Hydrochus pseudosecretus Oliva

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: 14-15

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Hydrochus pseudosecretus Oliva

new status

Hydrochus pseudosecretus Oliva   , new status

Figs. 2 View FIGURE 2 , 4A View FIGURES 4 , 10 View FIGURE 10

Hydrochus pseudosecretus Oliva 1996: 321   .

Hydrochus purpureus Knisch   : Makhan (1998: 148); misidentification

Material examined (211): Venezuela: Amazonas: AS-06-013 (4 SEMC)   ; VZ09-0115 View Materials   - 03 View Materials A (1 SEMC)   ; VZ09- 0115 View Materials   - 03 View Materials B (31 SEMC)   . Apure: AS-06-019 (2 SEMC)   ; VZ09-0117 View Materials - 01X (8 SEMC, MIZA)   . Barinas: VZ12-0125- 01A (2 SEMC)   , VZ12-0125 View Materials   - 02 View Materials A (1 SEMC)   ; VZ12-0126 View Materials   - 01 View Materials B (1 SEMC)   . Bolivar: VZ09-0112-01A (31 SEMC)   ; VZ09-0112 View Materials   - 01 View Materials B (1 SEMC)   ; VZ09-0112 View Materials   - 01 View Materials C (61 SEMC, MIZA, MALUZ)   ; VZ09-0112   - 02 A (3 SEMC)   ; VZ09- 0112 View Materials   - 02 View Materials B (1 SEMC)   . Cojedes: VZ12-0121-03A (1 SEMC)   . Guarico: VZ09-0108- 03X (1 SEMC)   ; VZ09-0110 View Materials   - 01 View Materials A (8 SEMC)   ; VZ09-0110 View Materials - 02X (9 SEMC)   ; VZ09-0111 View Materials   - 01 View Materials M3 View Materials (1 SEMC)   ; VZ10-0705 View Materials   - 02 View Materials B (1 SEMC)   ; Calabozo (44 km S), Hato Masaguaral , 5 Mar 1986, PJSpangler, colln#24 (42 NMNH)   ; Corozo Pando , (8kmN), 17–18 June 1984, blacklight, F. W. Eiland & V. Linares (11 NMNH)   ; Corozo Pando , (8kmN), 11 June 1984, F. W. Eiland II (1 NMNH)   ; Calabozo (44 km S); 8 km SE Calabozo, May 4, 1985, ex light trap, P.A. Stansly (3 TAMU)   . 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 large size (ca. 3.85–4.85 mm), the very coarsely densely punctate dorsum, the comparatively small pronotum, and the male genitalia ( Figs. 4A View FIGURES 4 , 10 View FIGURE 10 ; described below). The habitus is most similar to that of H. secretus Knisch   , which is not yet known from Venezuela; compare habitus with figures of the lectotype of that species in Perkins (in press).

Description: Habitus as illustrated ( Fig. 10 View FIGURE 10 ). Size of illustrated male (length/width, mm): body (length to elytral apices) 4.48 /2.83; head width 1.09; pronotum l/w 1.00 /0.96; PA 0.91; PB 0.74; elytra 2.83 /1.70. Large (ca. 3.85–4.85 mm, Venezuelan specimens), elongate, last third of elytra abruptly narrowed. Dorsum grey, rarely dull gold, iridescent, with a few small black spots on elytra. Legs dark brown with darker tibiofemoral joints. Pronotum very coarsely and densely punctate. Elytra striae with coarse punctures, round to polygonal. Interstriae narrower than striae. Callus on 5 th interstria small but very strongly raised.

Pronotum narrowed at base; sides weakly sinuate, smooth (coarse punctures giving an appearance of crenulation), with minute granules smaller than ommatidia; punctures on pronotum very coarse (3–4 times the size of ommatidia), dense; disk raised; depressions deep.

Elytra with strial punctures several times larger than those on pronotum; interstriae narrower than striae, with indistinct minute granules smaller than ommatidia; apices rounded and broadened, forming an outward angle, having a very finely granulated apical area, otherwise smooth, in which there is a single coarse puncture beyond the last puncture of 2 nd stria. Females and males approximately the same size, without differentiating external characters.

Ventral characters: Mentum coarsely punctate, with median fovea. Submentum with two foveae.

Male genitalia ( Figs. 4A View FIGURES 4 , 10 View FIGURE 10 ) general characters: paramere tips widened apically, with distal margin truncate; parameres basally fused, in both dorsal and ventral views; aedeagus lacking transition lines and lacking adbl, lateral margins very narrowly sclerotized; basal piece arcuate in lateral view, orifice large, with apicoventral process arcuate toward dorsad.

Dorsal surface: pdmm very narrowly overlapping alm.

Ventral surface: pvmm very narrowly overlapping alm.

Remarks. Unfortunately, the drawing of the habitus in Oliva (1996) is very inaccurate with regard to proportions. The pronotum in the illustration, compared to the elytra, is much larger than that of all specimens examined in this study. There are other misleading inaccuracies, especially width of the base of the pronotum compared to the head width, hw/pb is 1.29 in the illustration, 1.47 in the imaged specimen ( Fig. 10 View FIGURE 10 ). Also, the male genitalia drawing of Oliva (1996) is overly simplified, and is inaccurate in, especially, the shape of the aedeagus. In stark contrast, the description of external characters by Oliva is very thorough. I have not seen the holotype: several messages sent to MACN collections personnel requesting to borrow the holotype but no response was received. A. Oliva no longer works at the MACN, and therefore was unable to help. My concept is based on two paratypes, including one male, in the NMNH collection. The specimen imaged ( Fig. 10 View FIGURE 10 ) was collected at locality VZ09-0112-01A.

H. pseudosecretus Oliva   is hereby reinstituted as a valid species. Makhan (1998) incomprehensibly placed H. pseudosecretus   as a junior synonym of H. purpureus Knisch   , as the two species are markedly dissimilar in both habitus and male genitalia. Refer also to Perkins (2019) on the identity of Hydrochus purpureus Knisch.  


University of Kansas - Biodiversity Institute


Museo del Instituto de Zoologia Agricola Francisco Fernandez Yepez


Smithsonian Institution, National Museum of Natural History


Canadian Museum of Nature














Hydrochus pseudosecretus Oliva

Perkins, Philip D. 2019

Hydrochus purpureus

Makhan, D. 1998: 148

Hydrochus pseudosecretus

Oliva, A. 1996: 321