Stigmatonotum macronotum, Ban, 2023

Ban, Teruaki, 2023, A new species of the genus Stigmatonotum (Hemiptera: Heteroptera: Rhyparochromidae) from Japan, with notes on related species from the East Palaearctic and Oriental Regions, Acta Entomologica Musei Nationalis Pragae 63 (2), pp. 265-278 : 268-274

Stigmatonotum macronotum sp. nov.

[Japanese name: Kiyosumi-chibi-nagakamemushi]

( Figs 2–6 )

Type material. HOLOTYඉE: J, JAPAN / Honshu / Kantô dist. / Chiba Pref. / Ôtaki-machi / Ôtadai / N 35°10’35” E 140°10’12” / Alt., 256 m / 28.V.2022 / Teruaki Ban (CBM-ZI-179394). PARATYඉES (7 JJ 12 ♀♀): JAPAN: HONSHU: Chiba Pref.; 2 JJ 4 ♀♀, same data as holotype / Teruaki Ban (CBM-ZI 179395–179399, NMPC); 1 J 2 ♀♀, same locality as holotype / 6.V.2022 / Teruaki Ban (CBM-ZI 179402, TUA); 1 J 1 ♀, same locality as holotype / 4.XI.2022 / Teruaki Ban (CBM-ZI 179409–179410); 2 JJ, Ôtaki-machi / Tsutsumori / 28.IX.2020 / Y. Noto (CBM-ZI 179403–179404); 1 ♀, Kamogawa-shi / Yomogi / Daisenba-rindou / University of Tokyo Chiba forest / N 35°09’53.1576” E 140°08’30.7602” / 17.III.2015 / Kemrio Ozaki (CBM-ZI 179405); 2 ♀♀, Kamogawa-shi / Yomogi / Goudai-rindô / University of Tokyo Chiba forest / 2.VI.2022 / Teruaki Ban (CBM-ZI 179400–179401); 1 ♀, Kimitsu-shi / Inokawa-rindô / University of Tokyo Chiba forest / N 35°12’3.8874” E 140° 06’25.8474” / 16. V. 2013 / Akiko Saito (CBM- -ZI 179406); 1 J, Same locality / 19.VIII.2022 / Teruaki Ban (CBM-ZI 179407); 1 ♀, Kimitsu-shi / Sasa / Tashiro-rindô / 9.V.2021 / Teruaki Ban (CBM-ZI 179408).

Description. Male. Coloration. Head ( Fig. 2A ) black; long decumbent setae on vertex golden; clypeus black. Scape pale yellow, with reddish brown annulation at base to middle; antennomeres II and III brownish yellow, apex of each segment pale yellow; antennomere IV brown. Labiomere I dark brown with apex pale yellow; labiomeres II and III brownish yellow, basal quarter of labiomere III with dark brown annulation; basal third of labiomere IV brown, apical two-thirds of segment IV black. Pronotal collar dark reddish brown.Anterior lobe of pronotum ( Fig. 2A ) black; posterior lobe of pronotum ( Fig. 2A ) dark whitish yellow, covered with dark brown punctures; humeral angle with dark brown spot. Venter of mesothorax and metathorax matte grey, apical margin of metepisternum dull reddish brown. Metathoracic scent gland peritreme reddish brown; evaporatorium matte grey. Scutellum ( Fig. 2A ) black, with white spot at apex; trifurcate carina of scutellum dull brown. Corium ( Fig. 2A ) brown, area between anterior margin of corium and medial fracture pale yellow; dark brown spot in basal three-quarters of anterior margin of corium, apex of corium and basal quarter along medial fracture; inner angle of corium with shiny pale spot; clavus dark whitish brown; membrane subhyaline, with pale brownish maculation. Supracoxal lobes dark reddish brown; coxae shiny dark brown; trochanter yellow; each femur pale yellow in basal half, dark brown in apical half; tibiae pale yellow, with brown annulations at base and apex; tarsomeres I and II yellow, tarsomere III brown. Abdominal sternum black; trichobothria of segments V and VI shiny black; long decumbent setae on abdominal sternum golden.

Structure. Body length 2.7 times as long as wide across humeri. Head ( Fig. 2A ) 1.2 times as long as wide; clypeus projecting anteriorly; vertex weakly convex; distance between ocelli subequal to eye length; eye 1.3 times longer than its width. Antennal segments covered with setae; proportional length of antennal segments I to IV 1: 2.2: 1.5: 2.2. Labium reaching mesocoxae; proportional length of labiomeres I to IV 1: 1: 0.5: 0.6.

Pronotum ( Fig. 2A ) 1.4 times wider than its length, covered with sparse short decumbent setae and rough punctures; pronotal collar narrow, without distinct suture between collar and anterior lobe of pronotum; length of anterior lobe of pronotum subequal to length of posterior lobe of pronotum; posterior margin of pronotum almost straight, width of posterior margin of pronotum 2.3 times wider than anterior margin of pronotum; lateral margin of pronotum without carina. Scutellum triangular, as long as wide, covered with punctures; middle of scutellum with trifurcate carina. Hemelytra ( Fig. 2A ) exceeding apex of abdomen; corium covered with sparse short decumbent setae and punctures; claval commissure 1.4 times longer than apical margin of corium; apical margin of corium with rows of punctures vestigial; clavus with 3 rows of punctures, middle one with additional punctures forming short irregular row. Profemur ( Fig. 2A ) relatively slender, 1.4 times wider than metafemur, armed with 2 large spines in basal third and apical third, and small spine in apical quarter; tibiae and tarsus covered with short erect setae densely; each tibia straight, without spine.

Abdominal sternum densely covered with long decumbent setae; laterotergites covered by hemelytra in dorsal view.

Genital structures of paratypes: Pygophore ( Fig. 3A ) globose, covered with dense suberect setae; dorsal pygophore opening inverted trapezoidal, gradually broadened at base, then sharply narrowed by pair of rounded protrusions; posterior margin of pygophore and cup-like sclerite not fused; anterior margin of cup-like sclerite almost straight. Paramere ( Figs 3B–E ) sickle-shaped, gradually broadened in middle, covered with sparse erect setae; apex of inner and outer projections rounded. Phallus as in Figs 4A–C (= Type I sensu HARRINGTON 1980); phallotheca tubular, without wrinkles or processes; conjunctiva approximately of same length as phallotheca; lateral view of endophallic reservoir and holding sclerite almost straight, apex appearing somewhat hooked ( Fig. 4D ); endophallic reservoir as in Fig. 4E , wing sickle-shaped, rounded at apex; holding sclerites ( Fig. 4F ) pointed at apex.

Female. General aspect as in male ( Fig. 2C ). Middle of abdominal sternite V polished, without setae; sternite VI medially strongly narrowed ( Fig. 2D ), posterior margin of sternite VI curved anteriorly. Ovipositor truncated at about sternite VI ( Fig. 2D ). Spermatheca as in Fig. 4G ; distal duct coiled; apical receptacle elongated; apex of apical receptacle rounded.

Differential diagnosis. This new species can be distinguished from other congeners of Stigmatonotum as well as Humilocoris by the following combination of characters: Body length 3.8–4.6 mm (in S. geniculatum , body length 2.9–4.0 mm); scape pale yellow, with reddish brown annulation (vs. scape entirely unicolor); antennomere II twice longer than length of scape (in H. cephalotes and S. rufipes antennomere II less than twice longer than scape); pronotum, mesepisternum, scutellum and corium sparsely covered with short decumbent setae (in H. cephalotes , pronotum, mesepisternum, scutellum and corium densely covered with long erect setae); mesal pronotal length more than 1.0 mm (in the other Stigmatonotum species, mesal pronotal length less than 1.0 mm); length of anterior lobe of pronotum approximately of the same length as posterior lobe of pronotum (in H. cephalotes and S. rufipes , anterior lobe of pronotum 1.3 to 1.7 times longer than posterior lobe); width of posterior margin of pronotum more than 1.3 mm (in S. afrum , S. attenuatum , S. elongatum and S. geniculutum , width of posterior margin of pronotum less than 1.0 mm); corial margin with fine row of punctures vestigial (in the other species of Stigmatonotum , corial margin with distinct row of punctures or without); apical half of each femur dark brown (in H. cephalotes and S. rufipes , apical third of each femur yellowish brown); profemur armed with 2 large spines and 1 small spine (in H. cephalotes , armed with 2 large spines and 3 or 4 rows of small spines; in S. geniculatum and S. rufipes , profemur armed with only small spine; in S. capucinum and S. attenuatum , armed with two large spines); apex of endophallic reservoir sickle-shaped (in H. cephalotes , S. geniculatum and S. rufipes , apex of endophallic reservoir abruptly divergent).

Measurements (in mm; J n = 8 / ♀ n = 12, holotype in parentheses). Body length 3.80–4.30 (3.80) / 3.98–4.60; body height between coxae and dorsum 1.00–1.40 (1.23) / 1.25–1.45; head length 0.70–0.75 (0.70) / 0.72–0.85; head width across eyes 0.85–0.92 (0.85) / 0.88–1.00; interocular space 0.19–0.24 (0.23) / 0.23–0.29; eye length 0.24–0.30 (0.25) / 0.25–0.31; length of antennal segments I – 0.32– 0.38 (0.33) / 0.30–0.40, II – 0.65–0.74 (0.72) / 0.69–0.76, III – 0.50–0.60 (0.50) / 0.50–0.60, IV – 0.72–0.80 (0.73) / 0.72–0.82; length of labial segments I – 0.48–0.56 (0.50) / 0.50–0.58, II – 0.47–0.50 (0.48) / 0.48–0.52, III – 0.25–0.28 (0.25) / 0.25–0.32, IV – 0.28–0.32 (0.30) / 0.30–0.36; mesal pronotal length 1.00–1.12 (1.00) / 1.01–1.23; anterior pronotal length 0.48–0.60 (0.50) / 0.50–0.64; posterior pronotal length 0.48–0.55 (0.50) / 0.49–0.59; width of anterior margin of pronotum 0.60–0.75 (0.60) / 0.60–0.72; posterior pronotal width 1.40–1.44 (1.40) / 1.40–1.60; mesal scutellar length 0.72–0.80 (0.73) / 0.75–0.90; basal scutellar width 0.68–0.75 (0.72) / 0.75–0.88; hemelytral length 2.40–2.75 (2.40) / 2.40–2.75; maximum width across hemelytra 1.32–1.44 (1.40) / 1.40–1.60; corium length 1.80–1.90 (1.80) / 1.85–2.10; length of claval suture 0.30–0.40 (0.34) / 0.30–0.40; ovipositoral length 0.90–1.04.

Etymology. The species epithet “ macronotum ” (meaning large pronotum) is a Latin noun referring to the characteristic mesal pronotal length and posterior pronotal width.

Biology. This new species inhabits mountain slopes with moist evergreen forests. All specimens were collected from leaf litter under the roots of Carex multifolia Ohwi growing on slopes ( Figs 5A–D ) and were found from spring to early summer (March to June) and late summer to autumn (Late August to November). One larva was collected in November.

Distribution. Japan: Honshu: Chiba Pref. This species is endemic to Japan, representing six populations known to date from southern Chiba Prefecture ( Fig. 6 ).

Figures

Fig. 2. Dorsal and ventral view of Stigmatonotum macronotum sp. nov.A – holotype, male, dorsal view; B – paratype, male, ventral view; C–D – paratype, female (C – dorsal view; D – ventral view). Scale bars = 1 mm.

Fig. 3. Male genitalia of Stigmatonotum macronotum sp.nov.A – pygophore, dorsal view; B–E – left paramere, four different aspects. Scale bars = 0.1 mm.

Fig. 4. Male and female genitalia of Stigmatonotum macronotum sp. nov.A–C – phallus (A – dorsal view, B – ventral view, C – lateral view); D – endophallic reservoir and holding sclerite, lateral view; E – endophallic reservoir, dorsal view; F – holding sclerite; G – spermatheca. Scale bars = 0.1 mm.

Fig. 5. Habitats of Stigmatonotum macronotum sp. nov. A – Ôtaki-machi, Ôtadai, the collecting site of the holotype specimen of H. macronotum sp. nov.; B – Kamogawa-shi, Yomogi, Goudai-rindô, University of Tokyo Chiba forest, the collecting site of paratype specimens of S. macronotum sp. nov.; C–D – Carex multifolia Ohwi, from which holotype specimen of S. macronotum sp. nov. was collected.

Fig. 6. Distribution of Stigmatonotum macronotum sp. nov.