Micronecta adelaidae Chen, 1965

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 : 48-53

Micronecta adelaidae Chen, 1965

( Figs. 27–30 )

Micronecta adelaidae Chen, 1965: 155 .

Micronecta adelaidae: Wróblewski ; 1972b: 524. [list; classification]

Micronecta adelaidae: Cassis and Gross, 1995: 66 . [catalog]

Micronecta adelaidae: Andersen and Weir, 2004: 250 , 334. [key; list]

Diagnosis: Micronecta adelaidae is readily distinguished by the greatly enlarged pronotum and well-developed hemelytral patterning ( Figs. 27a–b ). The reduced apical scales of the left paramere ( Figs. 29a–d ) and combination of prothoracic lobe ( Fig. 28a ), metaxyphus ( Fig. 28b ), and sternal process of abdominal segment VII ( Fig. 28f ) also serve to distinguish the species from all other Australian Micronecta .

Size: ( Table 10). Macropterous form: 2.63–2.94. Brachypterous form unknown.

Derivation of specific epithet: Named for the type locality: Adelaide River , Northern Territory, Australia .

Notes on type material: Holotype and allotype: “ Adelaide River , 70 mi. South of Darwin, Northern Territory, Australia. 25-III-1954.” deposited in USNM ( Chen 1965) . Paratypes with same data ; one male in USNM, one male, one female in SEMC. I examined the two paratypes from SEMC. Holotype not located for examination.

Description: Based on macropterous form. Measurements. Length: male 2.66–2.81; female 2.71–2.94; Width: male 0.61–0.83; female 0.72–0.96; Width of head: male 0.92–0.96; female 0.96–1.04; Synthlipsis: male 0.38–0.43; female 0.38–0.42; Width of eye: male 0.26–0.33; female 0.32–0.35; Width of pronotum: male 0.87–0.93; female 0.92–0.99; Length of pronotum: male 0.28–0.31; female 0.34–0.39.

Color: Ground color light brown ( Figs. 27a–b ). Head yellowish-brown, eyes reddish-brown. Vertex yellowish-brown, three darker longitudinal lines from top of head to vertex, outer two lines placed laterally. Frons and clypeus brown, labium black. Clypeogenal area same color as frons, punctate laterally. Antennae yellowish-brown. Pronotum unicolorous brown, pale apical band absent. Hemelytra: clavus with irregular darker blotches, lateral markings forming a longitudinal series. Corium with three prominent, irregular longitudinal stripes. Transverse microsculptuirng present over clavus and corium. Scutellum short, unicolorous light brown. Prenodal embolar area long and broad, pruinose basally. Nodal furrow prominent, postnodal area short. Two discontinuous infuscated areas along medial portion of each embolium ( Figs. 27a–b ). Left membrane hyaline, unicolorous. Venter light brown, legs, natatorial setae of metatarsi, and metatarsal claws same color.

Structural characteristics: Ratio of body length/width: males 3.66; females 3.46. Head slightly wider than pronotum, interocular space slightly larger than width of eye, synthlipsis 1.2 times as wide as posterior width of eye. Ocular index: males 1.53; females 1.35. General facies of head (vertex, frons, and labium) proportionate. Antennae densely pilose, segments one and two very short, third segment long, elongated, upper margin nearly straight, lower margin rounded, and apex acuminate. Pronotum robust, broadly rounded apically, anterior margin with ill-developed short carina. Lateral margins squared. Pronotum averaging nearly three times as wide as long (W/L: males 0.91/0.30; females 0.97/0.36). Prothoracic lobe broad, anterior margin sharply squared, posterior and lower margins rounded ( Fig. 28a ). Hemelytra with smooth, even transverse microsculpturing throughout, setae densely and uniformly distributed. Lateral spines on abdominal segments IV–VIII: IV: one stout, short seta, two thin, long setae; V: three stout, setae of varying lengths, one long, stout seta; VI: two stout, short setae, one long, stout spine, one long, thin seta; VII: three short, stout spines, two thin, long setae; VIII: five stout, short spines, two long, thin setae. Metaxyphus of both sexes triangular, apex broadly produced, rounded ( Fig. 28b ).

Male foreleg ( Fig. 28c ): femur with two short, stout spines in basal third near ventral surface. Tibia with two short spines in apico-dorsal portion. Pala with five long dorsal setae; palmar area with 11–12 setae in upper row, 16–18 setae in lower row, ventral row setae more pronounced than dorsal row. Apex of pala with a long thickened seta. Palar claw ( Fig. 28d ) broad and elongate, widest apically with tip rounded. Female foreleg with same general setal arrangement as male. Mesotarsal claws equaling about one-third the length of the mesotarsus.

Lateral lobes of abdominal tergum IV comparatively broad, asymmetric. Right lobe truncate apically, with 11–12 long setae, left lobe slightly shorter, rounded apically with 12 long, evenly spaced apically placed setae. Prestrigilar flap of tergal segment V as in Figure 28e . Strigil ovate, long, with densely packed combs. Median lobe of sternite VII ( Fig. 28f ) longer, broad basally, with one to two longer setae restricted sub-basally, apex produced, narrowly rounded. Free lobe of tergite VIII ( Fig. 28g ) relatively broad, outer angle quadrate with five to six short setae placed in upper portion. Inner angle long, apex rounded, with 28–34 long, uniform setae placed apically. Pars stridens processus cleaner ridges of tergite VIII not examined. Male left paramere ( Figs. 29a–d ) with shaft nearly parallel-sided, apical portion spatulate, tip rounded ( Figs. 29a–d ). Base broad, with lower portion of base broadly rounded ( Figs. 29a–c ). Right paramere ( Figs. 29a–g ) longer, shaft parallel-sided, tapering to a point ( Fig. 29a–c, e–f ). Base longer, lower portion quadrate, with about 21 plectral ribs confined to rear portion ( Fig. 29g ). Aedeagus broad, as in Figures 29a–f .

Distribution and Habitat: ( Fig. 30 ). AUSTRALIA: Northern Territory, Western Australia. Previously recorded from New South Wales by Cassis and Gross (1995) and Andersen and Weir (2004). The species was not recorded from New South Wales during this research and is newly recorded here from Western Australia. Very little is known on the ecology or habits of this species. A series of 83 specimens (23♂, 63♀♀) was taken at lights in Northern Territory. No other habitat data are known.

Discussion: Micronecta adelaidae is unique among Australasian Micronectidae on the basis of the enlarged pronotum and distinct hemelytral patterning. The apical scales of the male left paramere, although reduced, place the species within the Micronecta annae species group. The male right paramere is similar in form to M. annae Kirkaldy.

Specimens examined: AUSTRALIA: Northern Territory: 32 km N Eliott. 7-IV-1980. Black Light. G. F. Hevel & J. A. Fortin. (23♂, 60♀♀). [ USNM] ; Western Australia: Munda Homestead - Pilbara. 31-VIII-2003. Pool. J. M. McRae. (2♂). [ CALM] ; Western Australia: Paradise Pool - Pilbara , PSW 034. 14-V-2004. J. M. McRae. (4♂, 2♀♀). [ CALM] .

Figures

FIGURE 27. Micronecta adelaidae Chen. a. Male. b. Female. Scale bars = 0.5 mm.

FIGURE 28. Micronecta adelaidae 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 29. Micronecta adelaidae Chen, male genitalia. a. Left paramere, lateral aspect, right paramere, dorsal aspect. b. Left paramere, medio-lateral aspect, right paramere, dorsal aspect. c. Left paramere, medio-lateral aspect, right paramere, lateral aspect. d. Left paramere, tip. e. Right paramere, lateral aspect. f. Ventro-lateral aspect. g. Pars stridens processus, base of right paramere.

FIGURE 30. Distribution of Micronecta adelaidae Chen.