Taxonomy of Guatemalan water beetles in the genus Hydrochus (Coleoptera: Hydrochidae)
Author
Perkins, Philip D.
text
Acta Entomologica Musei Nationalis Pragae
2020
2020-04-23
60
1
291
301
journal article
21739
10.37520/aemnp.2020.016
6f4e1328-0bba-4f1c-aa66-4c1fe1fda040
1804-6487
3879760
45563A23-8582-4C53-81F3-591948E7A74D
Hydrochus sinuatus
sp. nov.
(
Figs 1
,
6
)
Type
material.
HƟĿƟŦYPൾ:male (
NMNH
):‘
GUATEMALA
, 20 Mi. SW Puerto Barrios
VIII-16-1965
Paul J. Spanglerʼ.
Differential diagnosis.
Among Guatemalan species,
H. sinuatus
is recognized by the combination of moderately small size (ca.
2.39 mm
), the densely coarsely punctate pronotum, and the male genitalia (
Fig. 6
; described below). This species has a generalized
Hydrochus
habitus; reliable determinations will require dissection of males.
Description.
Habitus as in
Fig. 6
. Size (in mm):
holotype
: body (length to elytral apices / width) 2.39 / 0.89; head width 0.58; pronotum length / width 0.53 / 0.55; PA 0.53; PB 0.48; elytra 1.52 / 0.89. Body size moderate. Dorsum black, with moderately strong iridescence, elytra with non-iridescent black spots. Legs dark brown, with tibiofemoral joints slightly darker. Punctation on elytra ca. 2–4× that of pronotum. Elytra interstriae ca. 0.5–1.0× strial puncture diameter. Interstria 9
th
more convex than others, overhanging 10
th
interstria. Callus on usual area of 5
th
interstria small, weakly raised.
Fig. 7.
Hydrochus steineri
sp. nov.
, habitus and male genitalia of holotype.
Pronotum length slightly less than width, widest just behind anterior angles, narrowed at base, sides very slightly sinuate, minutely denticulate; anterior margin bisinuate; depressions, especially anteromedian, deep, reliefs sharply raised, depressions more densely punctate than reliefs.
Elytra with spaces between strial punctures ca. 0.5–1.0× their diameter; 3
rd
interseries slightly raised over basal fourth; 4
th
interseries raised in area anterior to callus of 5
th
; apices rather sharply conjointly rounded in dorsal view, in lateral view with submarginal row of large punctures, bordered above by low ridge, outer margin with strong angulation.
Male genitalia (
Fig. 6
). General characters: paramere tips slightly widened, distal ends pointed, lateral margins arcuate, medial margins of tips emarginate and well separated from lateral margins of aedeagus, distal end of tips extending very slightly beyond aedeagus, in lateral view tips narrow, sharply pointed;
pwsa
distinctive; aedeagus moderately narrow in both dorsal/ventral and lateral views, in dorsal/ventral views margins sinuate, distinctly narrowed slightly past midlength in dorsal/ventral views, with narrowly sclerotized lateral margins; basal piece shorter than parameres, with rim of orifice strongly sclerotized.
Dorsal surface:
adtl
located slightly distal to midlength;
pdmm
narrowly overlapping
alm
over basal two-thirds, then markedly arcuate where paramere tips begin;
adbl
large, distinctively shaped.
Ventral surface:
pvmm
very slightly overlapping alm at base.
Etymology.
Named in reference to the shape of the parameres and aedeagus, which have sinuate lateral margins. Adjective.