 (0 or 1).

Venter. Setae of 2 types: (i) conical to lanceolate setae, each about 2–10 µm long, present on marginal areas of head, thoracic segments and anterior abdominal segments; and (ii) relatively long and slender flagellate setae, each 15–88 (10–109) µm long, present on medial areas of body and marginal areas of posterior abdominal segments, longest on medial area of head. Multilocular disc pores, each 7–9 µm wide, mostly present in medial area of abdominal segments III–IX, occasionally a few also present on marginal areas of abdominal segments. Trilocular pores, same size as on dorsum, evenly distributed. Quinquelocular pores, each 6–7 (3–7) µm wide, present on medial area between lateral mouthparts and abdominal segment III, but occasionally restricted to an area lateral to mouthparts. Oral collar tubular ducts of 1 type, each about 2–4 µm in diameter, present on medial area between prothoracic segment and abdominal segment IX, and on marginal to submarginal areas of posterior abdominal segments, forming transverse bands across all abdominal segments; ducts in marginal areas usually larger; ducts gradually changing in size so cannot be divided into two distinct size types. Discoidal pores, same width as those on dorsum, sparsely present.

Host plants. On stems and roots of Bidens pilosa var. radiata (Asteraceae) .

Remarks. Phenacoccus miruku resembles P. sisymbriifolium Granara de Willink in Granara de Willink & Szumik 2007, described from Uruguay, in having occasional multilocular pores on the marginal areas of the dorsal abdomen, greatly varied conical-to-lanceolate dorsal setae, and conical-to-lanceolate ventral setae on the marginal areas of the venter. However, P. miruku differs from P. sisymbriifolium as follows (contrasting character states in P. sisymbriifolium in parentheses): (i) quinquelocular pores absent in area anterior to mouthparts (ca. 32 quinquelocular pores present in area anterior to mouthparts); (ii) quinquelocular pores absent from abdominal segments IV‒VII (pores present on abdominal segments IV–VII); (iii) translucent pores absent from hind tibiae (some pores present on hind tibiae); and (iv) circulus present or absent on venter, if present, oval (circulus always present, anvil-shaped). Phenacoccus miruku also resembles P. similis Granara de Willink 1983 , described from Argentina. However, it differs from the latter as follows (contrasting character states in P. sisymbriifolium in parentheses): (i) quinquelocular pores absent in area anterior to mouthparts (some pores present in area anterior to mouthparts); (ii) translucent pores absent from hind tibiae (some pores present on hind tibiae); and (iii) circulus present on or absent from venter, if present, oval (circulus always present, anvil-shaped).

In the phylogenetic tree ( Fig. 1 ), P. miruku was placed within the clade of the subfamily Phenacoccinae . The new species was nested within a clade including both Neotropical and Nearctic species, such as P. manihoti MatileFerrero 1977 , P. parvus Morrison 1924 , P. peruvianus Granara de Willink in Granara de Willink and Szumik 2007, P. solani Ferris 1918 and P. solenopsis Tinsley 1898 . Phenacoccus miruku was sister to a clade containing P. manihoti and P. peruvianus , although this was not well supported (UFBoot = 91). Phenacoccus parvus was placed outside the clade including P. miruku .

The molecular analysis does not support the generic designation of this new species in this study, which is based on adult female morphological characteristics. The analysis also indicated that P. miruku is not related to the type species of Phenacoccus , P. aceris ( Signoret, 1875) . However, Phenacoccus is known to be a polyphyletic group ( Choi & Lee 2022). Although this genus needs revision, we tentatively place the new species in Phenacoccus based on the current morphological classification.

Based on morphological and molecular evidence, P. miruku is related to Neotropical and Nearctic species, P. manihoti , P. parvus , P. peruvianus , P. sisymbriifolium , P. similis , P. solani and P. solenopsis , so it is possible that P. miruku might have been introduced from the Neotropical or Nearctic regions. It is necessary, therefore, to pay close attention to the current distribution and expansion trend of this species on Okinawa Island and in other regions of Japan.

Etymology. The specific epithet “ miruku ” is an Okinawan noun that refers to a visiting god in the mythology of the Japanese Southwest Islands that is sometimes thought to be the same being ethnologically as Miroku Bosatsu (Maitreya Bodhisattva) in Buddhism. The epithet is used as a noun in apposition.

Figures

FIGURE 1. Maximum likelihood (ML) tree of mealybugs (132 taxa) inferred in IQ-tree. COI, 18S and 28S D2 sequences of Dysmicoccus kunaw sp. nov. and Phenacoccus miruku sp. nov. were included in the molecular dataset of Choi & Lee (2022). 18S and 28S D2 sequences of P. peruvianus and P. manihoti from NCBI were also newly included in this analysis. ML ultrafast bootstrap values are shown at each node.

FIGURE 4. Phenacoccus miruku sp. nov. in life. A. Adult females on a stem of Bidens pilosa ver. radiata; B. Adult female producing an ovisac and laying eggs.

FIGURE 5. Phenacoccus miruku sp. nov. adult female collected in Okinawa Island, Japan in 2021. ALC, anal lobe cerarii; ANT, antenna; DP, discoidal pore; DS, dorsal setae; LG, hind tibia, tarsus and claw; MP, multilocular disc pores; OCD, oral collar duct; PLC, penultimate cerarius; TP, trilocular pore; VS, ventral setae of types I–II. Scale bars: 200 µm for ANT and LG; 50 µm for ALC and PLC; 10 µm for others.