Nonnullidens alvarezi Sartori & Salles, 2025, sp. nov.

Nonnullidens alvarezi sp. nov. Figs 36 B, 37, 38 Material examined. Holotype. • Papua New Guinea, one nymph on slide, Eastern Highlands Province, Akameku – Brahmin, Bismarck Range, 2200 m, 23.XI.2006, 05°56.801'S, 145°22.238'E, M. Balke & Kinibel col [PNG 106], GBIFCH 01223124 (ZSM). Paratypes. • Papua New Guinea, 2 nymphs in ethanol (UFVB), 2 nymphs on slide, GBIFCH 01223125, GBIFCH 01223126, 7 nymphs in ethanol, GBIFCH 01523456 same data as holotype (MZL). • Papua New Guinea, one nymph on slide, GBIFCH 01223127, gills and legs in ethanol, GBIFCH 01523457, Gulf Province, Marawaka, Mala, 1400 m, 11.XI.2006, 07°05.664'S, 145°44.467'E, M. Balke & Kinibel col [PNG 90] (MZL). Nymph. Body length, male: 5.5 mm; female: 6.5 mm. Diagnosis. Femora uniformly dark brown, without transverse bands; tarsal claw with 6–8 teeth; gill I – II uni-lamellate, without ventral lamella; gills III – VI with 5–8 filaments on dorsal lamella and four or five filaments on ventral lamella, gill VII with four or five filaments on dorsal lamella and one or two filaments on ventral lamella. Colouration. Head. Vertex dark brown, frons medium brown with an oval pale brown macula near the frons ocellus. Antenna broken. Compound eye upper portion reddish brown. Mouth parts pale brown. Thorax. Pronotum medium brown, lateral margins dark brown as well as medio anteriorly. Mesonotum pale brown washed with dark brown as in Fig. 36 B. Femur greyish brown, except the base whitish. Tibia yellowish grey, apex of fore tibia blackish. Tarsi pale brown. Abdomen. Terga dark brown, with a thin sagittal line lighter on segments V – VII, becoming wider on segments VIII – X, less visible on mature nymphs. Sterna greyish brown, segments VIII – IX darker. Gills greyish purple. Terminal filaments yellowish. Description. Head. Labrum cordiform (Fig. 37 A). Ratio labrum width / clypeus width 0.99–1.10. Ratio labrum width / insertion width 1.35–1.53. Medial emargination shallow with flat denticles. Proximal row of setae present, simple. Number of setae on proximal row ~ 45–61. Distal row of setae present, simple. Median part of labrum in ventral view with scattered thin setae (Fig. 37 B). Mandibles. Outer margin with row of setae on distal 1 / 2. Ending of the row near incisor. Right mandible with 6–10 setae below the mola (Fig. 37 C). Maxillae. Posterior margin of cardo with few hair-like and stout setae, together with one long and stout seta in submarginal position. Proximo-lateral margin of stipes with a bunch of six stout setae increasing in size distally. Apical-ventral row with 21–24 pectinate setae. Maxillary palp segment II 0.83–0.91 as long as segment I. Maxillary palp segment III 0.67–0.82 as long as segment I (Fig. 37 D). Stout setae on outer margin of segment I absent. Segment II inner margin with 2–4 stout setae. Segment II outer margin with 1–4 stout setae. Segment III inner margin with 4–6 stout setae, dorsal surface with few setae at apex. Segment III 1.83–2.00 × as long as base width. Labium. Labial palp segment II 0.72–0.80 as long as segment I. Labial palp segment III 0.78–0.88 as long as segment I (Fig. 37 E). Segment I inner margin with 10–15 stout setae, outer margin with 9–12 stout setae. Segment II outer margin with four or five stout setae. Segment III dorsal face with 3–5 stout setae. Segment III 3.00–3.86 × as long as base width. Hypopharynx. Apex of superlingua truncate (Fig. 37 F). Thorax. Dorsal margin of femur with a row of very long, stout, pointed setae; an irregular submarginal row of pointed setae as long as or a little bit shorter than those on the dorsal margin on fore femur, more regular on mid- and hind femur; ventral margin with short, stout setae and an irregular submarginal row of long, pointed stout setae; central area of upper surface with few long and short, stout, pointed setae (Fig. 38 A – B). Fore tibia with two rows of long simple or feathered setae on ventral margin, dorsal margin with few hair-like setae; middle tibia with a row of short, simple, pointed setae on ventral margin and a submarginal row of long, simple setae, outer margin with numerous hair-like setae; hind tibia with two rows of simple and feathered long, stout setae on ventral margin, outer margin with short and long pointed stout setae and numerous hair-like setae. Tarsal claw slightly hooked with 6–8 denticles progressively larger distally (Fig. 38 C). Abdomen. Gills I and II with single lamella (Fig. 38 E – F). Gills III – VII with dorsal and ventral lamellae, ventral lamella smaller. Gill I with three filaments on dorsal lamella, without ventral lamella, gill II with four or five filaments on dorsal lamella, without ventral lamella, gills III – VI with 5–8 filaments on dorsal lamella and four or five on ventral lamella (Fig. 38 G), gill VII with four or five filaments on dorsal lamella and one or two filaments on ventral lamella (Fig. 38 H). Posterior margin of terga IX with minute denticles (Fig. 38 D). Posterior margin of terga V – VIII without denticles. Posterolateral projections present on segments VIII – IX. Derivatio nominis. This species is dedicated to Prof. Nadir Alvarez, current director of Naturéum and instigator of the Cozzarolo et al. paper who revealed the diversity of New Guinean Thraulini.