Nikkoaspis Kuwana, 1928

Tian, Feng, Zheng, Xinyi & Xing, Jichun, 2021, Description of a new species of the genus Nikkoaspis Kuwana, 1928 (Hemiptera Coccomorpha: Diaspididae) from China, Zootaxa 4949 (2), pp. 363-370 : 364

Genus Nikkoaspis Kuwana, 1928

Nikkoaspis Kuwana, 1928: 37 ; Chou, 1982: 57–58; Hu, 1987: 138–140; Takagi, 1999: 114–115; Normark, 2019: 52, 67.

Type species. Nikkoaspis shiranensis Kuwana, 1928 .

Generic diagnosis (adult female). Scale cover of adult female white, elongate, convex; exuviae situated at anterior end, brownish.

Slide-mounted adult female body elongate pyriform; cephalothorax tapering anteriorly; abdomen broad and expanded. Lateral margin of each abdominal segment with numerous plates and simple gland spines. Pygidium broad with posterior margin rounded. Pygidial lobes numbering 2 pairs; median lobes (L 1) separated from each other, each L 1 split into 1 or 2 lobules; second lobes (L 2) each split into 2–4 lobules of equal size; each lobule slender, with or without apical incision. There are 2 plates between L 1; space between L 1 and L 2 with 1 or 2 plates. Margin lateral to L 2 with some plates that form a continuous row with plates on margins of prepygidial abdominal segments. Gland spines absent from between L 1; 1 gland spine present lateral to L 1, and 1 or 2 gland spines situated lateral to L 2. Anal opening situated slightly anterior to centre of pygidium. Perivulvar pores present in 5 groups. Dorsal macroducts small, densely covering the lateral margins of prepygidial abdominal segments, and extending along posterior margin of each pygidial segment to midline. Dorsal macroducts scattered and irregularly arranged ( Chou, 1982).

Distribution. Malaysia, China, Japan, Russia.

Remarks. Nikkoaspis and Kuwanaspis are so similar that Takahashi (1930) merged them into a single genus. However, according to Takagi (1970:122; 1999:115) Nikkoaspis species are found on high-altitude bamboo in boreo-montane forests, whereas Kuwanaspis species occur in a wide range of habitats from tropical lowlands to temperate regions. These differing distribution traits, together with the peculiar body shape and numerous dorsal macroducts, were used to justify acceptance of Nikkoaspis as a valid genus by Takagi (1970). However, in their molecular phylogenetic analysis, Normark et al. (2019) found that Nikkoaspis is nested within Kuwanaspis , such that Kuwanaspis as presently constituted is paraphyletic, probably being comprised of multiple morphologically cryptic genera. Their analysis also showed Nikkoaspis as being sister to a tropical clade of Kuwanaspis (all samples from lowland Borneo), whereas all the temperate samples of Kuwanaspis including the genotype, K. hikosani ( Kuwana, 1902) , formed a separate clade. In principle, these clades might be accepted as separate genera, despite their close morphological similarity, but Normark et al. (2019) did not do so; nor did they synonymise Nikkoaspis under Kuwanaspis . Revision of the genus-level taxonomy is beyond the scope of the present article but future revision may result in splitting Kuwanaspis (as presently understood) into more than one genus. The temperate clade containing K. hikosani would retain the name Kuwanaspis , and Nikkoaspis (as presently understood) might remain distinct or form part of the unnamed tropical clade.