﻿Revision of the water scavenger beetle genus Notionotus Spangler, 1972 in the Neotropical Region (Coleoptera, Hydrophilidae, Enochrinae)

﻿Abstract The Neotropical species of the water scavenger beetle genus Notionotus Spangler, 1972 are revised using an integrative taxonomic approach combining morphology with DNA sequence data from two genes. Support exists for four putative species groups into which 18 species are placed, including twelve that are described here as new: N.bicolorsp. nov. (Suriname), N.bifidussp. nov. (Venezuela), N.brunbadiussp. nov. (Brazil), N.garciaesp. nov. (Brazil), N.giraldoisp. nov. (Brazil), N.insignitussp. nov. (Venezuela), N.jumasp. nov. (Brazil), N.parvussp. nov. (Suriname), N.patamonasp. nov. (Guyana), N.peruensissp. nov. (Peru), N.retusussp. nov. (Guyana), and N.vatiussp. nov. (Brazil). Four new synonymies are created: N.shorti Queney syn. nov. is found to be conspecific with N.dilucidus Queney; N.edibethae García syn. nov., N.nucleus Perkins syn. nov., and N.perijanus García syn. nov. are found to be conspecific with N.tricarinatus Perkins. New records are provided for all previously described species except N.mexicanus Perkins. Within the Neotropical region, the range of the genus is greatly expanded and now known from as far south as Bolivia and the Brazilian state of Mato Grosso do Sul. While a few species are found in hygropetric habitats, most are associated with the margins of forested streams. Genitalia and habitus images are provided for nearly all species, as well as a key to the four species groups.


Introduction
The genus Notionotus Spangler, 1972 is a group of small to minute water scavenger beetles that occur in streams and seepages in the tropics of the New World and Southeast Asia. The original concept of Notionotus was based on two new species from the Venezuelan Andes (Spangler 1972). In the Neotropics, its range was soon expanded north to Mexico, with three species described by  from Guatemala, Mexico and Panama, and subsequent additional species from Venezuela (García 2000). Most recently, three species were described from French Guiana and Guyana  with additional new records being provided in a series of biotic surveys in Suriname and Guyana (Short and Kadosoe 2011;Short 2013;Short et al. 2017. Notionotus has also been reported from the Old World tropics, with seven species described from southeast India and Southeast Asia (Hebauer 2001(Hebauer , 2003 and southern China (Jia and Short 2011). Currently there are 17 described species, including ten from the Neotropics and seven from tropical Asia.
During the last two decades, extensive fieldwork for aquatic beetles in the Neotropics has resulted in the collection of many new specimens of Notionotus, including some that represent new species. We here use an integrative approach, combining adult morphological data with DNA sequences from two gene loci, to revise the Neotropical species of the genus. This revision provides a taxonomic foundation not only for future descriptive work on the genus, but also for evolutionary studies on the diversity and biogeography of the Neotropical region.

Molecular methods
We amplified and sequenced the mitochondrial gene COI and the nuclear ribosomal gene 28S for 56 specimens of Notionotus, including 55 specimens from the Neotropical region and one unidentified specimen from India which we used as an outgroup to root the tree. We sampled specimens from most localities for which we had appropriate material, including a broad geographic sampling of N. tricarinatus and N. dilucidus as these two species had large ranges with some observed variation in the aedeagus. All specimens were preserved as frozen tissue samples since collection with the exception of the specimen from Costa Rica (SLE2381) which was pinned. Molecular extraction and sequencing methods follow those of Kohlenberg and Short (2017). Resulting DNA sequences were assembled and edited in Geneious R 8.0.5 (Biomatters, http:// www.geneious.com/). All sequences are deposited in GenBank (see Table 1 for accession numbers). We used IQ-TREE 1.4.4 (Nguyen et al. 2015) to infer phylogenetic relationships. Each gene was placed in its own partition. The optimal models of substitution for each partition were selected using the Auto function in IQ- TREE 1.4.4. In order to assess nodal support, we performed 1000 ultrafast bootstrap replicates (Minh et al. 2013). Table 1. List of DNA voucher specimens and GenBank accession numbers used in this study. "N/A" indicates the gene fragment was not successfully amplified or sequenced.

Morphological methods
We examined more than 900 specimens for this work, including the holotypes of most previously described Neotropical species. The specimens were examined using Olympus SZ61 and SZX7 microscopes and preparation of the specimens and dissection of the genitalia were carried out following the methodology of Girón and Short (2017). There was a modification in the time of exposure to heat of the genitalia during the clearing process depending on the level of sclerotization of the structure, which we reduced the time from 60 min to 30-40 min. Morphological terminology mainly followed Hansen (1991) and terminology adapted from Lawrence and Ślipiński (2013) regarding the use of meso-and metaventrite. Cleared genitalia photos were taken with Olympus BX51 microscope to 400× magnification (except for N. rosalesi genitalia to 100×), ~ 7-15

Results
From our integrated approach of combining morphological data with DNA sequence data from two genes, we found support for 18 species in the Neotropical region, including twelve new species. At the same time, we found that two of the most widespread species have been described multiple times, resulting in four new synonymies.
For the 14 species that we had molecular data, the maximum likelihood analysis ( Fig. 1) recovered two well-supported species groups. We found morphological characters that can be used to diagnose these two clades, which we here define as the lohezi and liparus species groups. In addition, two species that were not included in our molecular analysis are assigned to their own monotypic species groups as they present unique character combinations that were not consistent with either of the other species groups. Among the 14 species for which we had molecular data, the minimum uncorrected pairwise distances in COI between any two species was 5.0% (between N. giraldoi and N. vatius) with the exception of N. dilucidus, in which the two specimens from Venezuela (SLE2366 and SLE2378) were 6% divergent from the remaining populations further to the east (Guyana, Brazil, Suriname, French Guiana). We sequenced one specimen from Peru that is known only from a single female, and we were unable to associate it with confidence to any of the described species for which we did not have DNA; however, due to the importance of the male genitalia in identifications, we refrain from describing this species here. Figure 1. Maximum likelihood phylogeny of Notionotus spp. inferred from COI and 28S sequence data. Extraction numbers are given next to each terminal name (see Table 1).

Notionotus liparus species group
Differential diagnosis for Neotropical species. Small to very small beetles, total body length 1.5-2.0 mm. Color yellow, reddish brown, dark and pale brown to black. Body shape oval in dorsal view; moderately convex to convex in lateral view. Antennae with eight antennomeres. Maxillary palps short, nearly half the width of the head, second segment bending outwards, apical segment ~ 2 × as long as the penultimate segment (Fig. 4J;e.g.,N. bifidus sp. nov.). Eyes reniform in dorsal view. Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Head, pronotum and elytra with ground and systematic punctures; systematic punctures of the head very sparse. The elytral ground punctation is more evident in some species ( Fig. 2A; e.g., N. liparus) than in others ( Fig. 4G; e.g., N. garciae sp. nov.); systematic punctures extremely reduce and sparse detectable for short seta, forming very sparse rows (Fig. 4B;e.g.,N. patamona sp. nov.); elytra without sutural stria. Prosternum carinate medially, strongly raised, and projected anteromedially. Elevation of mesoventrite strongly raised forming an anteromedial carina consisting of one (Fig. 10A, B) or two longitudinal ridges and one transverse (Fig. 10C, D), extending between procoxae on the same plane as metaventrite. Metaventrite densely pubescent, slightly elevated, with elevation broad posteromedially and convex medially forming a glabrous patch drop-shaped; and two posterolateral glabrous patches in a half-circle shape. Pro-and mesofemora mostly covered with pubescence on basal three-quarters ( Fig. 3B; e.g., N. tricarinatus); metafemora with pubescence, sometimes on basal three-quarters, or along basal three-quarters of the anterior margin with some setae on the posterior basal margin (Fig. 2H;e.g.,N. rosalesi). Abdominal ventrites densely pubescent, with fifth ventrite bearing an apical emargination to shallowly truncate. Aedeagus trilobed, size and form variable.
Remarks. As this revision only treats the New World species, we did not comprehensively examine the Old World species to generate a global genus description. Therefore, the diagnosis above should be considered for Neotropical species only. The Old World species of Notionotus are generally similar to the New World species, but some species do differ in significant characters: for example, N. suturalis Hebaeur, 2003 has a sutural stria and antennae with 9 antennomeres.
Remarks of diagnostic features of Notionotus Spangler, 1972. Body shape and coloration. The degree of convexity between species is variable; some are moderately convex, others weakly convex. The general dorsal coloration of the body among species ranges from yellow (e.g., N. tricarinatus, Fig. 3A) to nearly black (e.g., N. liparus, Fig. 2A), however color alone is usually not sufficient on its own to definitively identify most Notionotus species. This is due both to the fact that some species share the same coloration, as well as some species have a slight variation in dorsal coloration. Species with unique (so far as currently known) color patterns include N. liparus (entirely dark brown to black, Fig. 2A), N. rosalesi (tricolored, Fig. 2G) and N. insignitus sp. nov. (with pale spot on the elytral disc Fig. 4D). The coloration of the head in some species is uniform, but in others is bicolorous (with typically the frons being darker than the clypeus).
Mesoventrite. In Notionotus the elevation of the mesoventrite is composed of two or three laminae: one transverse ridge and one longitudinal (Fig. 10A, B) or two transverse ridges and one longitudinal ridge (Fig. 10C, D), which generally converge and fuse  medially; the shape of the longitudinal ridge shows high variation among species. In general, the transverse ridges are medially elevated and laterally concave. The apex of the transverse ridge can be nearly acute (Fig. 10B), or blunt (Fig. 10C), and lateral sides vary from very to slightly concave or straight. The longitudinal ridge varies, it can be completely sharp or sharp anteriorly and broadening posteriorly reaching the end of the elevation, but it can also be broad anteriorly and sharp posteriorly. The point where the two or three ridges merged can be rounded and obtuse or wide and blunt respectively.
Elytral punctation. The density of the ground punctation is typically sparse, and the degree of impression is variable between species within the genus. In some species, the ground punctation is very weakly impressed and may almost appear absent and low magnification (Fig. 4H;e.g.,N. vatius sp. nov.); in other cases, it is more coarse and moderately impressed (Fig. 4E;e.g.,N. juma sp. nov.).
Aedeagus. The shape of the aedeagus is the most important and often crucial feature to identify species of Notionotus. Most species in the Neotropics exhibit two different generalized aedeagal forms: in some species, the median lobe and basal piece have the same length, or the median lobe is slightly longer than the parameres (e.g., N. tricarinatus, Fig. 6A). However, some species present the median lobe and basal lobe that are shorter than the parameres (e.g., N. bicolor sp. nov. (Fig. 8A), N. retusus sp. nov. (Fig. 8E), N. parvus sp. nov. (Fig. 9E)). In terms of shape, some species present variation in the apex of the median lobe, this is usually rounded (e.g., N. patamona sp. nov., Fig. 8D), but it varies from acute (e.g., N. liparus, Fig. 7A), emarginated (e.g., N. juma, Fig. 8G), and bifurcated (e.g., N. bifidus sp. nov., Fig. 9D). Additionally, the width of the median lobe varies from very slender (e.g., N. giraldoi, Fig. 7D) to very wide (e.g., N. bifidus, Fig. 9D). Nevertheless, in most of the species, the median lobe is wide at the base and slightly narrowing towards the apex.

Notionotus dilucidus
Differential diagnosis. The general coloration of Notionotus dilucidus is similar to N. giraldoi, N. mexicanus, and N. tricarinatus and these species are very difficult to differentiate with external characters alone. However, the shape of the aedeagus in N. dilucidus is quite distinct: the outer and inner margins of the parameres are sinuate, the apex of the parameres presents an indentation in which the depth can vary from very deep, slightly deep, or almost not distinguishable and pointing outwards ( Fig. 5A-J).
Description. Size and form: Body length 1.6-1.8 mm. Body form elongate oval, moderately convex in lateral view (e.g., Fig. 2D). Color and punctation: Dorsally yellow to pale brown, head mostly yellow and frons pale brown; pronotum paler than elytra, with two small black round spots along posterior margin (e.g., Fig. 2D). Ventrally brown; maxillary palps and antennae yellow (antennal club slightly darker), mouth parts and legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 1-2 × their width); pronotum and elytra with ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged rounded and obtuse (Fig. 10A); elevation flat in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area, medial region patch drop-shaped; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters (e.g., Fig. 2E). Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 5A) basal piece nearly the same length of a paramere. Base of the parameres slightly narrower than the base of the median lobe; outer margins sinuate, tapering almost reaching the apex, inner margins sinuate, apex of the parameres slightly bending outwards, rounded in the outer margin with an indentation in the inner margin (the depth of the indentation varies, Fig. 5A-J). Median lobe nearly as long as the parameres or a bit longer, broad at the base and gradually narrowing to the apex, apex of the median lobe rounded.
Variation. There is significant variation in the apex of the parameres of the aedeagus. The paramere tip is weakly sclerotized, as evidenced by its very pale to white appearance in cleared specimens (e.g., Fig. 5A-J). This tip varies from nearly evenly rounded (e.g., Fig. 5D, G) to possessing some level of indentation on the inner margin (e.g., Fig. 5A, H). Although this variation seems in part to be real, it also seems to be partly caused by artificial distortions; for example, the weakly sclerotized apex may become indented or inflated depending on the state of the genitalia during preparation. This would explain why there is a large variation in form as well as why the tip appears to be exhibit subtly asymmetry between parameres (e.g., Fig. 5C, F).
Distribution. This species is widely distributed throughout the Guiana Shield region, from Tobogán de la Selva in Venezuela east to the coast of French Guiana (Fig. 15). Reported from Suriname in Short andKadosoe (2011) andShort (2013;as N. shorti) and from Guyana as Notionotus sp. B in .
Life history. This species is the most common and abundant species of the genus in the Guiana Shield region and is frequently collected in leaf packs or along the margins of forested streams. They are typically found in streams that are lined with detritus and have rocky or sandy substrates. Although some specimens have been collected in seepage-like habitats or adjacent to seepages, this does not seem to be a primary or favored habitat for this species.
Remarks.  described N. dilucidus based on specimens from several closely situated localities in French Guiana, and N. shorti based on a long series of specimens from a single collecting event in Guyana. The primary feature used to separate the two taxa was the apex of the parameters, which was given as "parameres apically shortly curved outwards" in N. dilucidus and "parameres apically almost straight" in N. shorti. We examined material from the type series of both species and confirmed there are notable differences in the paramere shape. If we only had access to the specimens that Queney (2010) examined and no other data, we also would have very likely concluded they were different species and described them as such. However, as we examined recently collected specimens from numerous other localities in the eastern Guiana Shield, we observed quite a bit of variation in the shape of the parameres that encompassed the forms present in N. dilucidus and N. shorti. In some cases, we noticed variation in this feature even among specimens from the same series. Additionally, the apex of the paramere even occasionally appears slightly asymmetrical in some dissections (e.g., Fig. 5F, J).
To help interpret these morphological observations, we sequenced 22 specimens that span the entire width of the Guiana Shield, including specimens from Venezuela, Brazil, Guyana, Suriname, and French Guiana. These specimens also represented a range of paramere form diversity. In general, we found little meaningful molecular divergence among these populations ( Fig. 1) and these differences were not correlated to observed variations in the paramere apex. Therefore, we here consider N. shorti as a junior subjective synonym of N. dilucidus.
Among all sequenced specimens, the maximum pairwise divergence in the gene COI was 6.0%. Although this is on the higher end of intraspecific divergence observed in hydrophilids, it is seen in some taxa (see Short and Girón 2018;Smith and Short 2020). Additionally, given that its geographic range spans 1500 kilometers, it is not surprising to see such divergences. The two Venezuelan populations (from Tobogán de Selva in Amazonas State and the Escalera region of Bolívar State) were the most genetically distinct and sister to the more eastern populations. Indeed, with these samples removed, the maximum intraspecific divergence among remaining specimens drops to just 3.8%. However, we did not observe any significant morphological differences from these Venezuelan populations and therefore consider them to be part of a broader definition of N. dilucidus.
As both N. dilucidus and N. shorti were proposed in the same work (Queney 2010), we use our authority as first revisors (ICZN article 24.2.2) to give precedence to N. dilucidus as the valid name for this species.
Differential diagnosis. The dorsal coloration, shape of the elevation of the mesoventrite, area of pubescence on the metafemur and degree of impression of the ground punctation of Notionotus giraldoi are very similar to N. dilucidus, N. mexicanus, N. tricarinatus. It can be distinguished only by its aedeagus, including the unique shape of the parameres with a depression of the inner margin, as well as by the abrupt narrowing in the midlength of the median lobe (Fig. 7D).
Description. Size and form: Body length 1.7-1.9 mm. Body form elongate oval, convex in lateral view (Fig. 4I). Color and punctation: Dorsally yellow, head yellow; pronotum paler than elytra, with two small black round spots along posterior margin (Fig. 4I). Ventrally brown; maxillary palps, mouthparts, antennae (antennal club slightly darker) and legs yellow. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra with ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged rounded and obtuse (e.g., Fig. 10A, B); elevation flat in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area, medial region patch drop-shaped; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 7D) with basal piece nearly the same length of a paramere. Base of the parameres slightly narrower than the base of the median lobe; outer margins sinuate, inner margins depressed in the midlength, depression extending to apex without reaching it; apex of parameres wide and blunt. Median lobe length almost equal to the parameres, wide at basal region, narrowing abruptly in the midlength, apical third slender, narrow, and rounded.
Etymology. L. M. González-Rodríguez names this species in honor of Juan José Giraldo Gutiérrez in gratitude for the encouragement and support in her career.
Distribution. Known from several localities in the Brazilian States of Rondonia and Mato Grosso do Sul (Fig. 14).
Life history. This species was collected along the margins of two adjacent streams, one with a sandy bottom and one with a rocky bottom (Fig. 13A). Specimens were collected by agitating the sand and detritus along the stream margin as well as washing root mats in tubs of water.  Fig. 2A). It can also be differentiated by sharply marked punctation of the pronotum and elytra. Moreover, the outer margin of the parameres is sinuate and the apical third is slim and tapered. It is the only species in the liparus group with the apex of the median lobe acute.

Notionotus liparus
Description. Size and form: Body length 1.6-1.8 mm. Body form elongate oval, convex in lateral view ( Fig. 2A). Color and punctation: Dorsally black, with lateral margins of the pronotum and elytra reddish brown ( Fig. 2A). Ventrally reddish brown, except for black abdominal ventrites; maxillary palps and antennae yellow (antennal club slightly darker) (Fig. 2B). Clypeus and labrum with dense, coarse, and moderately impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation dense, coarse, and moderately impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge narrowed anteriorly and broadening posteriorly, the point where the two ridges merged blunt (e.g., Fig. 10A, B); elevation concave in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of posterior margin, then apical half of the posterior margin with sparse setae (Fig. 2B). Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 7A) with basal piece 1.3 × the length of a paramere. Base of the parameres slightly narrower than the base of the median lobe; outer margin sinuate, inner margin nearly straight, tapering along apical third, parameres thin and rounded at apex. Median lobe shorter than the parameres, broad at the base and gradually widening to the apex, with the apex acute.
Distribution. This species is widespread in the Mérida Andes and Coastal Mountains of Venezuela (Fig. 14). Originally described from localities in the Venezuelan states of Barinas and Mérida (Spangler 1972, it was later recorded from the state of Aragua (García 2000). Here, we report additional localities in these three states as well as report it from the state of Trujillo for the first time.
Life history. This species is found in rock seepage habitats and wet rocks adjacent to waterfalls (Fig. 11A, B). Occasionally it is found in the pools that form at the best of these habitats.
Remarks. We sequenced four specimens from three Venezuelan states across the range of this species (Aragua, Barinas, and Mérida). The sequences are nearly identical ( Fig. 1), supporting the concept of a widespread species in the Mérida Andes and Coastal mountains. Differential diagnosis. Notionotus mexicanus is very similar morphologically to N. tricarinatus sharing characters such as body length, yellow dorsal coloration, pronotum and elytra with fine ground punctation, and elevation of the mesoventrite with a transversal and a longitudinal ridge. It can be distinguished by the shape of the aedeagus, specifically the shape of the parameres: inner margins straight and sinuate reaching the apex, parameres narrowing along apical third, and narrower than N. tricarinatus.

Notionotus mexicanus Perkins, 1979
Description. Size and form: Body length 1.8 mm. Body form elongate oval, convex in lateral view (Fig. 2D). Color and punctation: Dorsally yellow, head mostly yellow, frons pale brown; pronotum with two small black round spots along posterior margin (Fig. 2D). Ventrally brown; maxillary palps, mouthparts, antennae, pro and meso legs yellow, meta legs pale brown (Fig. 2E). Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged rounded and obtuse (e.g., Fig. 10A, B); elevation concave in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters (Fig. 2E). Abdomen: Abdominal ventrites very densely pubescent. Aedeagus ( Fig. 7B) with basal piece 1.1 × the length of a paramere. Base of the parameres broader than the base of the median lobe; outer margin slightly convex along basal two-thirds, then slightly sinuate apically, inner margins nearly straight along basal two-thirds and then sinuate apically; apex of parameres rounded. Median lobe shorter than the parameres, approximately triangular, with acute apex.
Distribution. Only known from the type locality in Mexico (Fig. 14). Life history. The type series was collected "from plant debris which had become trapped between stones in a rapid stream" ). . The labeled holotype is an undissected male with the aedeagus visible and still attached to the abdomen. We also examined a permanent genitalia slide that had been presumed to be from holotype and is labeled as this species. Type material examined. Holotype (male): [only the permanent slide mount of the aedeagus was examined] (MALUZ). As this species was described only from one male and one female specimen, we presume this slide is of the holotype specimen (Fig. 6C).   (3 exs.,SEMC); same data except PAN1C00 024 (5 exs., SEMC); same data except PAN1C00 025 (2 exs., SEMC); same data except PAN1C00 033 (1 ex., SEMC); same data except PAN1C00 0234 (1 ex., SEMC); same data except PAN1C00 014 (1 ex., SEMC); same data except 07-VI-1994, leg. D. Banks (2 exs., SEMC); same data except 08-VIII-1994, leg. D. Banks (1 ex., SEMC), same data except 08-VIII-1994, leg. D. Banks (1 ex., SEMC); same data except 04-VIII-1994, leg. D. Banks (1 ex., SEMC); same data except 01-VIII-1994, leg. Differential diagnosis. See differential diagnosis for Notionotus mexicanus. Description. Size and form: Body length 1.6-1.9 mm. Body form elongate oval, strongly convex in lateral view (Fig. 3A). Color and punctation: Dorsally yellow, head mostly pale brown or yellow, frons brown or dark brown; pronotum paler than elytra, with two small black round spots along posterior margin (Fig. 3A, D, G). Ventrally brown; maxillary palps, mouthparts, antennae yellow (antennal club slightly darker), legs pale brown (Fig. 3B, E, H). Clypeus and labrum with dense, fine, and weakly ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp and broadening posteriorly almost to the end, the point where the two ridges merged rounded and obtuse (e.g., Fig. 10A, B); elevation concave in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters (Fig. 3B, E, H). Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 6A-I) basal piece 1.2 × the length of a paramere. Parameres broad, base wider than the base of the median lobe, outer and inner margins convex, pinched at the apex, broad and rounded apex. Length of the median lobe can vary (median lobe as long as the parameres (Fig. 6F, I), slightly shorter (Fig. 6A, B) or longer than the parameres (Fig. 6H), median lobe with triangular shape, wide at base and gradually tapering to apical third, with rounded apex.

Notionotus nucleus
Distribution. Known from Guatemala, Costa Rica, Panama, and Venezuela (Fig. 14). Life history. This species is found along the margins and in leaf packs of streams in the mountains and foothills of the Northern Andes and Central America. It prefers gravelly or rocky streams, especially in the foothills where it may sometimes be abundant (Fig. 11C, D).
Remarks. We examined more than 155 specimens from a dozen localities of this species from Guatemala to several chains of the Venezuelan Andes. Although there are subtle variations in the apex of the aedeagal parameres, this variation is relatively small and not correlated to geography, other morphological characters, or molecular data. These subtle variations in paramere shape likely explain why this species has been described four times, once each from Guatemala and Panama  and twice from Venezuela (García 2000). Three of these four species were described from single collecting events. However, with significantly more material available to us for this study from a range of additional localities, it is apparent these differences in paramere shape are more easily considered as intraspecific variation in a widespread, common species than as indicative of species boundaries. This hypothesis is also supported by available DNA evidence: we sequenced specimens from Costa Rica, the Serranía de Perijá, the Mérida Andes, as well as the Coastal mountains of Venezuela. All specimens form a clade (Fig. 1) with a maximum pairwise divergence in COI of 3.9% (although we only had COI data from specimens from several Venezuelan localities). However, 28S sequence data from specimens from Venezuela and Costa Rica are identical, further supporting the concept of a single, widespread species. In addition, specimens throughout its range were found in very similar habitats: leaf packs or detrital margins of streams with a gravel or rocky substrate As both N. nucleus and N. tricarinatus were proposed in the same work , we use our authority as first revisors (ICZN article 24.2.2) to give precedence to N. tricarinatus as the valid name for this species. Differential diagnosis. Among the species of liparus group, Notionotus vatius can be recognized by the brown dorsal coloration, and quite unique color pattern of the head frons and medial region of the clypeus dark brown, lateral side of the clypeus pale brown. In addition, the shape of aedeagus, especially the apex of the parameres is broad, blunt, and pointing slightly outwards, and the gonopore has rounded shape and it is situated at midlength of median lobe.
Description. Size and form: Body length 1.7-2.3 mm. Body form elongate oval, strongly convex in lateral view (Fig. 4H). Color and punctation: Dorsally brown, head mostly brown, frons and medial region of the clypeus dark brown, lateral side of the clypeus pale brown; pronotum pale brown with two small black round spots along posterior margin, elytra dark brown (Fig. 4H). Ventrally dark brown; maxilla, maxillary palps, antennae (antennal club slightly darker) yellow, legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged rounded and obtuse (e.g., Fig. 10B); elevation flat in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area, medial region patch drop-shaped; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 7C) with basal piece nearly the same length as a paramere. Base of the parameres slightly narrower than the base of the median lobe; outer and inner margins sinuate; apex of parameres wide and blunt, pointing outwards. Median lobe of the same length as the parameres, wide at basal region, narrowing in the midlength, then widening along at apical third, apex rounded; gonopore with rounded shape and situated at midlength of median lobe.
Etymology. The name is derived from the Latin word vatius meaning bent outwards, after the form of the parameres slightly pointing outwards of the aedeagus.
Distribution. This species is known from several localities in Bahia and Mato Grosso do Sul States in Brazil (Fig. 14).
Life history. This species was collected on seepages and along the margins of rocky streams (Fig. 13B).
Remarks. Although the known localities of this species are widely dispersed in Brazil, they are from similar habitats at similar elevations on the Brazilian Shield. Moreover, the specimens from Bahia and Mato Grosso do Sul states are less than 3% divergent in uncorrected pairwise distances in COI.

Notionotus lohezi species group
Diagnosis. The lohezi species group can be distinguishable by the presence of three ridges in the elevation of the mesoventrite, two transverse ridge and one longitudinal (Fig. 10C, D); the basal piece is shorter than the parameres, the length of the median lobe is shorter than the parameres. Differential diagnosis. Notionotus bicolor shares the bicolorous dorsal coloration that can also be observed in N. garciae, N. patamona, and N. lohezi. It can be recognized by the shape of the aedeagus, the median lobe is much shorter than in N. insignitus (Fig. 8B) and N. patamona (Fig. 8D), and slightly longer than in N. lohezi (Fig.  8F). The margins of the median lobe are sinuate with a widening in the middle length, this differs in the other species where the margins are slightly straight. Moreover, the apex is slightly narrow and rounded, this differs in N. insignitus with acute apex, N. patamona with rounded and wide apex and N. lohezi with blunt apex.

Notionotus bicolor
Description. Size and form: Body length 1.7-2 mm. Body form elongate oval, moderately convex in lateral view (Fig. 4A). Color and punctation: Dorsally bicolor, head brown, frons dark brown; pronotum yellow with two small black round spots along posterior margin; elytra dark brown, elytra margins paler (Fig. 4A). Ventrally brown; maxillary palps, mouthparts, and antennae yellow (antennal club slightly darker), pro legs yellow, meso and meta legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3-4 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (Fig. 10D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and sparse pubescence along the entire basal posterior margin. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8A) with basal piece 0.7 × the length of a paramere. Base of the parameres slightly narrower than the base of the median lobe; outer margin convex, inner margins along basal two-thirds slightly convex, apical third straight; apex of parameres slightly acute, pointing inwards. Median lobe shorter than the parameres, wide at basal region, narrowing in the midlength, then sinuate, apex slightly acute; gonopore situated at the apex of median lobe.
Etymology. The name derived from the Latin words bi meaning two and color meaning hue, referring to the dorsal coloration of the species. This species has yellow coloration in the pronotum and black in the elytra.
Distribution. Known from two localities in central Suriname: Kabalebo and the summit of Tafelberg Tepui (Fig. 15).
Life history. At Kabalebo, this species was collected in several streams, including both along the margin, rock pools with detritus in the creek bed, and in seepage habitats (Fig. 12D). At Tafelberg, the species was collected along a rocky creek margin with detritus. Differential diagnosis. Notionotus bifidus can be separated from all other species of lohezi group by being the only species in the group that present uniformly dorsal yellow coloration (Fig. 4J), the rectangular shape of the median lobe and its bifurcation at the apex, and the abrupt tapering of the parameres along apical third (Fig. 9D).

Notionotus bifidus
Description. Size and form: Body length 1.5-1.7 mm. Body form elongate oval, moderately convex in lateral view (Fig. 4J). Color and punctation: Dorsally yellow, head mostly dark brown, frons and medial region of the clypeus dark brown, lateral sides of clypeus yellow; pronotum yellow with two small dark brown round spots along posterior margin; elytra yellow (Fig. 4J). Ventrally dark brown; maxillary palps, mouthparts, and antennae yellow. Pro legs yellow, meso and meta legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with broad glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of posterior margin, then apical half of posterior margin with sparse setae. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 9D) with basal piece 0.6 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; outer margins straight along basal two-thirds, then narrowing abruptly along apical third, inner margins convex along basal twothirds and then apically slightly concave; apex of parameres rounded. Median lobe shorter than the parameres, approximately rectangular, narrow along apical fifth, apex bifurcated; gonopore drop-shaped and situated at apical fourth of median lobe.
Etymology. The specific name comes from the Latin word bifidus meaning split into two parts, after the form of the median lobe "bifurcated apically" of the aedeagus.
Differential diagnosis. This species has a particular coloration pattern, dark reddish brown, which makes it easily distinguishable among the other species of the lohezi group. The shape of the parameres is slightly similar to N. lohezi (Fig. 8F) but the apex is less acute and bend much less inward. It can be separated by the triangular shape of the median lobe and acute apex (Fig. 8C).
Description. Size and form: Body length 1.7-1.9 mm. Body form elongate oval, moderately convex in lateral view (Fig. 4C). Color and punctation: Dorsally dark reddish brown, lateral margins of clypeus, pronotum and elytra yellow brown (Fig. 4C). Ventrally reddish brown, except for black abdominal ventrites; maxillary palps, mouth parts and antennae yellow (antennal club slightly darker). Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed, and sparser than on head (punctures separated by 3-4 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along three-quarters of the anterior basal margin and sparse pubescence along the posterior basal margin. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8C) with basal piece 0.7 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; outer margins slightly convex, inner margins straight; apex of parameres acute and pointing outwards. Median lobe shorter than the parameres, approximately triangular, wide at the basal region, then slightly narrowing to the apex, apex acute, gonopore oval in shape and situated at the apex of the median lobe.
Etymology. The name is a combination of two Latin words brun meaning dark and badius meaning reddish brown, highlighting the distinguishable dark reddish brown color of this species.
Distribution. Known only from the type locality near Manaus, Brazil (Fig. 15).

Life history.
The only known specimens were collected along the margin of a stream (Fig. 12C).  Differential diagnosis. Notionotus garciae is very similar to N. juma in the bicolor dorsal coloration, the shape of the elevation of the mesoventrite and the pubescent area of the metafemora. It can be distinguished by the punctation of the pronotum, the elytra shallowly marked (in N. juma is moderately impressed, Fig. 8G), and the distinctive rounded and broad apex of the median lobe (Fig. 8H). Description. Size and form: Body length 1.7-1.8 mm. Body form elongate oval, convex in lateral view (Fig. 4G). Color and punctation: Dorsally bicolor, head mostly brown, frons dark brown, posteromedial margin of the clypeus pale brown and lateral sides and anterior margin yellow; pronotum yellow with two small black round spots along posterior margin; elytra brown, lateral and posterior side of the elytra yellow (Fig. 4G). Ventrally dark brown; maxillary palps, mouthparts, and antennae yellow. Pro and meso legs yellow, meta legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation weakly impressed, fine, and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and sparse pubescence along the apical posterior margin. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8H) with basal piece 0.4 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; outer margins nearly convex along basal two-thirds, then curved inwards along apex, inner margins nearly straight; apex of parameres acute. Median lobe shorter than the parameres, wide at basal region, narrowing in the midlength and then slightly broadening to apex, apex rounded and wide; gonopore ovate in shape and situated at apical fourth of median lobe.

Notionotus garciae
Etymology. This species is named after Andrea Lorena García Hernández curator at the Colección de Insectos de la Universidad del Quindío (CIUQ) in recognition to her passion and contribution of the knowledge of the insects, specially hydrophilids in Colombia.
Distribution. This species is known from several collecting events at the Ducke Reserve near Manaus, Brazil (Fig. 15).
Life history. This species was collected along the margins of small streams in dense forest (Fig. 13D). Differential diagnosis. See differential diagnosis for Notionotus bicolor. In addition, N. insignitus has a particular and unique color pattern in the elytra among the other congeners. The elytra are mostly dark brown, the posterior margins yellow and in the middle region has a characteristic yellow spot.

Notionotus insignitus
Description. Size and form: Body length 1.6-1.8 mm. Body form elongate oval, convex in lateral view (Fig. 4D). Color and punctation: Dorsally bicolor, head mostly brown, frons and middle region of the clypeus dark brown, lateral sides of the clypeus pale brown; pronotum yellow with two small black round spots along posterior margin; elytra dark brown, with a yellow spot on the anterior third of the elytra, lateral and posterior margins of the elytra yellow (Fig. 4D). Ventrally dark brown; maxillary palps, mouthparts, and antennae yellow (antennal club slightly darker). Pro and meso legs yellow, meta legs pale brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (Fig. 10C); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of the posterior margin, then anterior half of posterior margin with sparse setae. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8B) with basal piece 0.6 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; outer margin straight along basal two-thirds, then apically slightly convex, inner margins convex along basal two-thirds and then apically straight; basal two-thirds of the parameres broad then apical third narrower; apex of parameres rounded and pointing inwards. Median lobe shorter than the parameres, approximately triangular, with acute apex; gonopore triangular and situated at apex of median lobe.
Etymology. The specific name comes from the Latin word insignitus meaning marked and refers to the distinctive yellow spot in the elytra of this species.
Distribution. Known only from the type locality in southeastern Venezuela (Fig. 15). Life history. The only known series of this species was collected along the margin of a forested rocky stream (Fig. 12B).  Differential diagnosis. See differential diagnosis for Notionotus garciae. In addition, the aedeagus of N. juma has an emargination in the apex of the medium lobe, being a particular feature among the species of the lohezi group.
Description. Size and form: Body length 1.6-1.9 mm. Body form elongate oval, convex in lateral view (Fig. 4E). Color and punctation: Dorsally bicolor, head pale brown, pronotum yellow with two small black round spots along posterior margin; elytra dark brown (Fig. 4E). Ventrally brown; maxillary palps, mouthparts, and antennae yellow (antennal club slightly darker). Pro and meso legs yellow, meta legs pale brown. Clypeus and labrum with dense, coarse, and moderately impressed ground punctation (punctures separated by 2 × their width); elytra and pronotum ground punctation coarse, moderately impressed and less dense than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8G) with basal piece nearly the same length as a paramere. Base of the parameres as wide as the base of the median lobe; outer margins convex, then curved inwards along apex, inner margins convex along basal two-thirds, and concave at apical third; apex of parameres rounded. Median lobe shorter than the parameres, wide at basal region, slightly narrowing in the midlength, apex wide and emarginate medially; gonopore with an oval shape and situated at apex of the median lobe.
Etymology. This species is named after the Juma, an indigenous tribe located in the Açuã River, in the southern part of the state of Amazonas-Brazil.

Notionotus lohezi
Differential diagnosis. See differential diagnosis for Notionotus bicolor. Description. Size and form: Body length 1.6-1.8 mm. Body form elongate oval, convex in lateral view (e.g., Fig. 4A). Color and punctation: Dorsally bicolor, head bicolor, frons dark brown, clypeus yellow; pronotum yellow with two small black round spots along posterior margin; elytra dark brown, elytra margins paler (e.g., Fig. 4A). Ventrally dark brown; maxillary palps, mouthparts, and antennae yellow (antennal club slightly darker), legs brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of the posterior margin, then apical half of the posterior margin with sparse setae. Abdomen: abdominal ventrites very densely pubescent. Aedeagus (Fig. 8F) with basal piece 0.8 × the length of the paramere. Base of the parameres slightly narrower than the base of the median lobe, inner margins straight, then convex reaching the apex, outer margins convex, and rounded apex pointing inwards. Median lobe shorter than the parameres, approximately rectangular with apex blunt; gonopore situated at the apex of the median lobe.
Distribution. This species is only known from a few localities in French Guiana (Fig. 15).
Life history. This species was collected in rocky streams with detritus along margins. Differential diagnosis. Notionotus parvus can be recognized by the pale reddish yellow color in the head and pronotum and reddish brown in the elytra (Fig. 4F). Furthermore, the aedeagus is quite unique, parameres tubular in shape with lanceolate appendages in the outer margin which are shorter than the length of the parameres, and gonopore with crown-shape located in the apical region of the median lobe (Fig. 9E).
Description. Size and form: Body length 1.7-1.9 mm. Body form elongate oval, convex in lateral view (Fig. 4F). Color and punctation: Dorsally reddish brown, head and pronotum pale reddish yellow; pronotum with two small black round spots along posterior margin; elytra dark reddish brown (Fig. 4F). Ventrally reddish brown; maxillary palps and mouthparts light yellow reddish, and antennae yellow (antennal club slightly darker). Pro and meso legs yellow, meta legs pale reddish brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation slightly convex in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and sparse pubescence along the apical posterior margin. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 9E) with basal piece 0.5 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; parameres tubular shape, outer margins sinuate and covered by lanceolate appendages that cover three-quarters of the margin; inner margins sinuate, apex of the parameres rounded. Median lobe shorter than the parameres, wide at basal region, narrowing apically, apex rounded and wide; gonopore crown-shaped and situated at apex of median lobe.
Etymology. The species name is derived from the Latin word parvus meaning little or small in reference to the small aedeagus size of this species.
Distribution. Only known from the type locality in southern Suriname (Fig. 15). Life history. This species was collected along the margins of a small, sandy-bottomed stream.  (Fig. 4B). Color and punctation: Dorsally bicolor, head brown, frons dark brown, clypeus pale brown; pronotum yellow with two small black round spots along posterior margin; elytra dark brown, elytra margins paler (Fig. 4B). Ventrally brown; maxillary palps, mouthparts, antennae, and legs yellow. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of the posterior margin, then apical half of the posterior margin with sparse setae. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 4B) with basal piece 0.7 × the length of a paramere. Base of the parameres narrower than the base of the median lobe; outer margins straight along basal two-thirds, then apically slightly convex, inner margins straight along basal two-thirds and then convex and tapering apically; apex of parameres rounded and pointing inwards. Median lobe shorter than the parameres, approximately triangular, gradually narrowing from the base, broad and rounded apex; gonopore oval-shaped and situated at apex of median lobe.

Notionotus patamona
Etymology. This species is named after the Patamona, an indigenous tribe located in the mountainous region from which this species is known.
Distribution. Known from several closely situated localities in western Guyana (Fig. 15).
Life history. This species was collected at several a variety of stream-associated habitats, including along the margins of detritus and sandy-based streams, as well as in rock seepage habitats adjacent to streams (Fig. 12C). In this species, the apex of the parameres is wide and rounded (acute in N. lohezi, Fig. 8F), the median lobe is much longer than in N. lohezi and the gonopore is elongated and oval (nearly rectangular in N. lohezi).
Description. Size and form: Body length 1.8 mm. Body form elongate oval, moderately convex in lateral view. Color and punctation: Dorsally bicolor, head mostly brown, frons brown, clypeus pale brown; pronotum yellow with two small black round spots along posterior margin; elytra dark brown. Ventrally brown; maxillary palps, mouthparts, antennae (antennal club slightly darker), legs brown. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed, and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, acute and pointing anteriorly. Elevation of mesoventrite with two transversal ridges, elevated medially, lateral sides concave; longitudinal ridge broad anteriorly and sharp posteriorly, the point where the three ridges merged wide and blunt (e.g., Fig. 10C, D); elevation flat in ventral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal one-quarter of posterior margin, then apical half of the posterior margin with sparse setae. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 8E) with basal piece 0.7 × the length of a paramere. Base of the parameres nearly the same as the base of the median lobe; outer margins convex, inner margins nearly straight; apex of parameres broad, rounded and slightly pointing inwards. Median lobe shorter than the parameres, wide at basal region, narrowing in basal third, margins straight and apex rounded and nearly notched; gonopore with an oval shape and covering approximately two-thirds of the length of the median lobe.
Etymology. The specific name comes from the Latin word retusus meaning rounded and notched, after the form of the apex of the median lobe of the aedeagus.
Distribution. This species is only known from the type locality in western Guyana (Fig. 15).
Life history. This species was collected in detrital-filled pools in a shallow ravine with dense forest cover (Fig. 13F). Although the pools might not be considered a stream, the pools were part of a drainage network.

Notionotus rosalesi species group
Diagnosis. The species of this group can be recognized by the unique dorsal coloration, being almost yellow with a wide brown band in the third anterior of the elytra (Fig. 2G), the elevation of the mesoventrite with one transversal and longitudinal ridge (e.g., Fig. 10B), the shape of the genitalia is quite distinct, being the only one within all Notionotus species of the Neotropical region with the apical third of the parameres membranous ( Fig. 9A-C). Differential diagnosis. Notionotus rosalesi can be distinguished by the wide brown band in the anterior third of the elytra, as well as, the unique shape of the genitalia, having many accessories at the base of the parameres, the apex of the parameres membranous and lanceolate.

Notionotus rosalesi Spangler, 1972
Description. Size and form: Body length 1.8-1.9 mm. Body form elongate oval, moderately convex in lateral view (Fig. 2G). Color and punctation: Dorsally bicolor, head mostly brown, frons brown, medially region of the clypeus pale brown with lateral margins yellow; pronotum yellow with two small black round spots along posterior margin; elytra yellow except by a brown wideband on the anterior third of the elytra (Fig. 2G). Ventrally brown; maxillary palps, mouthparts, antennae, and legs yellow (antennal club slightly darker) (Fig. 2H). Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 5 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge narrowed anteriorly and broadening posteriorly, the point where the two ridges merged acute (e.g., Fig. 10B); elevation concave in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora with dense hydrofuge pubescence along basal three-quarters of the anterior margin and along basal half of the posterior margin. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus (Fig. 9A-C) basal piece 0.4 × the length of a paramere; broad parameres, base of the parameres much wider than the base of the median lobe, base of the parameres with two accessories with ovate shape, outer margins of parameres strongly sinuate, inner margins slightly sinuate, with membranous acuminate apex, bending outwards; median lobe shorter than the parameres, approximately triangular, with apex rounded.
Distribution. Originally described from the Venezuelan states of Aragua and Barinas (Spangler 1972), it was later reported from the states of Trujillo and Falcón (García 2000). Here we report it for the first time from Trinidad (Fig. 14).
Life history. Although specific habitat information is limited, all specimens were collected in association with streams. Spangler (1972) characterized this species as a hygropetric specialist, although not all specimens known at that time were from seepages (the others were from a stream pool that "was in the bedrock and the bottom was covered with rotting leaves").
Remarks. The genitalia of the holotype appears to have some modest fungal growth on the median lobe (Fig. 9B), the circular "halo" at the tip of the median lobe appears to be unnatural and is not part of the original structure.

Notionotus peruensis species group
Diagnosis. The species of peruensis group can be diagnosed by the dorsal coloration completely yellow, the elevation of the mesoventrite with one transverse and one longitudinal (e.g., Fig. 10B), and by the shape of the genitalia (Fig. 9F). Differential diagnosis. Notionotus peruensis can be distinguished by the particular shape of the aedeagus, being nearly rectangular in the basal half and abruptly narrow in the apical half (Fig. 9F).
Description. Size and form: Body length 1.6 mm. Body form elongate oval, convex in lateral view (Fig. 4K). Color and punctation: Dorsally yellow, head mostly yellow and frons pale brown; pronotum with two small black round spots along posterior margin (Fig. 4K). Ventrally brown; maxillary palps, mouthparts, antennae (antennal club slightly darker) and legs yellow. Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 × their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 × their width). Head: Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax: Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged acute (e.g., Fig. 10B); elevation flat in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area, medial region patch drop-shaped; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters. Abdomen: Abdominal ventrites very densely pubescent. Aedeagus ( Fig. 9F) with basal piece 0.7 × the length of a paramere. Base of the parameres wider than the base of the median lobe; outer margins straight along basal two-thirds, then apically sinuate, inner margins straight along basal two-thirds and then convex and tapering apically; apex of parameres rounded and pointing outwards. Median lobe much shorter than the parameres, basal half rectangular, apical half narrowing abruptly, apex rounded.
Etymology. The species is named after Peru, the country where it was collected, as well as for being the first species described for the genus in this country.
Distribution. Known only from the type locality in Peru (Fig. 14). Life history. The single specimen was collected at a flight intercept trap; nothing is known about its habitat.
Notionotus spp. Remarks. We examined two single female specimens from unique localities that we refrain from identifying or describing, due to the lack of male genitalia for comparison. The specimen from Peru likely represents an undescribed species, as suggested by its distant position in our DNA tree (Fig. 1). The single female from Bolivia is the first and only known record of the genus from that country.

Key to the species groups of Notionotus of the Neotropical Region
Although it is fairly straightforward to key specimens (especially males) to species group, identification to species within each group almost always requires examination of the aedeagus. For this reason, as well as the fact that there are no doubt many yetto-be-described species, particularly in the southern Amazon region, we do not include a species key here.

1
Elevation of the mesoventrite composed by two ridges (one transverse and one longitudinal) (e.g., Fig. 10A

Discussion
Since Notionotus was first described as a hygropetric genus from the Andean Region of Venezuela fifty years ago (Spangler 1972), our knowledge of the genus has substantially expanded. Within the Neotropical region, this present work expands the distribution throughout much of tropical South America, including the first records from Peru, Bolivia, and Brazil. We also find that while the originally described species do appear to prefer hygropetric habitats (especially N. liparus), most species are not found in seepages but prefer leaf packs and margins of forested streams. The vast majority of specimens have been collected at sites under 1000 meters in elevation, though N. liparus has been found as high as 1770 m. Although the highest density of known specimen records remains in the northern quarter of South America, particularly Venezuela and the Guiana Shield region, this is almost certainly an artifact of collecting effort, as aquatic beetles are in general less well known in the central and southern Amazon region. While many new species undoubtedly remain to be described, we also found that some species have quite expansive ranges (e.g., N. dilucidus, N. tricarinatus, N. vatius) and care should be taken to put even seemingly geographically distant new collections in context with existing species. The integration of DNA sequence data proved invaluable in helping to establish species limits in these widespread taxa.