Stenelmis hayashii M. Satô, 1999

Hayashi, Masakazu, Kamite, Yuuki, Kobayashi, Takuya & Sota, Teiji, 2016, Description of larvae of genera Stenelmis, Ordobrevia and Nomuraelmis (Coleoptera: Elmidae: Elminae) of Japan with their molecular taxonomy, Zootaxa 4178 (4), pp. 451-480 : 464-467

Stenelmis hayashii M. Satô, 1999

( Figs 3 D–F, 10)

Material examined. JAPAN: Kagoshima Prefecture: Amami-Ôshima Is.: 1 ex. (dried), Chinaze-gawa (river), Naze-shi , 29.vi.2008, MH leg.; 4 exs. (dried: 3 exs. with an ultrathin coating of gold) and 2 exs. (in 70% ethanol), Naon-gawa (river), Yamato-son , 30.vi.2008, MH leg.; 1 ex. (in ethanol), Naon-gawa, Naon, Yamato-son, 18.vii.2006, YK leg.; Tokunoshima Is.: 1 ex. (in 60% ethanol), Itokina, Isen-chô, 25.viii.2013, YK leg.

Description. Body elongate, gradually narrowing from middle to apex; convex dorsally, flattened ventrally; slightly prominent spiracles on mesothorax and abdominal segments I–VIII. Color of body and appendages orange. Dorsal and ventral surfaces entirely smooth, dorsum with long simple setae and brush-like setae.

Head visible from above, well exposed from prothorax; as wide as long; clypeus transverse, with setae on front; a pair of small spines on both sides of clypeus; vertex smooth with brush-like setae.

Thorax not serrated on sides; dorsum entirely smooth with brush-like setae. Prothorax longer than width, 2.2 times as long as mesothorax; with 3 ventral sclerites, procoxae closed posteriorly; branched setae on hind margins. Meso- and metathorax transverse; metathorax longer than mesothorax; mesothorax with five ventral sclerites.

Abdomen 9-segmented; segments I–VIII transverse, dorsal surface entirely smooth with brush-like setae; pleural sclerites on segments I–VII. Scale-like setae on hind margin of segments I–VIII. Three or four teeth on lateral hind margin of segments I–VIII; tergal sutures on dorso-lateral area lacking. Last segment (segment IX) longer than wide, gradually narrowing to apex, without longitudinal ridge, apex with a pair of spines; dorsal surface smooth; ventral operculum, opercular claws, and anal gills present.

Habitat. Headwaters to upper stream reaches; larvae live in the gravel substrate.

Identification. The larva of this species was easily identified by its shiny orange-colored and small-sized body, based on specimens collected from Tokunoshima. The larva is accompanied with adults of S. hayashii in the habitat. The Stenelmis fauna of the island includes S. hayashii and S. hisamatsui .

Distribution. Ryukyus: Amami-Ôshima Is., Tokunoshima Is. (new record), Okinawajima Is. (type locality), Iheyajima Is.

Bibliography. The larva of this species is newly described in this paper.

Figures

FIGURE 3. Larvae of Stenelmis and Ordobrevia of Japan. A – C, S. aritai M. Satô; D – F, S. hayashii M. Satô; G – H, O. gotoi Nomura; I – J, O. maculata (Nomura); K – M, O. foveicollis (Schönfeldt). A, D, G, I, K, dorsal view; B, E, H, J, L, lateral view; C, F, M, ventral view. Scale bars: 1.0 mm.