Hydrochus triangularis, 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 : 36-37

publication ID

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

publication LSID

lsid:zoobank.org:pub:107FCA64-345F-40A4-99D3-5C1441EEAD93

DOI

https://doi.org/10.5281/zenodo.5043982

persistent identifier

https://treatment.plazi.org/id/03A187DE-FFDF-FFDB-6194-FCB207CEF646

treatment provided by

Plazi

scientific name

Hydrochus triangularis
status

sp. nov.

Hydrochus triangularis View in CoL , new species

Figs. 3 View FIGURE 3 , 7 View FIGURES 6–7 , 57 View FIGURES 57–58

Type Material. Holotype (male): Brazil: Mato Grosso, “ Rio Caraguata, M. Grosso, Brazil, IX-53, 21°48’S, 52°27’W, 400M alt., Fritz Plaumann leg.” ( NMNH). Paratypes (5): Bolivia: Beni Department, 7 km SW Trinidad, 14°52’12’’S, 64°57’32’’W, 163m, 18.vii.1998, leg. K. B. Miller ” (1 SEMC). Brazil: Mato Grosso, Corumba leg. F. Plaumann [no date] (1 NMNH). Paraguay: Central Dept. , 2 km N Luque, 23–24.vi.1969, leg. P. & P. Spangler (1 NMNH); Dep. Cordillera, San Bernadino, 23.vii.1998, leg. U. Drechsel (2 NMW). GoogleMaps

Differential Diagnosis. Among species in the study area, recognized by the combination of moderate size (ca. 3.20 mm), the brown dorsum without black spots, the nearly parallel-sided body form, the pronotal depressions moderately deep, much more densely punctate than the low reliefs between depressions, and the male genitalia ( Fig. 7 View FIGURES 6–7 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males. The paramere tips are shaped similarly to those of H. distinctus ( Fig. 6 View FIGURES 6–7 ); however, the other aspects of the male genitalia, and especially the dorsal habitus, differ in the two species.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 3.20/1.02; head width 0.75; pronotum l/w 0.69/0.70; PA 0.70; PB 0.59; elytra 2.06/1.02. Habitus as illustrated ( Fig. 7 View FIGURES 6–7 ). Body size moderate (ca. 3.20 mm). Dorsum brown, with very slight to no iridescence, elytra without black spots. Legs testaceous, with tibiofemoral joints darker. Body form narrow (l/w ratio ca. 86/27). Punctation on elytra ca. 1–2x that of pronotum. Elytra interstriae ca. 1–1.5x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th moderately raised, moderately elongate, ca. 5 punctures on each side.

Pronotum very slightly wider than long (ratio ca. 19/18), widest at anterior margin, narrowed at base, sides slightly arcuate or very weakly sinuate, minutely denticulate; anterior margin slightly bisinuate; depressions moderately deep, much more densely punctate than low reliefs between depressions.

Elytra with spaces between strial punctures narrow walls to ca. 0.5x their diameter; apices rather sharply separately rounded in dorsal view, in lateral view outer margin with slight angulation.

Ventral characters: Mentum punctate, with central depression; submentum with two foveae.

Male genitalia ( Fig. 7 View FIGURES 6–7 ) general characters: genitalia large, elongate, length ca. 5x greatest width, basal piece very slightly shorter than parameres (ratio ca. 39/41); paramere tips extending slightly beyond aedeagus tip, medial margins beyond aedeagus tip parallel, plsa large, rounded, lateral margins between plsa and apex slightly arcuate; in lateral view parameres slightly arcuate, wide basally, tapering to sharply pointed apically; aedeagus wide, agw at ca. proximal 1/3, narrowing from there to apex and to base; basal piece in dorsal/ventral views parallel-sided, width in dorsal/ventral views and lateral view ca. equal, in lateral view very slightly arcuate, orifice slightly asymmetrical, margin sclerotized.

Dorsal surface: adtl at ca. distal 1/5; pdmm well separated in distal 1/5, remainder sinuate and overlapping alm; adbl very large, rounded laterally.

Ventral surface: avtl not apparent; pvmm more widely separated than pdmm, overlapping alm except for ca. distal 1/5.

Etymology. Named in reference to the triangular paramere tips.

NMNH

Smithsonian Institution, National Museum of Natural History

SEMC

University of Kansas - Biodiversity Institute

NMW

Naturhistorisches Museum, Wien

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Hydrochidae

Genus

Hydrochus

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