Hydrochus sculptissimus, Perkins, 2021

Perkins, Philip D., 2021, Taxonomy of water beetles in the genus Hydrochus Leach, 1817, from Bolivia, Brazil and Paraguay (Coleoptera: Hydrochidae), Zootaxa 4994 (1), pp. 1-93 : 35-36

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https://doi.org/ 10.11646/zootaxa.4994.1.1

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Hydrochus sculptissimus

sp. nov.

Hydrochus sculptissimus View in CoL , new species

Figs. 1 View FIGURE 1 , 48 View FIGURES 48–49 , 55 View FIGURES 55–56 , 70 View FIGURE 70

Type Material. Holotype (male): “ BRAZIL: Para ; Rio Xingu Camp, (3°39’S, 52°22’W), Altamira (ca. 60km S.), 15 Oct. 1986, P. Spangler & O. Flint // Colln. #24 pond at 2nd palm grove on trail 1” ( NMNH). GoogleMaps

Differential Diagnosis. Among Brazilian species, recognized by the combination of small size (ca. 2.45 mm), black color, the highly sculptured dorsum, with deep foveae, costate elytral interseries, and abruptly raised, nipplelike, callus of 5 th elytral interstria, and the male genitalia ( Fig. 48 View FIGURES 48–49 ; described below). Reliable differentiation from other similarly small sized black species with costate elytra should include dissection of males.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.45/1.02; head width 0.62; pronotum l/w 0.65/0.65; PA 0.65; PB 0.46; elytra 1.51/1.02. Habitus as illustrated ( Fig. 48 View FIGURES 48–49 ). Dorsum black, except testaceous callus of 5 th interstria; very slight iridescence in depressions. Legs brown, lateral margin of tibiae with row of spines. Head with frons medially tumid, with longitudinal punctate groove on each side of tumidity. Punctation on elytra ca. 3–5x that of pronotum. Callus on 5 th small, round, high, very abruptly raised, with short setae.

Pronotum slightly wider than long (ratio ca. 9/8), widest slightly behind anterior margin, strongly narrowed at base, sides weakly sinuate, non-denticulate; anterior margin bisinuate; lateral and anterior margins with row of moderately long setae; depressions large, deep, much more densely punctate than almost impunctate rather sharp reliefs.

Elytra with sutural and intervals 3, 5, 7, and 9 costate; costa of 7 th interval interrupted in midlength, other costae complete; punctures very large, spaces between strial punctures narrow walls to ca. 0.5x their diameter, many punctures in off-set pattern; apices acuminate, rather sharply separately rounded in dorsal view, in lateral view outer margin without angulation.

Ventral characters: Mentum punctate, with central depression; submentum setose, without foveae.

Male genitalia ( Fig. 48 View FIGURES 48–49 ) general characters: genitalia without parameres, basal piece elongate, trisinuate in lateral view, in dorsal/ventral views straight, slightly widened at ca. midlength and at distal 3/4; distal end with concavity on dorsal surface, minute bifurcate process in concavity.

Etymology. Named in reference to the very highly sculptured dorsum.


Smithsonian Institution, National Museum of Natural History













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