Paramacronychus granulatus Nomura, 1958

Hayashi, Masakazu & Kamite, Yuuki, 2020, Description of larvae of Japanese Macronychini (Coleoptera: Elmidae: Elminae), Zootaxa 4859 (2), pp. 195-227 : 198-200

Paramacronychus granulatus Nomura, 1958

( Figs 1B , 4 , 18C , 20A, B )

Materials examined. JAPAN: [HONSHU]: 1 larva, Kongo-san, Chihaya-akasaka-mura, Osaka Pref., Honshu , 27.iii.2016, M. Hayashi leg. [KYUSHU]: 1 larva, Sataizashiki, Minamiosumi-chô, Kagoshima Pref., Kyushu , 2.iii.2019, D. Inoue leg.

Description. Body length of mature larva ca. 5.0 mm in expanded specimen.

Body elongate, narrowing from thorax to apex; convex dorsally and flattened ventrally; semicircular in cross section but ventral side more or less swollen; spiracles on mesothorax and abdominal segments I–VIII. Body and appendages orange colored. Dorsal and ventral surfaces entirely not smooth with flat granules ( Fig. 4B ; Kodada et al. 2016: 583) and various types of setae but prothorax and last abdominal segment partly smooth ( Fig. 4 E–G).

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 moderately smooth with granules and flat brush-like setae ( Fig. 18C ). Prothorax longer than wide, 2 times as long as mesothorax; with glabrous smooth area on dorsum; with six ventral sclerites (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 granules; pleural sclerites on segments I–VII. Last segment (segment IX) longer than wide, gradually narrowing to apex; tergal surface partly smooth with ridge on both sides ( Fig. 4E ); with longitudinal ridge on meson; apex deeply notched ( Fig. 4G ); ventrally swollen ( Fig. 4E ), with subpentagonal-shaped operculum, opercular claws, and anal gills.

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

Identification. The larva was identified by mitochondrial DNA sequences ( Hayashi & Sota 2010).

Distribution. Honshu (type locality), Shikoku, Kyushu and Yakushima Is.

Bibliography. Hayashi & Sota (2010: fig. 15).

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 4. Paramacronychus granulatus 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.