Papuanatula ( Fijifiliola ) tenebris, Kaltenbach, 2025

Kaltenbach, Thomas, 2025, Mayflies of the Fiji Islands (Ephemeroptera), ZooKeys 1259, pp. 205-276 : 205-276

Papuanatula ( Fijifiliola) tenebris sp. nov.

Figs 33 , 34 , 35

Material examined.

Holotype. FIJI • larva; Viti Levu , Ba Prov., near Abaca village, Savuione Riv.; 17 ° 40 ' 07 " S, 177 ° 32 ' 31 " E; 510 m; 24. x. 2024; leg. T. Kaltenbach; on slides; GBIFCH 01221831, GBIFCH 01581923; MZL.

Diagnosis.

Larva. Following combination of characters distinguishes P. tenebris sp. nov. from other species of Fijifiliola subgen. nov.: larva dorsally rather uniform blackish brown; femur on anterior side in basal ½ with dark brown, narrow, longitudinal streak in large, oblong blank (all legs), large dark grey band in distomedial area; labrum dorsally with irregular arrangement of submarginal setae; maxillary palp ~ 1.5 × length of galea-lacinia; tergalii rather large, skewed oval, with brown pigmentation; labial palp segment III conical; paracercus with 20 segments.

Description.

Larva (Figs 33 – 35 ). Body length 6.4 mm, cerci broken.

Colouration (Fig. 33 a – c ). Head, thorax and abdomen dorsally rather uniform blackish brown. Femur on anterior side in basal ½ with dark brown, narrow, longitudinal streak in large, oblong blank (all legs), large dark grey band in distomedial area; tibia and tarsus grey. Head, thorax and abdomen ventrally dark grey-brown. Caudalii dark grey.

Head. Antenna (Fig. 34 h ). Length ~ 1.5 × head length. As typical for subgenus.

Labrum (Fig. 34 a, b ). Length 0.5 × maximum width. Dorsally with irregular arrangement of submarginal setae. Otherwise, as typical for subgenus.

Right mandible (Fig. 34 f ). Margin between prostheca and mola almost straight, with minute denticles. Otherwise, as typical for subgenus.

Left mandible (Fig. 34 e ). Margin between prostheca and mola almost straight, with minute denticles toward subtriangular process. Otherwise, as typical for subgenus.

Hypopharynx and superlinguae (Fig. 34 d ). As typical for subgenus.

Maxilla (Fig. 34 g ). Maxillary palp ~ 1.5 × length of galea-lacinia; palp segment II approx. as long as segment I. Otherwise, as typical for subgenus.

Labium (Fig. 34 c ). Paraglossa with two spine-like setae on inner, distolateral margin. Labial palp with segment I approx. as long as segments II and III combined. Segment II dorsally with row of six spine-like setae plus additional one or two setae near outer, distolateral margin. Segment III conical, 0.6 × length of segment II. Otherwise, as typical for subgenus.

Legs (Fig. 35 a – g ). Ratio of leg segments: fore leg 1.0: 1.0: 0.3: 0.1, middle leg 1.0: 1.0: 0.3: 0.1 and hind leg 1.0: 1.0: 0.3: 0.1. Femur. Length ~ 3.5 × maximum width. Setae on outer margin long, flattened, pointed. Tibia. With row of short, blunt setae parallel to row of long, fine, simple setae. Claw with one row of ten or 11 denticles, distalmost denticle with distance to other denticles; one posterior seta. Otherwise, as typical for subgenus.

Abdomen. Terga (Fig. 35 h, i ). Posterior margin of terga: II – IX with triangular, sharply pointed denticles.

Tergalii (Fig. 35 j, k ). Rather large, skewed oval; tracheation well-developed, reaching margins, dark brown; brown pigmentation around tracheae. Margin with minute denticles and short, fine, simple setae.

Paraproct (Fig. 35 i ). Posterior margin with prolongation, with denticles. Cercotractor without denticles.

Caudalii (Fig. 34 i, j ). Cerci without swimming setae. Paracercus with 20 segments.

Pose of subimaginal gonostyli under larval cuticle. Unknown.

Subimago. Unknown.

Imago. Unknown.

Egg. Unknown.

Biological aspects.

Local species, larvae living in run of fast flowing mountain rivers with pristine water (Fig. 36 e ).

Etymology.

The name refers to the dark appearance of the species, tenebris meaning dark in Latin.

Distribution.

Fiji: Viti Levu (Fig. 40 d ).

Figures

Figure 33. Papuanatula (Fijifiliola) tenebris sp. nov., larva, habitus. a. Dorsal view; b. Lateral view; c. Ventral view. Scale bars: 1 mm.

Figure 34. Papuanatula (Fijifiliola) tenebris sp. nov., larva. a, b. Labrum; c. Labium; d. Hypopharynx and superlinguae; e. Left mandible; f. Right mandible; g. Maxilla; h. Head; i. Paracercus; j. Cercus. Scale bars: 100 µm (h); 50 µm (c, e – g); 20 µm (a, d); 10 µm (b, i, j).

Figure 35. Papuanatula (Fijifiliola) tenebris sp. nov., larva. a. Middle leg; b. Femur, outer margin; c. Femur, inner margin; d. Tibia; e. Tibia, inner margin; f. Tarsus, outer margin; g. Tarsus, claw; h. Abdomen; i. Abdominal terga; j, k. Tergalius IV; l. Paraproct. Scale bars: 100 µm (h); 50 µm (a, j); 10 µm (b – g, i, k, l).

Figure 36. Habitats. a. Overview map; b, c. Ba River near Outback Hotel (locations A, B; lowland river); d. Savuione River, close to beyond the Savuione waterfall, near Abaca village (location C; mountain river); e. Savuione River, downstream of the waterfall, near Abaca village (location C 1; mountain river). For characteristics of locations see Table 3.

Figure 40. Distribution of described species. a. Papuanatula (Fijifiliola) gattolliati sp. nov. (locations E, F); b. Papuanatula (Fijifiliola) grisea sp. nov. (locations A, B, I); c. Papuanatula (Fijifiliola) sekawa sp. nov. (location E); d. Papuanatula (Fijifiliola) tenebris sp. nov. (location C 1).