Microptila nakama, Ito, Tomiko, 2017

Ito, Tomiko, 2017, The genus Microptila Ris (Trichoptera, Hydroptilidae) in Japan, Zootaxa 4232 (1), pp. 104-112 : 107-111

Microptila nakama sp. nov.

( Figs 3 , 4 C, 5)

Diagnosis. The male of this species shows some similarities to Microptila pasak Wells 1993 , described from Bali, Indonesia, in having the subgenital plate bilobed distally, these lobes divergent, and a short apical or subapical process on each inferior appendage, but is distinguished from that species as follows: (1) Segment IX with rounded posterolateral angles ( Fig. 3 A, cf, IX with digitiform lobes laterally in M. pasak ); (2) the caudal excavation of the subgenital plate is narrow and deep ( Fig. 3 B, 3D, cf, the excavation wide and shallow in M. pasak ); and (3) the inferior appendages each have a short mesal process subapically ( Figs. 3 A,3C,3E, cf. the inferior appendages each have a peg-like process at the mesal-caudal corner in M. pasak ).

Male. Length of each forewing and hind wing 1.4–1.6 mm and 1.2 mm, respectively (n = 2). Antennae 18–19- segmented and 0.6 mm long (n = 2).

Genitalia ( Figs. 3 A–3F). Segment IX (IX) annular, in dorsal view ( Fig. 3 B) excavation of anterior margin deep and semi-circular, excavation of posterior margin deep and quadrate, transverse tegmental bridge broad, dorsal midline about 1/5 as long as segment IX; in ventral view ( Fig. 3 C) excavation of anterior margin shallow and semicircular, excavation of posterior margin shallow and quadrate. Tergite X (t X) quadrate, in dorsal view ( Fig. 3 B) with subquadrate excavation caudally, semimembranous and transparent with lateral margins lightly sclerotized. Subgenital plate (sg plate) large, strongly sclerotized, margins of basal half rounded laterally, distally bilobed, lobes slightly divergent ( Figs. 3 B, 3D); in lateral view ( Fig. 3 A) stout, rod-shaped, slightly curved ventrad. Inferior appendages (inf app) large, setose; in lateral view ( Fig. 3 A) main article stout at basal 4/5 and strongly tapered in apical 1/5; in ventral view ( Fig. 3 C) apices incurved, in ventral and ventromesal views ( Fig. 3 C, 3E) blunt mesal process subapically. Phallus long, slender, titillator (ti) arising at apical 1/3, encircling phallus 1.5 times ( Fig. 3 F).

Female. Unknown.

Holotype: male, 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., 30.x.2012, T. Ito (CBM-ZI 151363).

Paratype: 1 male, same data as holotype (CBM-ZI 151364).

Etymology. The specific name ( nakama , a noun) refers to the river where this species was collected.

Habitat ( Fig. 4 C). Adults of this species were collected from a fast-flowing stream with large boulders.

Distribution ( Fig. 5 ). Japan (Ryukyu Islands: Iriomote-jima). Known only from the type locality.

Japanese name. Nakama-mikuro-himetobikera.

Figures

FIGURE 3. Microptila nakama sp. nov. male, type specimens. 3 A, genitalia, left lateral; 3 B, same, dorsal; 3 C, same, ventral; 3 D, subgenital plate, dorsal; 3 E, left inferior appendage, ventromesal; 3 F, phallus, left lateral. Abbreviations: IX – X = abdominal segments IX – 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.