Austronecta Tinerella, 2013

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 : 6-7

Austronecta Tinerella , gen. nov.

( Figs. 1–15 )

Type species: Austronecta micra ( Kirkaldy, 1908)

Diagnosis: Small, generally ovate to slightly elongate micronectids. Distinguished by the acutely pointed triangular hind margin of head and prominent anterior pronotal carina. The small size and glabrous surface of the left paramere serve to distinguish the genus. Restricted to Australia.

Description: Small to medium (1.65–2.75 mm) micronectids. Ground color brown to reddish-brown, hemelytral markings developed, variable, and generally contrasting with the salebrose to rugose dorsum. Hemelytral patterning present as broad expanded dark areas generally over corium, or mottling throughout entire hemelytral surface. Patterning somewhat lineate only in Austronecta carinata . Vertex of head rounded to slightly conical ( Figs. 1 , 4 , 8 , 12 ). Head sclerites proportionately shorter, frons and clypeus expanded, surrounding the shortened labium (unsegmented rostrum). Labial apex nearly even with a line drawn through the apical genal margins; head nearly circular in frontal aspect. Prothoracic lobe compact and short, lobate, with lower margin generally rounded. Metaxyphus short, apex triangular ( Figs. 2 , 5 , 9 , 13 ).

Pronotum short in brachypterous forms, posterior margin truncate ( Figs. 1 , 4 , 8 , 12 ). Anterior pronotal carina well-developed in both brachypterous and macropterous forms. Pronotum proportionately expanded in macropterous forms, posterior margin narrowly rounded. Hemelytra with weakly developed microsculpture, obscured in part by prominent salebrose to rugose texture, short setae distributed uniformly over corium, scattered over clavus. Corium non-striate. Membrane ill-developed in both brachypterous and macropterous forms. Palae narrowed and short, palar claw of males narrowed, parallel-sided to medially expanded, apex rounded. Nodal furrow present, marked by diagonal suture not contacting wing margin. Prenodal embolar area expanded, embolar groove flanged. Postnodal embolar area inconspicuous. Lateral lobes of abdominal tergite IV short, broadly rounded. Strigil present, well-developed, ovate to rectangular. Strigil combs not resolved with light microscopy. Strigil not examined with scanning electron microscopy. Sternal process of abdominal segment VII broad, very short, apex acutely pointed. Free lobe of abdominal tergite VIII broad, outer angle rounded, apical setae reduced in numbers. Male parameres: left paramere generally short, shaft glabrous, lacking scale-like texture, base broad and expanded; right paramere generally parallel-sided, shaft convexly curved, apex lacking modification, base long, lobate. Pars stridens processus well-developed, consisting of variably spaced plectral ribs placed in medio-apical portion of base.

Discussion: The species herein placed in Austronecta appear to form a monophyletic group restricted to continental Australia, specifically in the east: A. carinata , A. australiensis and north/west: A. micra and A. bartzarum . The group is united by the triangular hind margin of the head, prominent anterior pronotal carina, lobate form of the prothoracic lobe, short, triangular metaxyphus, and unique male genitalic structure. Austronecta shows general similarities to New Guinea Papuanecta Tinerella , based on palar form, lateral lobes of abdominal tergum IV, and the short, acuminate sternal process of abdominal segment VII ( Tinerella 2006b, 2008). Species of Austronecta are predominately brachypterous, with only macropterous forms of A. australiensis and A. micra currently known.

Distribution: Australia.

Etymology: A combination of Austro, and the Greek necta, for swimmer. The generic name honors Australia, the type country and presently known natural distribution of this unique group of pygmy water boatmen.

Key to the Species of Austronecta New Genus of Australia

1. Interocular space wider than width of eye ( Figs. 1a–d ); hemelytral patterning in brachypters ( Figs. 1a–b ) and macropters ( Figs. 1c–d ); left male paramere long, apex ribbon-like ( Figs. 3d–e ); length 2.03–2.33 mm (brachypter) and 2.48–2.62 mm (macropter)................................................................. A. australiensis (Chen) (pg. ###)

– Interocular space equal to, or narrower than width of eye; hemelytral patterning not as above ( Figs. 4a–b , 8a–b , 12b–d ); left male paramere shorter, apex otherwise modified ( Figs. 6a–c , 10a–e , 15a–d ); length variable.......................... 2

2. Very small species, length 1.65–1.91 mm; dorsal facies generally reddish-brown, hemelytral patterning ill-developed with dark discontinuous areas restricted to embolar regions ( Figs. 4a–b ); distal portion of left paramere broad, apex with conspicuous hook ( Figs. 6a–c )............................................................... A. micra (Kirkaldy) (pg. ###)

– Larger species, 2.14–2.75 mm; dorsal facies brown, hemelytral patterning variably developed ( Figs. 8a–b , 12b–d ); distal portion of left paramere continous, acuminate or subquadrate ( Figs. 10a–e , 15a–d )..................................... 3

3. Length 2.14–2.28 mm (macropter 2.47 mm); hemeytral patterning ill-developed, consisting of small serially arranged dark dots along inner claval margin and outer corial margin ( Figs. 8a–b ); left paramere exceptionally short, with broad plate-like base, tip of paramere tapered and pointed ( Figs. 10a–e )................................ A. bartzarum sp. nov. (pg. ###)

– Length 2.58–2.75 mm; hemelytral patterning well-developed as darker blothches, patterning in corial area trending longitudinal ( Figs. 12b–d ); left paramere short, base shorter, tip of paramere broad, subquadrate ( Figs. 15a–d ).................................................................................................. A. carinata (Chen) (pg. ###)

Figures

FIGURE 1. Austronecta australiensis (Chen), dorsal habitus. a–b. Brachypterous form. a. Male. b. Female. c–d. Macropterous form. c. Male. d. Female. Scale bars = 0.5 mm.

FIGURE 2. Austronecta australiensis (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 tergum VIII. Scale bars = 0.1 mm.

FIGURE 3. Austronecta australiensis (Chen). a. Metaxyphus. b. Left male pala (tarsus), anterior view, palar claw folded in. c. Sternal process of abdominal segment VII. d. Left paramere, lateral aspect, right paramere, dorso-lateral aspect. e. Left paramere, tip, right paramere, tip. f. Right paramere, lateral aspect. g. Left paramere, medio-ventral aspect, right paramere, dorso-lateral aspect. h. Pars stridens processus, base of right paramere.

FIGURE 4. Austronecta micra (Kirkaldy). a. Male. b. Female. Scale bars = 0.5 mm.

FIGURE 5. Austronecta micra (Kirkaldy). 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 tergum VIII. Scale bars = 0.1 mm.

FIGURE 6. Austronecta micra (Kirkaldy), male genitalia. a. Left paramere, fronto-lateral aspect. b. Left paramere, lateral aspect. c. Left paramere, lateral aspect, right paramere, lateral aspect. d. Right paramere, lateral aspect. e. Pars stridens processus, base of right paramere.

FIGURE 7. Distribution of Austronecta micra (Kirkaldy).

FIGURE 8. Austronecta bartzarum, sp. nov. a. Male. b. Female. Scale bars = 0.5 mm.

FIGURE 9. Austronecta bartzarum sp. nov. a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw everted. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. g. Free lobe of abdominal tergum VIII. Scale bars = 0.1 mm.

FIGURE 10. Austronecta bartzarum sp. nov., male genitalia. a. Left paramere, lateral aspect, right paramere, dorso-medial aspect. b. Left paramere, lateral aspect (cf base Fig. a), right paramere, dorso-medial aspect. c. Left paramere, tip. d. Left paramere, base, right paramere, fronto-lateral aspect. e. Left paramere, base, right paramere, lateral aspect. f. Right paramere, tip. g. Pars stridens processus, base of right paramere.

FIGURE 11. Distribution of Austronecta bartzarum sp. nov.

FIGURE 12. Austronecta carinata (Chen), paratype and dorsal habitus. a. Locality and type labels. b. Paratype specimen, female, dorsal habitus. c. Male. d. Female. Scale bars = 0.5 mm.

FIGURE 13. Austronecta carinata (Chen). a. Prothoracic lobe, female. b. Metaxyphus. c. Left male foreleg, posterior aspect. d. Left male pala (tarsus), anterior aspect, palar claw everted. e. Prestrigilar flap of abdominal segment V. f. Sternal process of abdominal segment VII. g. Free lobe of abdominal tergum VIII. Scale bars = 0.1 mm.

FIGURE 14. Austronecta carinata (Chen). a. Metaxyphus. b. Left male pala (tarsus), anterior aspect, palar claw everted. c. Left male pala, ventral aspect. d. Sternal process of abdominal sternite VII.

FIGURE 15. Austronecta carinata (Chen). a. Left paramere, lateral aspect, right paramere, dorso-frontal aspect. b. Left paramere, medio-lateral aspect, right paramere, dorsal aspect. c. Left paramere, lateral aspect, right paramere, medio-lateral aspect. d. Left paramere, medio-lateral aspect (cf base Figs. a,b,c,e), right paramere, lateral aspect. e. Left parameres, base, right paramere, dorso-medial aspect. f. Pars stridens processus, base of right paramere.