Microptila genka, Ito, Tomiko, 2017

Ito, Tomiko, 2017, The genus Microptila Ris (Trichoptera, Hydroptilidae) in Japan, Zootaxa 4232 (1), pp. 104-112 : 107

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.

Figures

FIGURE 2. Microptila genka sp. nov. male and female, type specimens. Male (2 A – 2 F): 2 A, genitalia, left lateral; 2 B, same, dorsal; 2 C, same, ventral; 2 D, subgenital plate, dorsal; 2 E, right inferior appendage, ventromesal; 2 F, phallus, left lateral. Female (2 G): 2 G, abdominal segments VII – X, ventral. Abbreviations: VII – X = abdominal segments VII – X; inf app = inferior appendage (paired); ph = phallus; sg plate = subgenital plate; ti = titillator; t X = tergite X.

FIGURE 4. Type localities of the 3 Japanese species of Microptila. 4 A, M. orienthula (Japan, Hokkaido, Shiriuchi-cho, hygropetric zone beside Idesu-gawa, 1 July 2008); 4 B, M. genka (Japan, Ryukyu Islands, Okinawa-jima, Nago-shi, Genka, hygropetric zone near Hogen-hashi, 26 ˚ 36 ’ 16 ” N, 128 ˚ 04 ’ 29 ” E, 65 m a. s. l., 18 March 2012); 4 C, M. nakama (Japan, Ryukyu Islands, Iriomote-jima, Nakama-gawa river system, Nishi-funatsuki-gawa, Nishi-funatsuki-bashi, 24 ˚ 18 ’ 10 ” N, 123 ˚ 51 ’ 34 ” E, 10 m a. s. l., 1 March 2016) (Images by Shizuko Morimoto).

FIGURE 5. Distribution of the 3 Japanese species of Microptila. The boundary between East Palearctic and Oriental Regions is modified from Morse 2016.