Dysmicoccus bunagaya, Tanaka & Kamitani, 2021

Tanaka, Hirotaka & Kamitani, Satoshi, 2021, Two new species of Coccomorpha (Hemiptera: Sternorrhyncha) collected from Japanese silver grass, Miscanthus sinensis (Poaceae) in Okinawa Island, Japan, Zootaxa 4941 (4), pp. 569-579 : 574-577

publication ID	https://doi.org/ 10.11646/zootaxa.4941.4.6
publication LSID	lsid:zoobank.org:pub:A2324FE1-2671-40B0-95FA-7CD58EB91C7B
DOI	https://doi.org/10.5281/zenodo.4618239
persistent identifier	https://treatment.plazi.org/id/03C91D42-3223-334A-FF64-FC07FCE9FF1D
treatment provided by	Plazi
scientific name	Dysmicoccus bunagaya
status	sp. nov.

Treatment

Dysmicoccus bunagaya sp. nov. Ï†flvƎ†þưflŷLÿ

( Figs. 4–5 View FIGURE 4 View FIGURE 5 )

Material examined. Holotype: JAPAN / Okinawa prefecture / Okinawa Is. / Kunigami-son, Yona forest road / on Miscanthus / sinensis / 15.xi.2020 / coll. H. Tanaka; adult female mounted singly ( ELKU). Paratypes: same data as for holotype, 9 adult females mounted singly (5 EUMJ, 4 ELKU). Same locality, host plant and collector data as for holotype, 15.x.2019, 10 adult females mounted singly (5 EUMJ, 5 ELKU)

Description (n = 20). Live adult female feeds in the shoot apices of the host plant and secretes white powdery wax on all body surfaces ( Fig. 4 View FIGURE 4 ).

Slide-mounted adult female elongate oval, 3.5 (2.7–3.8) mm long and 1.1 (0.9–1.2) mm wide; derm membranous; segmentation relatively well-developed. Anal lobes distinct but not prominent, dorsal and ventral surfaces of each lobe with sclerotised area and ventral surface with long apical seta, 170–175 (140–183) µm long. Antenna 329–352 (281–385) µm long, with 7 or 8 segments and many flagellate setae; subapical segment with 1 (1) fleshy seta and apical segment with 3 (2–4) fleshy setae. Legs well-developed, with many flagellate setae; hind trochanter + femur 322–325 (270–362) µm long, hind tibia + tarsus 325 (280–359) µm long; claw 28–31 (26–33) µm long. Ratio of lengths of hind tibia + tarsus: trochanter + femur 1.0 (1.0–1.1); ratio of lengths of hind tibia to tarsus 1.9–2.0 (1.8–2.4). Paired tarsal digitules present, subequal in length to the minutely knobbed claw digitules. Hind leg with a few translucent pores present on dorsal surface of coxa and present or absent on dorsal surface of femur and tibia. Labium about 82 (40–86) µm long, shorter than clypeus. Circulus present or absent, if present located between abdominal segments III and IV, (8–32) µm long and (10–50) µm wide, sometimes divided by intersegmental line. Ostioles present, each with inner edges of lips weakly sclerotised; anterior ostioles each with a total for both lips of 22 (6–25) trilocular pores and 2 (0–4) setae; each posterior ostiole with a total for both lips of 34–32 (7–42) trilocular pores and 2–3 (0–4) setae. Anal ring 80 (75–108) µm wide, with 2–3 rows of cells, bearing 6 (6) setae, each seta 142–152 (115–193) µm long. Cerarii numbering 8 or 9 (8–13) pairs, with 1 pair of frontal cerarii on head, all other cerarii situated on abdominal and thoracic segments, but usually cerarii on thoracic segments and occasionally some cerarii on abdominal segments lacking. Anal lobe cerarii each situated on sclerotised cuticle, containing mostly 2 (rarely 3) conical setae, each seta 25–30 (20–35) µm long and about 10–12 (5–15) µm wide at base; 15 or 16 (11–17) auxiliary setae and a concentration of trilocular pores. Penultimate cerarii each situated on weakly sclerotised cuticle, containing 2 conical setae and a few auxiliary setae. Cerarii situated further forward generally each with 1–3 conical setae and a few auxiliary setae.

Dorsum. Setae slender and flagellate, each 15–48 (15–60) µm long, longest setae present on head or posterior abdomen. Trilocular pores evenly distributed. Oral collar tubular ducts of 2 sizes: (i) large-type ducts, each about 3–4 (3–4) µm in diameter, obviously wider than a trilocular pore, forming transverse bands across most abdominal segments, also present on marginal areas of head and thoracic segments, and medial areas of thoracic segments; (ii) small-type ducts, each about 1.5–2.0 (1.5–2.0) µm in diameter, relatively sparse on abdominal segments, intermixed with large-type ducts. Discoidal pores sparsely distributed. Multilocular disc pores each 7–8 (6–9) µm wide, present on abdominal segments as follows: segment I, 0 (0); II, 0 (0); III, 0 (0); IV, 0 (0); V, 0 (0–2); VI, 1 (0–3); VII, 1 (0–4); VIII, 0 (0).

Venter. With slender flagellate setae, each 18–60 (18–85) µm long, longest on posterior abdomen or head. Multilocular disc pores, each 7–9 (6–9) µm wide, mostly present in medial area of abdominal segments V–IX, also a few usually present on some thoracic segments. Trilocular pores evenly distributed. Oral collar tubular ducts present in 2 sizes, same as on dorsum: large-type ducts, each with outer ductule 3–4 (3–4) µm in diameter (obviously larger than that of a trilocular pore) forming an irregular submarginal band on head, and transverse bands across all thoracic and abdominal segments, but more densely distributed on abdominal segments; and small-type ducts more sparsely distributed on most abdominal segments and occasionally on thoracic segments, intermixed with larger type. Discoidal pores sparsely present.

Host plants. Miscanthus sinensis (Poaceae) .

Remarks. Some members of the genus Trionymus are very close to species of Dysmicoccus , including D. bunagaya sp. nov., and the current definitions of these genera are arbitrary ( Williams 2004). Most coccidologists follow McKenzie (1967), who placed species with 6 or more pairs of cerarii in Dysmicoccus , and species with 5 or fewer pairs of cerarii in Trionymus . However, it is difficult to determine the generic position of D. angustifrons ( Hall, 1926) , which possesses 2–6 (sometimes up to 10) pairs of cerarii ( Danzig & Gavrilov-Zimin 2015), resulting in some controversy regarding its genetic position ( Danzig & Gavrilov-Zimin 2015, Matile-Ferrero et al. 2015). A similar taxonomic problem also arises for D. bunagaya , because morphological differences between this species and Trionymus okiensis Tanaka, 2018 are quite small. In the present study, D. bunagaya (with 8–13 pairs of cerarii) is placed in the genus Dysmicoccus .

Dysmicoccus bunagaya sp. nov. is similar to T. okiensis in having a pair of frontal cerarii and oral-collar tubular ducts of 2 different sizes on the dorsal and ventral surfaces, and in using the same host plant ( M. sinensis ), but it differs from T. okiensis in having more than 8 pairs of cerarii ( T. okiensis has fewer than 6 pairs). There is often considerable individual variation in this morphological character, and sometimes it cannot be used as a criterion for species separation; however, individuals showing intermediate morphology between the two species have not been observed so far. The distributions of D. bunagaya and T. okiensis are geographically separated by the East China Sea and the Sea of Japan ( Fig. 6 View FIGURE 6 ). Hayakawa et al. (2013: Fig. 2 View FIGURE 2 ) showed that the genes of the Miscanthus sinensis populations differ between southern Japan (including the Okinawa Islands) and northern Japan (including the Oki Islands). Gene flow between these two grass populations may have been cut off by rising sea levels. As adult female mealybugs cannot fly, and neither winged adult males nor immature males have been observed in either lineage, the movement of individuals is extremely limited so the D. bunagaya and T. okiensis populations at these two sites are likely to be genetically different also. We have therefore concluded that they are allopatric, distinct species. Unfortunately, T. okiensis has only been found once in several surveys so it is likely to be very difficult to collect it again, for molecular analysis to test its degree of genetic differentiation from D. bunagaya .

The new species also resembles D. boninsis ( Kuwana, 1909) , the pantropical pest of sugarcane ( Saccharum officinarum ), in having a pair of frontal cerarii and oral-collar tubular ducts of 2 different sizes on the dorsal and ventral surfaces. However, D. bunagaya differs from D. boninsis as follows (characters of D. boninsis are given in parentheses): (i) anal lobe cerarius with more than 10 auxiliary setae (fewer than 10); (ii) dorsal multilocular pores present (absent); and (iii) body narrow and parallel-sided, ratio of maximum length: width 2.8–3.5 (body usually relatively broad, ratio of maximum body length: width 1.7–2.0).

Relationship with ants. Dysmicoccus bunagaya sp. nov. is frequently attended by exotic ant species, such as Technomyrmex brunneus Forel and Pheidole fervens Smith , and the abundance of the mealybug in the Yanbaru district of Okinawa Island is statistically significantly well-explained by the abundance of T. brunneus , in a generalised linear model for a response variable (abundance of D. bunagaya ) following a negative binomial distribution ( Tanaka et al. 2011: D. bunagaya was indicated in this analysis as Dysmicoccus sp. A). Dysmicoccus bunagaya is probably one of the most important trophobiotic mutualistic partners for T. brunneus in this region.

Etymology. The specific epithet “ bunagaya ” is an Okinawan noun that refers to a small tree spirit in the mythology of northern Okinawa Island, used in apposition.