Laccophilus Leach, 1815

Bistroem, Olof, Nilsson, Anders N. & Bergsten, Johannes, 2015, Taxonomic revision of Afrotropical Laccophilus Leach, 1815 (Coleoptera, Dytiscidae), ZooKeys 542, pp. 1-379 : 4-5

Taxon classification Animalia Coleoptera Dytiscidae

Genus Laccophilus Leach, 1815

Type species

(by monotypy). Dytiscus minutus Linnaeus, 1758.

Laccophilus Leach, 1815: 84 (673 alternative page number) (original description); Aubé 1838: 415 (description, global distribution); Sharp 1882: 286, 287 (description, faunistics, species list, faunistics, discussion, species group delimitation); Kolbe 1883: 386, 401 (faunistics, discussion); Peschet 1917: 23 (discussion, key); Zimmermann 1919: 119 (description); Zimmermann 1920a: 16 (catalogue, faunistics); Bertrand 1928a: 184 (description, faunistics); Bertrand 1928c: 364 (larva description); Guignot 1937: 137, 138 (discussion, description, key to genera; type species of genus incorrectly given as Laccophilus hyalinus De Geer); Guignot 1946a: 116 (type species Dytiscus minutus Linnaeus); Guignot 1946c: 260, 261, 315 (description, key to genus and species groups, discussion); Guignot 1948: 15 (description, key to genera); Bertrand 1948: 12 (description larva, faunistics); Bertrand 1951: 114 (discussion, faunistics); Bertrand 1954: 284, 288, 289 (discussion larva, description, faunistics); Guignot 1955a: 37 (biology); Omer-Cooper 1956: 21, 23 (faunistics, biology); Omer-Cooper 1957: 8, 11, 90 (key, description); Omer-Cooper 1958b: 36 (key, subgroups, description); Guignot 1959a: 530 (description, discussion, faunistics, 11 species groups distinguished and keyed); Omer-Cooper 1962: 294, 295 (faunistics); Bertrand 1963: 402, 411, 448 (juvenile discussion); Omer-Cooper 1965: 61, 65 (description, discussion, faunistics, biology); Bertrand 1970: 18, 38 (description, larva); 1971: 252 (larva, faunistics); Bertrand and Legros 1971: 244 (faunistics, biology); Forge 1981: 501 (description, faunistics); Brancucci 1983: 251, 253 (description, key); Brancucci 1983b: 241-426 (description, faunistics, discussion, taxonomic revision Oriental, East-Palearctic and Australian species); Pederzani 1988: 107 (faunistics); Nilsson et al. 1989: 299 (list, type species by monotypy, Dytiscus minutus Linnaeus, 1758); Nilsson and Persson 1993: 79 (discussion, faunistics, discussion); Pederzani 1995: 43, 73 (cosmpolitan genus, key, list); Nilsson et al. 1995: 505 (faunistics); Balke et al. 1997: 295-320 (review New Guinea species, melanism, discussion); Nilsson and Roughley 1997: 4 (list); Alarie et al. 2000: 121-164 ( Laccophilinae phylogeny discussion, based on larval morphology); Nilsson 2003: 76 (type species: Dytiscus minutus Linnaeus); Reintjes 2004: 66 (faunistics list, all continents); Bilardo and Rocchi 2006: 130, 133 (faunistics, discussion); Bilardo and Rocchi 2011: 226 (biology); Bilton 2015: 446 (biology); Nilsson 2015: 208 (catalogue, faunistics). [Comment: literature, associated with Africa are only included. Accordingly, the list is incomplete for non-African species.]

Diagnosis.

According to Miller and Bergsten (2014) the tribe Laccophilini , including the genus Laccophilus , is characterized by not visible scutellum when elytra closed, a single metatarsal claw, and prominent lobes at the anteroapical apices of the metatarsomeres. All African species of Laccophilus have bifid metatibial spines (Fig. 9), which separate them from the other Laccophilini genera in Africa.

Description.

Body parameters: Length of body 2.8-6.0 mm, width 1.5-3.4 mm. Shape somewhat variable, elongate to oval, rarely sub-cylindrical (Fig. 382). Often, posteriorly flattened, with various colour pattern (Figs 393, 401, 451, 457, 471, 489, 515, 526).

Microsculpture and reticulation of two different kinds: Simple (meshes equally large, almost uniform, no size categories of meshes distinguished) and double (meshes of two kinds; size categories distinguished). When distinctly double, body covered with large meshes which generally contain a various number (2-8) of fine (less pronounced) meshes. Commonly, lines of large meshes in part reduced and weakly developed; sometimes almost absent and only discerned as fragments/rudiments. Less commonly, lines of finer meshes are reduced and difficult to discern within larger meshes. Sometimes mesh-categories in part mixed and microsculpture appears indistinct or absent while distinct in another location of same specimen. Rarely meshes of microsculpture elongated, being comparatively long in relation to breadth. Dorsal surface of body shiny to mat. Large parts of body in ventral-aspect with very fine, simple and slightly undulate linear microsculpture, which can be reduced, in part absent. Punctures on dorsal surface of body generally sparse and concentrated to various regions. Head at eyes with fine and irregular punctures. Punctures at area of head often enlarged narrowly towards head-centre, forming a sparse, transverse row of punctures connecting ocular punctuate areas. On pronotum fine punctures often discernible, especially at pronotal margins. Elytra with fine, irregular, longitudinal rows of punctures often discernible on disc, dorsoventrally and laterally. Ventral surface largely lacking punctures. Apical ventrite, however, generally with scattered, fine punctures. Lateral, pre-apical furrow of elytra generally distinct and pubescent.

Ventral aspect: Prosternal process slender, often strongly extended posteriorly and apically pointed (Figs 1-5). Metacoxal plates often provided with transverse, slightly obscure and shallow furrows, which can be rather indistinct. Stridulatory apparatus, when present, is located posteriorly on metacoxal plates, quite close to midline of body. Apparatus consists of dense ridges forming a semicircular file (Fig. 6). All African Laccophilus species have curved, fine striae on basal ventrites of abdomen (Fig. 6). Apical ventrite variable in shape, often modified and asymmetric, provided with a fine knob-like process on one side (Figs 110, 118). Apical ventrite with posterior edge modified with medial part posteriorly to a variable degree extended (Figs 47, 112). Some species groups lack modifications on apical ventrite (Figs 26, 43). Metacoxal process posteriorly rarely expanded (Fig. 7).

Legs: Male pro-and mesotarsus slightly enlarged and provided with suckers, length of which is variable (Fig. 10) - female lacks suckers. Metatibial spurs bifid (Fig. 9).

Sexes: Similar but males provided with pro- and mesotarsal suckers. Male apical ventrites in many species groups more strongly modified than in female; often asymmetric with one-side lateral knob on apical ventrite. Rarely female epipleuron with intraspecific, partial enlargement (Fig. 8).

Distribution.

Global distribution covering all continents but Antarctica. According to the world catalogue 263 species recognized ( Nilsson 2015).

Ecology and collecting circumstances.

In Africa the genus occurs in all kinds of freshwater habitats. Often collected in quite shallow water with sparse vegetation on sandy-clay-bottom, e.g. in drinking pools for domestic animals. No comprehensive work on ecology of Laccophilus exists. Scattered information can be obtained by scrolling through faunistic literature, here listed. Additional sparse information on ecology is documented on many collecting labels. Experiences from Madagascar by the last author gives Laccophilus as one of the most ubiquitously occurring dytiscid genera. Different species have been found from sea level up to an altitude of over 2000m. Laccophilus inhabits many types of both lotic and lentic waters with different species and species groups more specialized. The Laccophilus alluaudi species group for example contains typical lotic species. The group is characteristic of small to medium-size canopy-covered rainforest streams with sandy or gravel bottoms lacking vegetation but collecting dead leaves at margins. Species from other groups like the Laccophilus taeniolatus group are often very abundant in red-clayish ponds visited by zebu cattle. The Laccophilus leonensis group can be found in vegetation-rich forest swamps and marshes or at margins of slow flowing vegetated sections of open landscape meandering rivers. When taken out of the water and put on dry land and when disturbed they can jump distances at least 20x their own body length. The behavior has not been studied in detail and could be both an anti-predatory escape behavior or used when semipermanent streams or side pools gradually dry out and the beetle can without flying move sideways or downstream to new habitats.