Hintonelmis spila, Pinedo-Garcia & Hamada & Nascimento, 2024

Pinedo-Garcia, Raul Bismarck, Hamada, Neusa & Nascimento, Jeane Marcelle Cavalcante Do, 2024, Hintonelmis spila sp. nov. (Elmidae: Elminae): a new species of riffle beetle from Amazonian region, Zootaxa 5497 (2), pp. 276-284 : 278-283

Hintonelmis spila sp. nov.

( Figs 1–5 )

Diagnosis. Body elongated; head with short yellow setae; antennal coloration uniform. Pronotum with a pair of short, strongly raised sublateral carinae along basal third. Elytra with yellowish-brown patches (one pair near the humeral region, the second pair shorter, approximately in apical 3/5, and a patch at the apex along the elytral suture). Phallobase about 3× longer than wide, approximately 0.74× the length of the penis. Parameres 3/5 the length of the penis. Penis 6.2× longer than wide, tapering towards apex on distal 1/3, apex rounded.

Description. Male ( Fig. 2A ). Body length = 2.1–3.2 mm, body mean width = 0.8–1.2 mm (n = 5). Body elongated; coloration brown with yellowish-brown patches on pronotum and elytra, legs yellowish brown.

Head ( Fig. 3D ). Antennae uniformly yellowish brown. Labrum ( Fig. 3A ): subrectangular, with lateral margins rounded; anterolateral margin with long setae; surface with long setae on distal half and short setae on basal half. Mandibles ( Fig. 3C, D ): lateral lobe subtriangular, slightly projected; posterolateral angle subtriangular; condyle 1.5× wider than long, semicircular. Maxilla ( Fig. 3B ): cardo longer than wide; stipes subtriangular; palpomere IV elongated, 1.5× longer than each of palpomeres I–III, truncate at apex; galea with apical segment subcylindrical, almost 2× longer than basal one, lateral margin with apex rounded, with long and thin setae; lacinia subrectangular, 2× longer than wide, lateral margin with long setae. Labium (3E): mentum 4× wider than long, lateral margins straight, anterolateral angles sharp; postmentum subtriangular, wider than long; prementum subrectangular, base and apex convex, 5× wider than long; ligula subrectangular, 2× wider than long, anterolateral region projected laterally and with median spines, ventral surface with two transverse rows of spines on disc; labial palpus with three palpomeres, palpomere III subcylindrical, 2× wider than the sum of the two basal ones combined, with rounded apex, sensory pores present, external margin with short setae.

Thorax. Pronotum ( Fig. 2A ) longer than wide (0.6/ 0.5 mm); with short yellow setae; lateral margins sinuous; anterolateral angles rounded; anterior margin broadly convex; posterolateral angles acute; posterior margin trisinuate; anterior portion narrower than posterior one; pair of short, strongly raised sublateral carinae on basal 1/3; median longitudinal impression on disc shallow, short; with a transverse impression on the anterior 2/5 extending from one lateral margin to the other; broad, yellowish-brown patch on medial region extending from anterior to posterior region. Elytra ( Fig. 2A ) subparallel, 1.9× longer than wide (length = 1.5 mm; maximum width = 0.8 mm); apex truncate; with yellowish-brown patches (one pair elongated, near humeral region, second pair shorter, approximately on apical 3/5, and apical patch along elytral suture). Scutellum cordiform, slightly longer than wide. Metathoracic wings present ( Fig. 4E ). Prosternum ( Fig. 2B ) 1.36× wider than long, anterior margin concave, anterolateral angles acute. Prosternal process ( Fig. 2B ) shorter than wide (0.17/ 0.23 mm). Mesoventrite ( Fig. 2B ) wider (0.3 mm) than long (0.2 mm); posterior margin concave. Metaventrite ( Fig. 2B ) with disc flat; anterior margin convex; lateral margins covered by tomentum, discrimen on posterior 4/5; surface with few, short setae; posterior region in front of coxae with pair of transverse arched sulci. Posterior leg ( Fig. 2D ). Femora 4× longer than wide. Tibia 9.7× longer than wide. Apical tarsomere 2× longer than the four basal ones combined. Claws large, stout, with feebly dentate base.

Abdomen ( Fig. 2B ). Ventrites I–V with tomentum on disc; ventrite V with yellowish setae on posterior margin. Tergite VIII ( Fig. 4B ) as broad as long, posterior margin rounded, with median setae; surface with microspines and median setae. Sternite VIII ( Fig. 4C ): 2× wider than long; surface with short setae and microspines; anterior median projection about 0.5× longer than the body length of sternite. Segment IX ( Fig. 4D ) subtriangular; apex bifurcated, lateral margins with sensorial pores. Genitalia ( Fig. 4A ). Phallobase 3× longer than wide, 0.74× length of penis. Parameres 3/5 length of the penis, wider at base, tapering towards apex; apex acute. Penis 6.2× longer than wide; tapering towards apex on distal 1/3, apex slightly rounded, with sensory micropores; lateral margin slightly sinuous; basolateral process 2× longer than wide.

Female. Similar to male. Body length = 2.3–3.2 mm, width = 0.8–1.2 mm (n = 5).

Tergite VIII ( Fig. 5B ) wider than long, posterior margin rounded, with short setae; surface with microspines and long setae. Sternite VIII ( Fig. 5C ) 1.7× wider than long; surface with median setae; anterior median projection 4.3× longer than the remaining part of sternite; posterior margin with short setae, surface with short setae and microspines. Ovipositor ( Fig. 5A ): valvifer dilated on posterior 1/3. Apical coxite 4.6× longer than wide, surface with sensory micropores; 1.9× longer than basal coxite, with sensory microspores. Stylus divergent, apex with short setae.

Etymology. From the Greek word spil (= stain), a reference to the elytra patches.

Comparative notes. Hintonelmis spila sp. nov. resembles H. anamarie , especially in coloration pattern of the elytra with five patches (one pair near the humeral region, one pair approximately on apical 3/5, and a patch at the apex along the elytral suture). However, both species can be easily differentiated as follows: in Hintonelmis spila sp. nov., the antenna has a uniform coloration, whereas in H. anamarie the antenna is bicolored; the pronotum of the new species has a broad, yellowish-brown patch in the medial region extending from the anterior to the posterior region, whereas in H. anamarie this patch is more rounded and located anteriorly in the medial region. The shape of the patches in the humeral region of the elytra can be helpful to differentiate both species: in the new species, the patches are elongated and do not reach the anterolateral margin of the elytra, whereas in H. anamarie , they are rounded, extending diagonally from the anterolateral margin. Additionally, the male genitalia of both species can be differentiated as follows: in Hintonelmis spila sp. nov., the parameres are 3/5 the length of the penis, and the phallobase is shorter than the penis; whereas in H. anamarie , the parameres are 4/5 the length of the penis, and the phallobase is nearly the same length as the penis. Hintonelmis spila sp. nov. also shares with H. roellae the antennae with uniform coloration, yellowish-brown, and elongated patches on the elytra. However, the anterior patches in H. roellae are more elongated, extending beyond the distal half of the elytra (in the new species, these patches do not extend beyond the distal half). In addition, H. roellae has a long and deep longitudinal impression on the disc, whereas H. spila sp. nov. has a short and shallow one. Finally, the male genitalia of both species can be differentiated as follows: in Hintonelmis spila sp. nov., the parameres are 3/5 the length of the penis, the phallobase is 3× longer than wide, and the penis is 6.2× longer than wide; in H. anamarie , the parameres are 4/5 the length of the penis, the phallobase is 2× longer than wide and the penis is 4× longer than wide.

Distribution. Brazil (Acre, Amazonas, Rondônia, and Pará states), Guyana, and Suriname ( Fig. 1 ).

Type material. Holotype. Male. BRAZIL, Acre. Mâncio Lima, Japiim river , 15.vi.2022, 07°60’34.7”S, 69°47’15.3”W; R.B. Pinedo-Garcia, J.O. Silva, G. Desiderio, A. Pes, H.L. Ferreira leg. ( INPA-body pinned, mouthparts and genitalia on slide).

Paratypes. Same data as holotype (10 ♂ and 10 ♀ in INPA-alcohol), (10 ♂ and 5 ♀ in MZUSP-alcohol). Rondônia. Urupá River , 31.vii.2021, 11°02’11.0”S, 62°08’42.0”W, L.S. Santos et al. leg. (16 in INPA-alcohol). Amazonas. Ipixuna, Liberdade River , 12–13.v.2011, 07°21’46”7S, 71°52’07”W, J.A. Rafael et al. leg. (10 ♂ in INPA- pinned). Gregorio River , 2021. v.2011, 07°10’11.7”S, 70°49’10.3”W, J.A. Rafael et al. leg. (10 ♂ in INPApinned). Pará. Goianesia, Capim River , 5–6.viii.2021, 3°42’35.3”S, 48°33’42.4”W, N. Hamada et al. leg. (6 in INPA-alcohol). GUYANA. Region 6, Upper Berbice, Base camp 1 in basecamp, 21–25.ix.2014, 4°09’2.89”N, 58°10’71.7”W, A. Short et al. leg. (GY14-0921-04A) (4 in KUNHM-ENT- pinned). SURINAME. Sipaliwini, District Camp 2, on Sipaliwini River , 27. viii–1.ix.2010, 2°10’9.73”N, 56°47’23.5’’W, A. Short et al. leg. (SR10-0827-LT2 2010 CI-RAP Survey) (10 in KUNHM-ENT- pinned) .

Figures

FIGURE 1. Map of South America with detailed area indicating the distributional records and general view of the sampled streams for Hintonelmis spila sp. nov. (Coleoptera: Elmidae).

FIGURE 2. Hintonelmis spila sp. nov. (Coleoptera: Elmidae). Adult male, habitus. (A) Dorsal view. (B) Ventral view. (C) Lateral view. (D) Front view. Scale bars = 0.5 mm.

FIGURE 3. Hintonelmis spila sp. nov. (Coleoptera: Elmidae). Adult, mouthparts. (A) Labrum, dorsal view. (B) Maxilla, dorsal view. (C) Right mandible, dorsal view. (D) Right mandible, ventral view. (E) Labium, ventral view. Scale bars = 0.1 mm.

FIGURE 4. Hintonelmis spila sp. nov. (Coleoptera: Elmidae).Adult, male. (A) Genitalia, ventral view. (B) Tergite VIII, ventral view. (C) Sternite VIII, dorsal view. (D). Segment IX, ventral view. (E) Metathoracic wing. Scale bars = 0.1 mm.

FIGURE 5. Hintonelmis spila sp. nov. (Coleoptera: Elmidae). Adult, female. (A) Ovipositor, ventral view. (B) Tergite VIII, dorsal view, with the anterior region highlighted. (C) Sternite VIII, dorsal view. Scale bars = 0.1 mm.