Novochares Giron & Short, 2021

Short, Andrew Edward Z. & Giron, Jennifer C., 2023, Revision of the Neotropical water scavenger beetle genus Novochares Giron & Short (Coleoptera, Hydrophilidae, Acidocerinae), ZooKeys 1171, pp. 1-112 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.1171.104142
publication LSID	lsid:zoobank.org:pub:267D0D45-59CA-4A18-A080-34768E652607
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scientific name	Novochares Giron & Short, 2021
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Treatment

Novochares Giron & Short, 2021 View in CoL

Novochares Girón & Short, 2021: 87.

Type species.

Helochares tectiformis Fernández, 1982 by original designation.

Diagnosis.

(Slightly modified from Girón and Short 2021). Body length 4.2-9.5 mm. Body shape oval in dorsal view (Figs 7 View Figure 7 , 14 View Figure 14 , 17 View Figure 17 , 24 View Figure 24 ); slightly to moderately convex in lateral view, with dorsal outline nearly flat along anterior 1/2 of elytra, or somewhat evenly curved. Coloration usually uniformly dark brown (Figs 14 View Figure 14 , 17 View Figure 17 , 24 View Figure 24 ), sometimes orange or pale brown (Fig. 7 View Figure 7 ), often paler along margins (e.g., Fig. 14A-C View Figure 14 ); opalescent sheen frequent in larger and darker species; ground punctation from very shallow (e.g., Fig. 17D View Figure 17 ) to moderately marked (e.g., Fig. 14A View Figure 14 ). Shape of head trapezoid (Fig. 6D View Figure 6 ). Eyes relatively large, not emarginated anteriorly, usually projected from outline of head (Fig. 6D View Figure 6 ). Clypeus trapezoid, with anterior margin broadly and roundly emarginate (Fig. 6D View Figure 6 ); membranous preclypeal area sometimes visible. Labrum fully exposed. Mentum with lateral longitudinal crenulations, lateral oblique ridges, and transverse crenulations along antero-medial area. Antennae with nine antennomeres; cupule strongly asymmetric, with rounded outline; antennomere 9 slightly to 2 × longer than antennomere 7. Maxillary palps slender, moderately long, 0.8 ( N. pastinum sp. nov.) to 1.8 × ( N. yanomami sp. nov.) the width of head; inner margin of maxillary palpomere 2 weakly and evenly curved to nearly straight, outer margin evenly curved or curved along apical 1/2; maxillary palpomere 3 slightly longer than 4. Prosternum flat to broadly and weakly convex. Elytra without sutural striae, with ground punctures usually shallowly marked; usually at least one row of systematic punctures visible along midline of each elytron (e.g., Figs 7C View Figure 7 , 14D View Figure 14 , 24C, D View Figure 24 ), often with visible rows along lateral and posterior regions of elytra; serial punctures sometimes visible along posterior 1/2 of elytra. Posterior elevation of mesoventrite, usually simply bulging (Fig. 6B View Figure 6 ), sometimes bulge impressed posteriorly (Fig. 6A View Figure 6 ); bulge often extending anteriorly as low, shiny, and glabrous longitudinal ridge (Fig. 6A, B View Figure 6 ); anapleural sutures concave, separated at anterior margin by distance 0.6-0.9 × the width of anterior margin of mesepisternum. Metaventrite with medial glabrous patch, sometimes very narrow and extending along entire length of metaventrite. Protibiae with spines of anterior row extremely reduced to tiny appressed denticles. Metafemora with tibial grooves well developed; hydrofuge pubescence covering basal 6/7 of anterior surface. Tarsomeres 1-4 with long, thick, and rather dense setae on ventral face, sometimes with only rows of short spines on metatarsomeres 2-4; metatarsomere 2 as long or slightly longer than 5 and as 3 and 4 combined. Fifth abdominal ventrite apically emarginate, with fringe of stout setae. Aedeagus divided (e.g., Figs 3 View Figure 3 - 5 View Figure 5 ); parameres separated from each other for most of their length; median lobe divided in dorsal and ventral plates; dorsal plate usually strongly sclerotized and elongated, often bifurcated, or otherwise shaped along apical region; ventral plate sometimes reduced, usually simple and of variable length; basal piece 0.3 × or less than length of parameres, usually clearly noticeable; gonopore usually clearly visible.

Differential diagnosis.

Novochares includes medium sized, pale brown to nearly black species that are somewhat dorsoventrally compressed and highly polished (smooth, and often shiny) to the naked eye. Across the Americas the most similar genus is Aulonochares Girón & Short, 2019, from which it can be differentiated by the shape of the head [trapezoid in Novochares (posterior margin of clypeus nearly twice as wide as anterior margin; Fig. 6D View Figure 6 ), subquadrate in Aulonochares (posterior margin of clypeus only nearly 1.3 × wider than anterior margin; Fig. 6C View Figure 6 )], and the sculpture of the mentum (variously strigate in Novochares , punctate in Aulonochares ). Some members of Helochares of the Americas may resemble Novochares in their external features, but the aedeagal form is completely different (tubular in Helochares , see fig. 7 in Short and Girón 2018; divided in Novochares , e.g., Figs 3 View Figure 3 - 5 View Figure 5 ).

Distribution.

Nearctic: U.S.A. (Florida). Neotropical: Argentina, Belize, Bolivia, Brazil ( Amapá *, Amazonas, Espírito Santo, Goiás *, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará *, Paraíba, Pernambuco, Piauí, Rio de Janeiro, Rondônia *, Roraima*, São Paulo), Colombia, Costa Rica, Cuba, Dominican Republic*, Ecuador, French Guiana, Guatemala, Lesser Antilles (Grenada, Guadeloupe, St. Vincent), Mexico, Panama, Paraguay, Peru*, Puerto Rico, Suriname, Trinidad and Tobago*, Uruguay, Venezuela (new country or state records indicated with an asterisk).

Habitat.

The genus occupies a broad range of aquatic habitats, including both lentic and lotic situations. We are not aware of any seepage specialists. The most commonly collected species (e.g., those in the N. abbreviatus species group) are typically associated with open swamps and marshes where they may also be attracted to lights, sometimes in large numbers. Many species are also found in forested pools and swamps that contain abundant detritus. They may also be abundant in detrital pools in drying streambeds or along the margins of slow moving or quiet streams. It is also important to note that a number of Novochares species can co-occur in the same habitat at the same time.

Immature stages.

The females of most if not all species in the genus carry their egg case around under their abdomen, a behavior also seen in other Helochares -group genera (such as the Neotropical Aulonochares , Radicitus , and Sindolus ; Girón and Short 2021). Only the immature stages (eggs, larvae, pupae) of N. pallipes have been described to date ( Fernández 1983).

Novochares abbreviatus species group

Species group diagnosis. Body length 5.5-8.1 mm. Coloration: Dorsal surfaces pale brown to yellowish brown (Fig. 7A, B View Figure 7 ), with paler (yellowish to orange) clypeus and margins of pronotum and elytra. Head: Maxillary palps 1.1-1.6 × width of head, uniformly yellow or orange to brown in color (Fig. 7A, B View Figure 7 ). Thorax: Ground punctation on pronotum and elytra relatively dense and very shallowly impressed. Elytra without rows of serial punctures, each with very faint rows (one dorsal and two or three lateral) of scarce and weakly marked systematic punctures. Prosternum medially weakly and broadly convex. Posterior elevation of mesoventrite broadly and somewhat triangularly elevated, sometimes posteriorly transversely impressed, with low medial longitudinal ridge extending anteriorly. Abdomen: Apical emargination of fifth ventrite shallow to moderately deep and broad, U-shaped. Aedeagus: (Figs 3 View Figure 3 , 8 View Figure 8 , 9 View Figure 9 ) Overall shape sub-rectangular to sub-rhomboid, 2.5-3.0 × longer than wide, joint basal margins of parameres truncate (e.g., Fig. 8M View Figure 8 ) to medially pointed (e.g., Fig. 8A, G View Figure 8 ); outer margin and apical region of each paramere variable, usually rounded at apex and laterally pointed; parameres longer than median lobe; parameres with apical region uniformly sclerotized and dorso-ventrally flattened; dorsal inner margin of each paramere usually medially broadly emarginate (see Fig. 5 View Figure 5 in blue); dorsal plate of median lobe (in dorsal view) with basal apodemes usually reaching base of parameres; dorsal plate of median lobe usually with long and narrow neck (see Fig. 5 View Figure 5 in yellow), variably expanded at apical region, usually with distal arms variable in shape and length; gonopore sitting proximal to base of median lobe; ventral plate of median lobe (in ventral view, see Fig. 5 View Figure 5 in red) somewhat triangular, moderately sclerotized; dorsal surface of ventral plate of median lobe slightly concave (lateral regions curved dorsally); basal piece nearly (see Fig. 5 View Figure 5 in green) 0.25-0.30 × length of a paramere. In lateral view, aedeagus triangular, nearly straight at base, with ventral outline of parameres 3.0-3.6 × longer than greatest width near base (e.g., Fig. 8C, F, I, L, O View Figure 8 ).

Composition. This species group contains three previously described species: Novochares abbreviatus (Fabricius, 1801), N. oculatus (Sharp, 1882), and N. pallipes ( Brullé, 1841) and three new species: N. baca sp. nov., N. latus sp. nov., and N. pilatus sp. nov.

Remarks. This is a widespread and certainly problematic species group. The external morphology of all the known species is annoyingly uniform, and the characteristics of the male genitalia, especially the apical region of the dorsal plate of the median lobe, when looking at long series of specimens from across the distributional ranges of N. abbreviatus and N. oculatus , exhibit gradual changes that blur the limits between both species. More thorough sampling and molecular data, perhaps in the context of international collaboration across the species group range, are needed to tackle the systematics and taxonomy of this species group.

The taxonomy and nomenclature of the N. abbreviatus group: the past

Fabricius (1801) described Hydrophilus abbreviatus (now N. abbreviatus ) from "America meridonali", the oldest species of what is now included in Novochares . Brullé (1841) described Philhydrus pallipes (now N. pallipes ) from Uruguay. Later, Sharp (1882) described Helochares oculatus from Guatemala. The descriptions of all three of these species are very brief and no consideration is given to the aedeagus (as was typical at the time). Following the publication of these descriptions, there does not seem to be any question that subsequent authors considered them to be very closely related species, if not all actually conspecific.

d’Orchymont (1926) considered Helochares oculatus Sharp, 1882 as a synonym of Philhydrus pallidus Castelnau, 1840, citing mostly similarities in dorsal coloration and elytral punctation. Ten years later, d’Orchymont (1936) examined a unique female specimen from the Schestedt-Lund collection, labeled as " H. abbreviatus ex. Ins. Amer." which he treated as the Fabrician type specimen, and attributed the locality to be in the Antilles ("il est donc des Antilles"; d’Orchymont 1936: 10). The existence of a single Fabrician specimen is corroborated by Zimsen (1964: 66), who also lists a single specimen housed in the Copenhagen collection, and by Spangler (1981) who also examined it himself. After examining this type, d’Orchymont (1936) considered Philhydrus pallidus Castelnau, 1840 as a synonym of H. abbreviatus , though he indicates this interpretation is based on a specimen of P. pallidus determined by Régimbart. Because d’Orchymont had already synonymized H. oculatus Sharp with H. pallidus , H. oculatus now became a synonym of H. abbreviatus . It is worth noting that the Castelnau collection is considered lost and possibly destroyed ( Evenhuis 2012), so the original identity of H. pallidus will likely never be known.

A few years later, d’Orchymont (1939) revisited the identity of H. abbreviatus after having examined the aedeagus in a variety of specimens. He noticed some male specimens from Mexico, Panama, and Brazil (Mato Grosso do Sul) have a larger tip of the dorsal plate of the median lobe and less acute teeth on the paramere apices (he illustrated both forms; fig. 4 in d’Orchymont 1939). He speculated that these specimens with the larger, broader apex of the dorsal plate of the median lobe may be the H. oculatus of Sharp. He suggests that the dissection of Sharp’s type specimens should confirm his hypothesis, though at that time it was not known if the types were male or female. It is also of note that d’Orchymont observed that both “forms” of the genitalia (i.e., both the Novochares abbreviatus form and the Novochares oculatus form) co-occur at a variety of localities. d’Orchymont (1939: 259) goes on to comment on the situation of the identity of H. abbreviatus (translated from French): "To justify these attributions [of the names H. abbreviatus and H. oculatus ] let us recall that there is a doubt as to the origin (South America or the Antilles?) of the type of Fabricius and that it is a female. There is therefore no inconvenience in considering definitively as typical the most widespread form in South America, like the one showing the aedeagus of figure 4." [which illustrates the modern concept of H. abbreviatus ]

The same year that d’Orchymont was lamenting the confusion around H. abbreviatus , Balfour-Browne (1939) described Helochares rufobrunneus from the Antilles, specifically from Grenada and St. Vincent. He said that his new species was "very similar to H. abbreviatus in color" but can be separated by the elytral punctation and a few other Novochares minor characters. Although he illustrates the aedeagus of H. rufobrunneus , which is a very good match to the “true” H. abbreviatus of d’Orchymont (1939), he remarks that the genitalia of the two species are "quite distinct" and refers to the apex of the median lobe being deeply forked and expanded in H. abbreviatus . Based on this later comment about the aedeagus, we believe that what Balfour-Browne considered to be H. abbreviatus was in fact H. oculatus , and therefore he inadvertently redescribed H. abbreviatus .

While summarizing aquatic beetles from Cuba, Spangler (1981) provided a detailed narrative on the status of H. abbreviatus and H. rufobrunneus , as he had examined the types of both species. He pointed out that the attribution of the type specimen of H. abbreviatus coming from the Antilles comes from details provided by Zimsen (1964). Specifically, that Smidt (the provider of the type specimen of H. abbreviatus to Fabricius) was a customhouse officer in St. Croix who collected insects while stationed there. He considered this to be important because as the Fabricius type was female, in theory it could represent a senior synonym of H. oculatus , further confounding the names. However, he had not seen any specimens from the Caribbean Islands with the H. oculatus form of the genitalia, and so concluded this was improbable. He concluded that H. rufobrunneus was a junior synonym of H. abbreviatus .

Subsequently, Fernández (1982a) confirmed that indeed the aedeagus of a syntype of H. oculatus matched the form that d’Orchymont (1939) had speculated was the true H. oculatus (see. Fig. 9D, E View Figure 9 ). She designated a lectotype, removed H. oculatus from synonymy with H. abbreviatus , and reinstated it as a distinct species. Unaware that Spangler had synonymized H. rufobrunneus with H. abbreviatus the year before, she also independently concluded that these two species were synonyms after examining the type of the former and proposed their synonymy.

The identity of the only other previously described species in this group, N. pallipes ( Brullé), has been much less controversial. Its modern identity has been constant since d’Orchymont (1939, fig. 3) examined the type specimen and illustrated the genitalia, which is fairly distinct by Novochares standards.

The taxonomy and nomenclature of the N. abbreviatus species group: the present and future

Soon after we began working on this revision, it became clear that this group of species would be particularly difficult to resolve-something that was not at all a surprise given the confusion it has posed in the past. Many of the challenges in this group are not unique within Novochares : The lack of external characters, the presence of extremely widespread species, and subtle variation in aedeagal forms are found in many species groups within the genus. However, each of these problems is extreme within the Novochares abbreviatus species group, combined with the fact that this is by far the most commonly found species group in collections. At least one species of Novochares probably inhabits most open marshlands and pond margin habitats from Mexico to Argentina. Despite being only a few of more than 50 species, it probably represents more than half of the specimens in collections, and in Mesoamerica and the Caribbean Islands, the overwhelming majority of specimens we observed are in this group.

We found there to be many subtle forms of variation in the aedeagus, much more so than we observed in other species groups. When we applied molecular data to try to resolve this issue, we found that Novochares abbreviatus truly is a very widespread species, with specimens from disparate localities such as Costa Rica and southern Brazil neatly grouping together, and that there are many distinct genetic lineages even within our very modest sampling (given the range and commonality of the group; see Fig. 2 View Figure 2 ) and the differences in the aedeagal morphology can be small (Figs 8 View Figure 8 , 9 View Figure 9 ). Despite all the material and data at our disposal, there remained uncertainty about the boundaries between some of these lineages/putative species, and if we were not confident in telling them apart, we know that others would struggle even more. We were able to generally circumscribe the previously named species and have chosen to describe three relatively distinct lineages as new species that are supported by both morphology and DNA data.