Hydrochus variabiloides, Perkins, 2019

Perkins, Philip D., 2019, Taxonomy of Venezuelan water beetles in the genus Hydrochus Leach, 1817, and an analysis of male genitalia morphology (Coleoptera: Hydrochidae), Zootaxa 4708 (1), pp. 1-59 : 32-34

Hydrochus variabiloides new species

Figs. 1 , 3 , 19

Type Material. Holotype (male): “Venezuela: Barinas State: 8° 28.477’ N, 70° 32.194’ W, 205m, E. Los Pasitos, marshy pond on hacienda, 14.vii.2009, leg. Short et al.; VZ09-0714-05A” ( MIZA) . Paratypes (87): Venezuela: Anzoategui: VZ10-0204-01A (8 SEMC) . Apure: VZ09-0118- 02X (7 SEMC, MALUZ) . Barinas: Same data as holotype (10 SEMC, MIZA) . Bolivar: El Dorado (65 km S), 1 Nov. 1982, John L. Hellman (2 NMNH) . Cojedes: VZ12-0121-02A (1 SEMC) . Guarico: Calabozo (44 km S), Hato Masaguaral , 6 Mar 1986, gate lagoon, PJSpangler, colln#28 (38 NMNH) ; Corozo Pando , (8kmN), 17–18 June 1984, blacklight, F. W. Eiland & V. Linares (1 NMNH) ; Calabozo (44 km S), Hato Masaguaral , 6 Mar 1986, PJSpangler & SBeaujon, colln#31 (16 NMNH) ; San Fernando , II-12-1969, P. & P. Spangler (2 NMNH) ; 15 km S. Calabozo II-9-13-1969, collected in Lago de Los Patos , P. & P. Spangler (1 NMNH) . Miranda: Guatopo NP, El Lucero , 28km N Altagracia, 620m, 1–14.VI.1987, S&J Peck, UV light trap 87-17 (1 CMN) .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of moderate size (ca. 2.38– 3.62 mm), the very low and relatively impunctate pronotal reliefs, and the distinctive male genitalia, with elongate parameres, the apices of which are laterally produced ( Fig. 19 ; described below). Externally, and male genitalically, quite similar to H. variabilis . This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males.

Description. Habitus as illustrated ( Fig. 19 ). Size: holotype (length/width, mm): (length/width, mm): body (length to elytral apices) 3.11/1.06; head width 0.71; pronotum l/w 0.69/0.74; PA 0.66; PB 0.60; elytra 1.89 /1.06. Size range ca. 2.38–3.62 mm. Dorsum grey, with slight iridescence, elytra with few elongate black spots. Legs testaceous, with tibiofemoral joints darker. 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, not overhanging 10 th interstria. Usual area of callus on 5 th very slightly raised.

Pronotum slightly wider than long, widest at behind anterior margin, narrowed at base, sides arcuate or very weakly sinuate, smooth; depressions very shallow to moderately deep, more densely punctate than very low reliefs between depressions, latter almost entirely impunctate.

Spaces between elytral strial punctures ca. 0.5– 2x their diameter; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with slight angulation.

Male genitalia ( Fig. 19 ) general characters: parameres extending well beyond distal end of aedeagus; paramere apices in dorsal and ventral views slightly widened and turning outward, medial margins of paramere tips parallel, in lateral view tips narrow, slightly sinuate, with tips slightly widened subapically, and distal ends sharply pointed; aedeagus almost parallel-sided; basal piece comparatively short and robust, rim of orifice strongly sclerotized and produced in very small process apicoventrally.

Dorsal surface: adtl subapical; pdmm sinuate and overlapping lateral margins of aedeagus; adbl large, shape as illustrated.

Ventral surface: avtl V-shaped, near basal 1/3 of aedeagus; pvmm more widely separated than pdmm. Etymology. Named in reference to the similarity of the male genitalia to that of H. variabilis .

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 3. Male genitalia characters of H. variabiloides n. sp., dorsal (left) and ventral.

FIGURE 19. Hydrochus variabiloides n. sp., habitus and male genitalia of holotype.