Taxonomy of Central American water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae)
Perkins, Philip D.
Zootaxa
2021
2021-05-21
4974
3
459
503
8Y4NX
Perkins, 2021
Perkins
2021
[151,440,1255,1282]
Insecta
Hydrochidae
Hydrochus
Animalia
Coleoptera
3
462
Arthropoda
species
aeruginosus
sp. nov.
Figs. 1, 26, 29
Type material. Holotype(male): “ MEXICO: Sonora, Rio Cuchujaqui, 7 mi.SE Alamos, ( 26°57’N, 108°51’W), black lite, 25-x-1972, E. M. Fisher” ( MCZ). Paratypes(27):Same data as holotype (21 MCZ); Mexico: Jalisco, Agua Caliente, unnamed stream, ( 20°23’N, 105°26’W), 15.i.2005, leg. W. D. Shepard(WDS-A-1624) (5 SEMC); Nayarit, Acaponeta, 15.viii.1960, leg. E. S. Ross, D. C. Rentz, P. H. Arnaud Jr. (1 CAS).
Differential diagnosis.Among Central American species, recognized by the combination of small size (ca. 2.50 mm), the smooth dorsum with relatively sparse pronotal punctation, the lack of a callus on the 5 thelytral interstria, the greenish-blue dorsal color, and the male genitalia ( Fig. 26; described below). This species has a generalized Hydrochushabitus; reliable determinations will require dissection of males. The male genitalia are readily recognized by the paramere tips which arc over the aedeagus, the latter being widest near the distal end, an unusual condition; also the shape of the basal piece orifice is unusual.
Description. Habitus as illustrated ( Fig. 3). Size: holotype(length/width, mm): body (length to elytral apices) 2.50/0.92; head width 0.65; pronotum l/w 0.58/0.65; PA 0.62; PB 0.52; elytra 1.63/0.92. Habitus as illustrated ( Fig. 26). Body size moderate (ca. 2.50 mm). Dorsum greenish blue, with strong to moderately strong iridescence, elytra without black spots. Punctation on elytra ca. 3–5x that of pronotum. Elytra interstriae ca. 0.5–1.5× strial puncture diameter. Interstria 9 thmore convex than others, overhanging 10 thinterstria. Usual area of callus on 5 thvery weakly raised, if at all. Pronotum slightly wider than long, widest slightly behind anterior margin, narrowed at base, sides arcuate, smooth; anterior margin slightly bisinuate; reliefs very sparsely punctate, depressions more densely punctate; depressions deep. FIGURE 1.Dorsal habitus of Central American Hydrochusspecies. FIGURE 2.Dorsal habitus of Central American Hydrochusspecies. Elytra with spaces between strial punctures narrow walls to ca. 1x their diameter; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with very slight angulation. Ventral characters: Mentum coarsely moderately densely punctate, with large median fovea. Submentum with two large foveae. Legs dark brown, tibiofemoral joints slightly darker. Male genitalia ( Fig. 26) general characters: paramere tips only moderately slender, without plsa, with pmsm, slightly narrower in lateral view than in dorsal/ventral views, in dorsal/ventral views with distal tips meeting, medial margins arcuate around distal end of aedeagus; pseudoparameres attaining ca. midlength of parameres, tapering distally; aedeagus in dorsal/ventral views widest subapically, tapering from widest point to base; in lateral view wider, especially basally; lateral margins of aedeagus sclerotized; basal piece shorter than parameres, parallel-sided or nearly so in dorsal/ventral views, orifice sclerotized and produced in semi-cup shape. Dorsal surface: pdmm wide at adtl, then very narrowly separated; adbl small; adtl at about distal 1/5. Ventral surface: pvmm much more widely separated than pdmm, approximating lateral margin of aedeagus; avtl at ca. midlength of aedeagus.
Etymology.Named in reference to the greenish-blue dorsal color.
3128194380
1972-10-25
MCZ
E. M. Fisher
Mexico
26.95
Rio Cuchujaqui
1239
-108.85
3
462
1
Sonora
holotype
3128194388
[662,1239,1400,1427]
1972-10-25
MCZ
E. M. Fisher
Mexico
26.95
Rio Cuchujaqui
1239
-108.85
3
462
1
Sonora
paratype
3128194559
2005-01-15
SEMC
W. D. Shepard
Mexico
20.383333
Agua Caliente
1268
-105.433334
3
462
1
Mexico
paratype
3128194515
[151,1134,1472,1499]
1960-08-15
CAS
E. S. Ross & Ross, D. C & Rentz, P. H
Mexico
Acaponeta
3
462
1
Nayarit
paratype