Microptila orienthula Kjaerandsen and Ito

Ito, Tomiko, 2017, The genus Microptila Ris (Trichoptera, Hydroptilidae) in Japan, Zootaxa 4232 (1), pp. 104-112 : 105-107

Microptila orienthula Kjaerandsen and Ito

( Figs 1 , 4 A, 5)

Microptila orienthula Kjaerandsen and Ito 2009 , 177–180, male, female, Japan (Hokkaido, Honshu); Nishimoto and Nishimoto 2014, 63, Japan (Honshu).

Male. Length of each forewing and hind wing 1.6–2.2 mm and 1.4–1.8 mm, respectively (n = 4). Antennae each 19-segmented and 0.6–0.9 mm long (n = 4).

Genitalia ( Figs. 1 B–1G). Segment IX (IX) annular, dorsally with deep and wide triangular excision at anterior margin, posterior margin with shallow and wide concavity, transverse tergal bridge very narrow, dorsal midline about 1/10 as long as segment IX in dorsal view ( Fig. 1 C); in ventral view ( Fig. 1 D) anteroventral margin with shallow triangular concavity, posteroventral margin with deep wide concavity. Tergite X (t X) quadrate with large median triangular concavity caudally in dorsal view ( Fig. 1 C), semimembranous and transparent, lateral margins lightly sclerotized. Subgenital plate (sg plate) semimembranous with slightly sclerotized lateral margins, twice as long as tergite X ( Figs. 1 B, 1C), long ovate with tiny U- or V-shaped excavation caudally in dorsal view ( Fig. 1 E). Inferior appendages (inf app) well developed, setose, without any branches, each with basal 2/3 stout, tapered in distal 1/3 ( Figs. 1 B, 1D), apex in ventral view incurved and acute ( Fig. 1 D), in ventromesal view ( Fig. 1 F) basal 2/ 3 with longitudinal setose ridge mesally and apical 1/3 triangular with strongly sclerotized dorsomesal edge. Phallus elongate, with slender titillator (ti) arising near apical 1/3, wrapped around phallus 1.5 times ( Fig. 1 G).

Female. Length of each forewing and hind wing 1.3–1.8 mm and 1.3–1.6 mm, respectively (n = 4). Antennae each 18-segmented and 0.4–0.6 mm long (n = 4).

Abdominal segments I–VII densely covered with long thick setae. Segment VII (VII) tergite and sternite fused laterally, conical in ventral view ( Fig. 1 H). Segment VIII (VIII) almost as long as segment VII, often withdrawn into segment VII, ventroposterior margin slightly protruded in some specimens ( Figs. 1 H–1J).

Specimens examined. Type specimens: 3 males, 2 females, Japan, Hokkaido, Shiriuchi-cho, hygropetric zone beside Idesu-gawa , 12.vii.2008, T. Ito (CBM-ZI 135131–135135, on slides).

Additional records (other than those of Kjaerandsen and Ito 2009): Japan, Honshu, Niigata: 42 males, 12 females, Itoigawa-shi, Kotaki-gawa , 300–400 m above sea level (a.s.l.), 14.viii.1998, T. Hattori . Toyama: 3 males, Nanto-shi, Taira-mura, Nashidani-gawa , 450 m a.s.l., 30.vii.1995, T. Hattori . Shizuoka: 10 males, 2 females, Shizuoka-shi, Nyujima , 400 m a.s.l., hygropetric zone, 5.vii.1989, T. Hattori ; 10 males, same locality, 11.vi.1999, T. Hattori ; 2 males, same locality, 18.vi.2001, T. Hattori ; 18 males, 2 females, Shizuoka-shi, Yugashima , 400 m a.s.l., hygropetric zone, 30.viii.2005, T. Hattori ; 3 males, 1 female, Shizuoka-shi, Akazawa, hygropetric zone, 2.ix.2009, T. Hattori; 1 male, same locality, 19.ix.2013, T. Hattori & T. Ito ; 9 males, 4 females, Hamamatsu-shi, Komyo-san, 29.viii.2009, T. Torii. Aichi: 5 males, 2 females, Shinshiro-shi, Horai, 4.viii.1998, H. Nishimoto . Shiga: 2 males, Higashi-omi-shi, Eigenji, Kanzaki-gawa, hygropetric zone near Kazakoshi-bashi, 9.ix.2014, T. Ito ; 8 males, 1 female, same locality, 11.vi.2016, T. Ito. Shikoku, Kochi : 2 males, Tosa-shimizu-shi, Akasho, small stream, 21.v.1999, T. Ito & A. Ohkawa. Kyushu, Nagasaki : 1 male, Isahaya-shi, Korai-cho, Todoroki-kyo, 18.ix.2000, A. Ohkawa. Yakushima: 1 male, 2 females, Nagata, Hamanaka, Nakano-bashi, 30.viii.1986, Y. Takemon; 1 female, unnamed tributary of Miyanoura-gawa, 10.v.2006, T. Ito.

Remarks. The males of this species are distinguished from other congeneric species by the large, stout inferior appendages and long oval subgenital plate with tiny U- or V-shaped excavation apically.

Habitat ( Fig. 4 A). Adults of this species were collected from hygropetric zones and fast flowing streams with large rocks.

Distribution ( Fig. 5 ). Japan (Hokkaido, Honshu, Shikoku, Kyushu, Yakushima). New to Shikoku, Kyushu and Yakushima.

Japanese name. Mikuro-himetobikera.

Figures

FIGURE 1. Microptila orienthula Kjaerandsen & Ito 2009 male and female; type specimens (1 A – 1 E, 1 G, 1 H), type locality (F), Shizuoka (I), Yakushima (J). Male (1 A – 1 G): 1 A, head and thorax, dorsal; 1 B, genitalia, left lateral; 1 C, same, dorsal; 1 D, same, ventral; 1 E, subgenital plate, dorsal; 1 F, right inferior appendage, ventromesal; 1 G, phallus, left lateral. Female (1 H – 1 J): 1 H, abdominal segments VII – X, ventral; 1 I and 1 J, abdominal segment VII, ventral, variation. 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.