Plateumaris roscida Weise, 1912

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 roscida Weise, 1912

Figs 8 , 9

Plateumaris roscida Weise, 1912: 77.

Plateumaris annularis Reitter, 1920: 41.

Type localities.

Plateumaris roscida : Russia, Transbaikalia (Zabaykalsky Krai): Tschita; Plateumaris annularis : Russia, Far East, Khabarovsk Krai, Nikolayevsk-on-Amur.

Type material.

Holotype of P. roscida : Russia • 1 ♂; East Siberia, Transbaikalia, Tschita; ZMHB. Label text: "Typus [red]// Plateumaris roscida m. //coll. J. Weise //Zool. Mus. Berlin //Holotype ♂ Plateumaris roscida Weise [red]// Plateumaris roscida Weise det. I.S. Askevold 1989".

No location label is tagged to the holotype, but the type locality “Tschita” is indicated in the original description by Weise (1912). The holotype was examined in May 2023.

Holotype of Plateumaris annularis : Russia • 1 ex.; Far East, Khabarovsk Krai, Nikolayevsk-on-Amur, "Amur region, Chabarowsk, Nikolajewsk"; L. Graeser leg.; depository unknown. At first stored in coll. W. Koltze, current depository presumably SDEI, but needs confirmation.

Taxonomic history and synonymies.

Weise (1912) described Plateumaris roscida (see Geiser and Geiser 2023) based on a specimen from Tschita. He obtained it from Johann Nepomuk Ertl (1860-1925, Munich, Germany), a dedicated beetle collector who had connections to missionaries. This specimen was presumably collected during a journey to China.

Reitter (1920) published an identification key for Palaearctic Donaciinae . In a footnote to P. sericea he described P. annularis from Russia, Far East, Amur region, Chabarowsk (krai), Nikolajewsk, coll. Koltze (see Geiser and Geiser 2023). Reitter did not mention in the description that this P. annularis is armed with a prominent metafemoral tooth, but he provided this information indirectly two paragraphs later when he contemplated if P. obsoleta could be the same species as P. annularis . He also described that, in contrast, P. obsoleta has completely dark legs and the posterior femora are practically unarmed, or only bluntly angled. This description and further notes in Reitter (1920) match completely with the characters of P. roscida .

Kolossow (1930: 29) synonymised P. annularis with P. roscida with the laconic line " Plateumaris annularis Reitt. (1920) = Pl. roscida Weise (1912) ". Goecke (1957a) studied a specimen from ZSM, labelled "Samml. Ertl" [= collection of Ertl] and " Pl. roscida n. sp. Wse" in the handwriting of Weise. He also examined four specimens from the then "Deutsches Entomologisches Institut Berlin" (now SDEI) labelled " Pl. annularis Reitter", one of them labelled "Nikolajewsk, Graeser" and " Pl. annularis Rtr., Chabaroska, Weise" and another two specimens labelled " Pl. annularis " without location labels. All four specimens were labelled as “Type”. He then compared the P. roscida specimen with the P. annularis specimens and confirmed the statement of Kolossow (1930) that they all belong to P. roscida .

Askevold (1991) studied other specimens from Russia and north China identified as P. annularis and confirmed that they belonged unambiguously to P. roscida . He also suggested that P. caucasica may be synonym of P. roscida because of the description of Zaitzev (1930), but he conceded that the geographic distance between the Caucasus and Transbaikalia caused a problem.

Diagnosis.

Upper side bronze, bluish, or purplish, flat-lustrous, habitus similar to P. sericea , antennomeres reddish basally and darkened apically, pronotum with flattened anterior tubercles, femora reddish on basal half and dark on apical half. Aedeagus with a conspicuous elongated peak.

Description.

Size: 6.7-9.7 mm.

Colour: Bronze or dark with bluish or purplish lustre.

Antennae: Slender, annulated, antennomeres basally rufous, apical dark or metallic, A2 <A3 <A4.

Pronotum: Almost quadratic or slightly longer than wide, anterior tubercles flattened, disc coarsely and closely punctate with fine wrinkles, median groove narrow or indistinct, in posterior part short and slightly deeper, then forked into two horizontal grooves near the bottom line.

Elytra: Oblong, with shallow impressions, coarsely and densely rugose on most of surface, punctures regular, strong, and deep, interstices wrinkled, interstices ~ 2-4 × puncture diameter.

Legs: In most specimens the femora are reddish on basal half and dark metallic on apical half, tibia reddish with dark parts, tarsomeres dark or with reddish basal part. Some specimens with entirely reddish legs. Metafemora with prominent, thorn-shaped tooth in most specimens.

Pygidium of females with an apical notch, males broadly emarginate.

Aedeagus: Median lobe with a conspicuous elongated peak, cap of tegmen with a deep apical notch (Fig. 9 ).

Two similar species are Plateumaris sericea and P. shirahatai which differ: in P. roscida the pronotum and its tubercles are flattened, legs with large reddish parts, and the aedeagus has a conspicuous elongated peak.

Biology.

Bieńkowski 2014 mentions: Carex sp. ( Cyperaceae ) as host plants. The larva has not yet been described.

Distribution.

East Palaearctic: East of Lake Baikal to Far East, the Sakha (Yakutia) Republic, Amur region in Russia and north-east China (Harbin, Heilongjiang). Records exist for Asia: northern China (Heilongjiang, Inner Mongolia) [new in PalCat], Russia (East Siberia, Far East).

New country records additional to Silfverberg (2010).

China - Heilongjiang • 1 ex.; Harbin; 3 Jul 1952; E. Geiser 2021 det.; BM1953-715, (BMNH). • 2 ex.; Xinkai (Khanka) Lake, Bathing beach area; 45°21'52"N, 132°18'55"E; 11 Jun 2018; among strandline detritus; R.B. Angus, F.L. Jia, Z.L. Liang leg., E. Geiser 2021 det.; BMNH.

China: Heilongjiang and Inner Mongolia: Askevold (1991).

Material examined.

More than 30 specimens from different localities throughout the distribution area.

Figures

Figure 8. Plateumaris roscida A habitus (photograph by K. Matsumoto) B metafemur with typical double colouring and prominent tooth (photograph by E. Geiser). Scale bars: one unit - 1 mm (A, B).

Figure 9. Plateumaris roscida aedeagus, photographed from different angles and drawings in frontal view A, B specimen from Primorsky Krai (ZMS) C specimen from Amur Oblast (NHMB) D median lobe E cap of tegmen (A-C photographs by E. Geiser, D, E drawings by G. Geiser). Scale bars: 1 mm.