Microptila genka sp. nov.

(Figs 2, 4 B, 5)

Diagnosis. The male of this species is similar to those of Microptila orienthula and the Vietnamese M. dironga Oláh and Johanson 2010, but can be distinguished from these as follows: (1) Segment IX has a broader tegmental bridge (cf. the very narrow bridge in M. orienthula and M. dironga), with the dorsal midline about 1/5 as long as segment IX (Fig. 2 B); (2) the subgenital plate is rounded caudally (Figs. 2 B, 2D, cf. the plate has a tiny U- or Vshaped excavation caudally in M. orienthula); and (3) the inferior appendages are stout with thick setose ridges mesally (Figs. 2 A, 2C, 2E, cf. the rather slender appendages in M. dironga). Females of this species are similar to those of M. orienthula, but can be distinguished from the latter by the presence of a triangular median process on the caudal margin of segment VII (Fig. 2 G, cf. the caudal margin of segment VII is wholly convex in M. orienthula).

Male. Length of each forewing and hind wing 1.6–1.7 mm and 1.4–1.5 mm, respectively (n = 3). Antennae each 19-segmented and 0.5–0.6 mm long (n = 3).

Genitalia (Figs. 2 A–2F). Segment IX (IX) annular, in dorsal view (Fig. 2 B) excavation of anterior margin semi-circular, excavation of posterior margin broadly concave; transverse tegmental bridge broad, dorsal midline about 1/5 as long as segment IX; in ventral view (Fig. 2 C) excavation of anterior margin broadly triangular, excavation of posterior margin wide and shallow. Tergite X (t X) semimembranous, transparent, with lightly sclerotized lateral and caudal margins, quadrate, with deep and wide triangular excavation caudally in dorsal view (Fig. 2 B). Subgenital plate (sg plate) twice as long as tergite X, elongate ovate, rounded caudally, semimembranous with lightly sclerotized lateral margins (Figs. 2 A, 2B, 2D). Inferior appendages (inf app) large, setose, without any branches; in ventral view (Fig. 2 C) each with basal 2/3 stout, apical 1/3 slender, apex incurved and acute; in ventromesal view (Fig. 2 E) basal 2/3 with longitudinal setose ridge mesally and apical 1/3 rectangular with strongly sclerotized ridge. Phallus long with slender, elongate titillator (ti) arising near apical 1/4, titillator encircling phallus 1.5 times (Fig. 2 F).

Female (Fig. 2). Length of each forewing and hind wing 1.6–1.8 mm and 1.3–1.4 mm, respectively (n = 4). Antennae each 19-segmented and 0.5–0.6 mm long (n = 4).

Abdominal segments I–VII densely covered with long thick setae. Segment VII (VII) tergite and sternite fused laterally, caudal margin with triangular median process in ventral view (Fig. 2 G). Segment VIII almost as long as segment VII, often withdrawn into segment VII.

Holotype: male, Japan, Ryukyu Islands, Okinawa-jima, Nago-shi, Genka, hygropetric zone near Hogenhashi, 26˚36’16” N, 128˚04’29” E, 65 m a.s.l., 8.iv.2011, T. Ito (CBM-ZI 151359).

Paratypes: 2 males, 1 female, same data as holotype (CBM-ZI 151360–151362).

Other specimens examined. 1 male, same data as holotype. Japan, Ryukyu Islands, Ishigaki-jima: 2 males, 3 females, hygropetric zone beside Nagura-gawa, 18.iii.2016, T. Ito; 1 male, 1 female, unnamed waterfall beside foot path of Mt. Omoto-dake, 20.iii.2016, T. Ito.

Habitat (Fig. 4 B). Adults of this species were collected at hygropetric zones and waterfalls.

Etymology. The specific name refers to the locality (nakama, a noun) where the type specimens were collected.

Distribution (Fig. 5). Japan (Ryukyu Islands: Okinawa-jima, Ishigaki-jima).

Japanese name. Genka-mikuro-himetobikera.