Plateumaris akiensis Tominaga & Katsura, 1984

Geiser, Elisabeth, 2023, Revision of the Palaearctic species of the genus Plateumaris C. G. Thomson, 1859 (Coleoptera, Chrysomelidae, Donaciinae), ZooKeys 1177, pp. 167-233 : 167

Plateumaris akiensis Tominaga & Katsura, 1984

Fig. 2

Plateumaris akiensis Tominaga & Katsura, 1984: 25.

Type locality.

Japan, Honshu, Shinkawa-tameike, altitude 770 m, Nishi-yawata-hara, Geihoku-cho, Yamagata-gun, Hiroshima Prefecture.

Type material.

Holotype: Japan • ♂; Honshu, Hiroshima Prefecture, Yamagata-gun, Geihoku-cho, Nishi-yawata-hara, Shinkawa-tameike; 770 m a.s.l.; 13 Jun 1982; I. Hiura leg.; OMNH-TI-16. The holotype was not examined.

Taxonomic history.

Because this species was not described until 1984 it is possible that some small Plateumaris specimens from Japan are misidentified as another species in old collections.

Diagnosis.

Habitus (Fig. 2A ) like a typical Plateumaris , but with conspicuously short elytra and legs, elytra length is at the most 1.6 × longer than wide, colour black or bronze-metallic, also with a bluish or greenish lustre, elytra shiny, antennomeres thicker than in most Plateumaris species, legs reddish but femora dark.

Description.

There are comprehensive descriptions in Tominaga and Katsura (1984) and in Hayashi (2020) with many detailed figures so the description below is confined to the essentials.

Size: 6.4-7.6 mm.

Colour: Colour of pronotum and elytra entirely metallic black or reddish coppery, some specimens with a bluish or greenish lustre.

Head: Supraocular furrow indistinct, frontal tubercle weakly convex.

Antennae: Antennae short and robust, slightly shorter than half as long as the body, A1 dark, A2-A11 entirely reddish brown or apical antennomeres with darker parts. A1 is longest, A2 is shortest, A3-A11 are only slightly longer than A2, A3 ≥ A4 ≤ A5.

Pronotum: Slightly longer than wide, outline more or less cordate, gradually narrowed backwards with anterior margin strongly produced forward; dorsal surface with feebly raised anterior and posterior tubercles, disc densely but finely punctate, median line shallow, with a conspicuous broad collar along the posterior margin.

Elytra: Robust and short, 1.6 × as long as wide, with arched outer margin, rows of punctures regular, their interstices smooth, usually sparsely but sometimes densely punctate.

Legs: Legs short, reddish brown, partly dark rufous or black, especially the apical half of the femora, metafemur robust in shape, with a tooth; T2 shorter than its width, T1> T2 <T3.

Pygidium: Entirely rufous, but apical part black, apex pubescent, shallowly emarginate in both sexes.

Aedeagus: See Fig. 2B, C .

Similar species.

Plateumaris akiensis looks similar to P. constricticollis but can be identified by its shorter elytra. In P. constricticollis the elytral length is distinctly> 1.6 × longer than wide.

Biology.

The adults feed on pollen of Carex sp. and Scirpus juncoides ( Hayashi 2020). Narita (2003) described the larvae from Carex otaruensis Franch. Scirpus sp. is also thought to be a larval host plant ( Hayashi 2020).

Distribution.

Endemic species found in Honshu, Japan. The only records so far are from Hiroshima and Shimane prefectures in south-west Honshu.

Material examined.

Five specimens from Hiroshima prefecture, stored in BMNH, HNHM, and NMPC.

Figures

Figure 2. Plateumaris akiensis A habitus (photograph by K. Matsumoto) B cap of tegmen C median lobe (B, C from Hayashi 2020). Scale bars: one unit - 1 mm (A); 0.5 mm (B, C).