Pilielmis abdera Hinton, 1971 (Figs 1, 23–26, 41F) Pilielmis abdera Hinton, 1971 a: 166 (original description). Diagnosis. Body subparallel; general coloration brown; antennae with uniform coloration, yellowish; pronotum with many golden setae; elytra with yellowish-brown marks; prosternal process as long as wide; hypomeron slightly narrow on anterior margin; femora with apical region darker. Male with phallobase 1.8x longer than wide; parameres reaching approximately half the length of the penis, lateral margins without crenulations; penis 4x longer than wide; basolateral process 6x longer than wide. Male redescription. Length: mean = 1.90 mm; width: mean = 0.78 mm (n = 5). Body subparallel (Figs 23A, 41F); general coloration brown, with yellowish-brown elytral marks. Head. Antennae with uniform coloration, yellowish (Fig. 23D). Labrum (Fig. 24A) subrectangular, 2x wider than long, with lateral margins rounded, anterolateral margins with long, thin setae, dorsal surface with sparse setae along its entire length. Mandibles (Fig. 24C, D): lateral lobe rounded; condyle semicircular, 2x wider than long. Maxilla (Fig. 24B): cardo subtriangular, wider than long; stipe subrectangular; palpomere IV subcylindrical, 2x longer than the previous one, apex truncated; galea with apical section suboval, 1.5x longer than the basal one, apex truncated, lateral margin rounded; lacinia subrectangular, 2x longer than wide, inner lateral margin with long setae. Labium (Fig. 24E): postmentum subtriangular; prementum subrectangular, base and apex convex, 5x wider than long; ligula subrectangular, 2.5x wider than long, anterolateral region rounded, with short setae, lateral margin sinuous, surface with spines on disc; gula with lateral margins almost straight, anterolateral angles sharp; labial palpomere III with truncated apex. Thorax. Pronotum (Fig.23A) approximately as long(0.52 mm)as wide (0.49mm); with a pair of sinuous, strongly raised sublateral carinae; lateral margins sinuous, with crenulations; anterolateral angles rounded; posterolateral angles acute; longitudinal impression on the disc shallow; surface covered by many golden setae; medial region with a carina on the apical half. Elytra (Fig. 23A) subparallel, 1.7x longer than wide (length = 1.22 mm; maximum width = 0.73 mm); apex rounded; with yellowish-brown marks (more evident along the elytral suture near the apex). Scutellum pentagonal, flat. Metathoracic wings present (Fig. 25E). Hypomeron 5x longer than wide; anterior margin slightly narrow. Prosternum (Fig. 23B) longer than wide; anterior margin truncated; anterolateral angles rounded. Prosternal process (Fig. 23B) as long as wide. Mesoventrite (Fig. 23B) wider (0.22 mm) than long (0.10 mm); anterior margin sinuous, convex in the median region; posterior margin truncated between the mesocoxae; cuticle similar to prosternum. Metaventrite (Fig. 23B) with an oval depression on posterior half; 2x wider than long; raised on anterior 1/4; lateral margins covered by tomentum. Hing legs (Fig. 23B, C). Trochanter 2x longer than wide. Femora 3.2x longer than wide, with apical region darker. Tibiae 6.5x longer than wide. Apical tarsomere 1.5x longer than the basal ones combined. Claws large and slender, with a tooth near base. Abdomen. Ventrite I without tomentum on disc, ventrite V covered by short golden setae (Fig. 23B). Tergite VIII (Fig. 25B) 1.4x wider than long; posterior margin rounded; surface with thin setae, spines and microspines (more abundant on lateral margins and posterior region). Sternite VIII (Fig. 25D) 2.9x wider than long; posterior margin arcuate, with long, slender setae; surface with setae and microspines; anterior median projection 2.4x longer than the sternite body length. Segment IX (Fig. 25C) subtriangular, with rounded apex; anterolateral margins with sensory pores. Genitalia (Fig. 25A). Phallobase 1.8x longer than wide; longer than the penis. Parameres 2.3x longer than wide; reaching approximately half the length of the penis; base wider than the apex, apical region narrowed; lateral margins without crenulations. Penis 4x longer than wide, apical region subtriangular; lateral margin straight; surface with sensory micropores throughout the area; basolateral process 6x longer than wide. Female redescription. Externally similar to male, except by the ventrite II without tomentum on disc. Length: mean = 1.82 mm; width: mean = 0.74 mm (n = 5). Tergite VIII (Fig. 26B) subtriangular, longer than wide; posterior margin rounded; surface with long setae (more abundant on anterior region) and short setae, spines and microspines. Sternite VIII (Fig. 26A) 2.5x wider than long; anterior median projection 2x longer than the sternite body length; surface with short setae and microspines. Ovipositor (Fig. 26C): valvifer 2.4x longer than the coxites, posterior margin with sensory pores. Apical coxite 2.5x longer than wide, 1.5x longer than the basal one. Stylus slightly curved, measuring approximately 1/5 the length of the apical coxite; apex with short setae. Comparative notes. As previously discussed, P. abdera resembles P. clita by sharing a body subparallel, antennae with uniform coloration (yellowish), pronotum with many golden setae, elytra without humeral marks, and penis with apical region subtriangular. For details about how to differentiate the two species, see the discussion presented for P. clita. Distribution: Brazil (Amazonas*, Rondônia, and Pará*) (Fig. 1). Material examined. Paratypes: Brazil, Rondônia, Porto Velho, vii-ix, 1937 H.E. Hinton (3♀ in NHMUK). Additional material. BRAZIL. Amazonas: Humaitá, Ipixuna River, 02.x.2014, 03°42′59.7′′ S, 48°08′39.8′′ W, Rafael et al. leg., Pinedo-Garcia & Polizei det. (pin) (205 in DZUP). Pará: Jacareacanga, x.1959, Alvarenga et al. leg., Pinedo-Garcia & Polizei det. (pin) (12 in UFMT); Pinedo-Garcia & Polizei det. (alcohol) (1♂ in INPA); 29.vii.2011, 03°42′59.7′′ S, 48°08′39.8′′ W, Brito et al. leg., Pinedo-Garcia & Polizei det. (alcohol) (6 in INPA).

Published as part of Pinedo-Garcia, Raul Bismarck, Polizei, Thiago Tadeu Silva, Hamada, Neusa & Nascimento, Jeane Marcelle Cavalcante Do, 2024, Systematics of Pilielmis Hinton, 1971 (Coleoptera: Dryopoidea: Elmidae), pp. 1-68 in Zootaxa 5421 (1) on pages 36-41, DOI: 10.11646/zootaxa.5421.1.1, http://zenodo.org/record/10805672