Rhantus Dejean, 1833

Balke, Michael, Hájek, Jiří & Hendrich, Lars, 2017, Generic reclassification of species formerly included in Rhantus Dejean (Coleoptera, Dytiscidae, Colymbetinae), Zootaxa 4258 (1), pp. 91-100 : 97-98

Rhantus Dejean, 1833

Rhantus Dejean, 1833: 54 , as Rantus ; type species: Colymbetes pulverosus Stephens, 1828 (= Colymbetes suturalis W.S. Macleay, 1825 ) by subsequent designation of Hope (1838); spelling fixed by ICZN (1954: Opinion 289).

Anisomeria Brinck, 1943: 140 , as replacement name for Anisomera Brullé, 1835 ; type species: Anisomera bistriata Brullé, 1835 designated by ICZN (1999: Article 67.8). Synonymy by Morinière et al. (2015).

Anisomera Brullé, 1835: 200 ; type species: Anisomera bistriata Brullé, 1835 by monotypy; preoccupied by Anisomera Meigen (1818: 210) ( Diptera : Limoniidae ). Synonymy by Morinière et al. (2015).

Senilites Brinck, 1948: 16 ; type species: Senilites tristanicola Brinck, 1948 by original designation. Synonymy by Morinière et al. (2015).

Diagnosis. Small to large (5–16 mm) species. Medial labral emargination deep. Sides of pronotum with border usually thin, often indistinct or missing; posterior pronotal angles weakly obtuse, rarely obtuse. Elytral reticulation simple (consisting of large polygonal meshes, meshes often incomplete, forming an irregular net), or double (meshes filled with fine polygonal cells). Setae on parameres apically often modified to trumpet-shaped “suction” setae (see Balke 1990). Notes: This character needs to be scored systematically across the genus which was beyond the scope of the present paper. Several species of the genus are illustrated in Figs 4 B–D ( Rhantus atricolor is an unusually large and dark Rhantus ; R. frontalis is a typical Rhantus species, and R. selkirki is a morphologically derived endemic of a small island).

Position. A monophyletic group, sister of the genus Nartus , and deeply nested within Colymbetinae ( Fig. 1 ). Species composition. Altogether 90 species occurring in all zoogeographical regions; for complete list see Nilsson & Hájek (2017).

Figures

FIGURE 1. Phylogenetic reconstruction of Colymbetinae relationships using different methods of phylogenetic inference (Bayesian, Maximum Likelihood, Parsimony, figure modified from Morinière et al. 2016 which contains more details on analytical procedures); node support for major backbone nodes indicated with asterisks: black meaning strong support, lighter shades of grey referring to increasingly weaker support. Distribution is coded in colour and ancestral areas were inferred using the software package BioGeoBEARS (details in Morinière et al. 2016). Notes: " R. signatus JFern. " refers to a specimen from Juan Fernandez Archipelago (originally described as R. kuscheli Guignot, 1952).

FIGURE 4. A) Nartus grapii (Gyllenhal, 1808), 11 mm, Germany; B) Rhantus atricolor (Aubé, 1838), 15 mm, Mexico; C) Rhantus frontalis (Marsham, 1802), 10.5 mm, Germany; D) Rhantus selkirki Jäch, Balke & Michat, 2014, 6.6 mm, Chile.