Quadriops similaris 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 : 126-131

Quadriops similaris Hansen, 1999 Figs 2 E–H, 8, 9C

Quadriops similaris Hansen, 1999: 136

Type material examined.

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" (CMNC). [Holotype female from Guyana in NHMUK, not examined].

Additional material examined

(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, NHMUK). GUYANA: Region 8: Iwokrama Forest, Pakatau hills, 70 m, 4°44'54"N, 59°1'36"W, 25-29 MAY 2001, R. Brooks, Z. Falin, GUY1BF01 061, ex: flight intercept trap // Barcode: SM0569493 (SEMC, 1); Iwokrama Forest, 1 km W Kurupukari, Iwokrama Field Stn., 60 m, 4°40'19"N, 58°41'4"W, 21 MAY 2001, R. Brooks, Z. Falin, GUY1BF01 005, ex: Acromyrmex hystrix refuse pile // Barcodes: SM0569493 (SEMC, 1); SM0568525 (SEMC, 1 male, dissected); SM0568547 (SEMC, 1 female, dissected); 26-29 MAY 2001, R. Brooks, Z. Falin, GUY1BF01 064, ex: flight intercept trap // Barcode: SM0569493 (SEMC, 1); Iwokrama Forest, 26 km SW Kurupukari, Iwokrama Mt., 300 m, 4°20'2"N, 58°47'18"W, 23-25 MAY 2001, R. Brooks, Z. Falin, GUY1BF01 031, ex: flight intercept trap // Barcode: SM0570965 (SEMC, 1); Iwokrama Forest, Turtle Mt. base camp, 50 m, 4°43'5"N, 58°43'5"W, 1 JUN 2001, R. Brooks, Z. Falin, GUY1BF01 105, ex: fogging splintered tree trunk // Barcodes: SM0564705 (SEMC, 1 male, dissected), SM0564703 (SEMC, 1 male), SM0564690 (SEMC, 1 male), SM0564710 (SEMC, 1), SM0564711 (SEMC, 1), SM0564721 (SEMC, 1). FRENCH GUIANA: Cayenne: 33.5 km S and 8.4 km NW of Hwy N2 on Hwy D5, 4°48'18"N, 52°28'41"W, 30 m, 26-28 MAY 1997; J. Ashe, R. Brooks, FG1AB97 057, ex: flight intercept trap // Barcode: SM0099106 (SEMC, 1 female, dissected); 29 MAY– 9 JUN 1997; J. Ashe, R. Brooks, FG1AB97 171, ex: flight intercept trap // Barcode: SM0102330 (SEMC, 1 male, dissected), SM0101058 (SEMC, 1 female), SM0131132 (SEMC, 1 male, dissected); Roura: 8.4 km SSE, 200 m, 4°40'41"N, 52°13'25"W, 22-24 MAY 1997; J. Ashe, R. Brooks, FG1AB97 027, ex: flight intercept trap // Barcodes: SM0101145 (SEMC, 1 female, dissected); SM0101159 (SEMC, 1 male, dissected); 4°40'0"N, 52°13'0"W, 29 MAY– 10 JUN 1997; J. Ashe, R. Brooks, FG1AB97 182, ex: flight intercept trap // Barcodes: SM0121078 (SEMC, 1); SM0121118 (SEMC, 1 female); 39.4 km SSE, 270 m, 4°32'43"N, 52°8'26"W, 10 JUN 1997; J. Ashe, R. Brooks, FG1AB97 173, ex: under fermenting bark // Barcode: SM0098799 (SEMC, 1 female). SURINAME: Saramacca: West Suriname Road, 178 km WSW Zanderij Airport, 25 m, 4°59'6"N, 56°18'48"W, 13 JUN 1999; Z. H. Falin; SUR1F99 070, ex: splintered tree trunk (pyrethrum fogging) // Barcodes: SM0181529 (SEMC, 1), SM0181531 (SEMC, 1 female, dissected); SM0181968 (SEMC, 1 male, dissected); Sipaliwini: Palumeu, 15 km NE, on Tapanahony River, trail to Poti Hill, ca 160 m, 3°27'N, 55°22'W, 6 JUL 1999; Z. H. Falin; SUR1F99 164, ex: splintered tree trunk (pyrethrum fogging) // Barcode: SM0184065 (SEMC, 1 male); Palumeu, ca 160 m, 3°20'56"N, 55°26'18"W, 8 JUL 1999; Z. H. Falin; SUR1F99 182, ex: splintered log (pyrethrum fogging) // Barcodes: SM0180696 (SEMC, 1), SM0180698 (SEMC, 1), SM0180699 (SEMC, 1 female, dissected); N 2.47700°, W 55.62941°, 275 m, Camp 1, Upper Palumeu, leg. A. Short; Flight Intercept Trap, 10-16.iii.2012; SR12-0310-TN1, 2012 CI-RAP Survey // Barcode: SEMC1089282 (SEMC, 1).

Differential diagnosis.

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. 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 uniformly convex), and the surface of the pseudepipleura posteriorly markedly canaliculated (see Fig. 2G; as opposed to smooth). Q. similaris can be distinguished from Q. depressus by the angulate shape of the apex of the parameres (see Fig. 8; as opposed to rounded, as in Fig. 7 A–D).

Redescription.

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. 8) with parameres usually longer than median lobe; parameres with outer margins straight to slightly convex along basal 3/4, then distinctly curved inwards at apical 1/4, or gradually curved from midlength; preapical area of inner margin of parameres concave; apex narrowly rounded, forming an acute angle pointing towards apex of aedeagus. Median lobe with lateral margins straight to somewhat sinuated, either parallel along basal 2/3 or converging from base; apex of aedeagus variable, wide to narrow, angulated to rounded; gonopore usually semicircu lar. Basal piece as long as 0.6-times the length of the median lobe, with lateral margins straight to sinuate; manubrium 0.3 times the length and clearly narrower than the basal piece at its base.

Variation.

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. 8H) in which the median lobe is longer than the parameres and the gonopore is rather oval.

Distribution.

Brazil (Amazonas), French Guiana, Guyana, Suriname, Venezuela ( Bolívar). See Fig. 9C.

Biology.

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.

Remarks.

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.