Quadriops clusia, Giron, Jennifer C. & Short, Andrew Edward Z., 2017

Giron, Jennifer C. & Short, Andrew Edward Z., 2017, Revision of the Neotropical water scavenger beetle genus Quadriops Hansen, 1999 (Coleoptera, Hydrophilidae, Acidocerinae), ZooKeys 705, pp. 115-141 : 119-121

Quadriops clusia sp. n. Figs 3 E–H, 6A, 7 I–K, 9B

Material examined.

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" (NZCS). Paratypes (210 exs.): BRAZIL: Amazonas: Reserva Ducke 26 km NE Manaus, Barbosa, M.G.V., Plot B, FIT 1, Feb 1995 (1 male, dissected, NHMUK). GUYANA: Region XIII: 5°0.673'N, 59°38.358'W, 500 m, Upper Potaro Camp I (c. 7 km NW Chenapau), near camp, rotten fruits of Clusia ; leg. A. Short, 12.iii.2014, GY14-0312-04A // Barcodes: SEMC1315733-37, 39, 42-46, 48, 52-55, 57, 60-61, 65, 67-69 (23 ex., incl. 1 female, 7 males [SEMC1315754 dissected]), SEMC1328917-45, 49-60, 62-65, 67-76, 78-85 (SEMC, CBDG, 63 ex., incl. 5 females [SEMC1328965, 78 dissected], 14 males [SEMC1328983 dissected], SEMC1329066-72, 74-75 (SEMC, 9, incl 2 males); 5°18.261'N, 59°50.257'W, 687 m, Ayanganna Airstrip, trail from airstrip to Ayanganna, rotten fruits of Clusia ; leg. A. Short, 17.iii.2014, GY14-0317-01B // Barcodes: SEMC1329083-84, 86-87, 89-90, 92-93, 96-97 (10, incl. 2 females SEMC1329090 dissected], 5 males [SEMC1329093 dissected], voucher SLE 1003, voucher SLE 1077, voucher SLE 1078; SURINAME: Brokopondo: 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 // Barcodes: SEMC1541993-2022; 2024 - 2119 (126 ex., SEMC, NZCS, MIZA). Sipaliwini: Raleighvallen Nature Reserve/ Lolopasie Area, 14.iii.2016, leg Short et al., Clusia fruits, SR16-0314-02B (SEMC; voucher SLE 1054); 4°42'28.8", -56°13'9.5448"; 24 m/ Raleighvallen Nature Reserve/ Lolopasie Area; 18.iii.2016/ Clusia fruits; leg. Short/ SR16-0318-01C (SEMC; voucher SLE 1071, female).

Differential diagnosis.

Quadriops clusia has well defined longitudinal rows of serial punctures (as opposed to uniform and randomly distributed as in Q. acroreius and Q. dentatus , see Fig. 1). The serial punctures on the striae are simple and similar in size as those on the interstria (Fig. 6A) (as opposed to ramified and conspicuously larger than the punctures on the interstrial surface, as on the remainder species, see Fig. 6B). Transverse ridge on the elevation of the mesoventrite rather blunt, and slightly bisinuate.

Description.

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. 6A); surface of pseudepipleura anteriorly undulated, particularly at limit with epipleura, posteriorly smooth. Metafemora with pubescence only along articulation with trochanter, and sometimes along proximal 1/6 of anterior margin. Aedeagus (Figs 7 I–K) with parameres as long as median lobe, and nearly as wide at apical 1/4; parameres with outer margins nearly straight, only slightly curved inwards at apical 1/3; apical 1/3 of inner margin of parameres concave; apical 1/3 of parameres rather digitiform and straight, parallel to longitudinal axis of aedeagus. Median lobe with lateral margins straight, converging towards the apex; apex of aedeagus widely rounded; gonopore rather semicircular. Basal piece as long as 0.5-times the length of the median lobe, with lateral margins straight; manubrium 0.5 times the length and nearly as wide as the base of basal piece.

Etymology.

Named after Clusia , the genus of plants on whose decomposing fruits the beetles have been collected.

Variation.

There is slight variation in the proportions of the aedeagus. Some specimens might have a comparatively wider median lobe (Fig. 7K), or seem more slender overall (Fig. 7J).

Distribution.

Brazil (Amazonas), Guyana, Suriname. See Fig. 9B.

Biology.

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. 10 A–B). In Suriname, this species was collected on and beneath the rotten fruits of several Clusia species, including C. grandiflora and C. cf. nemorosa (Fig. 10 C–D). The beetles appear most common on fruits in a stage of decay where they are soft and sticky (as opposed to more advanced stages of decay in which the fruits become dry or crumbly). The beetles were also present in leaves beneath the decaying fruits into which rotting fluids had seeped. Most specimens were collected by collecting these fruits and submerging them in pans of water, at which time the beetles float to the surface. We collected hundreds of specimens on several occasions using this method. However, not all rotten Clusia patches we examined (some even within 1 km of other patches with Quadriops abundance) contained many or any Quadriops specimens. We sifted general forest litter and did extensive aquatic collecting at sites in Guyana and Suriname where we found abundant Quadriops clusia populations, but no specimens were ever found in these habitats. We also laid baits of other fruits including bush cashews and bananas but these were not successful in attracting Quadriops . We believe the habitat of this species is likely restricted to rotten fruits, and possibly only those from Clusia . Quadriops clusia has been collected at elevations between 500 and 700 m.