Stenelmis hisamatsui M. Satô, 1960

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 : 459-462

Stenelmis hisamatsui M. Satô, 1960

( Figs 2 F–H, 7)

Material examined. JAPAN: Kagoshima Prefecture: Amami-Ôshima Is.: 6 exs. (dried), Kawauchi-gawa (river), Amami-chûô-rindô, Uken-son , 28.iv.2007, MH leg.; 1 ex. (dried) and 3 exs. (dried with an ultrathin coating of gold), 7 exs. (in 70% ethanol), Kawauchi-gawa, Kawauchi, Sumiyô-son, 28.iv.2007, MH leg.; 2 exs. (dried), Yakugachi-gawa (river), Niimura, Sumiyô-son, 28.iv.2007, MH leg.; 15 exs. (in 70% ethanol), Chinaze-gawa, 29.vi.2008, MH leg.; 1 ex. (in 60% ethanol), Agina-gawa (river), Agina, Setouchi-chô, 23.viii.2013, YK leg.; 1 ex. (in ethanol), Kinsakubaru, Naze, Amami-shi, 17.vii.2006, YK leg.; Tokunoshima Is.: 12 exs. (in 60% ethanol), Itokina, Isen-chô, 25.viii.2013, YK leg.; 4 exs. (in 60% ethanol), Todoroki, Tokunoshima-chô, 25.viii.2013, YK leg.; Okinoerabujima Is.: 20 exs. (in 60% ethanol), Amata-gawa (river), Saodu, China-chô, 8.vii.2012, YK leg.; 3 exs. (in 60% ethanol), Taniyama, Wadomari-chô, 6.vii.2012, YK leg. ; Okinawa Prefecture: Okinawajima Is.: 4 exs. (in 70% ethanol), Nago, Nago-shi , 3.iii.2003, H. Moriya leg. ; 2 exs. (in 70% ethanol), Oku, Kunigami-son , 4.iii.2003, H. Moriya leg. ; 2 exs. (in 60% ethanol), Oku-gawa-shiryû, Oku, Kunigami-son, 26.vii.2015, YK leg.; 5 exs. (in 70% ethanol), Fukuchi , Maihara , Nago , 9.v.2002, H. Moriya leg. ; 9 exs. (in ethanol), Ura-gawa, Ura, Kunigami-son , 17.v.2007, YK leg.; 20 exs. (in ethanol), Genka-ôkawa-shiryû (river), Genka, Nago-shi, 16.v.2007, YK leg.; 20 exs. (in ethanol), Ôura-gawa, Ôkawa, Nago-shi, 18.v.2007, YK leg.; 20 exs. (in 60% ethanol), Miharafukuchi-gawa (river), Mihara, Nago-shi, 13.iii.2015, YK leg.; 20 exs. (in 60% ethanol), Onna, Onna-son, 16.iii.2015, YK leg.; Iheyajima Is.: 1 ex. (in 60% ethanol), Shimajiri, Iheya-son, 14.iii.2015, YK leg.; 1 ex. (in 60% ethanol), Tanna-take-kita, Iheya-son, 14.iii.2015, YK 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 granules and setae, but last segment smooth on dorsal and ventral sides.

Head visible from above, well exposed from prothorax; as wide as long; clypeus transverse, with branched 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 with granules and setae, not entirely smooth. 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, dorsum entirely not smooth with granules, 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 with ramose setae; ventral operculum, opercular claws, and anal gills present.

Habitat. Middle stream reaches; larvae live in the gravel substrate.

Identification. The larva was determined using adult specimens from Okinoerabujima Is., because the Stenelmis fauna of Okinoerabujima includes only S. hisamatsui .

Distribution. Ryukyus: Amami-Ôshima Is. (type locality), Tokunoshima Is., Okinoerabujima Is., Okinawajima Is., Iheyajima Is., Tokashikijima Is.; Guam.

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

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.