Micronecta Kirkaldy, 1897

Tinerella, Paul P., 2008, Taxonomic revision and systematics of New Guinea and Oceania pygmy water boatmen (Hemiptera: Heteroptera: Corixoidea: Micronectidae), Zootaxa 1797 (1), pp. 1-66 : 27-28

Micronecta Kirkaldy

( Figs. 16–35 )

Micronecta Kirkaldy, 1897a: 260 ; (= Sigara sensu Leach, 1817: 14 , not Fabricius 1775 ( Puton 1899)). Distant, 1906: 50; Hale, 1922: 323; Hutchinson, 1929: 422; Jaczewski, 1937: 584, 586, 589; Hutchinson, 1940: 347; China, 1943: 283; Poisson, 1951: 1753; Villiers, 1952: 208; Usinger, 1963: 191; Chen, 1965: 147; Wróblewski, 1970: 681; Popov, 1971: 134; Wróblewski, 1972b: 517; Linnavuori, 1981: 2–4; Jansson, 1986: 8–19; Kanyukova, 1990: 13; Jansson, 1995: 27; Cassis and Gross, 1995: 66; Nieser, 1999a: 9, 1999b: 277; Nieser and Chen, 1999: 78; Chen et al., 2002: 195; Nieser, 2002a: 9, 2002b: 264; Nieser et al., 2004: 30; Tinerella and Polhemus, 2005: 183; Andersen and Weir, 2004: 246; Chen et al., 2005: 144.

Type species: By original designation, Notonecta minutissima Linnaeus, 1758 .

Description: Small (0.8–5.5 mm), generally ovate to subparallel-sided micronectids. Ground color brown to black, often with darker longitudinal, reticulate, or mottled patterning. Vertex of head rounded to conically produced, foveate depression absent. Head sclerites broader, frons and clypeus evenly proportionate surrounding the short labium (unsegmented rostrum). Labial apex exceeding a line drawn through apical genal margins, head thus appearing longer in lateral view Prothoracic lobe robust, often wider than long, subquadrate to rectangular. Metaxyphus longer, reaching beyond basal portion of hind coxae, triangular, often with acute apex.

Pronotum robust in macropters, well developed, convex and broadest medially. In brachypterous forms, pronotum proportionately reduced, often much shorter than individuals with fully developed flight muscles. Hemelytra uniformly clothed with numerous short spines, microsculpturing variable but always present. Nodal furrow entire, marked by well developed perpendicular suture, this reaching outer margin of wing. Prenodal embolar area well developed, post-nodal embolar area shorter, but pronounced. Palae generally robust, palar claw of males widened, often expanded, apex rounded. Profemur with two or four setae basally, near ventral margin. Tergal lobes of abdominal segment IV well developed, long, broadly rounded apically. Strigil on abdominal tergite VI varying in size but always conspicuous. Strigil absent in M. (Micronectella) acuta Lundblad and M. (Indonectella) grisea Fieber. Sternal process of abdominal segment VII long, apex broadly acuminate or rounded. Free lobe of abdominal tergite VIII with outer angle rounded and inner angle at least partly rounded. Male parameres: left paramere with or without apical modification, scales present on distal third in all Australian species. Right paramere with rectangular base, shaft length variable, apex often expanded; tip rounded or pointed. Pars stridens processus generally spanning entire width of paramere base: pars stridens processus distributed over at least medioapical portion and often expanded to basal portion.

Discussion: The genus Micronecta is currently divided into ten poorly defined subgenera ( Hutchinson 1940, Wróblewski 1967, Tinerella 2006b), with several taxa unplaced. Unplaced taxa include several Oriental species, which with some related species were tentatively placed by Jansson (1995) in the nominate subgenus. Further unplaced taxa include some African,, Philippine,, and most Australasian species. Complete examination and redescription of the genotype M. minutissima Linnaeus is needed to fix the generic concept. The generic definition given above is based on examination of specimens of M. minutissima , most subgenotypes representing the current subgeneric classification, and analysis and redescription of Australasian Micronecta . The generic definition given here for Micronecta Kirkaldy will undoubtedly be narrowed as other regional faunas are examined.

Australasian Micronecta are currently composed of two primary elements. The ‘ annae ’ species group as defined here consists of 12 species ( Table 6) restricted to the Australasian region, four of which are distributed throughout New Guinea and Oceania. Because of the current lack of resolution of the infrafamilial relationships of Micronecta , I have elected to treat these taxa as a species group, rather than propose an additional generic-level name. The annae species group as presently interpreted falls within the generic definition of Micronecta . The eight species of the annae group restricted to continental Australia will be treated in a forthcoming monograph.

Two widespread species form the second element of the Australasian Micronecta fauna: M. ludibunda Breddin and M. quadristrigata Breddin. Both species are distributed throughout Australasia and are known westward to India ( M. ludibunda ) and Iran ( M. quadristrigata ). The systematic position of these two species within Micronecta is discussed below.

The remaining Australian species (all endemic) include Micronecta micra Kirkaldy , Micronecta australiensis Chen , and Micronecta carinata Chen.

Figures

FIGURE 16. Dorsal habitus of Micronecta species. a–b. M. ludibunda Breddin, male and female. c–d. Micronecta jenniferae Tinerella, male and female. e–f. M. quadristrigata Breddin, male and female. g–h. M. queenslandica Chen, male and female. i–j. M. carbonaria Horvath, male and female. k–l. M. virgata Hale, male and female. Scale bars = 0.5 mm.

FIGURE 17. Micronecta ludibunda Breddin. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw folded in. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. g. Free lobe of abdominal tergite VIII. Scale bars = 0.1 mm.

FIGURE 18. Micronecta ludibunda Breddin, male genitalia. a. Left paramere, lateral aspect, right paramere, dorsal aspect. b. Left paramere, dorsolateral aspect, right paramere, dorsolateral aspect. c. Left paramere, tip, right paramere, tip. d. Left paramere, lateral aspect, right paramere dorsolateral aspect. e. Pars stridens processus, base of right paramere. f. Right paramere, base of shaft.

FIGURE 19. New Guinea distribution of Micronecta ludibunda Breddin.

FIGURE 20. Micronecta jenniferae Tinerella, locality labels, holotype, and dorsal habitus. a. Locality labels. b. Type label. c. Holotype specimen, male, dorsal habitus.

FIGURE 21. Micronecta jenniferae Tinerella. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw folded in. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. Scale bars = 0.1 mm. (Modified from Tinerella 2006)

FIGURE 22. Micronecta jenniferae Tinerella, male abdominal terminalia. a. Free lobe of abdominal tergite VIII. b. Pars stridens processus cleaner ridges of abdominal segment VIII. c. Left paramere, lateral aspect. d. Left paramere, ventrolateral aspect. e. Left paramere, ventrolateral aspect, right paramere, dorsal aspect. f. Left paramere, ventral aspect, right paramere dorsolateral aspect. g. Right paramere, lateral aspect. h. Pars stridens processus, base of right paramere.

FIGURE 23. Micronecta quadristrigata Breddin. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Prestrigilar flap of abdominal segment V. e. Sternal process of abdominal segment VII. f. Free lobe of abdominal tergite VIII. Scale bars = 0.1 mm.

FIGURE 24. Micronecta quadristrigata Breddin, male pala and abdominal terminalia. a. Male fore leg, anterior aspect, palar claw folded in. b. Free lobe of abdominal tergite VIII. c. Left paramere, dorsolateral aspect. d. Left paramere, tip. e. Right paramere, dorsolateral aspect. f. Right paramere, dorsolateral aspect. g. Right paramere, lateral aspect. h. Pars stridens processus, base of right paramere.

FIGURE 25. New Guinea distribution of Micronecta quadristrigata Breddin.

FIGURE 26. Micronecta queenslandica Chen. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw folded in. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. g. Free lobe of abdominal tergite VIII. Scale bars = 0.1 mm.

FIGURE 27. Micronecta queenslandica Chen, male genitalia. a. Left paramere, lateral aspect, right paramere, dorsolateral aspect. b. Left paramere, dorsolateral aspect, right paramere, tip. c. Right paramere, lateral aspect. d. Pars stridens processus, base of right paramere.

FIGURE 28. Distribution of Micronecta queenslandica Chen.

FIGURE 29. Micronecta carbonaria Horváth. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw folded in. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. Scale bars = 0.1 mm.

FIGURE 30. Micronecta carbonaria Horváth, male abdominal terminalia. a. Free lobe of abdominal tergite VIII. b. Left paramere, lateral aspect. c. Left paramere, tip. d. Right paramere, lateral aspect. e. Right paramere, dorsolateral aspect. f. Pars stridens processus, base of right paramere.

FIGURE 31. Distribution of Micronecta carbonaria Horváth.

FIGURE 32. Micronecta virgata Hale, holotype and dorsal habitus. a–b. Locality and type labels. c. Holotype male, dorsal habitus.

FIGURE 33. Micronecta virgata Hale. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw folded in. e. Prestrigilar flap of abdominal segment V. Scale bars = 0.1 mm.

FIGURE 34. Micronecta virgata Hale, male abdominal terminalia. a. Sternal process of abdominal segment VII. b. Free lobe of abdominal tergite VIII. c. Left paramere, lateral aspect, right paramere, dorsolateral aspect. d. Left paramere, dorsolateral aspect. e. Left paramere, dorsolateral aspect (cf Figs. c, d, f; base). f. Left paramere, lateroventral aspect, right paramere dorsolateral aspect. g. Right paramere, tip. h. Pars stridens processus, base of right paramere.

FIGURE 35. New Guinea distribution of Micronecta virgata Hale.