Contribution to the knowledge of Platambus maculatus (Linnaeus, 1758) (Dytiscidae: Coleoptera) in Serbia

Boris Novaković1, Marija Ilić2, Margareta Kračun-Kolarević2, Božica Vasiljević2, Bojana Tubić2 and Vanja Marković2

 

 

 

1 Serbian Environmental Protection Agency, Ministry of Agriculture and Environmental Protection, Ruže Jovanovića 27a, 11160 Belgrade, E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 Institute for Biological Research “Siniša Stanković”, Despota Stefana 142, 11060 Belgrade, E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

 

Abstract

Platambus maculatus (Linnaeus, 1758) is regarded as a widespread and common European dytiscid taxon. Its presence in Serbia is well documented. Investigations in the 2010-2013 period throughout Serbia have served to recheck distribution and ecological data regarding this species. The presence of P. maculatus was confirmed at only 19 localities including 17 rivers and one reservoir (the Uvac Reservoir). The estimated relative abundances of this species were low, with the high abundance only at the Beljina locality (the Beljanica River) in the Belgrade Region. Besides this finding in an urban area, findings of this species in large rivers such as the Velika Morava, Južna Morava, Crni and Beli Timok River are also of interest. The main habitats for this dytiscid were found to be small to medium streams, at elevations up to 500 m, with domination of large fractions of substrate, and relatively well preserved (natural) localities. It is distributed in lowland (<200 m a.s.l.), hilly/submountain (200-500m) and mountain (>500 m) regions, tolerating moderate organic pollution (Class III, ecological water status). As non-flyer/flightless species, P. maculatus has limited dispersal ability, and as such is more vulnerable to negative human impact on aquatic habitats. This paper should provide an update to our knowledge regarding the presence of P. maculatus in Serbia.

Keywords: Platambus maculatus, aquatic beetle, distribution, field research, Serbia.

 

Introduction

The predaceous diving beetles (Dytiscidae: Coleoptera) with at least 3,800 species (Nilsson, 2001) are among the most diverse aquatic Coleoptera, with a wide range of successful aquatic adaptations (Ribera and Nilsson, 1995). They spend almost their entire life submerged in water (of the main life stages – eggs, larvae, pupa and adult, only the pupa is terrestrial, although they breathe atmospheric air, and larvae are not very good swimmers (Franciscolo, 1979; Crowson, 1981; Kriska, 2013). Adult dytiscids are good fliers with high dispersal potential. An exception are members of the genus Platambus Thomson, 1859, which are considered to be non-flyers (Jackson, 1973; Kriska, 2013).

As the common name of the group (predaceous diving beetles) reveals, members of dytiscids are predators, both in larval and adult stages, feeding on all aquatic organisms they can overcome, which in the case of the largest ones (Dytiscus) could include even smaller fish and other vertebrates, along with almost all invertebrates they encounter (Franciscolo, 1979).

Being considerably smaller, with an adult size of 7.0-7.4 to 8.5 mm, and a larval size of the final instar in the same range (Franciscolo, 1979; Kriska, 2013), members of the Platambus genus feed on small specimens of various aquatic invertebrates, mainly chironomids, gammarids, mayflies, etc. On the other hand, small beetles (as well as smaller instars of larger ones) are prey for vertebrates (fishes, amphibians, etc.) and for larger predatory invertebrates, including odonates, hemipterans and larger beetles, even of the same species (Franciscolo, 1979; Bosi, 2001).

The taxon traditionally is considered as typical rheobiont/lotic taxa, preferring clear water with vegetation (phytophylous), dominantly mountain and submountain watercourses (Franciscolo, 1979; Eyre, 1986; AQEM, 2002). However, this opinion is modified, in line with the increased number of findings of this beetle in lentic environments such as pools, lakes, reservoirs, in lowlands as well as in highlands, and even in some urban areas (Cojocaru, 2007; Edokpayi, 2010). During their study of aquatic beetle fauna in urban area of the city of Olsztyn in Poland, Pakulnicka and Biesiadka (2011) classified P. maculatus as a lacustrine and riparian taxon. Furthermore, this species was recorded in brackish water as well (Gulf of Bothinia; Nilsson and Holmen, 1995). In his study of the Central European aquatic Coleoptera, Hebauer (1994) placed P. maculatus in the "torrenticole" group, as a common inhabitant of either bank zones of rivers/streams, preferably with plenty of vegetation, or lotic zones of lake banks, where it could be found in large numbers on vegetation or driftwood. As a phytophylous taxon Platambus is sensitive to hydro-alterations which include degradation and destruction of this bank zone (Brauns et al, 2007).

The life cycle of Platambus maculatus in Central Europe is univoltine (Nilsson and Holmen, 1995). Oviposition occurs in autumn, between algal mats on submerged plants and various plant material. As typical dytiscid larvae are poor swimmers and must regularly crawl up or use their positive buoyancy to reach the surface, where they breathe atmospheric air (Crawson, 1981; Franciscolo, 1979). The larvae occur mainly from autumn to spring (Dettner et al, 1986; Nilsson and Holmen, 1995). The pupation, as in most water beetles, taking place in soil chambers on land as larvae crawl up on the river or lake/pond bank. Emerged adults then return to water (Franciscolo, 1979; Kriska, 2013). Unlike most other dytiscid adults of Platambus, as mentioned earlier, they cannot fly (Jackson, 1973; Kriska, 2013).