Micronecta (Dichaetonecta) sahlbergi ZVNU
Creators: name: Ha, Tuyet Ngan
name: Tran, Anh Duc
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Corixidae
Micronecta
Micronecta sahlbergi

description: Micronecta (Dichaetonecta) sahlbergi (Jakovlev, 1881)
Fig. 4D–G
Sigara sahlbergi Jakovlev, 1881: 213–214 (type locality: Amur, Russia).
Micronecta formosana Matsumura, 1915: 114–115, 119, pl. III, fig. 8 (type locality: Taiwan).
Micronecta sahlbergi – Horváth 1899: 101 (key). — Hutchinson 1940: 373–374 (listed as possibly identical to M. siva). — Wróblewski 1960: 306–309, pl. XV (redescription, synonymised M. formosana with M. sahlbergi); 1963: 476–478 (distribution); 1968: 776 (checklist). — Yang 1967: 46 (key). — Jansson 1995: 27 (catalogue).
Micronecta formosana – Chen 1960: 104, 106, pl. I (key, redescription).
Diagnosis
Body length 2.2–3.1. Pronotum slightly longer than median head length. Hemelytron punctate, generally pale.
Males: fore femur with a set of four spines on proximal third ventrally; fore tibia without spine; palar claw narrow. Median lobe of sternite VII with one long seta and a long and narrowly rounded apex. Free lobe posteriorly strongly broadened, posterior margin nearly straight, lateral angle produced (Fig. 4D). Left paramere: shaft slender, mesial side with barbs, apical part sinuate, covered with small scales, apex narrowly rounded; basal lobe tongue-shaped (Fig. 4F–G). Right paramere: shaft evenly curved, from distal fourth tapering towards narrowly rounded apex (Fig. 4E).
Material examined
VIETNAM – Hanoi • 1 ♂; Nhue River, in Lien Mac area; 25 Mar. 2010; T.M. Pham leg.; HN08; ZVNU.
Distribution
First record for Vietnam. Other countries: Russia (Amur-Ussuri), Korea, China (Beijing, Hong Kong, and southern China), Taiwan (Wrósblewski 1960, 1963, 1968; Chen 1960).
Remarks
Wróblewski (1963) and Jansson (1995) placed M. sahlbergi in the subgenus Basileonecta. Subsequently, Nieser et al. (2005) placed it in the subgenus Dichaetonecta without explanation. We find that this species matches the definition of Dichaetonecta rather than Basileonecta, by having a moderately widened palar claw, a well-developed median lobe of sternite VII with one long seta, and a distally-widened free lobe.
The five species of Dichaetonecta occurring in Vietnam can easily be separated from each other by the structures of the left paramere. The left paramere of M. decorata is apically constricted and twisted. That of M. ludibunda is constricted before widening to a broad, flat, and suboval apex. The left paramere of M. sahlbergi is uniquely sinuate at the apical part, which is covered with small scales. In M. desertana, the apical part of left paramere is rather simple, only slightly constricted, but neither twisted nor sinuate. The left paramere of M. johorensis has a large triangular tooth near the middle section of the shaft. The right paramere of M. johorensis is unique in having longitudinal striations on the stout shaft. In addition, the shape of the free lobe of M. decorata is clearly distinct from that of the other three species besides M. johorensis, with the posterior margin produced into an obtuse angle, while in the other three species the posterior margin of the free lobe is straight or slightly concave. The free lobe of M. ludibunda is more like that of M. sahlbergi, with both having a more strongly widened distal part. The free lobe of M. desertana is only slightly widened at the distal part.
description: Published as part of Ha, Tuyet Ngan & Tran, Anh Duc, 2021, Taxonomy of Micronectidae (Heteroptera: Nepomorpha) from Vietnam, with descriptions of 11 new species, pp. 1-82 in European Journal of Taxonomy 756 on page 23, DOI: 10.5852/ejt.2021.756.1407, http://zenodo.org/record/5033010