Ecnomus tenellus ( Rambur 1842 )

Kuhara, Naotoshi, 2016, Revision of Japanese species of the genus Ecnomus McLachlan (Trichoptera: Ecnomidae), with descriptions of two new species, Zootaxa 4114 (5), pp. 561-571 : 564-565

Ecnomus tenellus ( Rambur 1842)

( Figs. 2 A–D, 6)

Philopotamus tenellus Rambur 1842: 503 [Type locality: France]. (Type not seen.) Ecnomus omiensis Tsuda 1942: 268 –269, fig. 27 [Type locality: Japan, Honshû, Shiga and Kyôto]. Synonymized by Schmid (1958).

Ecnomus kososiensis Kobayashi 1987: 16 , figs. 4–8, male, female [Type locality: Japan, Honshû, Shimane, Matsue]. New synonym.

Diagnosis. This species is easily distinguished from the other Japanese species by the upcurved inferior appendages each with a short ear-like dorsal projection at midlength in the male, and the posteromesal rectangular notch of the ventromesal plate of segment VII in the female.

Nielsen (1957, 1980) described external and internal morphology of the genital segments in detail for the male and female of this species, respectively. In addition, several authors described and illustrated the general morphology and genitalia of the two sexes (e.g., Schmid 1958; Li & Morse 1997; Arefina 2003). Illustrations of male ( Fig. 2 A–C) and female ( Fig. 2 D) genitalia of Japanese specimens are provided.

Specimens examined. 1 male (holotype of Ecnomus kososhiensis ; CBM; specimen number of Kobayashi, 8294), ‘Kososhi (30 m), Matsue-shi, Shimane Pref.’, 15.X.1965, H. Kadowaki; 1 male, 1 female (paratypes of Ecnomus kososhiensis ; CBM; specimens no. of Kobayashi, 8286), same location, 24.IX.1965, H. Kadowaki. [Hokkaidô] Kushiro, 171 males, 225 females; Tokachi, 44 males, 11 females; Sôya, 183 males, 140 females; Rumoi, 104 males, 58 females; Kamikawa, 96 males, 111 females; Ishikari, 178 males, 228 females; Iburi, 184 males, 176 females; Hiyama, 1 male; Oshima, 175 males, 78 females. [Honshû] Ibaraki, 2 males, 1 female; Gumma, 1 male; Kanagawa, 5 males, 4 females; Niigata, 2 males; Fukui, 2 males, 2 females; Yamanashi, 2 males; Nagano, 16 males, 47 females; Shizuoka, 2 males; Mie, 5 males, 2 females; Shiga, 9 males, 4 females; Shimane, 17 males, 12 females. [Shikoku] Ehime, 2 females; Kochi, 6 males, 5 females. [Kyûshû] Fukuoka, 6 males, 8 females. [Small islands around 4 mainlands] Rishiri-tô, 26 males; Iki-no-shima, 3 females. [Ryûkyû Islands] Okinawa-tô, 7 males, 2 females; Kume-jima, 5 males, 4 females; Ishigaki-jima, 13 males, 86 females, Iriomote-jima, 2 males, 7 females; Yonaguni-jima, 4 males, 1 female. [Europe] Great Britain, 5 males; Germany, 11 males, 3 females; Poland, 2 males, 2 females.

Distribution. Widely distributed in the East and West Palaearctic, Oriental and Afrotropical regions. In Japan: Hokkaidô, Honshû, Shikoku, Kyûshû, Rishiri-tô, Iki-no-shima, Ryûkyû Islands (Okinawa-tô, Kume-jima, Ishigakijima, Iriomote-jima, Yonaguni-jima).

Habitat. Most specimens shown above were collected along shorelines of lakes and ponds, suggesting that the larvae prefer lentic waters. In Britain, however, larvae of this species also inhabit slow-flowing rivers in addition to lakes ( Edington & Hildrew, 1995).

Remarks. Kobayashi (1987) described E. kososiensis from Honshû, Japan. Judging from the original description, this species seems to be similar to E. tenellus , but he did not mentioned the diagnostic characters to discriminate them. My examination of the type specimen of E. kososiensis reveals that it agrees well with specimens of E. tenellus collected in Japan and Europe, and hence E. kososiensis is placed as a junior subjective synonym of E. tenellus .

Figures

FIGURE 2. Ecnomus tenellus Rambur (Hokkaidô, Shikotsu-ko). 2 A – 2 C, male genitalia: 2 A, left lateral; 2 B, dorsal; 2 C, ventral; 2 D, female genitalia, ventral.