Gyrinus (Neogyrinus) ovatus Aubé, 1838

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 : 493-497

Gyrinus (Neogyrinus) ovatus Aubé, 1838

( Figs 3 , 7–9 , 20–21 , 29 , 53 , 64–67, 74, 78)

Gyrinus ovatus Aubé, 1838: 708 (original description). Gyrinus (Neogyrinus) ovatus: OCHS (1935a) : 126 (new status). Gyrinus (Neogyrinus) racenisi Ochs, 1953: 188 (original description), syn. nov. Neogyrinus ovatus: CRESPO (1989) : 239 (new combination).

Type localities. Gyrinus ovatus : ‘ Brésil et Cayenne’ [ Brazil and Cayenne region, French Guiana]. Gyrinus racenisi : ‘Espino, Est. Guárico’ [ Venezuela].

Type material. Gyrinus ovatus : not studied, type depository unknown.

Gyrinus racenisi : PARATYPE: ♀ ( Fig. 78 ), ‘ ♀ [beige label, typed black ink]’ ‘ESPINO, GUÁR. / 29.2.50 / RACENIS L. [beige label handwritten in pencil]’ ‘R: 42 [beige label, typed black ink]’ ‘Coll. / G.Ochs [white label, typed black ink] ‘Para- / typoid / SMC C 9258 [red label, black border, typed black ink]’ ‘Senckenberg- /

Museum / Frankfurt / Main [white label, typed black ink]’ ‘ racenisi Ochs [beige label, handwritten, blue ink, handwriting Ochs’]’ ( SMF).

Other material examined. VENEZUELA: ANZOÁTEGUI: ‘ Transect #1’, 9°16’00.1”N, 64°13’42.9”W, 256 m, 15.viii.2009, leg. R.Cordero, temporary pond at a crossroad, VZ09-0815-11 A, SEMC0909798 – SEMC0909808 ; SEMC0909811 – SEMC0909813 ; SEMC0909816 (11 spec. SEMC) . APURE: San Fernando de Apure , 2.viii.1975, leg. J. K. Bouseman & R. B. Selander, USNM ENT 00717231 (1 spec. USNM) . FALCÓN: Sierra San Luis, W Curimagua, Blackwater lagoon, 11°10.342’N, 69°42.730’W, 1330 m, 11.vii.2009, leg. Short et al., VZ09-0711- 01 A, SEMC0862274 – SEMC0862284 ; SEMC0862294 – SEMC0862297 ; SEMC0862299 , SEMC0862307 – SEMC0862310 ; SEMC0862312 – SEMC0862314 ; SEMC0862318 – SEMC0862319 ; SEMC0862321 , SEMC0862323 – SEMC0862324 ; SEMC0862327 – SEMC0862328 ; SEMC0862330 – SEMC0862332 ; SEMC0862334 – SEMC0862342 ; SEMC0862345 – SEMC0862347 ; SEMC0862351 – SEMC0862354 ; SEMC0862358 , SEMC0862360 – SEMC0862366 ; SEMC0862368 , SEMC0862370 – SEMC0862373 ; SEMC0862375 – SEMC0862376 ; SEMC0862556 – SEMC0862558 ; SEMC082562 ; SEMC0862568 – SEMC0862574 ; SEMC0862576 – SEMC0862580 ; SEMC0862582 – SEMC0862583 ; SEMC0862585 – SEMC0862591 ; SEMC0862594 – SEMC0862597 ; SEMC0862599 , SEMC0862600 , SEMC0862603 , SEMC0862606 , SEMC0862610 SEMC0862613 ; SEMC0862616 – SEMC0862617 ; SEMC0862619 – SEMC08621 ; SEMC0862625 - SEMC0862627 ; SEMC0862629 – SEMC0862637 ; SEMC0862639 (120 spec. SEMC) ; Medanos de Coro , 11°26.215’N, 69°40.112’W, 8 m, 9.vii.2009, leg. Short et al., large pond in dunes, VZ09-0709-03 A, SEMC0862641 – SEMC0862649 ; SEMC0862651 – SEMC0862652 , SEMC0862654 – SEMC0862655 ; SEMC0862657 – SEMC0862665 ; SEMC0862786 – SEMC0862788 ; SEMC0862792 ; SEMC0862794 – SEMC0862799 ; SEMC0862801 ; SEMC0862833 – SEMC0862838 ; SEMC0862840 –SEMCSEMC0862858 ; SEMC0862860 – SEMC0862871 ; SEMC0862804 , SEMC0862808 – SEMC0862816 ; SEMC0862818 – SEMC0862821 ; SEMC0876793 ; SEMC0876816 ; SEMC0876846 ; SEMC0877874 ; SEMC0880612 – SEMC0880613 ; SEMC0880653 – SEMC0880655 ; SEMC0880666 . (95 spec. SEMC, MIZA, MALUZ) ; SE Tocopero , 11°26.922’N, 69°13.109’W, 12 m, 10.vii.2009, leg. Short et al., margin of large open pond, VZ09-0710-03 A, SEMC0862505 – SEMC0862506 ; SEMC0862508 – SEMC0862511 ; SEMC0862513 – SEMC0862514 ; SEMC0862516 ; SEMC0862520 ; SEMC0862522 – SEMC0862523 ; SEMC0862525 – SEMC0862526 ; SEMC0862528 – SEMC0862529 ; SEMC0862532 – SEMC0862533 ; SEMC0862538 – SEMC0862539 (20 spec. SEMC) . GUÁRICO: 20 km S Calabozo, collected in Rio Orituco , 8–13.ii.1969, leg. P. & P. Spangler, USNM ENT 00717229 (1 spec. USNM) ; 44 km S Calabozo, Hato Masaguaral , 5.iii.1986, leg. P. J. Spangler, colln#25, USNM ENT 00717232 (1 spec. USNM) ; Camaguan , 12.ii.1969, leg. P. & P. Spangler, USNM ENT 00717230 (1 spec. USNM) ; pond W Las Mercedes Rivs. , 9°5.067’N, 66°28.500’W, 8.i.2009, leg. Short & Miller, VZ 09010804 (1 spec. KBMC) ; nr. Socorro , 8°59’1.9”N, 65°44’18.8”W, 110 m, 29.vii.2008, leg. A. Short & M. García, muddy ditch, AS-08-050, SM0827656 (1 spec. SEMC). Non-Venezuelan material examined . BRAZIL: RIO DE JANERIO: Itatiaia , 17.iv.1960, leg. Borvs Malkin, temporary ‘middy’ puddle (27 spec. FSCA) .

Diagnosis. Body form ( Fig. 3 ) broadly oval, strongly convex in lateral view; pronotal and elytral margins broad, often yellow in color; elytral disc with non-uniform reticulation, medially appearing polished, laterally bronzy-metallic in appearance; striae V–XI ( Fig. 7 ) evident with distinctpunctures ( Fig. 21 ), striae VI–IXsulcate ( Fig. 7 ); elytral intervals VII–IX convex; elytral apex obliquely truncate ( Fig. 8 ), border incomplete, epipleural angle distinct, often with denticle ( Fig. 9 ); metanepisternal ostiole absent; aedeagus ( Fig. 29 ) with median lobe shorter than parameres, narrow, with leaf-like apical process; gonocoxae ( Fig. 53 ) short, with strongly truncate apices.

Gyrinus ovatus is most similar to G. gibbus , but can be distinguished from G. gibbus by having more evident elytral striae ( Fig. 7 , V–XI strongly evident), with VI–IX sulcate, and elytral intervals VIII–X distinctly convex, while in G. gibbus fewer elytral striae are evident ( Fig. 10 , only VI–XI), and the elytra are evenly convex and normally none-sulcate, with only striae VIII–IX being at times weakly sulcate. The two species can further be distinguished by their elytral apices: in G. ovatus the elytral apices are obliquely truncate ( Fig. 8 ) with a distinct epipleural angle often bearing a denticle ( Fig. 9 ), while in G. gibbus the elytral apices are most often rounded ( Fig. 11 ), infrequently subtruncate, and never with adistinct epipleural angle. Although less reliably, G. ovatus frequently has yellow lateral margins of the elytraand pronotum, compared to G. gibbus which often has these similarly colored as the remainder of the elytra and pronotum, and only infrequently has yellow lateral margins of the elytra only. The aedeagus is quite different between the two species (cf. Figs 12–17 and 29 ) and is the most reliable way to separate them. The gonocoxae also easily separate the two species, as G. ovatus has much shorter and more quadrate gonocoxae ( Fig. 53 ) compared to the more elongate gonocoxae ( Figs 51–52 ) of G. gibbus .

Redescription. Size. Length = 3.5–5.5 mm, width = 2.5–3.0 mm. Habitus. Body form broadly oval, attenuatedanteriorly and very weakly soposteriorly, widest point at elytral midlength; in lateral view strongly dorsoventrally convex, greatest convexity posterior to scutellar region, weakly depressed anteriorly, strongly depressed posteriorly.

Coloration ( Fig. 3 ). Dorsally, head, pronotum, elytra bronzy-green, lateral margins of pronotum and elytral often yellow, some specimens reddish, others similarly colored as remainder of pronotum and elytra; ventrally lightly colored, mouthparts, ventral surface of pedicel, hypomeron, elytral epipleuron, light yellow, remainder of venter slightly darker yellow to orangish-yellow in color.

Sculpture and structure. Pronotum with broad lateral margins. Elytra ( Fig. 7 ) with striae I–IV weakly present, evident as reticulate stripes with variously developed sparse, weakly impressed punctures; V–XI strongly evident, composed of distinct punctures; VI–IX sulcate with distinct punctures ( Fig. 21 ) evident inshallow depression; stria X non-sulcate, punctures widely separate; stria XI marginal, weakly elevated briefly in basal 1/3. Elytral intervals I–III ( Fig. 20 ) with reticulation composed of meshes with small sculpticells, producing a polished appearance; intervals IV–VI with reticulation more strongly impressed basally, meshes composed of larger sculpticells producing a metallic appearance; intervals VII–XI ( Fig. 21 ) entirely with more strongly impressed metallic reticulation; intervals VIII–X distinctly convex. Elytra without pre-apical medial plica; apices obliquely truncate ( Fig. 8 ); border incomplete, present laterally, effaced medially; epipleural angle prominent, often with small denticle ( Fig. 9 ). Metanepisternal ostiole absent. Ultimate abdominal tergite without strong medial acumination.

Male genitalia ( Fig. 29 ). Aedeagus with median lobe just shorter than parameres, gradually narrowing apically, abruptly laterally expanded in apical 1/4 forming a leaf-like process, apex rounded, weakly bifid medially; parameres with apex obliquely truncate, often weakly marginated. Female genitalia ( Fig. 53 ). Gonocoxae short, quadrate with truncate apices.

Variability. This species is most variable in the development of the punctures of the elytral striae. In some populations examined the punctures of elytral stria IV were regularly evident, and even those of striae II and III apically in some specimens. The size of the punctures of striae VII–IX also varied considerably with many specimens from Venezuela having large coarse punctures, while the additional specimens examined from Brazil had very small and widely spaced punctures.

How stronglysulcatethe lateralstriae appeared varied among populations, butall specimens had at least striae VII–IX sulcate. Specimens from near Tocopero in Falcón had only elytral striae VII–IX sulcate, and very weakly so. Those from Medanos de Coro in the same state similarly hadonly striae VII–IX evidently sulcate, but considerablymore strongly sulcate than those from Tocopero. Specimens from Guárico had the most strongly sulcate elytra among the Venezuelan populations studied, with striae VI also appearing weakly sulcate, similar to the additional material examined from Itatiaia, São Paulo, Brazil.

The shape of the elytral apices also varied noticeably. Most populations have the elytral apices obliquely truncate with the epipleural angle possessing a denticle. However, some specimens had somewhat more rounded elytral apices, with the epipleural angle distinct, but without a noticeable denticle. The development of the border of the elytral apex also varied, but was never fully present in a manner truly comparable to G. gibbus .

Habitat. In Venezuela, this species has been collected in a variety of lentic habitats, including ponds, ditches, and marshes (Figs 64–67).

Distribution. This is a very widely distributed Neotropical specieswith a similar distribution to G. gibbus , found from Argentina to Mexico ( OCHS 1948, 1949). Within Venezuela, this species has been found in the Llanos and along the northwest coast ( Fig. 74 ).

Discussion. OCHS (1953) described G. racenisi ( Fig. 78 ) from specimens collected in the central Venezuelan state of Guárico, considering them distinct from G. ovatus by having more strongly impressed lateral striae with more convex associated elytral intervals, and a reddish color to the lateral margin of the pronotum and elytra. These differences represent intraspecific variation in elytral features, as how sulcate the lateral striae are (affecting both impression and convexity of nearby intervals) is one of the most common ways this species varies (see above discussion of variability). The lateral margins of the pronotum andelytra of all species of Neogyrinus species commonly vary considerably in their color (see structures of taxonomic importance). Furthermore, dissection of male specimensfrom Guáricowith this variation reveals identical genitalia to G. ovatus . While thetype material of G. ovatus appears lost (H. Fery pers. comm.), the identity of G. ovatus has remained clear givenits unique elytral apices (figured as early as RÉGIMBART 1884: Pl. 6, Fig. 93) and its very distinctive median lobe (first described by OCHS 1935a). Given this, and the few variable, external characters used to erect G. racenisi we here synonymize it with G. ovatus .

Figures

Figs 1–6. Dorsal habitus of Neogyrinus species, scale bar = 1 mm. 1 – Gyrinus sabanensis sp. nov. 2 – G. gibbus Aubé, 1838 from Amazonian Venezuela. 3 – G. ovatus Aubé, 1838. 4 – G. guianus Ochs, 1935. 5 – G. gibbus ‘var. apicalis’ Sharp, 1877 from Caracas valley, Venezuela. 6 – G. rozei Ochs, 1953.

Figs 7–11. 7–9 – SEM images of Gyrinus ovatus Aubé, 1838 elytral morphology. 7 – elytron, box indicates region shown in Fig. 8, scale bar = 1 mm. 8 – elytral apex, box indicates region shown in Fig. 9. 9 – denticle of epipleural angle of elytral apex. 10–11 – SEM images of G. gibbus Aubé, 1838 elytral morphology. 10 – elytron, box indicates region shown in Fig. 11. 11 – elytral apex of G. gibbus, showing complete border.

Figs 18–21. SEM images of elytral interval reticulation and strial punctures. 18–19 – Gyrinus gibbus Aubé, 1838. 18 – intervals II and III, striae I–III. 19 – intervals IX and X, striae VIII–X. 20–21 – G. ovatus Aubé, 1838. 20 – intervals II and III, striae I–III. 21 – intervals IX and X, striae VIII–X.

Figs 29–33. Dorsal and lateral view of the aedeagus of Neogyrinus species, not to scale. 29 – G. ovatus Aubé, 1838. 30 – G. sabanensis sp. nov. 31 – G. guianus Ochs, 1935. 32 – G. rozei Ochs, 1953.

Figs 51–59. Ventral view of gonocoxae of Venezuelan Gyrinus species, not to scale. 51–56 – Neogyrinus species. 51 – G. gibbus Aubé, 1838 from Caracas valley, Venezuela (FMNH). 52 – G. gibbus from Amazonian Venezuela: Amazonas stream along Rio Sipapo (KBMC). 53 – G. ovatus Aubé, 1838 from Venezuela: Falcón: W. Curimagua, Blackwater Lagoon.54 – G. guianus Ochs, 1935 from Amazonian Venezuela:Amazonas:river near Orinoco /Sipapo confluence (KBMC). 55 – G. rozei Ochs, 1953. 56 – G. sabanensis sp. nov. 57–59 – Oreogyrinus species: 57 – G. iridinus sp. nov. 58 – G. venezolensis Ochs, 1953. 59 – G. vinolentus sp. nov.

Figs 76–81. Type specimens and associated labels. 76 – Gyrinus amazonicus Ochs, 1958, paratype male (BMNH). 77 – G. guianus Ochs, 1935, holotype female (BMNH). 78 – G. racenisi Ochs, 1953, paratype female (SMF). 79 – G. rozei Ochs, 1953, paratype male (SMF). 80 – G. venezolensis Ochs, 1953, paratypes, male and female (SMF). 81 – G. opalinus Régimbart, 1883, syntype male and labels (MNHN).

Figs 12–17.Dorsal and lateral view of the aedeagus of G. gibbus Aubé, 1838 specimens from throughout its range, not to scale. 12 – historical specimen from Mexico (FMNH). 13 – Caracas valley, Venezuela ‘var. apicalis’ Sharp, 1877 (FMNH). 14 – Amazonian Venezuela:Amazonas, river near Orinoco /Sipapo confluence (KBMC). 15 – Amazonian Peru: Mariscal Ramón Castilla, Estiron, Rio Ampiácu (FSCA). 16 – Amazonian Bolivia: Beni, Chacobo indigenous village, Río Benicito (FSCA). 17 – São Paulo (FMNH).

Figs 72–75. Distribution maps of Gyrinus species within Venezuela.