Opistoplatys minimus, Ishikawa, Tadashi, Cai, Wanzhi & Tomokuni, Masaaki, 2015

Ishikawa, Tadashi, Cai, Wanzhi & Tomokuni, Masaaki, 2015, The assassin bug subfamily Tribelocephalinae (Hemiptera: Heteroptera: Reduviidae) from Japan, with descriptions of eight new species in the genera Opistoplatys and Abelocephala, Zootaxa 3936 (2), pp. 151-180 : 154-155

Opistoplatys minimus sp. nov.

( Figs. 3, 4 , 6–9 , 12–17 , 21 , 23, 24 , 29, 30 , 33–35, 39, 40)

Diagnosis. This species is recognized by the following combination of character states: body brownish, approximately 6.7 mm long; head a little more than twice as long as width across eyes and 1.5 times longer than pronotum; anteoculus 1.8 times in male and 1.6 times in female longer than postoculus; eye approximately 3 times in male and 1.4 times in female wider than interocular space in dorsal view; anterior pronotal lobe 0.45 times as long as posterior lobe along midline; and in male posterior margin of abdominal segment VII slightly concave at middle.

Description. Male. Body ( Fig. 3 ) mostly brown. Antennae, rostrum, humeral angles, and legs brownish yellow. Hemelytra dark brown to blackish, with extreme bases, corial veins, and basal parts of veins on membranes brownish yellow. Abdomen yellowish brown to dark brown.

Head ( Figs. 6, 7 ) a little more than twice as long as width across eyes, approximately 1.5 times longer than pronotum; anteoculus 1.8 times longer than postoculus, as long as width across antenniferous tubercles; postoculus 0.7 times as long as its maximum width. Eye ( Figs. 6, 7 ) approximately 3 times wider than interocular space in dorsal view. Antennal segment I slender, 0.9 times as long as segment II ( Figs. 12, 13 ), 1.7 times longer than anteoculus ( Fig. 3 ); flagellum ( Fig. 14 ) 1.3 times longer than segment I, a little longer than segment II. Rostral segment I 1.2 times longer than segment II ( Fig. 7 ).

Pronotum ( Fig. 6 ) approximately 0.7 times as long as humeral width; anterior lobe 0.45 times as long as posterior lobe along midline. Hemelytra ( Fig. 3 ) reaching or slightly exceeding apex of abdomen.

Abdomen 1.6 times longer than its maximum width, covered with suberect and decumbent setae, with posterior margin of segment VII slightly concave at middle ( Fig. 21 ). Pygophore ( Fig. 23 ) somewhat compressed dorsoventrally; posterior process ( Fig. 24 ) gently curved posteriorly at base, finely rugose ventrally, at blunt apex in lateral view. Parameres ( Figs. 29, 30 ) evenly curved, at obtuse apex in dorsal view. Phallosoma of phallus (Figs. 33, 34) compressed dorsoventrally, sclerotized laterally, strongly extended laterad at base; struts (Fig. 35) fused in apical two-thirds, rounded apically in dorsal view.

Female. Almost same as male in general habitus ( Fig. 4 ). Anteoculus ( Figs. 8, 9 ) 1.6 times longer than postoculus, slightly longer than width across antenniferous tubercles. Eye ( Figs. 8, 9 ) approximately 1.4 times wider than interocular space in dorsal view. Antennal segment I ( Fig. 15 ) stouter than that of male, a little shorter than segment II, 1.3 times longer than anteoculus ( Fig. 4 ); flagellum ( Fig. 17 ) 1.4 times longer than segment I. Hemelytra ( Fig. 4 ) at most reaching middle of abdominal segment VII. Abdomen 1.4 times longer than its maximum width; segment VII truncate at apex, with posterolateral angles weakly protuberant posteriad; tergite IX ( Fig. 40 ) almost trapezoidal; valvifer I ( Fig. 39 ) elliptical; valvula I ( Fig. 39 ) with approximately 7 setae.

Measurements [in mm, ♂ (n=21) / ♀ (n=20), holotype in parentheses]. Body length 6.10–7.10/6.37–7.25 (7.10). Head length 1.36–1.52/1.46–1.62 (1.52), width across eyes 0.65–0.73/0.69–0.72 (0.73). Lengths of antennal segments I and II 1.03–1.23/0.89–1.00 (1.23) and 1.10–1.33/0.92–1.03 (1.33), respectively. Lengths of rostral segments I and II 0.80–0.90/0.89–0.95 (0.90) and 0.67–0.77/0.71–0.78 (0.77), respectively. Pronotum length 0.92–1.05/0.87–1.12 (1.05), width across humeri 1.40–1.54/1.30–1.60 (1.54). Hemelytron length 4.17–4.75/ 3.57–4.28 (4.75). Lengths of femur and tibia of fore leg 1.50–1.65/1.44–1.66 (1.65) and 1.40–1.61/1.34–1.58 (1.61); of mid leg 1.40–1.61/1.38–1.60 (1.61) and 1.38–1.52/1.30–1.52 (1.52); of hind leg 1.85–2.17/1.87–2.10 (2.17) and 1.95–2.29/1.92–2.30 (2.29). Abdomen length 3.50–4.10/3.75–4.15 (4.10), maximum width 2.06–2.54/ 2.60–2.90 (2.54).

Holotype. ♂ ( Fig. 3 ), “[ JAPAN] Mt. Nosoko-dake, Ishigaki Is., The Ryukyus, 10. VI. 2003, T. Ishikawa leg.” ( LETUA IC 2014-00001) ( TUA).

Paratypes (20 ♂, 20 ♀). JAPAN [Ishigaki Is.] Mt. Nosoko-dake: 1 ♀, 26.ix.2002, T. Nakata ( LETUA IC 2014- 00002) ( TUA), 1 ♀, 17.i.2002, T. Nakata ( LETUA IC 2014-00003) ( TUA), 1 ♂ ( Figs. 23, 24 , 29, 30 ), 5.ii.2003, T. Nakata ( LETUA IC 2014-00004) ( TUA), 2 ♂, 1 ♀, same data as holotype ( LETUA IC 2014-00005–00007) ( TUA), 1 ♂, 1 ♀, 10.vi.2003, H. Mizushima ( LETUA IC 2014-00008–00009) ( TUA), 2 ♂ (one shown in Figs. 21 , 33–35), 5 ♀, 12.vi.2003, H. Mizushima ( LETUA IC 2014-00010–00016) ( TUA), 11 ♂ (one shown in Figs. 6, 7 , 12–14 ), 7 ♀ (each one shown in Fig. 4 , Figs. 8, 9 , 15–17 , and Figs. 39, 40 ), 16.vi.2003, BLT, H. Mizushima ( LETUA IC 2014-00017–00034) ( TUA, CAU, NSMT). near Maezato Dam: 2 ♂, 18.iii.2001, M. Takai ( LETUA IC 2014-00035–00036) ( TUA). [Iriomote Is.] Komi: 1 ♂, 2.v.2002, S. Nagashima ( LETUA IC 2014-00037) ( TUA), 2 ♀, 26.iv.2004, T. Osafune ( LETUA IC 2014-00038–00039) ( TUA), 2 ♂, 26.iv.2004, T. Ishikawa ( LETUA IC 2014-00040–00041) ( TUA).

Distribution. Japan: Ryukyu Islands (Ishigaki Is., Iriomote Is.).

Etymology. From the Latin minimus , referring to the relatively small body size of the members of Opistoplatys ; an adjective.

Remarks. In general habitus, this new species resembles Opistoplatys perakensis Miller, 1940 , which is known from Malaysia ( Miller 1940) and China ( Hsiao & Ren 1981). The new species is distinguished from O. perakensis by its smaller body length (6.2–7.3 mm vs. 7.7–8.0 mm), longer head [approximately 1.5 times longer than the pronotum ( Fig. 6 ) vs. approximately 1.3 times longer than the pronotum], longer anteoculus [markedly longer than the postoculus ( Figs. 6, 7 ) vs. slightly longer than the postoculus], and longer anterior pronotal lobe [approximately half as long as the posterior lobe ( Fig. 6 ) vs. about one-third as long as the posterior lobe].

Opistoplatys minimus sp. nov. seems to inhabit relatively moist forest. Most specimens examined in the present study were collected from the surface of small dead tree branches and the cracks of dead trees lying on the forest floor. The remaining specimens were collected by using BLTs placed on trees at a height of approximately 3 m above the forest floor.

Figures

FIGURES 3 – 5. Opistoplatys spp., habitus in dorsal view. 3 – 4, O. minimus, male (3) and female (4); 5, O. flavolineatus, male. Scale bars: 2 mm.

FIGURES 6 – 11. Head and pronotum (6, 10) and head (7 – 9, 11) of Opistoplatys spp., dorsal (6, 8, 10) and lateral (7, 9, 11) views. 6 – 9, O. minimus, male (6, 7) and female (8, 9); 10, 11, O. flavolineatus, male. Scale bar: 1 mm.

FIGURES 12 – 20. Left antenna of Opistoplatys minimus (12 – 17) and O. flavolineatus (18 – 20), dorsal view, setae omitted. 12 – 14, 18 – 20, male; 15 – 17, female. 12, 15, 18, segment I; 13, 16, 19, segment II; 14, 17, 20, flagellum. Scale bars: 0.5 mm.

FIGURES 21 – 22. Apical part of male abdomen of Opistoplatys minimus (21) and O. flavolineatus (22), ventral view, pygophore removed and setae omitted. Scale bar: 1 mm.

FIGURES 23 – 28. Pygophore (23, 25) and posterior process (24, 26 – 28) of Opistoplatys minimus (23, 24) and O. flavolineatus (25 – 28), lateral view, setae omitted. Scale bars: 0.2 mm (23, 25); 0.05 mm (24, 26 – 28).

FIGURES 29 – 32. Paramere of Opistoplatys minimus (29, 30) and O. flavolineatus (31, 32), ventrolateral (29, 31) and dorsal (30, 32) views. Scale bar: 0.2 mm.

FIGURES 39 – 40. Valvifer I and valvula I (39) and female abdominal tergite IX (40) of Opistoplatys minimus, setae on valvifer I omitted. Abbreviations: vf, valvifer I; vl, valvula I. Scale bar: 0.2 mm.