Mordellistena koelleri Ermisch, 1956

Zemoglyadchuk, Aleksei & Buialska, Nataliia, 2020, Description of the larvae of three species of the genus Mordellistena (Coleoptera: Mordellidae) with notes on their ecology, Zootaxa 4743 (3), pp. 371-381 : 373

Mordellistena koelleri Ermisch, 1956

Material examined: Belarus: Gomel Region, the city of Gomel, 52°42’N 31°03’E, floodplain of the Sozh River , meadow, in the stems of Phleum pratense , 09.xii.2017, 3 larvae ; same locality, 24.xii.2017, 4 larvae ; same locality, 09.v.2018, 2 larvae . Ukraine: Chernihiv Region, near the city of Chernihiv, 51°48’N 31°31’E, floodplain of the Desna River , meadow, in the stems of Phleum pratense , 12.v.2018, 10 larvae ; same locality, 30.v.2018, 4 larvae ; same locality, 03.v.2019, 3 larvae .

Body shape: Body cylindrical, stout, slightly expanded in middle, 4.9–5.3× as long as wide ( Figs 3–4 ).

Coloration: Body white or yellowish, with brownish head.

Size: Body length: 5.5–6.1 mm.

Head: Head slightly flattened, in frontal aspect oval, 1.1× as long as wide, 1.5–1.6× narrower than prothorax, with one stemma beneath relatively large cuticular lens on each side; epistome weakly sclerotized in middle; primary head setae relatively short; secondary head setae few, absent above level of genal seta 2 ( Fig. 15 ). Antennae 1-segmented, each with narrow sensorium, one long and two comparatively short sensilla chaetica and four short sensilla basiconica ( Fig. 16 ). Clypeus smooth. Labrum evenly sclerotized, 1.1× as wide as long, slightly rounded on apical margin, without microtrichia in lateral portions, with two long median setae, two long lateral setae, four short setae placed close to anterior margin and four short setae on border with epipharynx. Mandibles each with weakly sclerotized triangular area and two setae in lateral portions, subapical tooth almost absent ( Fig. 17 ). Maxillolabial complex gradually narrowed to base in proximal portion ( Fig. 18 ); cardo sclerotized, with one short seta; stipes not expanded, weakly sclerotized, with few setae, almost straight on inner margin; palpifer slightly or moderately sclerotized; maxillary palp 2-segmented, basal palpomere 1.2–1.3× as wide as long, with two setae, distal palpomere with one seta, 1.4–1.6× as long as wide, 1.1–1.2× shorter than basal palpomere; postmentum with two long setae; prementum with two long setae in middle and two short setae in lateral portions; palpiger slightly sclerotized on medial side, with 1 setae; ligula narrowed to apex, with 2 short setae and spines; labial palp 2-segmented, basal palpomere 2.0× as wide as long, distal palpomere with four short sensilla basiconica at apex, 1.4× as long as wide, 1.3× longer than basal palpomere ( Fig. 19 ).

Thorax: Prothoracic tergum oval, with sparse setae, without sclerotized asperities and transversal sulcus; mesothoracic and metathoracic terga with rather sparse setae in lateral portions. Mesothoracic spiracles round.

Legs: Relatively large, moderately stout, with sparse setae; apex of distal segment without setae.

Abdomen: Abdominal segments with setae approximately equal in length in lateral portions; dorsal protuberances on abdominal segments I–VI rather weakly prominent; lateral protuberances on abdominal segments I–VIII rather narrow; abdominal segment IX relatively short, helmet-shaped, narrowly elongated at apex, with one pair of small dorsal teeth near apical processes and often with few additional smaller teeth; preanal tubercles small, with 9–15 setae. Apical processes small, cylindrical, with well-defined dorsal and ventral teeth, not fused, each with one relatively short seta medially ( Figs 20–22 ). Abdominal spiracles round.

Figures

FIGURES 1–6. Habitus of the larvae. 1, 2: Mordellistena luteipalpis Schilsky, 1895 (1: dorsal view; 2: lateral view); 3, 4: Mordellistena koelleri Ermisch, 1956 (3: dorsal view; 4: lateral view); 5, 6: Mordellistena brevicauda (Bohemann, 1849) (5: dorsal view; 6: lateral view). Scale bars: 1 mm.

FIGURES 15–22. Details of the larva of Mordellistena koelleri Ermisch, 1956. 15: head; 16: antenna; 17: mandible, ventral view; 18: maxillolabial complex; 19: labial palp; 20: apical process, lateral view; 21: apical processes, dorsal view; 22: apical processes, posterior view.