Orientelmis parvula ( Nomura & Baba, 1961 )

Hayashi, Masakazu, Yoshitomi, Hiroyuki, Kamite, Yuuki, Kobayashi, Takuya & Sota, Teiji, 2019, Description of adults and larvae of Orientelmis parvula (Nomura & Baba, 1961) (Coleoptera: Elmidae) with their molecular phylogenetic analysis, Zootaxa 4568 (3), pp. 483-500 : 488-490

Orientelmis parvula ( Nomura & Baba, 1961)

( Figs 2–10 )

Material examined. JAPAN: Aichi Prefecture: 10 adults, Osawa, Miuchi-chô, Toyota-shi , 1. X. 2017, Y. Ichikawa leg. [EUMJ] . Shimane Prefecture: one adult, Yoshino, Sada-chô, Izumo-shi , 28. VII. 2015, H. Yoshitomi leg. [EUMJ]; one adult, same locality, 20. VIII. 2 0 15, H. Yoshitomi leg. [HOWP] . Tottori Prefecture: two adults (dried, with ultrathin coating of gold), Inga-gawa (river), Inga, Nichinan-chô , 10. VIII. 2015, M. Hayashi leg. [HOWP]; three mature larvae (two specimens in 70% ethanol; one specimen dried, with ultrathin coating of gold), same locality, laboratory-reared, fixed on 19. V. 2016 (five adults used for rearing, collected on 10. VIII. 2 0 15, M. Hayashi leg.) [HOWP] .

Adults. ( Figs 2–4 , 5F )

Supplementary description. Mandibles ( Fig. 2A ) with two apical teeth. Antennae ( Fig. 2D ) 11-segmented, relatively long, approximate ratio of each antennomere (n = 1) 1.8:1.3:1.0:1.0:1.0:1.0:1.2:1.2:1.2:1.3:3.0. Maxillae ( Fig. 2B ) with long terminal segment of galea; maxillary palpi 3-segmented, terminal palpomere longer than the remaining segments combined. Labial palpi ( Fig. 2C ) 3-segmented; terminal palpomere oblong, a little shorter than the remaining segments combined.

Male. Tergite VIII ( Fig. 3A ) wide, semicircular, bearing short setae. Sternite VIII ( Fig. 3B ) Y-shaped, with a short median strut. Sternite IX ( Fig. 3C ) slightly sclerotized, larger than aedeagus, elongate, sparsely covered with short setae in apical part, with short paraprocts. Aedeagus ( Fig. 3 D–F) relatively short and small; phallobase short, deeply concave at basal margin; parameres relatively short, sparsely punctate, slightly projecting dorso-interiorly in proximal 2/3 of dorsal part; median lobe long, about 1.1 the length of parameres, gently and evenly tapered posteriorly, with long rod-like fibula.

Female. Tergite VIII ( Fig. 3G ) transverse, semicircular, bearing short setae. Sternite VIII ( Fig. 3H ) semicircular, with a long median strut. Ovipositor ( Fig. 3I, J ) shorter than sternite VIII, bearing curved short sensilla at the apex of the stylus and coxite; approximate ratio of stylus, distal part of coxite, basal part of coxite, and valvifer (n = 1) 1.0:3.0:2.5:5.5.

Measurements (unsexed; n = 10). TL 1.42–1.55 (1.48) mm; PW 0.75–0.82 (0.80) mm; PL 0.40–0.45 (0.42) mm; EL 1.00–1.10 (1.06) mm; EW 0.88–0.98 (0.93) mm; PW/PL 1.74–2.00 (1.90); EL/EW 1.11–1.25 (1.15); EL/ PL 2.33–2.75 (2.54); EW/PW 1.12–1.23 (1.16); TL/EW 1.53–1.74 (1.60).

Larvae. ( Figs 5 A–E, 6–10)

Description. Body length of mature larva ca. 3.0 mm, head width 0.3 mm, pronotal length 0.4 mm and width 0.4 mm.

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 with dark and light spots dorsally, and appendages yellowish brown. Apical half of prothorax light yellow. Dorsal and ventral surfaces not smooth, with minute granules and setae, but last segment smooth on ventral surface.

Head visible from above, well exposed from prothorax; as wide as long; clypeus transverse, with setae anteriorly; a pair of spines on both sides of clypeus lacking; vertex with granules and brush-like setae; eyes large but lens of stemmata not developed. Antenna with three antennomeres; antennomere 1 shorter than antennomere 2; antennomere 1 with short branched setae; antennomere 2 with short sensorial appendage; antennomere 3 short with small sensorial appendage. Maxillae and labium forming a unit (maxillolabial unit). Maxilla with four palpomeres; cardo small; stipes large; galea and lacinia separate, setose apically. Labium narrow with two palpomeres; ligula short and transverse; mentum long; submentum short and transverse.

Thorax not serrated on lateral sides; entire dorsum not smooth, with granules and flat long setae. Prothorax as long as wide, twice as long as mesothorax; glabrous spots on basal half; with four ventral sclerites, procoxae not closed posteriorly; flat long setae on hind margins. Meso- and metathorax transverse; metathorax slightly longer than mesothorax. Mesothorax with five ventral sclerites.

Abdomen 9-segmented; segments I–VIII transverse, entire dorsal surface not smooth, with minute granules and long setae; pleural sclerites on segments I–VI; tergal sutures on dorso-lateral area indistinct. Last segment (segment IX) longer than wide, gradually narrowing toward apex, without longitudinal ridge, apex with a pair of developed spines; dorsal surface smooth but with long setae; ventral operculum, opercular claws, and anal gills present.

Habitat. Middle to lower stream reaches; larvae and adults live in submerged roots of reeds and riparian woods.

Distribution. JAPAN: Honshu [Niigata Pref. ( Nomura & Baba 1961), Aichi Pref. ( Ichikawa & Iwata 2017), Ishikawa Pref. ( Watanabe 2018), Hiroshima Pref. ( Akiyama 2003, Sakamoto 2014), Yamaguchi Pref. ( Nakajima 2007), Tottori Pref. ( Hayashi & Kadowaki 2008a, b), Shimane Pref.], Kyushu [Fukuoka Pref. ( Satô et al. 2005; Ogata & Nakajima 2006), Kumamoto Pref. (Onikura & Nakajima 2007)]. This is the first record of this species from Shimane Prefecture.

Figures

FIGURE 2. Adult mouth parts of Orientelmis parvula (Nomura & Baba). A, Mandible in dorsal view; B, maxilla in ventral view; C, labium in ventral view; D, antenna.

FIGURE 3. Male (A–F) and female (G–J) genitalia of Orientelmis parvula (Nomura & Baba). A, G, tergite VIII; B, H, sternite VIII; C, sternite IX; D–F, aedeagus in dorsal (D), ventral (E), and lateral (F) views; I, ovipositor; J, stylus and distal part of coxite.

FIGURE 4. Scanning electron microscopy photographs of adult Orientelmis parvula (Nomura & Baba). A, habitus; B, pronotum and basal area of elytron; C, apical area of elytron; D, ventral surface; E, head and sterna of thorax; F, plastron setae of abdominal sternites. A–C, dorsal view; D–F, ventral view. Scale bars: 100 µm in F; 200 µm in A–C, E; 500 µm in D.

FIGURE 5. Orientelmis parvula (Nomura & Baba). A–C, habitus of the larva (scale bar is 1.0 mm); D, E, living larva; F, living adult. A, D, dorsal view; B, E, lateral view; C, ventral view.

FIGURE 6. Larva of Orientelmis parvula (Nomura & Baba). A, dorsal view; B, lateral view; C, ventral view.

FIGURE 7. Scanning electron microscopy photographs of larva of Orientelmis parvula (Nomura & Baba). A, head and prothorax; B, right half of the head; C, F, head and thorax; D, E, left side of the head; G, H, ventral side of the head. A, B, dorsal view; C–E, lateral view; F–H, ventral view. Scale bars: 20 µm in E; 50 µm in B; 100 µm in A, D, G, H; 200 µm in C, F.

FIGURE 8. Scanning electron microscopy photographs of larva of Orientelmis parvula (Nomura & Baba). A–G, prothorax: B, middle part; C–F, left half. H, mesothorax. A–E, dorsal view; F, H. lateral view; G, ventral view. Scale bars: 20 µm in E; 50 µm in B–D; 100 µm in A, F–H.

FIGURE 9. Scanning electron microscopy photographs of larva of Orientelmis parvula (Nomura & Baba). A, mesothorax; B, meso- and metathorax; C–F, metathorax; G, thorax and abdominal segments I–III; H, abdominal segment II. A, D, E, F, dorsal view; G, H, lateral view; B, C, ventral view. Scale bars: 20 µm in F; 50 µm in A, D, E, H; 100 µm in B, C; 200 µm in G.

FIGURE 10. Scanning electron microscopy photographs of larva of Orientelmis parvula (Nomura & Baba). A, F, abdominal segments VI–IX; B, abdominal segment VIII; C–E, G, H, abdominal segment IX. A–E, dorsal view; F–H, ventral view. Scale bars: 20 µm in E; 50 µm in B, D, H; 200 µm in A, C, F, G.