Ectamenogonus miyakoensis Arimoto 2022, sp. n.

Ectamenogonus miyakoensis Arimoto, sp. n.

(Figures 1B, 1C, 5, 6, 7, 10A)

Homotechnes plebejus (Candèze, 1873); Kishii, 1961: 42 (comment about distribution) [partim].

Ectamenogonus plebejus (Candèze, 1873); Kishii, 1999: 56 (comment about distribution) [partim].

Etymology. Specific epithet derived from Miyako Island, the type locality.

Type material. Holotype. Male [EMM01], Japan, Ryukyu, Okinawa Prefecture, Miyakojima City (Miyako Island), Hirara-higashinakasonezoe, Mt. Ôno-yama, 24.8013°N, 125.3174°E, 4 m, 6 VII 2015, Kôichi Arimoto leg., by simple light trap. Paratypes. 2 females [EMF01, EMF02], same data as the holotype.

Diagnosis. Antennae not reaching pronotum posterior lateral apices by apical antennomere in male.Antennomere IV 1.2–1.3 x longer than II–III combined. Prothorax 1.2 x longer than wide. Posterior edge of scutellar shield shallowly emarginate medially. Elytra 2.4–2.5 x longer than wide, 1.9–2.0 x longer than pronotum length. Aedeagus 4.0 x longer than wide. Median lobe exceeding apices of parameres by apical 1/3. Paramere apex length 1.9–2.1 x width of parameres at expansions. Spiculum ventrale 4.0–4.1 x longer than sternite VIII. Ovipositor 1.3 x longer than length of midline of abdominal ventrites. Bursa copulatrix 2.4–2.7 x length of uterus, with two clusters of sclerotized spines.

Measurements. Male. BL: 11.2, BW: 3.16, MAE: 1.88, MBE: 1.18; OI: 159, PL: 3.87, PML: 3.18, PW: 3.16, PI: 122, EL: 7.39, EW: 3.07, EI: 241, BI: 191. Female. BL: 11.5–11.6, BW: 3.10–3.35, MAE: 1.84–1.85, MBE: 1.19–1.13; OI: 155–165, PL: 3.82–3.97, PML: 3.21–3.30, PW: 3.10–3.35, PI: 119–123, EL: 7.59–7,65, EW: 3.05–3.16, EI: 242–249, BI: 193–199.

Description. Body widest around pronotum hind angles; surface with microstructures; interspaces between punctures generally as long as puncture diameter but partially smaller than puncture diameter; frons, hypomeron, scutellar shield and abdomen interspaces between punctures larger than puncture diameter (Fig. 5A, B, G). Color. Body brown to black-brown (Fig. 1B, C). Labrum reddish (Fig. 5C). Antennae orange (Fig. 5A). Mandible reddish but apical parts black (Fig. 5C). Maxillary palpomeres orange (Fig. 5C). Posterior edge of pronotum, anterior lobe of prosternum and mesial margin and posterior part of hypomeron reddish (Figs. 1B, 1C, 5C, 5H). Elytra around striae blackish, orange in posterior margin (Fig. 1B, C). Legs orange (Fig. 5A). Posterior margin of abdominal ventrite V orange (Fig. 5A). Male. Tergites and sternites VIII‒X and aedeagus yellow (Fig. 6). Female. Tergites and sternites VIII red-brown (Fig. 7A). Body covered with orange to red-brown setae.

Head. Frons beyond eyes 0.3 x longer than wide (Fig. 5B); supra-antennal carina in ventral view emarginate medially (Fig. 5C). Antennae not reaching pronotum posterior lateral apices by apical antennomere (Fig. 1B, C). Male. Antennae extending beyond pronotum posterior margin excluding posterior angles by apical antennomere (Fig. 10A); antennomere II 0.8 x longer than wide; III 1.1 x longer than wide; IV 1.8 x longer than wide, 1.4 x longer than II–III combined (Fig. 5D), 1.1 x longer than V; V 1.7 x longer than wide; XI 2.8 x longer than wide (Fig. 5E). Female. Antennae not reaching pronotum posterior margin excluding posterior angles by apical antennomere (Fig. 1C); antennomere II 0.9–1.1 x longer than wide; III 1.2–1.3 x longer than wide; IV 2.0 x longer than wide, 1.2–1.3 x longer than II–III combined, 1.0–1.1 x longer than V; V 1.8 x longer than wide; XI 2.5–2.7 x longer than wide.

Prothorax 1.2 x longer than wide, widening posteriad, widest behind hind angles in holotype and at posterior lateral apices in paratypes; sides rounded in anterior 1/3, straight in posterior 2/3. Pronotum posteriorly with slight median longitudinal depression. Prosternum: ventral margin weakly inclined in anterior half (at 8–15 degrees against prosternal horizontal line, Fig. 5F); anterior lobe exceeding anterior angles of prothorax (Fig. 1F). Prosternal process depressed between procoxae (Fig. 5H), in profile strongly inclined and then almost horizontal behind procoxae (Fig. 5F); sides of dorsal lobe almost straight and parallel anteriorly and then roundly narrowed; ventral margin of ventral lobe in profile straight anteriorly and rounded posteriorly; apex in ventral and lateral views rounded (Fig. 5A, F). Hypomeron slightly grooved next to impunctate ridge (Fig. 5H: white arrow). Pronotosternal sutures moderately opened anteriorly (Fig. 5H). Scutellar shield 1.5–1.7 x longer than wide (Fig. 5G), widest anteriorly, convex, strongly inclined anterior-downwards, not visible in profile (Fig. 5F); anterior edge broadly rounded; sides almost straight or broadly rounded anteriorly; posterior edge shallowly emarginate medially (Fig. 5G: arrow). Mesosternum: posterior edge 0.1 x wider than mesosternum width, triangularly emarginate (Fig. 5I: arrow), with narrowly rounded angles; borders of mesosternal cavity in profile horizontal anteriorly and then roundly and abruptly inclined (Fig. 5F). Elytra 2.4–2.5 x longer than wide, 1.9–2.0 x longer than pronotum length; apex emarginate; apical outer edge of each elytron rounded; apical internal edge of each elytron slightly pointed or rounded (likely due to damage) (Fig. 5J).

Abdomen. Ventrite V 0.6–0.7 x longer than wide (Fig. 5A). Male. Tergite VIII 1.3 x longer than wide, rounded apically (Fig. 6A). Sternite VIII with deep and rounded median notch (Fig. 6B). Tergite IX 0.9 x length of tergite X, with median notch rounded (Fig. 6C). Tergite X 1.5 x longer than wide, rounded apically (Fig. 6C). Sternite IX 3.5 x longer than wide, rounded apically (Fig. 6D). Aedeagus 4.0 x longer than wide (Fig. 6E, F). Phallobase 0.5 x total length of aedeagus, 2.0 x longer than wide. Median lobe exceeding apices of parameres by apical 1/3; basal struts 0.4 x total length of median lobe. Parameres fused ventrally; preapical expansions not projecting laterally beyond side of apex; apex beyond preapical expansions blade-like shaped (Fig. 6G), rounded laterally, with two setae dorsally, with three setae ventrally; apex length 1.9–2.1 x width of parameres at expansions in ventral side. Female. Terigite VIII 1.5 x longer than wide (Fig. 7B). Sternite VIII 1.2–1.3 x longer than wide (Fig. 7C); spiculum ventrale 4.0–4.1 x longer than sternite VIII (Fig. 7A). Ovipositor 1.3 x longer than length of midline of abdominal ventrites; coxites two segmented at ventral side (Fig. 7H), with some setae; stylus with setae around apex (Fig. 7H). Vagina long; uterus globular (Fig. 7A); bursa copulatrix U-shaped (Fig. 7A), long, 2.4–2.7 x length of uterus, with 61–71 sclerotized spines, of which 25–26 spines forming cluster in first half (Fig. 7D) and 35–46 spines forming rows in latter half (Fig. 7E); long thin sac extending from apex of bursa copulatrix (Fig. 7F), with thin coiled sac near apex of bursa copulatrix (Fig. 7F, G).

Comparative note. Ectamenogonus miyakoensis is similar to E. plebejus in the proportions of the prothorax and elytra and shape of the aedeagus, but it is distinguished from E. plebejus by the following contrasting characters (E. plebejus in parentheses): antennae not reaching pronotum posterior lateral apices by apical antennomere in male (antennae just reaching or extending beyond pronotum posterior lateral apices by apical antennomere in male); posterior edge of scutellar shield shallowly emarginate medially (posterior edge of scutellar shield rounded but truncate in some); elytra 1.9–2.0 x longer than pronotum length, BI: 191–199 (elytra 2.0–2.3 x longer than pronotum length, BI: 202–229); bursa copulatrix 2.4–2.7 x length of uterus (bursa copulatrix 1.7–2.3 x length of uterus).

Discussion. Kishii (1961) included Miyako Island in the distribution of E. plebejus, but he did not give specimen information. This study did not find specimens that served as evidence of the distribution information in Kishii (1961). Specimens newly collected from Miyako Island (EMM01 and EMF01–02) are distinguished from E. plebejus by the antenna length, proportion of body, shape of the scutellar shield, and length of the bursa copulatrix (see comparative note of E. miyakoensis). Therefore, the specimens from Miyako Island were determined to be a new species, E. miyakoensis, and removed E. plebejus from Miyako Island.

Distribution (Fig. 20B). Japan: Miyako Islands of the Ryukyu Islands (Miyako Island).

Ecology. The type specimens were collected at night using simple light traps made by combining a flight interception trap with a 4 W chemical fluorescent light.