Diagnoses and key for the larvae of Progomphus Selys, 1854 from Argentina (Anisoptera: Gomphidae), with first larval descriptions for P. aberrans Belle, 1973 and P. kimminsi Belle, 1973 Author Molineri, Carlos Instituto de Biodiversidad Neotropical, CONICET-UNT (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán), Facultad de Ciencias Naturales e Instituto M. Lillo, Tucumán, Argentina. Author Rodríguez, José Sebastián 0000-0002-8917-2882 Instituto de Biodiversidad Neotropical, CONICET-UNT (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán), Facultad de Ciencias Naturales e Instituto M. Lillo, Tucumán, Argentina. & josephum @ hotmail. com; https: // orcid. org / 0000 - 0002 - 8917 - 2882 josephum@hotmail.com Author Leiva, Marta Facultad de Ciencias Forestales (FCF), Universidad Nacional de Santiago del Estero (UNSE), Avenida Belgrano (Sur) 1912, Santiago del Estero, Argentina. Author Márquez, Javier Andrés Departamento de Ciencias Naturales, Instituto de Ciencias de la Tierra, Biodiversidad y Ambiente (ICBIA), Universidad Nacional de Río Cuarto- CONICET, Córdoba, Argentina. text Zootaxa 2023 2023-06-01 5297 2 239 259 http://dx.doi.org/10.11646/zootaxa.5297.2.4 journal article 30657 10.11646/zootaxa.5297.2.4 1b436143-c24e-4803-a584-c11c1090f230 1175-5326 7993190 454B72E3-2659-4F3D-9C9A-503DBABEE9CE Progomphus lepidus Ris, 1911 ( Figs. 10–11 ) Reared material. ARGENTINA :1 last instar larva (pharate female, not emerged) from Misiones , arroyo Uruzú , 25.85805° S , 54.16945° W , 322 m , 7/Dec/1999 , C. Molineri leg. FIGURE 10. P. lepidus Ris , last instar female larva: a, left mandible, occlusal view; b, right mandible, occlusal view; c, same, dorso-occlusal view; d, maxilla, dorsdal view; e, maxila, ventral view (arrow indicates first tooth); f, detail of ligula; g, prementum, ventral view with detail of marginal microspines; h, subgenital lobe from pharate female. FIGURE 11. P. lepidus Ris , mature larva, female: a, dorsal habitus; b, antennae (antennomeres are numbered); c, abdomen lateral; d, abdominal sterna S7–10 (numbers indicate plates on S8, dotted lines indicate lateral sutures); e, anal pyramid, lateral. Measurements (in mm, n=1): Total length excluding caudal appendages, 19.0; abdomen without caudal appendages (ventral), 10.5; maximum width of head, 4.1; hind femur (lateral), 2.7; lateral spine on S8 (ventral, on inner margin), 0.25; epiprocts (dorsal), 1.0; paraprocts (dorsal) 1.0; cerci (dorsal), 0.5. Larval diagnosis. The larva of P. lepidus can be distinguished from all other congeners by the following combination of characters: fourth antennomere reduced and knob-like ( Fig. 11b ); mandibular formula: L 1 2 3 4 0 a (m 1,2,3,4) b; R 1 2 3 4 y ab ( Figs. 10a–c ); galeolacinia with 4 ventral teeth, the first one (basal) 1/2 length of the second ( Fig. 10e ), palp stout, with very thin marginal setae on basal 2/3 of outer margin, and stiff setae on apical 1/3 ( Fig. 10d ); prementum subquadrate ( Fig. 10g ), lateral margins with a row of minute spines, dorsal surface with a subbasal group of 3–4 stout spine like setae; ligula not projected, with 14 tubercles and two rows of flat setae (the ventral row formed by short blunt ones, the dorsal row by slender and acute ones, Fig. 10f ); palp with tongue-like distal projection 1/2 length of movable hook, inner margin crenulated; movable hook stout, slightly shorter than outer palpal margin; claws normal (long and acutely pointed, flattened), not cheliform ( Fig. 10g ), hind claw with a subapical seta; thorax and legs with whitish setae; pro- and mesotibia with distal spurs; hind tarsi concolorous with others; posterolateral spines present on S6–9 ( Fig. 11a ); large blunt and laterally flattened dorsal tubercles on terga S2–9 ( Figs. 11c ); sterna S2–9 formed by 3 plates, except S8 by 5 plates ( Fig. 11d ); apical abdominal segments and anal pyramid stout, relative length of sternum S8: S9: S10: paraproct = 1.4: 1.4: 1: 1.2 ( Figs. 11d–e ). The larva diagnosed above was identified as P. lepidus following the original description and figures ( Needham 1941 ). From the list above, most important characters include the form of third antennal segment and the short cerci. An unidentified larva of Progomphus was also collected in Misiones , very similar to L. lepidus , except for the presence of 25 tubercles in the ligula (instead of 14 in P. lepidus ), and the shape of third antennal segment, oblong and relatively slender (stout and subcircular in P. lepidus ). See further discussion under P. joergenseni . Distribution. Argentina (Misiones), Brazil and Uruguay ( Belle, 1973 ; von Ellenrieder et al. 2009 ; Kittel & Engels 2016 ).