Gyrinus (Oreogyrinus) colombicus Régimbart, 1883

Gustafson, Grey T. & Short, Andrew E. Z., 2017, Review of the whirligig beetle genus Gyrinus of Venezuela (Coleoptera: Gyrinidae), Acta Entomologica Musei Nationalis Pragae 57 (2), pp. 479-520 : 501-502

Gyrinus (Oreogyrinus) colombicus Régimbart, 1883

( Fig. 47 )

Gyrinus colombicus Régimbart, 1883: 180 (original description). Gyrinus (Oreogyrinus) colombicus: OCHS (1953) : 184 (new status).

Type locality. ‘Colombia’.

Typematerial examined. SYNTYPE: J, ‘Colombie [beige label, handwrittenblack ink]’ ‘MUSEUM PARIS / COLL. MAURICE REGIMBART / 1908 [green label, typed black ink]’ ‘R. Mouchamps vid., 1955 / GYRINUS / colombicus Rég / [white label, R. Mouchamps vid., 19- typed black ink, -55 GYRINUS colombicus Rég. Handwritten black ink]’ ( MNHN).

Other material examined. VENEZUELA: without additional data (1 spec. BMNH). Non-Venezuelan material examined. COLOMBIA: ‘Colombie’, Sharp Col. 1905-313 (1 spec. BMNH). SUCRE: Cuenca (1 spec. BMNH). Without locality: Sharp Col. 1905-313 (2 spec. BMNH).

Diagnosis. Body form oval, in lateral view strongly convex; pronotal disc with transverse creased strongly impressed, laterally with sparse wrinkles; elytral disc of female with at most intervals I–II non-reticulate, III–X strongly reticulate, XI non-reticulate; female elytral striae VI–IX sulcate, only VII–IX strongly so; elytrallateral marginweakly interrupted before apex; metanepisternal ostiole present; aedeagus ( Fig. 47 ) with median lobe evenly narrowed for 2/3 length, weakly expanded towards apex in apical 1/3, apex broadly rounded; parameres truncate apically.

Gyrinus colombicus is most similar to G. venezolensis having a relatively weakly wrinkled pronotum. The strongly reticulate female elytra of G. colombicus should easily prevent confusion with females of both G. venezolensis and G. vinolentus sp. nov. as the reticulation covers nearly the entire elytron (at least to interval II), whereas in G. venezolensis and G. vinolentus sp. nov. females the reticulation is present up to at most interval IV. The aedeagus ( Fig. 47 ) will easily distinguish males of G. colombicus from both G. venezolensis and G. vinolentus sp. nov.

Redescription. Size. Female length = 5.5– 6.0 mm, width = 3.5 mm; male length = 4.5–5.0 mm, width = 3.0 mm. Habitus. Body form evenly oval, attenuated anteriorly and posteriorly, slightly more so posteriorly, widest point just posteriad of humeral region; in lateral view dorsoventrally strongly convex, greatest convexity posterior to scutellar region, evenly depressed anteriorly and posteriorly.

Coloration. Dorsally, head, pronotum, elytra black, with blue reflections; laterally reflections bronzy yellow and green, especially in females whose elytral lateral reticulation appears strongly bronzy green. Venter overall darkly colored; mouthparts, ventral surface of antennal pedicel, hypomeron, elytral epipleuron, mesoventrite medially, mesocoxae, and ultimate abdominal ventrite lighter in color – reddish brown to darker orange yellow; legs yellow in color; remainder of venter dark brown to black.

Sculpture and structure. Pronotum ofboth sexes with broad riffled lateral margins; pronotal disc laterally weakly wrinkled, wrinkles present anteriorly and associated with pronotal transverse impressed line, wrinkles also present posteriorly near posterior margin of pronotum. Female elytra with striae I–IV non-sulcate, elytral striae Vweakly sulcate medially, VI slightly more sulcate medially, VI–IV strongly sulcate posteriad of humeral region with linear punctures medially, stria X non-sulcate, stria XI strictly marginal. Female elytral disc nearly entirely reticulate with at most intervals I–II free of reticulation, XI never with reticulation, reticulation composed of scale-like sculpticells. Male elytra with striae I–VII non-sulcate; VIII–IX weakly sulcate just posterior to humeral region, ending before apical 1/3 of elytron; stria X non-sulcate; stria XI strictly marginal. Male elytral disc with intervals I–XI without reticulation. Elytra ofboth sexes withlateralmargins weakly interrupted inapical 1/5 by minor swelling; elytral apex truncate to weakly rounded. Metanepisternal ostiole small.

Male genitalia ( Fig. 47 ). Aedeagus with median lobe narrow, shorter than parameres, attenuated towards apex in basal 2/3, in apical 1/3 weakly laterally expanded towards apex, apex broadly rounded, medially weakly raised; in lateral view median lobe thick, strongly dorsally curved; parameres with apex strongly truncate.

Variability. Of the few female specimens examined, there was variability in the extant of the reticulate region of the elytra. Two of the three specimens examined had the reticulation extending to elytral interval II, while the third had the reticulation extending all the way onto interval I, reaching the elytral sutural border in areas.

Habitat. Unknown

Distribution. Colombia.

Discussion. This species is primarily known from historical specimens from Colombia and ‘Venezuela’, often withlittle orno further specific localityinformation ( RÉGIMBART 1907, OCHS 1953). In his first treatmentof the Venezuelan Gyrinidae, OCHS (1953) included G. colombicus stating the species is likely to be found in western Venezuela. However, he only examined specimens from Colombia, and believed most of the historical Colombian specimens to be from Bogotá ( OCHS 1953). In our study, only a single historical specimen was examined with the locality of ‘Venezuela’ from the BMNH, and the species was not recollected during the Venezuelan aquatic insect survey, despite multiple sampling localities in the western Venezuelan Andes. It seems likely the historical specimens from ‘Venezuela’ are in error, and that the species does not truly occur in Venezuela. For this reason, we did not extensively treat G. colombicus , but to aid in its identification, should it be found in Venezuela in the future, we provide a redescription of the specimens examined and an image of the aedeagus of a syntype in the MNHN.

Figures

Figs 47–50. Dorsal and lateral view of the aedeagus of Oreogyrinus species, not to scale. 47 – Gyrinus colombicus Régimbart, 1883, syntype (MNHN). 48 – G. venezolensis Ochs, 1953. 49 – G. vinolentus sp. nov. 50 – G. iridinus sp. nov.