Papuanatula (Fijifiliola), Kaltenbach, 2025

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

Subgenus Fijifiliola subgen. nov.

Type species.

Papuanatula ( Fijifiliola) aji sp. nov.

Diagnosis

(larval characters) (Table 3 , Fig. 5 ).

Distal part of antenna asymmetric, each flagellomere with anterior side more convex than posterior side, with brown hypodermal spot near apex of anterior side (Fig. 8 j ).

Labrum (Fig. 7 a, b ) widest in middle area, laterally rounded; dorsally with submarginal row of long, simple setae.

Hypopharynx and superlinguae (Fig. 7 d ). Apex of lingua usually with a well-developed, bifid bunch of stout setae. Distolateral margin of superlinguae with medium, fine setae; lateral margins almost straight.

Both mandibles long, with incisor strongly elongated (blade-like); full-length incisors present only at the beginning of each instar, usually worn at the end of instar (Fig. 7 e, f ).

Right mandible (Fig. 7 f ). Kinetodontium deeply separated from incisor; incisor with three denticles; kinetodontium terminating with three or four denticles, with distal denticle longest. Mola with setae on proximal corner.

Left mandible (Fig. 7 e ). Incisor and kinetodontium fused at most of its length; incisor with three denticles; kinetodontium terminating with three or four denticles, with distal denticle longest. Mola with setae on proximal corner.

Maxilla (Fig. 7 g ). With one or two simple setae under canines. Medially with one spine-like, feathered seta and usually three short to long simple setae. Maxillary palp apically constricted.

Labium (Fig. 7 c ). Glossae longer than half of paraglossae; with several long setae at and near apex. Paraglossae with one medium simple seta in medioproximal area. Labial palp with poorly developed, rounded, distomedial projection on segment II.

Thorax and abdomen dorsally and ventrally usually without protuberances. The only known exception is a minute spine posteromedially on fore protoptera of mature larvae of P. aji sp. nov. Posterior margin of abdominal sternites smooth, without spines.

Legs (Fig. 8 a – d ). Outer side of femur usually with single, regular row of long, slender, flattened setae with blunt apex; additionally in distal ½ row of medium to long, fine, simple setae; apex with short, stout, blunt setae; short to medium, spine-like setae along inner margin. Anterior side of tibia with regular row of long, fine, simple setae; parallel one or two rows of short, stout setae with blunt apices. Tarsus with regular row of long, fine, simple setae along outer margin; inner margin subdistally usually with one much longer, thinner, pointed seta. Claw with single row of denticles and usually one posterior seta.

Paraproct (Fig. 8 h ). Posterior margin usually with prolongation and with split denticles. Cercotractor usually with small denticles.

Pose of subimaginal gonostyli under larval cuticle (Fig. 7 j ). Subimaginal gonostyli developing under cuticle of last instar male larvae folded in “ Labiobaetis - type ” ( Kluge 2004: fig. 29 I): 1 st segment directed laterally, 2 nd and 3 rd segments directed medially, whereby second segment is closest to posterior margin of the ninth segment.

Etymology.

The new genus-group name Fijifiliola subgen. nov. is formed from the nouns Fiji and filiola (meaning “ little daughter ” in Latin), and can be understood as “ little daughter of Fiji ”. Gender is feminine.

Figures

Figure 5. Papuanatula, comparison of main characters between subgenera: left column: Papuanatula s. str.; middle column: Papuafiliola; right column: Fijifiliola subgen. nov.; row one (top): labrum, shape, and dorsal submarginal arc of setae; row two: labial palp segment II / III; row three: right mandible; row four: femur, outer margin row of setae; row five (bottom): tibia, anterior surface, row of setae.

Figure 7. Papuanatula (Fijifiliola) aji sp. nov., larva. a, b. Labrum; c. Labium; d. Hypopharynx and superlinguae; e. Left mandible; f. Right mandible; g. Maxilla; h. Paracercus; i. Cercus; j. Male mature larva, developing subimaginal gonostylus; k. Fore protoptera, protuberance. Scale bars: 20 µm (a, c – h). 10 µm (b, i – k).

Figure 8. Papuanatula (Fijifiliola) aji sp. nov., larva. a. Hind leg; b. Femur, outer margin; c. Tibia; d. Tarsus, outer margin; e. Tarsus, claw; f. Abdomen; g. Abdominal terga; h. Paraproct; i. Tergalius IV; j. Head. Scale bars: 100 µm (f, j). 50 µm (a); 10 µm (b – e, g – i).