Hydrophilus (Dibolocelus) violaceonitens Jacquelin du Val, 1857

Arce-Pérez, Roberto, Arriaga-Varela, Emmanuel, Novelo-Gutiérrez, Rodolfo & Navarrete-Heredia, José L., 2021, Giant water scavenger beetles Hydrophilus subgenus Dibolocelus (Coleoptera Hydrophilidae) from Mexico with description of two new species, Zootaxa 5027 (3), pp. 387-407 : 395-401

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Hydrophilus (Dibolocelus) violaceonitens Jacquelin du Val, 1857


Hydrophilus (Dibolocelus) violaceonitens Jacquelin du Val, 1857 status restored

Figs. 19, 20 View FIGURES 19–24 ; 25–28 View FIGURES 25–36 , 37–40 View FIGURES 37–40 , 43, 46–49.

Hydrophilus violaceo-nitens Jacquelin du Val, 1857: 49 .

Stethoxus (Dibolocelus) violaceonitens (Jacquelin du Val) ; Bedel, 1891: 314.

Hydrous (Dibolocelus) violaceonitens (Jacquelin du Val) ; Kuwert, 1893: 83.

Hydrophilus (Dibolocelus) smaragdinus Brullé. Syn. : Régimbart, 1901: 227.

Hydrophilus (Dibolocelus) smaragdinus Brullé (in part), Hansen, 1999: 162.

Type material. [ Studied through photographs] Female ? holotype, MNHN: “ Cuba / C. Chevrolat”, “Type”, “ Hydrophilus / violaceo-nitens ”, “ smaragdinus Br. / v. violaceo nitens Duv.”, “ MUSÉUM PARIS / 1922 / coll. L. Bedel”, “ HOLOTYPE ”, “ HOLOTYPE / Hydrophilus / violaceonitens Jacquelin du / Val, 1857” / “ MNHN, Paris/ EC11750/ [barcode]”. [Specimen is damaged; maxillary palpi, mesotarsi and left metatarsus are missing]

Additional material (19♂, 6♀). MEXICO: Campeche: Kalkiní, El Remate, [20°22’21’’N, 90°03’03’’O] 26.iv.1982, M GoogleMaps . García col. 3♂, 2♀ ( CNIN); El Remate , entre raíces de manglar, 12.xii. 2020, S . Ospina col. 1♂ ( IEXA) ; Chiapas: Salto de Agua [17°33′00″N 92°20′00″O] iv.1907, C GoogleMaps . C GoogleMaps . Hoffmann col. 1♂ ( CNIN) ; Quintana Roo: Tulum [20°12′43″N 87°27′57″O],. xi. 1981, E GoogleMaps . Pech col. 2♂ ( CNIN); Puerto Morelos, [20°51′13″N 86°52′31″O] Gasolinera , 10.vii.1983, O GoogleMaps . Canul col. 2♂ 1♀ ( CNIN); El Naranjo, Selva alta, 7.vii.1985, A . Cadena y Conde cols. Noct. 1♀ ( IEXA); F . Carrillo Puerto, [19°34′43″N 88°02′43″O] Laguna Chunyaxche , 30.viii.1988, Fernán- dez y Barba cols. 1♂ ( CNIN); F GoogleMaps . Carrillo Puerto, 2.x.1983, 1♂ ( IEXA); Puerto Morelos , [20°51′13″N 86°52′31″O 1.v.1982] V GoogleMaps . Meléndez col. 1♂, 1♀ ( CNIN) ; Tabasco: Villa Hermosa, Macultepec [18°09′00″N 92°52′00″O], v.1953, J GoogleMaps . Hendrichs col. 1♂ ( CNIN) ; Veracruz: Las Choapas, [17°54′00″N 94°05′24″O], 28.v.1976, E GoogleMaps . Barrera col. 1♂, 1♀ ( CNIN); Las Choapas, 28.i.1980, Sánchez Aguilera col. 1♂ ( IEXA); Tecolutla, Flores Magón, [20°23′17″N 97°01′31″O], 13.x.2001, Cabrera col. 1♂ ( IEXA); Actopan , La Mancha [19°30′13″N 96°37′09″O], 24.v.2002, a la luz, R GoogleMaps . Arce col. 1♂ ( IEXA); Mexico, Vera Cruz , Flohr / B . C . A. Col. I . 2. Hydrophilus violaceo-nitens, Jaquelin du Val 2 ♂ ( BMNH) . CUBA: Provincia Matanzas, Playa Girón, Martin Vyklicky leg. 19.v.2004 1♂ ( NMPC) .

Diagnosis. This species can be distinguished by the following combination of characters: Maxillary palpi long and narrow; anterior tibiae with internal spur sub-rectangular with bifid apex; fifth protarsomere shorter than basal ones together, without internal projection or expansion. This species can be distinguished from H. (D.) smaragdinus Brullé a species from South America with which it was synonymized until now, by [characters of H. (D.) smaragdinus provided in brackets for comparative purposes]: H. (D.) violaceonitens without setose patch in the apical region of hind tibiae of males ( Fig. 38 View FIGURES 37–40 ) [ H. (D.) smaragdinus has a dense patch of short setae in the medial apical region of the posterior tibiae in males ( Fig. 40 View FIGURES 37–40 )]; prosternal lobe sharply truncated apically ( Fig.37 View FIGURES 37–40 ) [prosternal lobes apically acute ( Fig 39 View FIGURES 37–40 )]; ventrites 3–5 raised but not forming a sharp keel ( Figs. 20 View FIGURES 19–24 , 27 View FIGURES 25–36 ), [ventrites 3–5 raised as a sharp keel]; fifth protarsomere with straight internal margin and with reduced number of suction cups ( Fig. 26 View FIGURES 25–36 ) [fifth protarso- mere wide with rounded internal margin, and with numerous suction cups]; male genitalia wide, parameres broad, abruptly narrowed towards apexapically, with a long internal oval concavity in the apical third, and with subapical elongated-oval gonopore ( Fig. 28 a, b View FIGURES 25–36 ) [male genitalia slender with narrow parameres gradually tapering towards apex, and apex slightly widened]. Additionally, among the Mexican species H. (D.) violaceonitens is externally more similar to H. (D.) nucleoensis sp. nov., but differs from it by [the characters of H. (D.) nucleoensis provided in square brackets for comparative purposes]: in H. (D.) violaceonitens the mentum is broad, with parallel lateral margins in the basal half and in the apical half markedly curved, the apical margin truncated and slightly concave ( Fig. 25 View FIGURES 25–36 ) [mentum not wide, with lateral margins parallel and slightly curved in the basal half, apically markedly convergent, the apical margin truncated and straight ( Fig. 15 View FIGURES 7–18 )]; fifth protarsomer shorter than the previous ones together and without internal projection ( Fig. 26 View FIGURES 25–36 ) [fifth protarsomer as long as the previous ones together, flat and with an evident internal laminar expansion ( Fig. 16 View FIGURES 7–18 )]; anterior tibiae with sub-rectangular internal spur with bifid apex ( Fig. 26 View FIGURES 25–36 ) [anterior tibiae with sub-rectangular internal spur with straight and truncated apex ( Fig. 16 View FIGURES 7–18 )].

Redescription. Body elongated-fusiform, length 33 mm, width 17 mm at humeri, 1.9× longer than wide, dorsally strongly convex and glabrous, ventrally flat and pubescent; dorsal color black with dark green hue; ventrally black with reddish hue, ventral vestiture reddish yellow; antennae and palpi reddish yellow, legs black with reddish hue ( Figs 19, 20 View FIGURES 19–24 ).

Head: Antennae short with scape large and robust, longer than the next four antennomeres together, pedicel subequal to the following three antennomeres together, sixth antennomere long and oval, subequal to the previous four together, not covering the first article of antennal club. Maxillary palpi long and slender, with four palpomeres with lengths: 3.0, 2.8, 2.0, 1.5 mm; first palpomere small, sub-conical, second long, curved, slightly broadened towards apex, third similar to the previous one but shorter, fourth short, oval, with truncated apex. Mentum hexagonal, 2× wider at base than long, lateral margins parallel at basal half, apically markedly curved, apex truncated and slightly concave. Labial palpi short, length of palpomeres: 0.2, 0.8, 0.6 mm; first palpomere very small and subconical, second long and slightly broadened towards apex, 1.3× longer than the third, with short golden setae near the internal apex, third palpomere short and oval, with apex rounded ( Fig. 25 View FIGURES 25–36 ).

Thorax: Prosternal lobes raised and apically obtusely truncate, with long reddish-yellow setae at anterior margin of apex ( Fig. 37 View FIGURES 37–40 ); mesoventrite with broad keel, with lateral margins rounded and convergent towards apex, with a deep oval concavity at basal half, deeper towards apex ( Fig. 37 View FIGURES 37–40 ) and with transverse striae. Metaventrite with keel wide and flat, with feeble median longitudinal groove, ending as a short spine reaching 3/4 of the second abdominal ventrite ( Fig. 20 View FIGURES 19–24 ). Each elytron with two well-marked rows of black spots, one sublateral starting after the humerus, and other incomplete on the sides ( Fig. 19 View FIGURES 19–24 ).

Legs: Anterior tibiae with internal spur shortest, flat, sub-rectangular with apex bifid, external spur longer, sub-triangular, acute; fifth protarsomere shorter than basal ones together, without projections, tarsal claws curved, without basal tooth, internal claw slightly longer than external one, all protarsomeres with tufts of golden setae in the external margin, fifth protarsomere bearing a small apical ventral spine ( Fig. 26 View FIGURES 25–36 ), hind tibia without setose patch ( Fig. 38 View FIGURES 37–40 ).

Abdomen: Vestiture leaving a slender and long glabrous oval area at mid-line in ventrites 3–4; and a broader sub-rectangular one in ventrite 5. Ventrites 3 and 4 raised and slightly acute above, with its apex slightly acute and projecting over the next ventrite, ventrite 5 raised and subacute medially ( Fig. 27 View FIGURES 25–36 ).

Genitalia: Total length 5.2 mm; phallobase long (length: 2.25, width 1.85 mm), narrow, with apex of manubrium rounded; parameres long (length: 4 mm), broadened at basal 3/5, elongated-oval at apical 2/5, with a deep oval concavity not reaching the apex, with minute teeth in the internal margin at the apical half, getting more abundant apically; median lobe slightly shorter than the parameres (3.7 mm), broad sub-triangular, with a median sulci, apex rounded ( Fig. 28a,b View FIGURES 25–36 ).

Sexual dimorphism. Females similar to males but with narrow maxillary palpi, anterior tibiae with long subtriangular spurs, tarsal claws curved and acute, with and basal acute tooth.

Variation. Body length between 27–33 mm, width 16.5–17.5 mm, 1.8–1.9× longer than wide; dorsal body color from dark greenish to black, ventral color can be dark reddish to black, sixth antennomere and antennal club from reddish yellow to pitch black; average length of maxillary palpomeres: 3.0, 2.7, 2.0 and 1.4 mm; total length of labial palpi: 1.8 mm.

Taxonomic comments. This species was originally described by Jacquelin du Val (1845) from Cuba, and later recorded in Mexico by Sharp (1887) based on two specimens from Veracruz. Later Régimbart (1901) synonymized it under H. (D.) smaragdinus Brullé a species described from South America. Currently H. (D.) smaragdinus is recorded from several countries in the Neotropical Region: Bolivia, Brazil, French Guiana, Peru, Venezuela, Cuba and Mexico ( Bachmann 1968; Hansen 1999). Although, unfortunately we did not have the chance of directly studying the holotype deposited in Museum National d’historie Naturelle, Paris, we had access to high-definition photographs of the probably female holotype kindly provided by the curators of the museum ( Figs 46–49 View FIGURES 44–49 ). After its study and the thorough examination of the morphology of the specimens from Veracruz studied by Sharp, multiple other specimens from Mexico, one recently collected specimen from Cuba, and its comparison with specimens of H. (D.) smaragdinus from Brazil and Venezuela (AOBC, NMPC), identified by A.O. Bachmann and Martin Fikáček respectively ( Figs 37–40 View FIGURES 37–40 ), we conclude that the specimens from Cuba and Mexico are not conspecific with H. (D.) smaragdinus Brullé , therefore the restoration of H. (D.) violaceonitens as a valid species is fully justified. The present description of this species is based on a male from Mexico (Veracruz, La Choapas) compared to the material that Sharp (1887) cited from Veracruz and to a male specimens from Cuba (Matanzas, 1♂) and other specimens from Mexico.

Distribution. Cuba: Matanzas; Mexico: Campeche, Chiapas, Quintana Roo, Tabasco, Veracruz (Fig. 43)


Museum National d'Histoire Naturelle


University of Copenhagen


Nationaal Herbarium Nederland, Leiden University branch


Botanische Staatssammlung München


Coleccion Nacional de Insectos, Universidad Nacional Autonoma de Mexico


Department of Botany, Swedish Museum of Natural History


Royal Botanic Garden Edinburgh


Botanical Museum - University of Oslo


Harvard University - Arnold Arboretum


Field Museum of Natural History, Botany Department


Royal British Columbia Museum - Herbarium


University of the Witwatersrand


Departamento de Geologia, Universidad de Chile


Botanischer Garten und Botanisches Museum Berlin-Dahlem, Zentraleinrichtung der Freien Universitaet


"Alexandru Ioan Cuza" University


National Museum Prague














Hydrophilus (Dibolocelus) violaceonitens Jacquelin du Val, 1857

Arce-Pérez, Roberto, Arriaga-Varela, Emmanuel, Novelo-Gutiérrez, Rodolfo & Navarrete-Heredia, José L. 2021

Hydrophilus (Dibolocelus) smaragdinus Brullé

Hansen, M. 1999: 162

Hydrophilus (Dibolocelus) smaragdinus Brullé. Syn.

Regimbart, M. 1901: 227

Hydrous (Dibolocelus) violaceonitens (Jacquelin du Val)

Kuwert, A. 1893: 83

Stethoxus (Dibolocelus) violaceonitens (Jacquelin du Val)

Bedel, L. 1891: 314