Papuanatula (Papuanatula) duplex sp. nov. Figs 44, 45, 46, 47 Etymology. The species name duplex is based on the Latin word for “ double ”, referring to the paired protuberances on abdominal terga. Material examined. Holotype. Papua New Guinea • larva; Simbu Prov., Haia; ~ 750 m; 06. vii. 2001; on slides; GBIFCH 00592632, GBIFCH 00976077; MZL. Diagnosis. Larva. The following combination of characters distinguishes P. duplex sp. nov. from other species of Papuanatula s. str.: body dorsally without row of long, fine, simple setae along midline; pronotum dorsally with posteromedial, paired, triangular protuberances; metanotum dorsally with posteromedial, paired, long, cylindrical, distally slightly conical protuberances; abdomen dorsally with posteromedial, paired protuberances: terga I – VI long, subcylindrical, distally slightly conical; terga VII – IX shorter, compressed, triangular. Description. Larva (Figs 44 – 47). Body length 4.5 mm, cerci broken. Cuticular coloration (Fig. 44 a – c). Head, thorax and abdomen dorsally yellow-brown to brown; metanotum and abdominal terga I – IV darker than V – IX; Head, thorax, and abdominal segment I ventrally pale yellow-brown, abdominal segments II – IX yellow-brown; posterolateral protuberances on thorax brown. Legs yellow-brown; femur with long, narrow blank along dorsal margin. Hypodermal coloration (Fig. 44 a). Abdominal segments I – IX dorsally with transverse band along posterior margins. Head. Antenna (Fig. 44 a, b). Length ~ 1.5 × head length. Developing turbinate eyes in last instar male larva unknown. Labrum (Fig. 45 a, b). Length 0.5 × maximum width, laterally convex. Dorsal, sub-marginal arc with ~ 12 feathered setae. Right mandible (Fig. 45 d, e). Margin between prostheca and mola with row of short denticles. Otherwise, as typical for subgenus. Left mandible (Fig. 45 f, g). Margin between prostheca and mola with row of short denticles. Otherwise, as typical for subgenus. Hypopharynx (Fig. 45 c). As typical for genus. Maxilla (Fig. 45 j, k). Maxillary palp subequal in length to galea-lacinia; palp segment II slightly longer than segment I. Otherwise, as typical for genus. Labium (Fig. 45 h, i). As typical for the genus. Paraglossa with two spine-like setae on inner, distolateral margin. Labial palp with segment I 0.9 × length of segments II and III combined. Segment II without distomedial protuberance, dorsally with row of five spine-like setae near outer, distolateral margin. Segment III slightly oblong, pointed, as long as segment II. Thorax. Sterna. With small protuberances on sides of prosternum and close to openings of mesothoracic and metathoracic sternal apodemes (as in Fig. 108 a). Terga (Figs 44 a, b, 47 a – c) Pronotum with posteromedial, paired, triangular protuberances; metanotum with posteromedial, paired, long, cylindrical, distally slightly conical protuberances. Legs (Fig. 46 a – c). Ratio of leg segments: fore leg 1.0: 1.0: 0.3: 0.2, middle leg 1.0: 1.0: 0.3: 0.2 and hind leg 1.0: 1.0: 0.4: 0.2. Femur. Length ~ 3 × maximum width. Claw with one row of eight denticles; one posterior seta. Abdomen. Terga (Figs 44 a, b, 46 d, e, 47 a, b, d) I – IX with posteromedial, paired protuberances: I – VI long, subcylindrical, distally slightly conical; VII – IX shorter, compressed, triangular. Posterior margin of terga: I – V unknown; VI – IX with minute denticles, apically split with several points. Surface with scattered small, triangular, pointed, striated scales. Tergalii (Fig. 46 g) ovoid, tracheation developed; margins smooth, with few short, fine, simple setae. Paraproct (Fig. 46 f). Posterior margin with prolongation and row of minute denticles. Caudalii. Unknown. Pose of subimaginal gonostyli under larval cuticle. Unknown. Subimago. Unknown. Imago. Unknown. Egg. Unknown. Distribution. New Guinea (Fig. 146).

Published as part of Kaltenbach, Thomas, Kluge, Nikita J. & Gattolliat, Jean-Luc, 2025, Redescription of Papuanatula Lugo-Ortiz & McCafferty (Ephemeroptera, Baetidae), with description of a new subgenus and 20 new species, pp. 159-347 in ZooKeys 1227 on pages 159-347, DOI: 10.3897/zookeys.1227.138100