Zaitzeviaria brevis (Nomura, 1958)

Hayashi, Masakazu & Kamite, Yuuki, 2020, Description of larvae of Japanese Macronychini (Coleoptera: Elmidae: Elminae), Zootaxa 4859 (2), pp. 195-227 : 204-211

Zaitzeviaria brevis (Nomura, 1958)

( Figs 1E , 7 , 18F , 20D )

Materials examined. JAPAN: [HONSHU]: 4 larvae, Shakunouchi Park, Kisuki, Unnan-shi , Shimane Pref., Honshu , 17.i.2018, M. Hayashi leg. 7 larvae, Ibo-gawa, Hikawa, Izumo , Shimane Pref., Honshu , 12.x.2014, M. Hayashi leg.

Description. Body length of mature larva ca. 3.0 mm in expanded specimen.

Body elongate, narrowing from thorax to apex; convex dorsally and flattened ventrally; subtriangular in cross section; spiracles on mesothorax and abdominal segments I–VIII. Body color light brown to brown, and appendages yellowish brown. Dorsal and ventral surfaces not smooth with minute flat granules ( Fig. 7D ; Kodada et al. 2016: 583) and various types of setae.

Head visible from above, well exposed from prothorax; as wide as long; clypeus transverse, setose; without a pair of spines on both sides of clypeus (frontal tooth); vertex rugose with brush-like setae; eyes large but lens of stemmata absent. Antenna with three antennomeres; antennomere 1 shorter than antennomere 2, with short branched setae; antennomere 2 with long sensorial appendage; antennomere 3 short with small sensorial appendage. Maxillae and labium forming a unit (maxillolabial unit). Maxilla with three 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; dorsum entirely not smooth with granules and simple long setae ( Fig. 18F ). Prothorax wider than long, 2 times as long as mesothorax; with glabrous areas on basal half; with seven ventral sclerites (one between coxae, two anteromedial, two anterolateral, and two posterolateral), procoxae not closed posteriorly; flat feather-like setae on hind margins. Meso- and metathorax transverse; metathorax slightly longer than mesothorax. Meso- and metathorax with five ventral sclerites (one large anteromedial, two anterolateral, and two posterolateral).

Abdomen 9-segmented; segments I–VIII transverse, dorsal surface entirely not smooth with coarse and minute granules; pleural sclerites on segments I–VII. Last segment (segment IX) elongate, gradually narrowing to apex; tergal surface with minute granules and coarse granules sparsely; without ridge on both sides ( Fig. 7E ); with longitudinal ridge on meson; apex truncate and slightly dentate; ventrally flat, with subpentagonal-shaped operculum, opercular claws, and anal gills.

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

Identification. The larva was identified by association with adult Z. brevis from Shakunouchi Park, Unnan, Shimane Pref., Honshu, because the genus Zaitzeviaria fauna of the park includes only Z. brevis .

Distribution. Hokkaido, Honshu, Shikoku (type locality), Kyushu, Sado Is.

Bibliography. The larva of this species is described here for the first time.

Figures

FIGURE 1. Macronychini larvae of Japan. A, Sinonychus tsujunensis Yoshitomi & Nakajima, 2012; B, Paramacronychus granulatus Nomura, 1958; C, Zaitzeviaria gotoi (Nomura, 1959); D, Zaitzeviaria ovata (Nomura, 1959); E, Zaitzeviaria brevis (Nomura, 1958); F, Zaitzeviaria kuriharai Kamite, Ogata & Satô, 2006; G, Zaitzeviaria sotai Hayashi & Yoshitomi, 2015; H, Zaitzevia elongata Nomura, 1962. Scale bar = 1.0 mm.

FIGURE 7. Zaitzeviaria brevis (Nomura, 1958). A, C, Head and prothorax; B, D, prothorax; E–H, last abdominal segment. A, B, E, lateral view; C, D, F, G, dorsal view; H, ventral view.

FIGURE 18. Flat granules and setae on prothorax. A, Podonychus gyobu Yoshitomi & Hayashi, 2020; B, Sinonychus tsujunensis Yoshitomi & Nakajima, 2012; C, Paramacronychus granulatus Nomura, 1958; D, Zaitzeviaria gotoi (Nomura, 1959); E, Zaitzeviaria ovata (Nomura, 1959); F, Zaitzeviaria brevis (Nomura, 1958); G, Zaitzeviaria kuriharai Kamite, Ogata & Satô, 2006; H, Zaitzeviaria sotai Hayashi & Yoshitomi, 2015.

FIGURE 20. Living larvae. A, B, Paramacronychus granulatus Nomura, 1958; C, Zaitzeviaria ovata (Nomura, 1959); D, Zaitzeviaria brevis (Nomura, 1958); E, Zaitzeviaria kuriharai Kamite, Ogata & Satô, 2006; F, Zaitzeviaria sotai Hayashi & Yoshitomi, 2015; G, Zaitzevia awana (Kôno, 1934); H, I, Zaitzevia rivalis Nomura, 1963; J, Zaitzevia tsushimana Nomura, 1963. Not to scale. H, immature larva; others, mature larva.