Stenelmis nipponica Nomura, 1958

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 : 459

Stenelmis nipponica Nomura, 1958

( Figs 2 D–E, 6)

Material examined. JAPAN: Tottori Prefecture: 4 exs. (dried with an ultrathin coating of gold), Hossyoji-gawa (river), Noujiku , Nanbu-chô , 20.ix.2009, H. Kadowaki leg.

Description. Body elongate, gradually narrowing from middle to apex; convex dorsally and flattened ventrally; slightly prominent spiracles on mesothorax and abdominal segments I–VIII. Body color entirely brown or black, and appendages yellowish brown. Dorsal and ventral surfaces not smooth with minute granules and setae, but last segment smooth on dorsal and ventral surfaces.

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

Thorax not serrated on lateral sides; dorsum entirely not smooth with granules and brush-like setae. Prothorax longer than width, 2.5 times as long as mesothorax; glabrous spots on basal half; with three ventral sclerites, procoxae closed posteriorly; scale-like 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 not smooth with minute granules and setae, brush-like and plumose setae; pleural sclerites on segments I–VII; tergal sutures on dorso-lateral area of segments II–VII but short in VII. Last segment (segment IX) longer than wide, gradually narrowing to apex, without longitudinal ridge, apex with a pair of spines; dorsal surface smooth but with ramose setae; ventral operculum, opercular claws, and anal gills present.

Habitat. Middle to lower stream reaches; larvae live in the gravel substrate, roots of reeds or decaying wood.

Identification. The larva was identified by mitochondrial DNA sequences ( Hayashi & Sota 2010). This identification has also been confirmed by breeding in the laboratory (Hayashi, unpublished).

Distribution. Honshu, Shikoku, Kyushu, Tsushima Isls.; Korea.

Bibliography. Hayashi & Sota (2010: fig. 5).

Figures

FIGURE 2. Larvae of Stenelmis of Japan. A – C, S. vulgaris Nomura; D – E, S. nipponica Nomura; F – H, S. hisamatsui M. Satô; I – K, S. ishiharai M. Satô. A, D, F, I, dorsal view; B, E, G, J, lateral view; C, H, K, ventral view. Scale bars: 1.0 mm.