Micronecta (Dichaetonecta) decorata Lundblad, 1933

Chen, Ping-ping, Nieser, Nico & Lapidin, Johnny, 2015, A review of Bornean Micronectidae (Hemiptera, Heteroptera, Nepomorpha) with descriptions of two new species from Sabah, Malaysia 1, ZooKeys 501, pp. 27-62 : 34

Taxon classification Animalia Hemiptera Micronectidae

Micronecta (Dichaetonecta) decorata Lundblad, 1933 Figs 14, 24, 30, 31, 43, 51, 58, 66, 74, 75, 90

Micronecta decorata Lundblad, 1933: 93-94 (original description).

Micronecta decorata : Wróblewski 1968: 775 (checklist).

Micronecta decorata : Nieser 2000: 287 (key).

Micronecta decorata : Chen et al. 2005: 420 (checklist).

Material examined.

THAILAND (new record for Thailand): Chiang Mai Province: Doi Saket, Ban Pong Ao, Kuang River at bridge in road 118, 38 km NE Chiang Mai City, 30.i.2002, leg. P. Chen, N. Nieser, A. Thanyakam & C. Duangsupa, C0220, 19 males 30 females. Uttaradit Province: Baan Muangchedton, Lake Naam Pat, 10 km W of Ban Khok town, 10.ii.2002, stagnant ponds downstream of barrage, 10.ii.2002, leg. P. Chen, N. Nieser, A. Thanyakam, C. Duangsupa & W. Jaiyai, C0231, 7 males 13 females. All macropterous (samples stored in ethanol 70%). MALAYSIA: Sabah (confirmation of occurrence in Borneo): Kota Belud Dist., Crocker Range Park, Sungai Mahua at substation beside restaurant, 05°47.53'N, 116°24.19'E, 1053 m. a.s.l., 22.ix.2012, leg. P. Chen, N. Nieser & J. Lapidin, CN1283, 1 male and 1 female macropterous. (All are in the collection of NCTN).

Redescription.

Macropterous specimens. Generally a medium-sized, (length 2.2-2.4 mm) yellowish-brown species, with darker markings varying from virtually absent (Fig. 14) to quite distinct, medium- brown: a V-shaped stripe on clavus and four interrupted longitudinal stripes on corium (Fig. 24); eyes castaneous to grayish.

Dimensions. Body length: male 2.2-2.3, female 2.2-2.4; width: male 1.01-1.06, female 1.00-1.18; diatone: male 0.77-0.81, female 0.75-0.84; width of pronotum: male 0.82-0.88, female 0.81-0.93; ocular index: male 1.56-1.77, female 1.48-1.65. Body length twice the maximal width (male 2.23/1.04, female 2.33/1.12). Pronotum slightly wider than head (H/P male 0.80/0.85, female 0.81/0.88), synthlipsis one and half times the posterior width of an eye (S/E male 0.37/0.21, female 0.36/0.24).

Colour. Frons and vertex sordid yellow, eyes castaneous to grayish. Pronotum yellowish-brown, disk without markings except for a distinct yellowish stripe on posterior margin. Hemelytra light brown, with elongate darker marks arranged in four interrupted, longitudinal, brown stripes on corium (Fig. 24). Right membrane slightly paler than corium, without markings; left membrane hyaline. Embolium yellowish brown with three brown spots. Venter, abdomen, thorax, and legs pale yellow. [Our Thai material contains specimens with only a very vague or virtually absent hemelytral pattern. The Borneo specimens show a hemelytral pattern similar to Micronecta quadristrigata as stated by Lundblad (1933). Apparently, the hemelytral pattern fades when the specimens are stored in 70% or 96% ethanol].

Pronotum. About two and a half times as wide as long (W/L 0.87/0.36), dorsally convex with lateral margins straight and more or less truncate (Fig. 14). Hemelytra smooth, with four shallow, longitudinal grooves on corium, densely beset with small spinules, notably on corium. The right membrane texture same as corium, smooth without grooves or spines. Spines laterally on abdominal segments: V with two short and one longer stout spine; VI with three short and one long spine; VII with two or three short and one long stout spine; VIII with four or five short and one long, stout spine or sometimes without a long spine and two long hair-like bristles.

Legs. Length of segments: fore leg: male: femur 0.28, tibia 0.14, pala 0.15; female: femur 0.31, tibiotarsus 0.30; middle leg: male: femur 0.85, tibia 0.27, tarsus 0.39, claw 0.30; female: femur 0.85, tibia 0.29, tarsus 0.40, claw 0.28; hind leg: male: femur 0.51, tibia 0.40, tarsus I 0.39, tarsus II 0.19, claw 0.13; female: femur 0.52, tibia 0.42, tarsus I 0.37, tarsus II 0.19, claw 0.12. Palmar bristles: 21-23 in upper row, 17-18 in lower row.

Male. Fore femur (Fig. 30), with a pair of pegs on proximal third, a small peg distally, and a larger bristle-like spine sub-distally; pala with four long dorsal hairs. Claw (Fig. 31) parallel sided, with a transverse carina. Dorsum of abdomen: prestrigilar lobe sub-triangular, with a short, obtusely rounded apex (Fig. 43); strigil small, sub-oval, comb with about 45 comparatively distinct teeth (Fig. 51); free lobe of left part of tergite VIII with an expanded apex (Fig. 66), a sinuate apical margin, and 10-15 apical bristles. Left paramere (Fig. 75) with a narrow, apically, slightly dilated shaft and a subapical indentation; right paramere in lateral view (Fig. 74) with an evenly curved, sickle-shaped shaft, apex acutely tapering, basal lobe with about 25 stridulatory ridges. Mediocaudal lobe of sternite VII (Fig. 58) with apical part acutely pointed, with one strongly developed bristle.

Female. Fore femur with the same general arrangement of pegs and setae as in male. The seminal capsule of spermatheca clavate (Fig. 90).

Comparative notes.

Males can be recognized by the form of the free lobe of tergite VIII. The palmar claw of the male, with its oblique carina, also is unique but it is often folded into the palm, usually making it difficult to observe.

Habitat.

We have taken this species several times in Chiang Mai and other northern provinces in Thailand, where it is apparently quite common. Sample C0220 was taken from shallow virtually stagnant water in a wide unshaded river bed with a sandy bottom.

Distribution.

Thailand (see above); Malay Peninsula ( Wróblewski 1968: record for Malaysia without exact locality; Fernando and Cheng 1974); INDONESIA: Sumatra ( Lundblad 1933), Java ( Lundblad 1933); and Borneo.

Note.

Wróblewski (1968) recorded this species from Borneo with a question mark. His speculation is confirmed here.