Quadriops depressus Hansen, 1999

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 : 122-123

Quadriops depressus Hansen, 1999 Figs 2 A–D, 7 A–D, 9A

Quadriops amazonensis García, 2000: 59, syn. n.

Quadriops depressus Hansen, 1999: 136.

Quadriops politus Hansen, 1999: 135, syn. n.

Type material examined.

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" (SEMC). Paratypes: Q. depressus : "PERU: Dept. [Departamento] Loreto/ Teniente Lopez/ 2°35.66'S, 76°06.94'W / 23 July 1993, 210-240 m/ Richard Leschen #191/ ex flight intercept trap", "[Handwritten] HOLOTYPE/ Quadriops depressus / M. Hansen" (SEMC); "PERU: Dept. [Departamento] Loreto/ Campamento San Jacinto/ 2°18.75'S, 75°51.77'W / 11 July 1993, 175-215 m/ Richard Leschen #84/ ex: flight intercept trap", "[Handwritten] PARATYPE/ Quadriops depressus / M. Hansen" (SEMC).

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". (MALUZ).

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" (SEMC). Paratype: "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] PARATYPE/ Quadriops politus / M. Hansen", "[Barcode]/ SEMC0965917/ KUNHM-ENT" (SEMC).

Additional material examined

(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 (SEMC, 1); Madre de Dios: Pantiacolla Lodge, 8 km NW El Mirador Trail, Alto Madre de Dios River, 800 m, 12°38'30"S, 71°16'41"W, 23-26 OCT 2000, R. Brooks, PERU1B00 102, ex. flight intercept trap // "Barcode/ SM0260334/ KUNHM-ENT" (SEMC, 1 female). VENEZUELA: Amazonas: T. F. Amaz. Cerro de la Neblina Basecamp, 140 m, 0°50'N, 66°10'W, 10-20 February 1985// Flight intercept pan trap in rainforest, P. J. & P. M. Spangler, R. A. Faitoute, W. E. Steiner colrs." (1 male, USNM).

Differential diagnosis.

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. 1), 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. 6). It can be separated from Q. reticulatus by the dorsal outline of the body being nearly flat (as opposed to moderately convex), and the surface of the pseudepipleura posteriorly markedly canaliculated (see Fig. 2C; as opposed to smooth). Quadriops depressus can be distinguished from Q. similaris by the rounded shape of the apex of the parameres (see Fig. 7 A–D; as opposed to angulate, as in Fig. 8).

Redescription.

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 7 A–D) with parameres slightly longer than median lobe; parameres with outer margins nearly straight, only slightly curved inwards at apical 1/3; apical 1/3 of inner margin of parameres concave; apical 1/6 of parameres digitiform, with rounded apex slightly directed towards longitudinal axis of aedeagus. Median lobe with lateral margins straight, slightly converging from base; apex of aedeagus widely rounded; gonopore rather semicircular. Basal piece as long as 0.4-times the length of the median lobe, with lateral margins straight; manubrium 0.5-times the length and clearly narrower than the base of basal piece.

Variation.

There is variation on the density and presence of reticulation on the surface of the frons and clypeus.

Distribution.

Peru (Loreto), Ecuador (Napo), Venezuela (Amazonas). See Fig. 9B.

Biology.

All known specimens were collected with flight intercept traps.

Remarks.

It is known that the shape of the aedeagus exhibit intraspecific variation in several acidocerine species (see Short et al. 2017), including Q. similaris below. Given the similarity of the illustrations provided by Hansen (1999) and García (2000), and the lack of external characters (beyond the density and presence of reticulation on the surface of the frons and clypeus) to clearly distinguish Q. amazonensis and Q. politus from Q. depressus , we dismounted the aedeagi of the holotypes of the latter two species to compare them directly. The aedeaegus of all three type specimens, along with an additional male from Venezuela, share the same overall shape, with only slight variations in proportions that may be due in part to the preparation of the structures. Further, we found the illustration of the aedeagus of the type of Q. politus to be incor rectly interpreted ( Hansen 1999: fig. 24); specifically, the apex of the median lobe is drawn to appear very constricted and acutely pointed, while in fact it is broad and blunt as with most other Quadriops . This apex of the median lobe was strongly cleared in the type and was not readily visible until we dismounted the genitalia to view it with transmitted light. This mistaken interpretation of the aedeagal shape seems likely to be why Hansen had considered this to be a separate species when in fact it does not appear so. Given the similarity of the aedeagi, coupled with the lack of any detectable external differences, we consider Q. amazonensis and Q. politus both junior synonyms of Q. depressus .