Research Article |
Corresponding author: Andrew Edward Z. Short ( aezshort@gmail.com ) Academic editor: Mariano Michat
© 2017 Jennifer C. Girón, Andrew Edward Z. Short.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Girón JC, Short AEZ (2017) Revision of the Neotropical water scavenger beetle genus Quadriops Hansen, 1999 (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 705: 115-141. https://doi.org/10.3897/zookeys.705.19815
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The genus Quadriops Hansen, 1999 is revised and redescribed. The genus is found to contain six species, including two that are here described as new: Quadriops clusia sp. n. (Brazil, Guyana, Suriname) and Q. acroreius sp. n. (Suriname, French Guiana). Two species are found to be junior subjective synonyms of Q. depressus Hansen, 1999: Q. amazonensis García, 2000, syn. n. and Q. politus Hansen, 1999, syn. n. The male of Q. similaris Hansen, 1999 is described for the first time. New records are provided for Q. dentatus Hansen, 1999, Q. reticulatus Hansen, 1999, and Q. similaris. All species are described and illustrated in detail. Most species are confirmed as having a terrestrial way of life, with several species being found in rotten fruits, sap flows, and dead wood. Furthermore, we discuss ecological trends of the species given their collecting information.
El género Quadriops Hansen, 1999 es revisado y redescrito. El género contiene seis especies, incluyendo dos que se describen aquí como nuevas: Quadriops clusia sp. n. (Brasil, Guyana, Surinam) y Q. acroreius sp. n. (Surinam, Guyana Francesa). Dos especies se sinonimizan con Q. depressus Hansen, 1999: Q. amazonensis García, 2000, syn. n. y Q. politus Hansen, 1999, syn. n. El macho de Q. similaris Hansen, 1999 se describe por primera vez. Se proveen nuevos registros para Q. dentatus Hansen, 1999, Q. reticulatus Hansen, 1999, y Q. similaris. Todas las especies son descritas e ilustradas en detalle. La mayoría de las especies presentan un modo de vida terrestre, con varias especies encontradas en frutos podridos, flujos de savia y madera muerta. Además, se discuten tendencias ecológicas de las especies dada su información de colecta.
terrestrial aquatic beetles, new species, taxonomy
The water scavenger beetle genus Quadriops Hansen, 1999 is endemic to the Neotropical region, with a known distribution from as far north as Costa Rica to as far south as Amazonian Peru (
Species of Quadriops can be easily recognized by their small size (ca. 2 mm), completely divided eyes, short and stout maxillary palps, mostly glabrous posterior femora, and the rounded apex (as opposed to truncate or emarginate) of the fifth abdominal ventrite. In general terms, and as happens with some other Neotropical acidocerines (e.g., Globulosis García, 2001), the external morphology is highly homogeneous among species. However, the distribution of the elytral punctures constitutes a useful character to recognize species groups.
Previous species descriptions were based on one or a few specimens, all but one of them collected by flight intercept traps. According to
Recent fieldwork in northern South America has significantly expanded our knowledge of Quadriops. This has included increasing the number of known specimens by almost 100 fold, expanding the range of some species, as well as revealing new species and habits of the beetles unknown until now. Based on all the gathered material, here we redescribe the genus and the previously known species, based on morphological characters of the adults. We synonymize Q. amazonensis García, 2000 and Q. politus Hansen, 1999 with Q. depressus Hansen, 1999, based on external morphology as well as on characters of the aedeagus. Additionally, we describe two new species: Q. acroreius sp. n. from French Guiana and Suriname, and Q. clusia sp. n. from Guyana, Suriname, and Brazil, which has been collected on the rotten fruits of Clusia trees. We also discuss the ecology and distribution of the species.
Depositories of examined material:
MALUZ Museo de Artrópodos de la Universidad del Zulia, Maracaibo, Venezuela (J. Camacho, M. García)
Morphological methods. Specimens were examined using Olympus SZX7 and SZX16 stereo microscopes (magnifications: 0.8–5.6× with DF PLAPO 1–4× objective lens and 20× eyepieces; 0.7–11.5×, with SDF PLAPO1×PF objective lens and 10× eyepieces, respectively). Genitalia dissections were prepared, in part, by the protocols described by
Images of internal structures were produced by stacking images taken through an Olympus DP72 camera attached to an Olympus BX51 microscope to 200× magnification. Habitus photographs were taken with a Visionary Digital imaging system, using a Canon MP-E 65mm f/2.8 1–5X Macro Lens mounted on a Canon EOS 6D camera body. All final images were created by stacking multiple individual photographs from different focal planes using the software Zerene Stacker. Scanning electron micrographs were taken by using a FEI Versa 3D Dual Beam Scanning Electron Microscope. Specimens were mounted on carbon tape and coated in gold.
Descriptive sequence and morphological terminology largely follows
In the examined material section of the descriptions, the sex of the specimens is indicated only for those in which the genitalia was exposed. For the remainder specimens the sex was not determined.
Quadriops acroreius sp. n. Suriname, French Guiana
Quadriops clusia sp. n. Guyana, Suriname, Brazil
Quadriops dentatus Hansen, 1999 Venezuela (Bolivar), French Guiana, Suriname
Quadriops depressus Hansen, 1999 Peru, Ecuador, Venezuela (Amazonas)
Q. amazonensis García, 2000, syn. n.
Q. politus Hansen, 1999, syn. n.
Quadriops reticulatus Hansen, 1999 Costa Rica, Panama
Quadriops similaris Hansen, 1999 Venezuela (Bolivar), Guyana, Suriname, French Guiana
For the most part, species of Quadriops are externally homogeneous (at least within the species groups). We also observed very low intraspecific variation, even across large series (hundreds) of specimens. Variation was found mainly in the following characters:
Body shape in lateral view. Though the shape of the body in lateral view might be described as subhemispherical, there is interspecific variation in the degree of convexity. The outline of some species can be described as uniformly convex: Q. dentatus, Q. acroreius, Q. reticulatus and Q. clusia (see Figs
Coloration. Body coloration, which tends to be uniform across most regions of the beetle, does not represent a diagnostic feature for separating Quadriops species. While coloration in specimens examined ranges from yellowish to reddish to dark brown, this is mostly attributable to intraspecific variation as well as varying degrees of sclerotization. Appendages and the ventral side of the beetles tend to be slightly paler than the dorsal surface of the body.
Microsculpture. One of the main characters used by
Elytra. Two main groups of species can be distinguished according to the distribution of the ground and serial punctures of the elytra: those in which the punctures are randomly and uniformly distributed over the surface (Q. acroreius and Q. dentatus, see Fig.
Mesoventrite. In Quadriops, the mesoventrite is broadly elevated posteriorly. The wide elevation usually has a transverse ridge, which varies in shape and sharpness. In the known species with irregularly distributed elytral punctures, the transverse ridge is strongly produced. It forms a blunt, vertical, median tooth in Q. dentatus, whereas in Q. acroreius it forms a wide, transverse, straight and blunt carina. As for species with elytral punctures aligned into striae, the transverse ridge can be simply curved, slightly angulate or bisinuate. For this group of species, the shape of the transverse ridge exhibits more intraspecific variation, and is not consistent within series of specimens.
Aedeagus. The general shape of the aedeagus and the length ratio between the basal piece and the median lobe + parameres is generally consistent within species. There is both inter- and intraspecific variation in the outer margins of the basal piece and the shape of the outer margins and apex of the parameres. The gonopore is positioned at the apex of the median lobe, but its shape exhibits intraspecific variation. The shape of the apices of both the median lobe and the parameres tend to be consistent within species. It is important to highlight that some differences observed in the aedeagi presented here may be a result of incomplete clearing, owed to positioning during the photographing process, and/or product of imperfect focus from the stacking process.
Quadriops Hansen, 1999: 131.
Quadriops depressus Hansen, 1999 by original designation.
Small to very small beetles, total body length 1.6–2.6 mm, width 1.1–1.6 mm. Color yellowish to reddish to dark brown. Body shape oval in dorsal view; subhemispherical and sometimes dorsally flattened in lateral view (see Figs
Body broadly oval, weakly convex, with dorsum distinctly flattened in some species. Head. Eyes completely divided into dorsal and ventral faces by lateral canthus of the frons; dorsal face of eye tear-drop shaped, smaller in size relative to the ventral face. Antennae (see Fig.
Larvae: The immature stages are unknown.
Costa Rica (Cartago, Heredia, Limón, Puntarenas), Panama (Chiriquí, Darién), Ecuador (Napo), Peru (Loreto, Madre de Dios), Venezuela (Amazonas, Bolívar), Guyana, Suriname, French Guiana, Brazil (Amazonas). See Fig.
Extensive collecting data as well as field observations confirm that the genus is terrestrial. While many specimens have been caught using flight intercept traps, many long series have been collected on decaying Clusia fruits. Additional specimens have been collected in rotten logs, sap flows on freshly cut trees, and in the refuse pile of leafcutter ants. The genus has never been collected from aquatic or semiaquatic habitats. It has been found at elevations from 30 to 1600 m. Q. acroreius, Q. dentatus and Q. similaris are not found higher than 350 m, whereas Q. reticulatus is usually found higher than 1000 m.
Holotype (female). “SURINAME: Sipaliwini District, 2°28'37.1994"N, 55°37'45.876"W, 275m/ Camp 1: Upper Palemeu,/ 10–16.iii.2012, leg. A.E.Z. Short/ Flight Intercept Trap/ SR12-0310-TN1” (
Quadriops acroreius is very similar to Q. dentatus, both species being moderately convex (as opposed to dorsally flattened) and the serial punctures of the elytra are randomly and uniformly distributed, not aligned to form well-defined longitudinal rows. It can be easily distinguished by the shape of the elevation of the mesoventrite, which is a wide, transverse, straight carina (as opposed to a toothlike projection as in Q. dentatus); in addition, the surface of head and clypeus between punctures is smooth (as opposed to reticulated).
Body length 1.9–2.0 mm, width 1.2–1.3 mm. Body elongate oval, moderately convex. General coloration uniform dark brown. Surface of pronotum and elytra, smooth (as opposed to reticulated between punctures), only slightly reticulated on head and clypeus. Elevation of mesoventrite forming a wide, transverse, straight, blunt, strongly raised carina. Metaventrite with a postero median semi triangular glabrous area. Elytra with randomly and uniformly distributed punctures, not aligned into striae; surface of pseudepipleura anteriorly reticulated, posteriorly smooth. Metafemora with basal 1/8 covered by pubescence.
Named from the Greek “akroreia”, meaning mountain ridge (Brown 1956), in reference to the pronounced transverse carina on the elevation of the mesoventrite.
Suriname; French Guiana. See Fig.
The male of the species is not known. Specimens were collected at flight intercept traps.
Holotype (male). “SURINAME: Brokopondo District/ 4.95069'N, -55.18599, 470 m/ Brownsberg Nature Park, Leo Val trail, nr. Pump station/ rotting Clusia fruits; 22.iii.2017/ leg. Short et al., SR17-0322-03A // Barcode: SEMC1542023” (
Quadriops clusia has well defined longitudinal rows of serial punctures (as opposed to uniform and randomly distributed as in Q. acroreiusand Q. dentatus, see Fig.
Body length 2.1–2.5 mm, width 1.2–1.4 mm. Body elongate oval, moderately and evenly convex. General coloration reddish brown, with pronotum and clypeus only slightly paler. Surface of head, frons and pronotum reticulated. Clypeus with anterior margin nearly straight. Elevation of mesoventrite with transverse ridge rather broad, and slightly bisinuate. Elytra with ten well defined longitudinal rows of serial punctures; punctures on the interstrial surface similar in size to serial punctures (Fig.
Named after Clusia, the genus of plants on whose decomposing fruits the beetles have been collected.
There is slight variation in the proportions of the aedeagus. Some specimens might have a comparatively wider median lobe (Fig.
Brazil (Amazonas), Guyana, Suriname. See Fig.
Most known specimens have been collected on rotten fruits of Clusia trees, sometimes in series of many hundreds of individuals. In Guyana, this species was found on and beneath rotten fruits of Clusia grandiflora (Fig.
Quadriops dentatus Hansen, 1999: 134.
Holotype (female): “VENEZ [Venezuela] : Bolivar/ 105 km S El Dorado/ 17.VII–7.VIII.86/ B. Gill 350m”, “Flight intercept/ trap”, “HOLOTYPE”, “[Handwritten] HOLOTYPE/ Quadriops dentatus/ M. Hansen”, “[Barcode] Canadian Museum of/ Musée canadien de la/ NATURE/ CMNEN 0011502” (
(5 exs.). FRENCH GUIANA: Matoury: 41.5 km SSW on Hwy N2, 4°37'22"N, 52°22'35W, 50m, 29 May–9 Jun 1997, J. Ashe, R. Brooks, FG1A97 170, ex: flight intercept trap // Barcodes: SM0134289 (
Quadriops dentatus is very similar to Q. acroreius, both species being moderately convex (as opposed to dorsally flattened) and the serial punctures of the elytra are randomly and uniformly distributed, not aligned to form well defined longitudinal rows. It can be easily distinguished by the toothlike projection of the mesoventrite (as opposed to a wide, transverse, straight, blunt carina as in Q. acroreius); in addition, the surface of head and clypeus is smooth between punctures (as opposed to reticulated).
Body length 1.6–2.2 mm, width 1.1–1.2 mm. Body elongate oval, moderately convex. General coloration uniform yellowish to dark brown. Surface smooth (as opposed to reticulated between punctures) on head, pronotum and elytra. Elevation of mesoventrite forming a basally transverse acute tooth. Metaventrite with a posterior, short, glabrous and narrow stripe. Elytra with randomly and uniformly distributed punctures, not aligned into striae; surface of pseudepipleura smooth throughout, at most only slightly reticulated at base. Metafemora with pubescence only along dorsal area of articulation to trochanter.
There is variation in size with the type specimen being the largest.
Venezuela (Bolívar), Suriname (Sipaliwini), French Guiana (Matoury, Roura). See Fig.
The male of this species remains unknown. All known specimens were collected using flight intercept traps, at elevations between 50 and 350 m.
Quadriops amazonensis García, 2000: 59, syn. n.
Quadriops depressus Hansen, 1999: 136.
Quadriops politus Hansen, 1999: 135, syn. n.
Holotype (male): Q. depressus: “PERU: Dept. [Departamento] Loreto/ 1.5km N Teniente Lopez/ 2°35.66'S,76°06.92'W/ 22 July 1993, 210–240 m/ Richard Leschen #164/ ex: flight intercept trap”, “[Handwritten] PARATYPE/ Quadriops depressus/ M. Hansen”, “[Barcode]/ SEMC0965921/ KUNHM-ENT” (
Q. amazonensis: Holotype (male): “Venezuela, Amazonas,/ Mcipio. [Municipio] Guinia, Yavita,/ Caño Chivichi, 600 m,/ 29–31 / VIII/ 1996 / Trampa interceptación”, “Colector:/ J. Camacho”, “Holotipo [male symbol, handwritten]/ [Handwritten] Quadriops/ [Handwritten] amazonensis/ Dcrip. M. García, 1998”, “[Barcode]/ MALUZ10158/ LUZ-Venezuela”. (
Q. politus: Holotype (male): “PERU: Dept. [Departamento] Loreto/ Campamento San Jacinto/ 2°18.75'S, 75°51.77'W/ 11 July 1993, 175–215 m/ Richard Leschen #83/ ex: flight intercept trap”, “[Handwritten] HOLOTYPE/ Quadriops politus/ M. Hansen”, “[Barcode]/ SEMC0965917/ KUNHM-ENT” (
(3 exs.). PERU: Loreto: Campamento San Jacinto, 2°18.75'S, 75°51.77'W, 11 July 1993, 175–215 m/ Richard Leschen #82/ ex: flight intercept trap (
Quadriops depressus is externally very similar to Q. similaris, and Q. reticulatus, as all have well defined longitudinal rows of serial punctures (as opposed to uniform and randomly distributed as in Q. acroreius and Q. dentatus, see Fig.
Aedeagus of Quadriops similaris: A SURINAME: Marowijne: Palumeu [SUR1F99 164] B GUYANA: Iwokrama Forest [GUY1BF01 005] C BRASIL: Manaus D SURINAME: Marowijne: Palumeu [SUR1F99 182] E FRENCH GUIANA: Roura [FG1AB97 027] F GUYANA: Iwokrama Forest [GUY1BF01 105] G FRENCH GUIANA: Cayenne: [FG1AB97 171] H SURINAME: Saramacca [SUR1F99 070]. Scale bar 0.1 mm.
Body length 2.1–2.5 mm, width 1.3–1.4 mm. Body elongate oval, moderately convex, with dorsal outline nearly flat. General coloration reddish to dark brown, with pronotum and clypeus only slightly paler. Surface of clypeus smooth to reticulated, usually smooth on frons and pronotum. Elevation of mesoventrite with transverse ridge rather fine and curved (posteriorly concave). Elytra with ten well defined longitudinal rows of serial punctures; punctures on the interstrial surface noticeably smaller than serial punctures; surface of pseudepipleura anteriorly undulated, particularly at limit with epipleura, posteriorly reticulated. Metafemora with pubescence only at base of anterior margin at most. Aedeagus (Figs
Aedeagus of Quadriops spp.: Q. depressus: A holotype B ‘politus’ holotype C ‘amazonensis’ holotype D VENEZUELA: Amazonas: Cerro de la Neblina; Q. reticulatus: E holotype F PANAMA: Chiriquí G COSTA RICA: Puntarenas [CR1ABF00 059] H COSTA RICA, Heredia [CR-11TN/16/016]; Q. clusia I BRAZIL: Manaus J GUYANA, Upper Potaro [GY14-0312-04A] K GUYANA, Ayanganna Airstrip [GY14-0317-01B]. Scale bar 0.1 mm.
There is variation on the density and presence of reticulation on the surface of the frons and clypeus.
Peru (Loreto), Ecuador (Napo), Venezuela (Amazonas). See Fig.
All known specimens were collected with flight intercept traps.
It is known that the shape of the aedeagus exhibit intraspecific variation in several acidocerine species (see
Quadriops reticulatus Hansen, 1999: 135
Holotype (male): “COSTA RICA: Puntarenas/ Las Alturas (Stanford/ Biol. [Biological] Sta. [Station]) ca. 29km NE San/ Vito, 1500m, 27 May 1993/ J.S. & A.K. Ashe #063/ ex: flight intercept trap”, “[Handwritten] HOLOTYPE/ Quadriops reticulatus/ M. Hansen”, “[Barcode]/ SEMC0965918/ KUNHM-ENT” (
(135 exs.). COSTA RICA: Cartago: 19.3 km NE San José, 17 May 1993, 1010 m, J. & A. Ashe, #105, ex: flight intercept trap (
Quadriops reticulatus is externally very similar to Q. depressus, and Q. similaris, as all have well defined longitudinal rows of serial punctures (as opposed to uniform and randomly distributed as in Q. acroreius and Q. dentatus), and the serial punctures are conspicuously larger than the punctures on the interstrial surface (as opposed to similarly large as in Q. clusia, see Fig.
Body length 2.0–2.4 mm, width 1.2–1.45 mm. Body elongate oval, moderately convex, with dorsal outline only slightly flat. General coloration reddish to dark brown, with margins of pronotum and clypeus only slightly paler. Surface of clypeus, frons and pronotum reticulated. Elevation of mesoventrite with transverse ridge rather fine and curved (posteriorly concave). Elytra with ten well defined longitudinal rows of serial punctures; punctures on the interstrial surface noticeably smaller than serial punctures; surface of pseudepipleura anteriorly undulated, particularly at limit with epipleura, posteriorly smooth. Metafemora with pubescence only on anterior basal corner. Aedeagus (Fig.
The degree of sharpness of the transverse ridge of mesoventrite varies from being blunt and moderately marked to sharp. There is variation on the shape of the aedeagus, even though the overall shape is conserved across the species. Specimens from Panama tend to be smaller.
Costa Rica: Cartago, Heredia, Limón, Puntarenas; Panama: Chiriquí, Darién. See Fig.
Most known specimens have been collected by using flight intercept traps. A few specimens were collected from “fungusy logs”. Additionally, a disassociated note at
The female specimen from the Darién of Panama has a differently shaped transversal ridge of the mesoventrite, but no other characters were found to differentiate it from Q. reticulatus. However, when males are found it may be shown to represent a distinct species. Several specimens were also observed to have mites on the dorsal surface of the elytra.
Quadriops similaris Hansen, 1999: 136
Paratype (female): “VENEZ [Venezuela]: Bolivar/ 105 km S El Dorado/ 17.VII-7.VIII.86/ B. Gill, FIT [handwritten] 350m”, “Flight intercept/ trap”, “PARATYPE”, “[Handwritten] PARATYPE/ Quadriops/ similaris/ M. Hansen”, “CMNEN 2003-1173” (
(34 exs.). BRAZIL: Amazonas: Reserva Ducke 26 km NE Manaus, Barbosa, M.G.V., Plot B, FIT 1, Feb 1995 (2 males (1 dissected); 1 female,
Quadriops similaris is externally very similar to Q. depressus and Q. reticulatus, as all have well defined longitudinal rows of serial punctures (as opposed to uniform and randomly distributed as in Q. acroreius and Q. dentatus, see Fig.
Body length 2.2–2.6 mm, width 1.4–1.6 mm. Body elongate oval, moderately convex, with dorsal outline nearly flat. General coloration reddish brown, with sides of pronotum and clypeus only slightly paler. Surface of clypeus, frons and sides of pronotum reticulated. Elevation of mesoventrite with transverse ridge usually rather sharp, curved to somewhat roof-like shaped. Elytra with ten well defined longitudinal rows of serial punctures; punctures on the interstrial surface noticeably smaller than serial punctures; surface of pseudepipleura anteriorly undulated, posteriorly markedly canaliculated. Metafemora with pubescence only along proximal 1/5 of anterior margin. Aedeagus (Fig.
There is variation in the shape and sharpness of the transverse ridge; the general shape of the aedeagus is consistent within the species, but varies in specific characters: shape of outer margins of parameres, width and shape of apex of parameres, shape of apex of aedeagus. There is one male specimen from Suriname (Collecting event SUR1F99 070; see Fig.
Most specimens were collected in flight intercept traps. The species was also collected on the refuse pile of the ant Acromyrmex hystrix, under fermenting bark and by fogging a splintered tree trunk. Q. similaris has been collected at elevations between 25 and 350 m.
The male of Q. similaris was unknown until now. Specimens collected in Guiana were recognized as belonging to this species by the posteriorly markedly canaliculated pseudepipleura, a character shared with Q. depressus. There are no consistent external characters that distinguish both species, but the shape of the apex of the parameres is remarkably different.
Habitat of Quadriops clusia sp. n.: AClusia cf. grandiflora on the forest floor, collecting event GY14-0312-04A B A specimen of Quadriops clusia sp. n. crawling on the surface of a rotting Clusia fruit, collecting event GY14-0312-04A CClusia cf. nemorosa in Brownsberg Nature Park, Suriname on which Quadriops clusia sp. n. was collected D Collecting Quadriops and other terrestrial hydrophilid specimens by submerging collected rotting Clusia fruits in pans of water and waiting for the beetles to float to the surface, collecting event SR17-0322-03A.
1 | Elytra with punctures randomly and uniformly distributed (see Fig. |
2 |
– | Elytra with punctures arranged as well defined longitudinal series, forming striae (see Figs |
3 |
2 | Elevation of mesoventrite as a narrow toothlike projection |
Q. dentatus Hansen (Fig. |
– | Elevation of mesoventrite as a wide, transverse, straight blunt carina |
Q. acroreius sp. n. (Fig. |
3 | Serial elytral punctures simple; the ones on striae similar in size as those on the interstrial surface (Figs |
Q. clusia sp. n. |
– | Serial elytral punctures ramified; the ones on striae evidently larger in size than those on the interstrial surface (Fig. |
4 |
4 | Surface of pseudepipleura smooth throughout; dorsal outline of body in lateral view moderately and uniformly convex |
Q. reticulatus Hansen (Fig. |
– | Surface of pseudepipleura posteriorly markedly canaliculated (e.g. Fig. |
5 |
5 | Apex of parameres widely to narrowly rounded (Figs |
Q. depressus Hansen (Fig. |
– | Apex of parameres angulate (Fig. |
Q. similaris Hansen (Fig. |
The data now strongly support the conclusion that Quadriops is an exclusively terrestrial genus. Previously, all but one specimen were from flight intercept traps, leaving their preferred habitat a mystery. One paratype specimen of Q. reticulatus was taken from oak forest litter, leading Hansen to consider them “apparently terrestrial”, though it should be noted that incidental collections of otherwise aquatic or semiaquatic taxa in leaf litter are not rare. We located older material that confirmed additional collecting events from sifted litter as well as rotten logs and sap flows, further substantiating the terrestrial habits of several species, including Q. reticulatus and Q. similaris. In 2013, AEZS first observed several Quadriops clusia specimens crawling on a rotting Clusia fruit in Guyana, and was able to subsequently collect several long series. Since that time, we have actively sought to collect in Clusia fruits on subsequent expeditions in Suriname and Guyana. In most of the cases in which we have collected in the fruits, we have been able to find at least one individual, and in some cases have encountered hundreds once again. We have collected hydrophilid larvae from these fruits as well, but we have not yet confirmed that they belong to Quadriops (other water scavenger beetles from the tribes Megasternini and Coelostomatini were also collected with Quadriops in the fruits). Interestingly, although several Quadriops geographically co-occur with Q. clusia in Guyana and Suriname, none have been found in Clusia fruits. Additionally, no Quadriops has been found in any aquatic or semiaquatic habitats despite extensive recent collecting activity in northern South America.
When Quadriops was first described from a total of 17 specimens by
We are grateful for the assistance and support of many colleagues during fieldwork, including Mauricio García (