Papuanatula (Fijifiliola) grisea sp. nov. Figs 27, 28, 29 Material examined. Holotype. FIJI • larva; Viti Levu, Ba Prov., Ba Riv., near Outback Hotel; 17°37'35"S, 177°45'04"E; 20 m; 22. x. 2024; leg. T. Kaltenbach; on slide; GBIFCH 01582000; MZL. Paratypes. • 4 larvae; same data as holotype; 3 on slides; GBIFCH 01581958, GBIFCH 01581959, GBIFCH 01221840, GBIFCH 01221836 (gonostylus); 1 in alcohol; GBIFCH 01582030; MZL • 4 larvae; Viti Levu, Ba Prov., Ba Riv., near Outback Hotel; 17°37'35"S, 177°45'04"E; 20 m; 21. x. 2024; leg. T. Kaltenbach; 1 on slide; GBIFCH 01581940; 2 in alcohol; GBIFCH 01582011, GBIFCH 01582029; MZL • 2 larvae; Viti Levu, Ba Prov., Sabeto Riv., near Sabeto; 17°43'09"S, 177°31'21"E; 30 m; 17. xi. 2024; leg. T. Kaltenbach; 1 on slide; GBIFCH 01581972; 1 in alcohol; GBIFCH 01582026; MZL. Diagnosis. Larva. Following combination of characters distinguishes P. grisea sp. nov. from other species of Fijifiliola subgen. nov.: larva dorsally grey; legs grey, femur on anterior side in basal part with reddish brown, hypodermal streak (poorly developed on middle leg, nearly absent on hind leg) in large, wedge-shaped blank; labial palp segment III slightly pentagonal; paracercus with 10–15 segments; cerci with 1–5 swimming setae in middle part. Description. Larva (Figs 27 – 29). Body length 3.0– 3.4 mm, cerci subequal to body length. Colouration (Fig. 27 a – c). Head, thorax and abdomen dorsally grey with indistinct pattern as in Fig. 27 a, fore protoptera grey. Legs grey, femur on anterior side in basal part with reddish brown, hypodermal streak (poorly developed on middle leg, nearly absent on hind leg) in large, wedge-shaped blank, medially with dark brown marking; femur on posterior side yellowish grey, without marking. Head, thorax and abdomen ventrally light grey. Caudalii grey. Head. Antenna (Fig. 28 j). Length ~ 1.5 × head length. As typical for subgenus. Labrum (Fig. 28 a, b). Length 0.5 × maximum width. Otherwise, as typical for subgenus. Right mandible (Fig. 28 f). Margin between prostheca and mola straight, with few minute denticles. Otherwise, as typical for subgenus. Left mandible (Fig. 28 e). Margin between prostheca and mola straight, with few minute denticles toward subtriangular process. Otherwise, as typical for subgenus. Hypopharynx and superlinguae (Fig. 28 d). As typical for subgenus. Maxilla (Fig. 28 g). Maxillary palp slightly longer than galea-lacinia; palp segment II subequal to length of segment I. Otherwise, as typical for subgenus. Labium (Fig. 28 c). Paraglossa with one spine-like seta on inner, distolateral margin. Labial palp with segment I ~ 1.4 × length of segments II and III combined. Segment II dorsally with row of four spine-like setae near outer, distolateral margin. Segment III slightly pentagonal, 0.6 × length of segment II. Otherwise, as typical for subgenus. Legs (Fig. 29 a – e). Ratio of leg segments: fore leg 0.9: 1.0: 0.3: 0.2, middle leg 1.0: 1.0: 0.4: 0.2 and hind leg 1.1: 1.0: 0.4: 0.2. Femur. Length ~ 3 × maximum width. Tibia. With row of short, blunt setae on each side parallel to row of long, fine, simple setae. Claw with one row of 10–12 denticles; one posterior setae. Otherwise, as typical for subgenus. Abdomen. Terga (Fig. 29 f, g). Posterior margin of terga: I smooth, without denticles, II – IX with triangular, partly split denticles. Tergalii (Fig. 29 i). Elongate oval; tracheation mainly limited to main trunk, dark brown. Margin smooth, with short, fine, simple setae. Paraproct (Fig. 29 h). Posterior margin with prolongation, with split denticles. Caudalii (Fig. 28 h, i). Cerci with 1–5 swimming setae in middle part. Paracercus with 10–15 segments. Pose of subimaginal gonostyli under larval cuticle (Fig. 28 k). As typical for subgenus. Subimago. Unknown. Imago. Unknown. Egg. Unknown. Biological aspects. Larvae living in run or riffles of medium fast flowing lowland rivers (Figs 36 b, c, 37 b). Etymology. The species name refers to the predominant grey colour, which distinguishes it easily from the often co-occurring species P. aji sp. nov. Distribution. Fiji: Viti Levu (Fig. 40 b).

Published as part of Kaltenbach, Thomas, 2025, Mayflies of the Fiji Islands (Ephemeroptera), pp. 205-276 in ZooKeys 1259 on pages 205-276, DOI: 10.3897/zookeys.1259.168521