Micronecta Kirkaldy

Tinerella, Paul P., 2013, <strong> Taxonomic revision and systematics of continental Australian pygmy water boatmen (Hemiptera: Heteroptera: Corixoidea: Micronectidae) </ strong>, Zootaxa 3623 (1), pp. 1-121 : 31-33

Micronecta Kirkaldy

( Figs. 16–64)

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; Andersen and Weir, 2004: 246; Tinerella and Polhemus, 2005: 183; Chen et al., 2005: 144; Tinerella, 2006b: 141; Tinerella, 2008: 27 .

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

Description: Small (0.8–5.5 mm), generally ovate to sub-parallel 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 proportionate surrounding the short labium (unsegmented rostrum). Labial apex exceeding a line drawn through apical genal margins, head thus appearing longer in general outline. Prothoracic lobe robust, often wider than long, subquadrate to rectangular. Metaxyphus longer, reaching beyond basal portion of hind coxae, triangular, and often with acute apex.

Pronotum robust in macropters, well-developed, convex and broadest medially. In brachypterous forms, the pronotum is proportionately reduced, often much shorter than exemplars with fully developed flight muscles. Anterior pronotal carina weakly developed to absent. Hemelytra uniformly clothed with numerous short spines, microsculpturing variable though always present. Nodal furrow entire, marked by well-developed perpendicular suture which reaches outer margin of wing. Prenodal embolar area well-developed, post-nodal embolar area shorter, though 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 welldeveloped, long and broadly rounded apically. Strigil present, of variable sizes, though always conspicuous. Strigil absent in Micronecta (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 apical modification or not, scales present in 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 medio-apical portion and often expanded to basal portion.

Discussion: The current generic-level classification of Micronecta was discussed in detail by Tinerella (2006a, 2006b, 2008). Within Micronecta , the present subgeneric classification consists of ten marginally defined subgenera and numerous unplaced taxa. Complete examination and redescription of the genotype M. minutissima Linnaeus is needed to fix the generic concept. The generic definition given above for Micronecta is based on examination of exemplars of M. minutissima , most subgenotypes representing the current subgeneric classification, and analysis and redescription of Australasian Micronecta (see also Tinerella 2006b, 2008). This definition will undoubtedly be narrowed as other regional faunae are examined and generic limits revised.

Australian Micronecta are currently comprised of two primary elements. The ‘ M. annae ’ species group ( Tinerella 2006b, 2008) consists of 13 species ( Table 6). Nine species are restricted to continental Australia, two species share distributions with New Guinea, one species, M. carbonaria , is endemic to New Guinea, and the last species, M. jenniferae Tinerella , is presently only known from Fiji. Micronecta paragoga sp. nov., is herein placed within the M. annae species group, based on the shared male genitalic characters (viz. apical scales of the male left paramere) and similar abdominal morphology (lateral lobes of abdominal segment IV and shape of the free lobe of abdominal tergite VIII) shared with other species of the annae group. The species of the annae group occurring in New Guinea and Oceania were recently revised by Tinerella (2008).

Two widespread species form the second element of the Australian Micronecta fauna: M. ludibunda and M. quadristrigata Breddin. Both species are distributed throughout Australasia and are known westward from India ( M. ludibunda ) and Iran ( M. quadristrigata ). Micronecta ludibunda is newly reported here for Australia, based on one macropterous male specimen examined from Queensland. The systematic position of these two species within Micronecta is unclear and was discussed by Tinerella (2006b, 2008). Additional discussion is provided below.

Key to the Species of Micronecta Kirkaldy of Australia

1. Small, generally ovate species, length 1.79–2.36 mm; pronotum short, narrow to broadly triangular; ground color brown, hemelytral patterning with or without longitudinal stripes ( Figs. 16a–b, 20a–b); metaxyphus short, apex produced as a rounded lobe ( Figs. 17b, 21b)................................................................................... 2

– Larger species, length> 2.51 mm; pronotum generally well-developed and proportionate with head; ground color light brown with hemelytral patterning developed as longitudinal stripes or effaced; metaxyphus long and triangular, apex not produced....... 3

2(1). Small, ovate species, length of brachypter 1.79–1.93 mm, macropterous form slightly larger, length 2.28–2.32 mm; interocular space wider than width of eye ( Figs. 16a–b); pronotum short, embracing broadly rounded margin of head ( Figs. 16a–b); hemelytral patterning mottled medio-apically, with expanded diagonal lightened corial area ( Figs. 16a–b); metaxyphus ( Fig. 17b); male parameres ( Figs. 18a–e)................................................... M. paragoga sp. nov. (pg. ####)

– Small, elongate species, length of brachypter 1.86–2.23 mm, length of macropter 2.14–2.36 mm; interocular space narrower than width of eye ( Figs. 20a–b); pronotum longer, triangular, and often with dark transverse medial band ( Figs. 20a–b); ground color brown, hemelytral patterning consisting of longitudinal dark stripes ( Figs. 20a–b); metaxyphus ( Fig. 21b); male parameres ( Figs. 22a–f)....................................................... M. ludibunda Breddin (pg. ####)

3(1). Pronotum and head proportionately very short ( Figs. 23a–d); hemelytral patterning effaced or with four weakly developed longitudinal stripes ( Figs. 23a–d); hind tibia armed with numerous long, stout spines; male parameres ( Figs. 25a–g); length 2.82–3.28 mm ............................................................ M. lansburyi Wróblewski (pg. ####)

– Pronotum and head proportionately longer; hemelytral patterning variable; hind tibia with regular series of spines; length variable................................................................................................ 4

4(3). Pronotum exceptionally large, longer than head ( Figs. 27a–b); hemelytral patterning consisting of two or three discontinuous longitudinal stripes, embolium with dark discontinuous areas ( Figs. 27a–b); male left paramere with apical scales highly reduced ( Figs. 29a–d)........................................................... M. adelaidae Chen (pg. ####)

– Pronotum and head length generally equal; hemelytral patterning variable; male left paramere with apical scales.......... 5

5(4). Larger species,> 3.5 mm ................................................................................ 6

– Smaller species, <3.5 mm ............................................................................... 7

6(5). Length 4.15–4.54 mm; vertex of both sexes conically produced ( Figs. 31a–b); ground color dark brown, corium with two or three short dark longitudinal lines ( Figs. 31a–b); male left paramere ( Figs. 33a–f), right paramere abruptly expanded distally ( Figs. 33a–f)..................................................................... M. major Chen (pg. ####)

– Length 3.52–4.09 mm; vertex of both sexes rounded, at most only slightly produced ( Figs. 35c–e); hemelytral patterning faint, corium with four long, dark longitudinal stripes ( Figs. 35c–e); male left paramere ( Figs. 37d–g); right paramere broadly expanded apically ( Figs. 37d–g)..................................................... M. robusta Hale (pg. ####)

7(5). Vertex in both sexes conically produced.................................................................... 8

– Vertex in both sexes rounded............................................................................ 9

8(7). Ground color sandy-brown, hemelytral patterning entirely effaced ( Figs. 38a–b); pronotum unicolorous ( Figs. 38a–b); male left paramere ( Figs. 40a–c), right paramere evenly expanded apically ( Figs. 40d–e); length 3.13–3.71 mm ....................................................................................... M. tasmanica Wróblewski (pg. ####)

– Ground color light brown, hemelytral markings variable, unicolorous dark, to markings present as dark longitudinal lines ( Figs. 41c–e, 42a–b, 43a–d); pronotum often with dark transverse bar ( Figs. 41c–e); left paramere convexly curved, with sharp apical hook ( Figs. 45d–f), right paramere parallel-sided, pointed apically ( Figs. 45d–g); brachypter length 2.74–3.44 mm, macropter length 3.18–3.62 mm ................................................... M. annae Kirkaldy (pg. ####)

9(7). Slender, elongate species ( Figs. 46c–e), length 2.75–3.82 mm; hemelytral markings present as interrupted longitudinal streaks ( Figs. 46c–e); male palar claw broadly expanded ( Figs. 47d, 48a); left paramere long and slender, with sharp apical hook ( Figs. 48b–f)......................................................................... M. gracilis Hale (pg. ####)

– Wider, evenly proportionate species; hemelytral markings weakly developed or present as distinct longitudinal stripes; male palar claw narrow; left paramere not modified as above...................................................... 10

10(9). Hemelytra with four distinct, dark longitudinal stripes ( Figs. 49c–e); larger species, 2.89–3.50 mm; left male paramere ( Figs. 51c–f); right male paramere long, tip expanded and broadly rounded ( Figs. 51c–g); Australia, Papua New Guinea, Solomon Islands.......................................... ………………………………………… M. virgata Hale (pg. ####)

– Hemelytral patterning weakly developed as discontinuous longitudinal markings length 2.51–3.34 mm ................. 11

11(10). Hemelytral patterning ill-developed, at most a faint longitudinal series in medial portion of corium ( Figs. 53b–d); length 2.77–3.34 mm; palar claw expanded apically ( Fig. 54d); sternal process of abdominal segment VII short, apex acute ( Fig. 54f); left male paramere ( Figs. 55a–d)....................................................... M. halei Chen (pg. ####)

– Hemelytral patterning forming a faint series of three or four discontinuous longitudinal bands…....................... 12

12(11). Length 2.51–2.90 mm; hemelytra with dark markings present as interrupted longitudinal series forming four broken bands ( Figs. 57a–b); palar claw parallel-sided, rounded apically ( Fig. 59a); sternal process of abdominal segment VII long, apex finger-like ( Fig. 58e); left male paramere with pronounced hook-shaped apex ( Figs. 59c–d); right paramere long, slender ( Figs. 59c–g); widespread, Iran to Oceania.......................................... M. quadristrigata Breddin (pg. ####)

– Length 2.6–3.0 mm; hemelytra with lighter markings forming three discontinuous longitudinal stripes ( Figs. 61a–b); palar claw narrow ( Fig. 62d); sternal process of abdominal segment VII short, apex blunt ( Fig. 62f); left male paramere with triangular apex ( Figs. 63a–c); right male paramere broad ( Figs. 63a–c); Papua New Guinea, northern Australia........................................................................................... M. queenslandica Chen (pg. ####)