Thraulus (Thraulus) longinquus, Sartori & Salles, 2025

Sartori, Michel & Salles, Frederico F., 2025, The Leptophlebiidae of New Guinea (Ephemeroptera, Choroterpinae, Thraulini), ZooKeys 1245, pp. 41-175 : 41-175

Thraulus (Thraulus) longinquus sp. nov.

Figs 7 , 8

Material examined.

Holotype. • Papua New Guinea, nymph on slide, Madang Province, Aiome area , 130 m, 11.III.2007, 05°10.593'S, 144°42.800'E, Kinibel col [PNG 156], GBIFCH 01223098 ( ZSM) . Paratype. • Papua New Guinea, one nymph in ethanol, GBIFCH 01523473 , same data as holotype ( MZL) .

Nymph.

Body length, male: 5.5 mm.

Diagnosis.

Labrum cordiform, medial emargination shallow with flat denticles; dorsal face of labrum with a simple row in distal position; median part of labrum in ventral view with stout setae in row; apical ventral row of maxilla composed of 17 pectinate setae; tarsal claw with six teeth; gill lamellae on segments II – VI with> 25 filaments each; posterolateral projections of the abdomen present on segments VII – IX.

Colouration.

Head. Yellowish brown, medium brown between ocelli. Antenna yellowish, pedicel dark brown. Compound eye lower portion black, upper portion medium brown. Mouth parts yellowish brown. Thorax. Pronotum pale brown washed with medium brown. Mesonotum pale brown washed with medium brown. Femur whitish, apex tinted with dark brown. Tibia whitish. Tarsi yellowish. Abdomen. Terga uniformly dark brown, sagittal line somewhat paler. Sterna greyish brown. Gills lamellae pale grey, filaments greyish purple. Terminal filaments broken.

Description.

Head. Labrum cordiform (Fig. 7 A ). Ratio labrum width / clypeus width 0.91. Ratio labrum width / insertion width 1.21. Medial emargination shallow with flat denticles. Proximal row of setae present, simple. Number of setae on proximal row ~ 24. Distal row of setae present, simple. Median part of labrum in ventral view with stout setae in row (Fig. 7 B ). Mandibles. Outer margin with middle and distal tuft of setae. Right mandible with 12 setae below the mola (Fig. 7 C ). Maxillae. Posterior margin of cardo broken. Proximo-lateral margin of stipes with a single long and stout seta. Apical-ventral row with 17 pectinate setae. Maxillary palp segment II 0.82 as long as segment I. Maxillary palp segment III 0.75 as long as segment I (Fig. 7 D ). Stout setae on outer margin of segment I absent. Segment II inner margin with three stout setae. Segment II outer margin without stout setae. Segment III inner margin with four stout setae. Segment III dorsal surface with few setae at apex. Segment III 1.60 × as long as base width. Labium. Labial palp segment II 0.68 as long as segment I. Labial palp segment III 0.76 as long as segment I (Fig. 7 E ). Segment I inner margin with nine stout setae, outer margin with eight stout setae. Segment II outer margin with four stout setae. Segment III dorsal face with four stout setae. Segment III 3.11 × as long as base width. Hypopharynx. Apex of superlingua pointed (Fig. 7 F ).

Thorax. Dorsal margin of femur with a row of long, stout, pointed setae; irregular submarginal row of shorter pointed setae; ventral margin with short stout setae and a submarginal row of long, pointed, stout setae, except on hind leg where those on ventral margin are very short and blunt (Fig. 8 A ); central area of upper surface with minute pointed setae. Middle tibia with two rows of long, simple, feathered, or pointed setae on ventral margin, outer margin with few hair-like setae; hind tibia with row of simple long and thin setae on ventral margin, upper and lower surface covered with simple and feathered setae, outer margin with short and long pointed, stout setae and hair-like setae. Tarsal claw straight with six denticles progressively larger apically (Fig. 8 B ).

Abdomen. Gill I with single bifid lamella. Gills II – VII with dorsal and ventral lamellae of the same size. Gill II – VI with upper lamella lacking filaments on basal half of outer margin, with ~ 25–30 filaments on each lamella (Fig. 8 C ); gill VII with ~ 15 filaments on each lamella. Posterior margin of terga IX with denticles. Posterior margin of terga VIII with minute denticles. Posterior margin of terga V – VII without denticles. Posterolateral projections present on segments VII – IX.

Derivatio nominis.

The Latin adjective longinquus means distant or lost, as an indication of the remote place where the species was found.

Figures

Figure 7. Thraulus (Thraulus) longinquus sp. nov. nymphal mouthparts. A. Labrum, dorsal view; B. Emargination of the labrum; C. Right mandible; D. Maxilla; E. Labium; F. Superlingua of hypopharynx. Scale bars: 100 µm (A, F); 50 µm (B); 200 µm (C – E).

Figure 8. Thraulus (Thraulus) longinquus sp. nov. thorax and abdomen. A. Hind femur; B. Claw; C. Gill IV. Scale bars: 200 µm (A); 50 µm (B).