Naucoris minutus, Polhemus & Polhemus, 2013

Polhemus, Dan A. & Polhemus, John T., 2013, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Xi. Infraorder Nepomorpha- Families Naucoridae And Aphelocheiridae, Raffles Bulletin of Zoology 61 (2), pp. 665-686 : 668-669

publication ID	https://doi.org/ 10.5281/zenodo.5352700
persistent identifier	https://treatment.plazi.org/id/03FE7253-F51A-FFE1-FEFA-FC23FB90FB90
treatment provided by	Tatiana
scientific name	Naucoris minutus
status	sp. nov.

Treatment

Naucoris minutus , new species

( Figs. 7–11 View Figs View Figs , 15 View Fig )

brown spot on anterior third, posterior margin broadly grayish brown; lateral margins nearly parallel, very weakly explanate, humeri slightly raised posterolaterally, dorsal surface broadly and evenly domed, not depressed medially behind vertex, width/length (midline) = 2.30/1.00, posterolateral

Material examined. — Holotype, male, SINGAPORE, Chestnut Drive [Selatar Reservoir area], 10 May 1994, Nature Reserves Survey, NS 130B ( ZRC) . Paratypes: SINGAPORE: 2 males, 3 females, same data as holotype ( ZRC, BPBM) ; 1 female, Chestnut Drive, stagnant pool, 10 May 1994, NS130B ( ZRC) .

Description. — Macropterous form: Of small size for genus, general body form ovate, widest across basal abdomen, basic colouration pale brown, with scutellum, hemelytra and wing membrane dark brown ( Fig. 15 View Fig ). Male length 4.40 mm; maximum width (across abdomen) 2.40 mm; female length 4.80 mm, maximum width 2.90 mm.

Head tan, with scattered dark brown dots centrally on vertex, these dots coagulating to form a large, irregular brown patch adjacent to posterior margin of vertex, width across eyes/ length = 1.45/0.90; eyes dark red, shining, roughly teardropshaped when viewed from above with weakly developed lateral flange, tapering anteriorly, width/length = 0.40/0.60, inner margins straight and slightly convergent anteriorly, lateral margins broadly curving, separated from vertex by shallow furrows, anterior/posterior interocular width = 0.80/0.95; posterior margin of vertex broadly and gently curved, slightly produced behind eyes; anteclypeus broadly rounded, projecting slightly ahead of eyes, anterior margin not projecting beyond rostrum, lacking pits or other sensory structures; labrum golden, semicircular, ventral margin broadly rounded, apex blunt; rostrum evenly tapering to apex, all segments golden brown; antennae with all segments relatively slender, not extending to lateral margin of head, segments II–IV subequal in length.

Pronotum tan, irregularly dotted and mottled with dark brown, lateral margins each with a single more prominent angles blunt, rounded. Scutellum medium brown, rugulose, anterior margin narrowly transversely depressed, width/ length (midline) = 1.20/0.70, basal and lateral margins very broadly and weakly sinuate. Hemelytra dark blackish-brown, rugulose, basal half of embolium translucent golden yellow, posterior margin of this pale area forming a straight line perpendicular to embolar margin; clavus and corium well defined, membrane completely developed; tips of hemelytra broadly rounded, extending nearly to apex of genital segment; embolium demarcated by broadly arcuate furrow along inner margin, lateral margin lacking setae or spinules.

Abdomen with lateral portions of segments II–IV very slightly exposed beyond lateral wing margins when viewed dorsally, all visible paratergites pale golden yellow, dark brown on posterior thirds, posterolateral angles symmetrical, not produced, lateral margins bearing short golden setae.

Ventral surface pale brown, bearing very fine, appressed golden setae, long golden setae present on central sections of mesosternum and abdominal ventrites I–VII; propleura not reflexed posteriorly, barely covering basolateral portions of mesosternal plate, anterolateral angles lacking hydrostatic sense organs; mesosternal plate with anteromedial section raised into a roughly conical tumescence, this anterior tumescence separated by a low sulcus from the broadly tumescent posteromedial section of plate; metasternal plate small, medially carinate. Abdominal sternites and parasternites delineated by distinct sutures; all parasternites dull brown, each with 2 ovate glabrous patches.

Legs pale yellow; fore coxa and trochanter lacking hair pads; anterior femur greatly expanded, concave anteroventrally, pale yellow marked with scattered light brown spots posteroventrally, bearing a thick fringe of short, dense gold setae along anterior margin, posterior margin lacking setae; anterior tibia broadly curving, tapering distally, ventral margin lacking setal pads; anterior tarsi one segmented, bearing one tiny claw, ventral tarsal surfaces lacking hair pads; middle and hind femora each bearing a longitudinal row of tightly packed, tiny reddish spinules along posterior margins; middle and hind tibiae bearing numerous short, stout reddish-brown spines, posterior margin of hind tibia with fringe of long gold swimming hairs.

Male genitalia with parameres asymmetrical ( Figs. 7, 8 View Figs ); phallotheca slender, elongate, asymmetrical, apex acute ( Fig. 9 View Figs ); proctiger elongate ( Fig. 10 View Figs ). Female subgenital plate roughly trapezoidal, distal section elongate and parallel sided, posterior margin broadly rounded ( Fig. 11 View Figs ).

Brachypterous form: Unknown.

Distribution. — Currently known only from Singapore.

Discussion. — Naucoris minutus is the smallest species of Naucoris so far known from Southeast Asia. The shapes of the parameres are distinctive ( Figs. 7, 8 View Figs ), and in combination with the shape of the female’s subgenital plate ( Fig. 11 View Figs ) and small body size easily separate this species from other Southeast Asian congenors.