Pilielmis muricula, Pinedo-Garcia & Polizei & Hamada & Nascimento, 2024

Pinedo-Garcia, Raul Bismarck, Polizei, Thiago Tadeu Silva, Hamada, Neusa & Nascimento, Jeane Marcelle Cavalcante Do, 2024, Systematics of Pilielmis Hinton, 1971 (Coleoptera: Dryopoidea: Elmidae), Zootaxa 5421 (1), pp. 1-68 : 50-54

Pilielmis muricula sp. nov.

( Figs 1 , 34–36 )

Diagnosis. Body subparallel; general coloration yellowish-brown; antennae with uniform coloration, yellowish; anterolateral margins of the labrum with curly setae; pronotum with a carina posteriorly; elytra with humeral region and posterior region along the elytral suture yellowish; elytral apex projected; metathoracic wings present.

Description. Female. Length = 1.71 mm; width = 0.60 mm (n = 1). Body subparallel ( Fig. 34A ); general coloration yellowish-brown; elytra with humeral region and posterior region along the elytral suture yellowish.

Head. Antennae with uniform coloration, yellowish ( Fig. 34D ). Labrum ( Fig. 35A ) subrectangular, 2x wider than long; lateral margins rounded; anterolateral margins with curly setae; dorsal surface with short, sparse setae along its entire length. Mandible ( Fig. 35C, D ): lateral lobe rounded, slightly projected; molar area projected; posterolateral angle slightly rounded; condyle rounded, wider than long. Maxilla ( Fig. 35B ): subtriangular cardo longer than wide, lateral margin sinuous; stipe longer than wide; palpus with palpomere IV elongated, 2.5x longer than the previous one, apex rounded; galea with basal section 2x wider than long; apical article elongated, 3x longer than the basal one, apex rounded; lacinia subrectangular, 1.8x longer than wide, with long setae on inner lateral margin. Labium ( Fig. 35E ): postmentum subtriangular, 2x wider than long; prementum subrectangular, 2x wider than long; ligula subrectangular, 3x wider than long, anterior margin straight; lateral margins almost straight; surface with thin setae and spines; labial palpomere III with apex rounded.

Thorax. Pronotum ( Fig. 34A ) longer (0.54 mm) than wide (0.52 mm); lateral margins sinuous, with crenulations; anterolateral angles rounded, posterolateral angles acute; with a pair of sinuous, strongly raised sublateral carinae; longitudinal impression on the disc deep; surface of the pronotal disc covered by short, golden setae; medial region of the pronotum with a carina on posterior half. Elytra ( Fig. 34A ) subparallel, 1.9x longer than wide (length = 1.14 mm; maximum width = 0.60 mm); apex with a pair of short projections; humeral region and apex along the elytral suture yellowish. Scutellum pentagonal ( Fig. 34A ). Metathoracic wings present ( Fig. 36B ). Hypomeron 5x longer than wide. Prosternum ( Fig. 34B ) longer than wide; anterior margin slightly concave; anterolateral margins truncated. Prosternal process ( Fig. 34B ) wider (0.23 mm) than long (0.13 mm). Mesoventrite ( Fig. 34B ) wider (0.25 mm) than long (0.6 mm); anterior margin sinuous, convex in the disc; posterior margin truncated between the mesocoxae; cuticle similar to prosternum. Metaventrite ( Fig. 34B ) 2x wider than long; disc flat; anterior margin truncated between mesocoxae; discrimen conspicuous on anterior half. Hing legs ( Fig. 34B, C ). Trochanter 2x longer than wide. Femora 3x longer than wide. Tibiae 6.8x longer than wide. Apical tarsomere 1.3x longer than the basal ones combined. Claws large and slender, with a tooth near base.

Abdomen. Ventrites I–III without tomentum on disc ( Fig. 34B ). Tergite VIII ( Fig. 36C ) 1.2x wider than long; posterior margin rounded; surface with thin setae, spines and microspines. Sternite VIII ( Fig. 36D ) 1.8x wider than long; surface with setae, sensory pores and microspines; with anterior median projection 1.9x longer than the sternite body length. Ovipositor ( Fig. 36A ): valvifer 2.5x longer than the coxites; posterior margin with sensory pores.Apical coxite 1.9x 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.

Male. Unknown.

Etymology. From the Latin word muricul (= slightly pointed), a reference to the pair of short projections on the apex of the elytra.

Comparative notes. Pilielmis muricula sp.nov. can be easily distinguished from any other congeners by the apex of the elytra with a pair of short projections, which is a characteristic exclusive to this new species. So far, all other species in Pilielmis have this region rounded. Based on the general coloration pattern, P. muricula sp. nov. is most similar to P. clita ; both species have a yellowish-brown body color, pronotum and elytra without contrasting marks and the posterior region of the elytra has a yellowish mark along the elytral suture.

Distribution: Brazil (Amapá) ( Fig. 1 ).

Type material. Holotype.Female. Brasil, Amapá, Serra do Navio, Cachaço River, Fernando stream, 02.viii.2011, 00°53′18,3′′ N, 52°01′22,9′′ W, Hamada et al. leg., ( INPA —body in alcohol; mouthparts, wing and genitalia on slide).

Figures

FIGURE 1. Map of SouthAmerica with detailed area indicating the distributional records forPilielmis Hinton, 1971 (Coleoptera: Elmidae).

FIGURE 34. Pilielmis muricula sp. nov. (Coleoptera: Elmidae).Adult female. Holotype. (A) Dorsal view. (B) Ventral view. (C) Lateral view. (D) Front view. Scale bars = 0.5 mm.

FIGURE 35. Pilielmis muricula sp. nov. (Coleoptera: Elmidae). Adult mouthparts. (A) Labrum, dorsal view. (B) Maxilla, dorsal view. (C) Mandible, dorsal view. (D) Mandible, ventral view (broken anterior region). (E) Labium, ventral view. Scale bars = 0.1 mm.

FIGURE 36. Pilielmis muricula sp. nov. (Coleoptera: Elmidae). Adult female. (A) Ovipositor, ventral view. (B) Metathoracic wing. (C) Tergite VIII, dorsal view. (D) Sternite VIII, dorsal view, with the anterior region highlighted.