Research Article |
Corresponding author: Hirotaka Tanaka ( coccoidea@gmail.com ) Academic editor: Roger Blackman
© 2021 Hirotaka Tanaka, Kenji Suetsugu, Satoshi Kamitani.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Tanaka H, Suetsugu K, Kamitani S (2021) A parasitic insect on a parasitic plant: a new species of the genus Formicoccus Takahashi (Hemiptera, Coccomorpha, Pseudococcidae) from Ishigaki Island, Japan. ZooKeys 1060: 171-182. https://doi.org/10.3897/zookeys.1060.71652
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A new species of the genus Formicoccus Takahashi (Hemiptera, Coccomorpha, Pseudococcidae) collected from the holoparasitic plant Balanophora fungosa J. R. & G. Forst (Balanophoraceae), on Ishigaki Island, Japan, is described as Formicoccus yoshinoi Tanaka, sp. nov. based on the morphology of adult females. This species is similar to F. formicarius (1900) and F. erythrinae Williams, 2004, but differs from them by having fewer than six cerarii, and only one type of ventral oral collar tubular duct distributed on the medial area of the posterior abdominal segments. Keys to the Oriental species of the genus Formicoccus are provided.
Description, fungus root, mealybug, morphology, Nansei-shoto, taxonomy
Mealybugs of the family Pseudococcidae (Hemiptera), are the second largest group of the infraorder Coccomorpha (
To date, 78 species of mealybugs in 32 genera have been recorded in Japan (
During a botanical survey led by the second author (KS) in the southwestern islands of Japan (the Ryukyu Islands), on Ishigaki Island, a unique undescribed species was found belonging to the genus Formicoccus (Pseudococcidae) parasitising a Japanese fungus root, Balanophora fungosa J. R. & G. Forst (Balanophoraceae), which is one of the non-photosynthetic and holoparasitic plants in Japan. The present study describes and illustrates the species as new to science based on the morphology of adult females. Keys to the Oriental species of Formicoccus are provided.
The specimens described in the present study were collected on 14 December 2019 from Balanophora fungosa on Ishigaki Island, Japan, by Mr. Keiya Yoshino. The slide-mounting method used followed the method described by
Formicoccus cinnamomi Takahashi, original designation.
(adapted and modified from
1 | Antennae with 9 segments | F. schimae Takahashi, 1929 |
– | Antennae with 6–8 segments | 2 |
2 | Cerarii numbering 17–18 pairs | 3 |
– | Cerarii numbering 16 or fewer pairs | 4 |
3 | Anal ring with 6 setae | 6 |
– | Anal ring with 8 or more setae | 7 |
4 | Cerarii numbering fewer than 6 pairs; only one type of ventral oral collar tubular duct present | F. yoshinoi Tanaka, sp. nov. |
– | Cerarii numbering 14–16 pairs; 2 types of ventral oral collar tubular ducts present | 5 |
5 | Penultimate cerarii (C17) with ca. 9–12 conical setae; several dorsal setae associated with 2 or 3 trilocular pores | F. tripurensis Williams, 2004, in part |
– | Penultimate cerarii (C17) with 2–8 conical setae; dorsal setae not associated with trilocular pores | F. robustus (Ezzat & McConnell, 1956), in part |
6 | Circulus absent | F. lingnani (Ferris, 1954) |
– | Circulus present | 9 |
7 | Circulus absent | F. dispersus Williams, 2004 |
– | Circulus present | 8 |
8 | Anal ring with more than 10 setae | F. cinnamomi Takahashi, 1928 |
– | Anal ring with fewer than 10 setae | F. polysperes Williams, 2004, in part |
9 | Dorsal surface of each anal lobe moderately to heavily sclerotised | 10 |
– | Dorsal surface of each anal lobe membranous, except for possible weak sclerotisation around some setal collars only | 13 |
10 | Many dorsal setae conical, those on midline of abdomen associated with trilocular pores forming dorsal cerarii | F. monicola (Green, 1922) |
– | Dorsal setae not conical, each one short, slender, and stiff, or elongate and flagellate, not forming dorsal cerarii on midline of abdomen | 11 |
11 | Dorsal setae short and stiff, 15–25 µm long | 12 |
– | Dorsal setae long and flagellate, mostly 55–75 µm long | F. matileae Williams, 2004 |
12 | Anal lobe cerarii (C18) with 4 conical setae. Penultimate cerarii (C17) with 7 conical setae | F. burckhardti Williams, 2004 |
– | Anal lobe cerarii (C18) with 6 conical setae. Penultimate cerarii (C17) with 4 or 5 conical setae | F. bambusicola (Takahashi, 1930) |
13 | All cerarii containing short, conical setae | 17 |
– | Either all cerarii with many long, conical, or flagellate setae forming tufts, or some cerarii on head and thorax containing paired flagellate setae | 14 |
14 | Abdominal cerarii with short and conical setae only. Cerarii on head and thorax with long paired flagellate setae. Oral collar tubular ducts on venter absent from thorax. Abdominal segments not strongly lobed laterally | F. acerneus Williams, 2004 |
– | All cerarii each with many elongate cerarian setae, either conical or flagellate, forming tufts, cerarian setae often extending onto venter even in teneral specimens. Oral collar tubular ducts on venter present on thorax. Abdominal segments usually strongly lobed laterally | 15 |
15 | Multilocular disc pores present on ventral abdominal margins. Most dorsal setae on head and thorax long, each 50–100 µm long | 16 |
– | Multilocular disc pores absent from ventral abdominal margins. Most dorsal setae on head and thorax short, each 25–40 µm long | F. formicarii (Green, 1922) |
16 | Most cerarian setae conical although elongate, sometimes with flagellate tips. Hind femur without translucent pores | F. simplicior (Green, 1922) |
– | All cerarian setae elongate and flagellate. Hind femur with translucent pores | F. formicarius (Newstead, 1900) |
17 | Anal lobe cerarii (C18) each mostly with 2 conical cerarian setae | 18 |
– | Anal lobe cerarii (C18) each mostly with more than 2 conical cerarian setae | 20 |
18 | Penultimate cerarii (C17) each with 2 conical cerarian setae | 19 |
– | Penultimate cerarii (C17) each mostly with more than 2 conical cerarian setae | F. erythrinae Williams, 2004 |
19 | Conical cerarian setae on anal lobe cerarii (C18) with flagellate tips. Dorsal setae mostly longer than anal ring length | F. macarangae (Takahashi, 1940) |
– | Conical cerarian setae on anal lobe cerarii (C18) without flagellate tips. Dorsal setae mostly shorter than anal ring length | F. sibolangiticus Williams, 2004 |
20 | Ventral oral collar tubular ducts present anterior to abdomen, on head only or head and thorax | 24 |
– | Ventral oral collar tubular ducts absent from head and thorax, confined to abdomen | 21 |
21 | Cerarii on head not clearly separated; boundaries of cerarii on head not clear | F. citricola (Tang, 1992) |
– | Cerarii on head mostly clearly separated; boundaries of cerarii on head clear | 22 |
22 | Ventral setae thick, stout and curved, including anal lobe bar setae, cisanal and obanal setae | F. tripurensis Williams, 2004, in part |
– | Ventral setae slender and flagellate, including anal lobe bar setae, cisanal and obanal setae | 23 |
23 | Hind coxae noticeably wider and larger than anterior coxae. Multilocular disc pores on venter absent from abdominal segment IV. Most cerarii on head and thorax with slender cerarian setae | F. cameronensis (Takahashi, 1951) |
– | Hind coxae same shape as anterior coxae, only slightly larger. Multilocular disc pores on venter present on abdominal segment IV. Most cerarii on head and thorax with conical cerarian setae | F. robustus (Ezzat & McConnell, 1956), in part |
24 | Most dorsal setae short and weakly knobbed, except for conspicuously long flagellate setae on abdominal segment VIII on either side of anal ring | F. latens Williams, 2004 |
– | Dorsal setae all short and pointed. Setae situated on either side of anal ring little if any longer than other dorsal setae | 25 |
25 | Most dorsal setae anterior to abdominal segment VIII short and thick, 6.0–10.0 µm long; base of most setae ca. as wide as a trilocular pore and often wider. Ventral oral collar tubular ducts absent from opposite ocular cerarii (C3) and from margins of mesothorax and metathorax | F. polysperes Williams, 2004, in part |
– | Most dorsal setae anterior to abdominal segment VIII short and slender, 10–17 µm long; base of most setae narrower than a trilocular pore. Ventral oral collar tubular ducts present opposite ocular cerarii (C3) and on margins of mesothorax and metathorax | F. mangiferacola Williams, 2004 |
Holotype
: Adult ♀, Japan / Okinawa prefecture / Ishigaki Is., Sakieda / 24.445794°N / 124.079765°E / on Balanophora / fungosa / 14.xii.2019 / coll. K. Yoshino; mounted singly (
Slide-mounted adult female mostly oval. Anal lobes with well-developed and narrow anal lobe bar. Antenna mostly with seven segments and many flagellate setae. Legs relatively short and stout, but well developed. Hind legs with numerous translucent pores present on both dorsal and ventral surfaces of coxae. Circulus present between ventral abdominal segments III and IV. Ostioles present. Anal ring situated ca. half length from apex of abdomen or end of posterior abdominal segments, bearing 6 setae. Cerarii numbering fewer than 6 pairs; all cerarii situated on posterior abdominal segments. Dorsal setae slender, relatively long and flagellate, densely present and covering almost entire body surface. Dosal trilocular pores evenly distributed. Oral rim ducts and oral collar tubular ducts absent on dorsum. Discoidal pores sparsely distributed on both body surface. Multilocular disc pores mostly present in medial area of ventral abdominal segments VI–IX. One size of oral collar tubular ducts present on venter, forming an irregular submarginal band on posterior abdominal segments and forming transverse rows on medial area of abdominal segments VI–IX.
(n = 7). Live adult female feeding on the underground part of host plant (Figs
Slide-mounted adult female mostly oval, 2.4 (2.4–3.2) mm long and 1.6 (1.6–2.9) mm wide; derm membranous; segmentation relatively well-developed. Anal lobes distinct but not prominent, dorsal and ventral surfaces of each lobe with weakly sclerotised area, ventral surface with long apical seta, 192–194 (178–194) µm long and with well-developed and narrow anal lobe bar; anal lobe bar fairly conspicuous, but occasionally fainted and rarely difficult to see. Antenna 368–372 (322–407) µm long, with 7 (7–8) segments and many flagellate setae; subapical segment with one fleshy seta and apical segment with 4 (3–4) fleshy setae. Legs relatively short and stout, but well-developed, with many flagellate setae; hind trochanter + femur 319–332 (300–356) µm long, hind tibia + tarsus 243–250 (239–278) µm long; claw 38–43 (38–46) µm long. Ratio of lengths of hind tibia + tarsus: trochanter + femur 0.73–0.78 (0.73–0.82); ratio of lengths of hind tibia to tarsus 1.87–2.07 (1.60–2.13). Paired tarsal digitules present, subequal in length to the minutely knobbed claw digitules. Hind legs with numerous translucent pores present on both dorsal and ventral surface of coxae. Labium ca. 280 (220–285) µm long, slightly longer than clypeus. Circulus present between abdominal segments III and IV, 85 (50–100) µm long and 215 (140–235) µm wide. Ostioles present, each with inner edges of lips not sclerotised; anterior ostioles each with a total for both lips of 106–118 (46–118) trilocular pores and 19–21 (16–25) setae; each posterior ostiole with a total for both lips of 105–118 (64–122) trilocular pores and 18–23 (16–24) setae. Anal ring 108 (90–108) µm wide, situated ca. half the length from apex of abdomen to end of posterior abdominal segments, with two rows of cells, bearing six setae (Fig.
Formicoccus yoshinoi Tanaka, sp. nov., adult female. Abbreviations: ALC, anal lobe cerarius (C18); ANT, antenna; AR, anal ring; DP, discoidal pore; LG, hind tibia. tarsus and claw; MP, multilocular pore; OCD, oral collar duct; PLC, penultimate cerarius (C17); TP, trilocular pore. Scale bars: 200 µm for ANT and LG; 100 µm for ALC, AR, and PLC; 10 µm for other details.
Dorsum. Setae slender, relatively long and flagellate, each 21–68 (14–68) µm long, longest setae present on medial area of posterior abdominal segments, densely present and covering almost entire body surface. Trilocular pores ca. 3–4 µm wide, evenly distributed. Oral rim ducts and oral collar tubular ducts absent. Discoidal pores slightly smaller than trilocular pores, sparsely distributed on body surface.
Venter. Ventral derm with slender flagellate setae, each 31–123 (15–123) µm long, longest on medial area of posterior abdominal segments. Multilocular disc pores, each 7–9 (6–9) µm wide, mostly present in medial area of abdominal segments VI–IX. Trilocular pores ca. 3–4 µm wide, evenly distributed. Oral rim ducts absent. Oral collar tubular ducts present, of one size, each with outer ductule 2–4 µm in diameter (slightly smaller than that of a trilocular pore) forming an irregular submarginal band on posterior abdominal segments and forming transverse rows on medial area of abdominal segments VI–IX. Discoidal pores slightly smaller than trilocular pores, sparsely present on body surface.
Balanophora fungosa (Balanophoraceae).
Balanophora fungosa is characterized by unusual mushroom-shaped inflorescences that emerge above the ground and warty tubers that are attached to their host plants (
In his taxonomic revision of the genus Formicoccus Takahashi, 1928, in Southern Asia,
Formicoccus yoshinoi Tanaka, sp. nov. is similar to F. formicarius (Newstead, 1900) in having: (i) long flagellate dorsal setae; (ii) relatively short and stout legs; (iii) only one type of ventral oral collar tubular duct; and (iv) a round body shape, but differs from this species as follows (characters of F. formicarius are given in parentheses): (i) having fewer than six cerarii with 0–6 conical cerarian setae (with 18 pairs of cerarii with long and stout flagellate setae); and (ii) having a transverse row of ventral oral collar tubular ducts on the medial area of posterior abdominal segments (lacking ventral oral collar tubular ducts on medial area of abdominal segments). The species is also similar to F. erythrinae Williams, 2004, in having: (i) long flagellate dorsal setae; (ii) relatively short legs; and (iii) round body shape, but differs from the latter species as follows (characters of F. erythrinae are given in parentheses): (i) having fewer than six cerarii (having 18 cerarii); and (ii) having only one type of ventral oral collar tubular duct (with two types of ventral oral collar tubular ducts).
Named after the collector of type series, an independent researcher of plants in Ishigaki Is., Mr. Keiya Yoshino.
The authors are grateful to Dr. Takumasa Kondo, Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), Colombia, for reviewing this manuscript. We also thank an independent researcher, Mr. Keiya Yoshino, for help with field study and photography. We would like to thank Editage (www.editage.com) for English language editing.