Hydraena xingu, Perkins, Philip D., 2011

Perkins, Philip D., 2011, New records and description of fifty-four new species of aquatic beetles in the genus Hydraena Kugelann from South America (Coleoptera: Hydraenidae), Zootaxa 3074, pp. 1-198 : 16

Hydraena xingu , new species

Figs. 5 (habitus), 12 (aedeagus), 156 (spermatheca), 193 (map)

Type Material. Holotype (male): Brazil: Para, Rio Xingu Camp, Altamira (ca 60km S.), 1st jungle stream on trail 4, colln. #6, 3° 39' S, 52° 22' W, 13 x 1986, P. J. Spangler & O. S. Flint. Deposited in the USNM. Paratypes (48): Brazil: Para, Rio Xingu Camp, Altamira (ca 60km S.), 1st jungle stream on trail 4, colln. #6, stream, 3° 39' S, 52° 22' W, 3 x 1986, P. J. Spangler & O. S. Flint (1 USNM); same locality, 3° 39' S, 52° 22' W, 8 x 1986, P. J. Spangler & O. S. Flint (10 USNM); same locality, 3° 39' S, 52° 22' W, 10 x 1986, P. J. Spangler & O. S. Flint (1 USNM); same locality, 3° 39' S, 52° 22' W, 13 x 1986, P. J. Spangler & O. S. Flint (29 USNM); Rio Xingu Camp, Altamira (ca 60km S.), Igarape Jabuti, malaise trap, day and night collection, 3° 39' S, 52° 22' W, 8–16 x 1986, P. J. Spangler & O. S. Flint (1 USNM); Rio Xingu Camp, Altamira (ca 60km S.), pond at 2nd palm grove on trail 1, colln. #20, pond, 3° 39' S, 52° 22' W, 12 x 1986, P. J. Spangler & O. S. Flint (3 USNM); same locality, 3° 39' S, 52° 22' W, 15 x 1986, P. J. Spangler & O. S. Flint (3 USNM).

Differential Diagnosis. Similar in dorsal habitus to H. paeminosa ( Figs. 3 , 5 ); differentiated therefrom by the much less coarsely punctate frons and slightly larger size (ca. 1.76 mm vs. 1.70 mm). Reliable determinations will require careful examination of the male genitalia ( Figs. 9, 12).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.76/0.75; head 0.25/0.40; pronotum 0.43/0.51, PA 0.44, PB 0.47; elytra 1.08/0.75. Dorsum of head dark brown to piceous; pronotum brown in front of and behind diffusely margined dark brown to piceous fascia, ratios of color bands, as measured in midline, ca. 8/12/6; elytra dark brown; legs brown; palpi brown to testaceous, tip not darker.

Dorsum of head microreticulate, dull. Frons punctures shallow, faint, ca. 1xef. Clypeus punctures obsolete. Mentum effacedly microreticulate, very sparsely very finely punctulate, dull; postmentum very finely densely micropunctulate and dull in median area, anterior margin smooth, shining. Genae raised in ridge posteriorly, except median 1/4 lacking ridge.

Pronotum and elytra coarsely densely punctate, subscabrous, interstices microreticulate, more markedly on pronotum than elytra. Pronotum with median 1/3 of anterior margin emarginate; scintilla absent; PF1 and PF2 absent; PF3 and PF4 deep, confluent, separated from lateral margin by low irregular ridge. Elytra with summit of posterior declivity slightly past midlength; lateral explanate margins narrow; punctures random. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. x/2 /7/4. P1 laminate; median carina sinuate in profile. P2 tapering to sharp point, tip contiguous with low median carina of metaventrite. Plaques moderately wide, narrowly separated, parallel, weakly raised, located at sides of shallow median depression. Metaventrite with median carina in anterior 1/2, also with very short point on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. equal plaque separation. Pro- and mesotibia very slightly arcuate, slen- der. Metatibia slender, straight. Male abdominal apex symmetrical; last tergite with apicomedian notch. Female (microslide mount, n=1): last tergite broadly rounded, without apicomedian notch, ca. 32 slightly hooked, long setae; gonocoxite divided by weakly sclerotized midlongitudinal area, apical margin broadly rounded, lacking transverse ridge; spermatheca disc type ( Fig. 156).

Etymology. Named in reference to the type locality.

Distribution. Currently known only from the type locality ( Fig. 193 ).

Figures

FIGURE 3. Hydraena paeminosa, holotype, dorsal and lateral habitus, and venter.

FIGURE 5. Hydraena xingu, holotype, dorsal and lateral habitus, and venter.

FIGURES 193 – 194. 193. Geographical distributions of species in the Paeminosa Group. 194. Geographical distributions of species in the Curvosa and Multispina Groups.