Papuanecta sinistra ( Chen, 1965 ) Tinerella, 2008

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 : 9-12

Papuanecta sinistra ( Chen, 1965) , comb. nov.

( Figs. 1a–b , 2–3 )

Micronecta sinistra Chen, 1965: 161 .

Micronecta sinistra: Tinerella and Polhemus, 2005: 187 . [faunistics]

Diagnosis: Recognized by the reversed abdominal asymmetry of males, and bizarre, similarly shaped parameres ( Figs. 2h–k ). Females identified by size, ground color, dark line in embolium and short poorly developed striae in apical third of corium ( Figs. 1a–b ).

Size: ( Table 2). Macropterous form: 1.71–2.03. Brachypterous form unknown.

L= length, LP= length of pronotum, W= body width, WH= width of head, S= synthlipsis, WE= width of eye, WP= width of pronotum, L:W= ratio body length to width, S:E= ratio of synthlipsis to eye width, OcI= ocular index.

Derivation of specific epithet: From the Latin sinistra , meaning on the left; referring to the reversed (sinistral) asymmetry of males.

Notes on type material: Chen (1965) listed depositing the single male specimen in HNHM. No type material was located for examination.

Description: Based on macropterous form. Measurements. Length: male 1.71–1.91; female 1.90–2.03; Width: male 0.79–0.87; female 0.81–0.92; Width of head: male 0.63–0.67; female 0.69–0.73; Synthlipsis: male 0.24–0.26; female 0.25–0.30; Width of eye: male 0.19–0.22; female 0.21–0.24; Width of pronotum: male 0.68–0.78; female 0.73–0.81; Length of pronotum: male 0.22–0.28; female 0.29–0.32.

Color. Ground color brown ( Figs. 1a–b ). Head pale yellow, eyes brownish-black. Frons and clypeus pale yellow, vertex with central darker area in upper margin. Labium black. Genae same color as rest of head. Antennae pale yellowish-brown. Pronotum dark brown, with narrow pale band along apical margin. Scutellum pale yellowish-brown. Clavus with basal diagonal area generally developed, pale brown to reddish-ochre. Medial and apical portion of clavus same brownish color as in corium and membrane. Claval-corial commisure with narrow, pale band spanning entire length. Corium solid brown, apical portion with irregular darker markings, most prominent in lateral portions. Prenodal embolar area brown in basal half, with lateral margins yellow, lacking pruinosity. Postnodal embolar area absent. Left membrane in both sexes subhyaline, brown, right membrane coriaceous, brown, inner margin pale. Venter of males darkened, female venter pale. Legs of both sexes pale, distal portion of meso- and metatarsus darker brown. Natatorial setae darker than leg segments.

Structural Characteristics. Ratio of body length/width: males 2.22; females 2.32. Head narrower than pronotum, interocular space greater than width of eye, synthlipsis 1.2 times as wide as posterior width of eye. Ocular index: males 1.28; females 1.24. General facies of head (vertex, frons, labium) reduced, very short. Antennae densely pilose, segments one and two very short, segment three elongate, apex acuminate. Prothoracic lobe compact, with short minute setae, anterior and posterior margins broadly rounded ( Fig. 2a ). Pronotum very large, convex, widest at middle with lateral margins subquadrate, about 2.6 times as wide as long (W/L males 0.69/0.26; females 0.74/0.28). Hemelytra with fine, transverse microsculpturing. Short, minute setae evenly distributed over clavus, corium, and right membrane, setation absent from left membrane. Nodal furrow marked by a diagonal suture not contacting wing margin. Pre-nodal embolar area well developed, postnodal embolar area absent. Medial and apical portions of corium in females with two to three raised, wide striae. Metathoracic wings well developed, reaching apices of hemelytra. Lateral spines and setae on abdominal segments IV–VIII: IV: one short, stout spine, one long, stout spine; V: one short, stout spine, one long, stout spine, one long, thin seta; VI: two short, stout spines, one long, stout spine, one long, thin spine; VII: two short, stout spines, one long, stout spine; VIII: four short, stout spines, one long, thin seta. Metaxyphus of both sexes short, triangular, apex narrowly rounded; setae absent ( Fig. 2b ). Male foreleg ( Fig. 2c ): femur with two short, stout spines on basal third near ventral surface, and one spine apicoventrally. Pala elongate, with three dorsal setae on apical portion, palmar area with about 11 setae in dorsal row and 10 setae in lower row, lower row setae more pronounced than those of dorsal row. Apex of pala with single short, thickened seta. Palar claw ( Fig. 2d ) broad, tapered proximad, parallel-sided and with slightly curved distal lower margin. Female foreleg with same general setal arrangement as male. Mesotarsal claws short, about one-half the length of mesotarsus. Lateral lobes of abdominal tergum IV very short, rounded, left lobe longer than right. Right lobe with about 14 long setae and left lobe with about 10 long setae, more or less evenly spaced. Prestrigilar flap of abdominal tergum V compact, subquadrate, lower margin broadly rounded ( Fig. 2e ). Strigil indistinct, rectangular in outline. Median lobe of abdominal sternum VII ( Fig. 2f ) short, apex longer, sharply acuminate, setae restricted to mediobasal portion with three to four larger setae interspersed with numerous shorter setae. Free lobe of abdominal tergite VIII ( Fig. 2g ) nearly square in outline, lower margin broadly produced. One to three large setae placed medially, several short setae along upper margin; darkened areas appearing as round spots, limited to medial portion of lobe. Pars stridens processus cleaner ridges of abdominal segment VIII not discernible with light microscopy. Right and left parameres ( Figs. 2h–k ) similar. Left paramere base broad, rounded, shaft curved, apex broad, and expanded distally ( Figs. 2j–k ). Base of right paramere rectangular, shaft curved, apex with broad quadrate plate ( Figs. 2h–i ). Aedeagus short, narrow.

Distribution and habitat: ( Fig. 3 ). Indonesian New Guinea, Irian Jaya Prov. [= Papua Prov.]. The male type specimen was described from Astrolabe Bay, northeastern Papua New Guinea ( Chen 1965). The disjunct distribution seen with the type specimen and specimens recorded here suggests the species ranges widely across the northern portion of the island. All specimens examined here were taken at lights. There are no recorded habitat data.

Discussion: Papuanecta sinistra is very similar in habitus to other members of the genus. The reversed abdominal asymmetry of the males, along with the unique free lobe of abdominal segment VIII and the paramere morphology, serve to isolate the species. Further examination of the male terminalia using scanning electron microscopy will help resolve the species relationships within Papuanecta .

All specimens examined from this writing exhibit reversed abdominal asymmetry. The incidence of reversed abdominal asymmetry has been recorded for other micronectid taxa (e.g., Micronecta quadristrigata Breddin ( Wróblewski 1962b) , and M. annae Kirkaldy ( Tinerella 2006b)) ; however, this occurrence is rare, as all other known Australasian taxa exhibit dextral asymmetry. Reversed (sinistral) abdominal asymmetry is seen also in some corixid taxa, in particular the genera Corixa Geoffroy , Heliocorisa Lundblad , Trichocorixa Kirkaldy , and some species of Neosigara Lundblad ( Tinerella and Polhemus 2006) . Reversed abdominal asymmetry is common in dextral males of Krizousacorixa Hungerford ( Hungerford 1948) . The stability of the sinistral asymmetry in P. sinistra serves further to isolate the species. Chen (1965) acknowledged the unique characteristics of P. sinistra , calling the species an “independent offshoot from the original stock.”

Specimens Examined: INDONESIA: Irian Jaya Prov. [= Papua Prov.]: Bodem , 100m, 11km SE of Oerberfaren. 10-VII-1959. T . C. Maa. MV Light Trap. (1♂). [ BPBM] ; Irian Jaya Prov. [= Papua Prov.]: NETH ., Bodem. (10–17)- VII-1959. T . C. Maa. (5♂♂, 9♀♀). [ BPBM] .

Figures

FIGURE 1. Dorsal habitus of Papuanecta species. a–b. P. sinistra (Chen), male and female. c–d. P. inelryjelnor sp. nov., male and female. e–f. P. minajerwi (Tinerella & Polhemus), male and female. g–h. P. minjerwioides sp. nov., male and female. Scale bars = 0.5mm.

FIGURE 2. Papuanecta sinistra (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. h–i. Right paramere, opposite views. j– k. Left paramere, opposite views. Scale bars = 0.1 mm. (Figs. h–k redrawn, in part, from Chen 1965)

FIGURE 3. Distribution of Papuanecta sinistra (Chen).