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).