Recent Distribution and Ecological Notes on the Dryopid Beetle Pomatinus substriatus Müller, 1806 (Dryopidae: Coleoptera) in Serbia

 

Boris Novaković1, Marija Ilić2, Stefan Anđus2, Jelena Čanak Atlagić2, Nikola Marinković2, Jelena Đuknić2

 

 

1 Serbian Environmental Protection Agency, Ministry of Agriculture and Enviromental 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

The aim of this paper is to present recent distribution and to provide some ecological notes on the dryopid beetle Pomatinus substriatus (Müller, 1806) in Serbia on the basis of field research in the period from 2010 to 2013. During the research, P. substriatus was recorded at 36 localities situated at 27 streams and rivers in total and one reservoir in Serbia (the Bojnik Reservoir). The species was found to be the dominant water beetle species at 12 localities/watercourses: The Mosna/Porečka River, Gornjak/Mlava, Neresnica/Pek, Kusići/Pek, Ušće/ Studenica, Lepenac/Rasina, Svođe/Lužica, Vlasotince/Vlasina, Krivi Do/Visočica, Trnski Odorovci/Jerma, Lučani (upstream Stenjevac Brook confluence)/Bjelica and the Gugaljski Most/Zapadna Morava River. According to the national watercourse classification (Official Gazette of the Republic of Serbia, 74/2011), most of the watercourses where the species was recorded belong to Type 3 (small to medium streams, altitude to 500 m, with domination of large fractions of substrate). The highest abundance of adults was detected in August and September of 2013 at 3 localities (Mosna/Porečka River, Lepenac/Rasina and Svođe/Lužnica). Larvae were very rare in samples and found only at two localities (Ušće/Studenica, June 16 2011 and Leskovac/Veternica, May 29 2012). Considering the species' habitat preference, it was found that larvae and adults of P. substriatus predominantly inhabit stretches of streams with domination of medium or large-sized stones, while occasionally it can be found in small stagnant water puddles. Additionally, some individuals were found in fragments of tree trunks and rotting branches submerged in water. The population trend of P. substriatus could not be assessed based on the collected data. The objective of the study is to contribute to the general knowledge of the species autecological characteristics and distribution in Serbia.

Keywords: Pomatinus substriatus, distribution, ecological notes, Serbia, field research

 

 

Introduction

Dryopidae (Coleoptera) or long-toed water beetles are small beetles (size range 3.0 to 5.5 mm), usually found on the edges or in the emergent vegetation of shallow stagnant waters, yet some species also occur in rivers and brooks. The adults crawl under the surface clinging to water plants, where they feed on decaying plant matter. Long-toed water beetles are incapable of swimming; their locomotion is aided by their strong, clawed legs (Kriska, 2014). Adults of nominotipic Dryops are typically riparian and can take flight directly from water surface when disturbed; those of Pomatinus are truly aquatic, which like elmids (riffle beetles, Coleoptera: Elmidae) use a plastron for breathing (LeSage, 1991). Pupation takes place in the moist soil near the water line. The elongate, strongly sclerotised larvae develop among the waterside debris, where they feed on plant remnants (Kriska, 2014).

Pomatinus is a name reclaimed for Helichus substriatus (Müller, 1806). Pomatinus substriatus is a southern and central European species, known north to Lithuania and Sweden, south to Algeria and Morocco, and east to Turkey, Israel, the Lebanon, and Syria (Foster, 2010).

Pomatinus wireworm-like larvae, which feed on wet, rotting wood, and may occur in damp soil, have been described by Olmi (Olmi, 1976). Olmi also described the eggs, which are inserted into rotting tree branches under water (Ibidem).

Pomatinus larva (Fig. 1a) has a single hook on the 8th urotergit, medially positioned, pointing to the caudal edge; on the 9th urotergit there are 2 hooks, directed to the oral edge. On the oral edge of the tergits, from the mesothorax to the 9th urit, there are deep grooves separated by small dark sclerotised cerci. Dryops larvae are differentiated from Pomatinus larvae by the lack of hooks and grooves on the oral edge of tergits (Ibidem). The Pomatinus adult (Fig. 1b) is easily distinguished from Dryops by the general form and the recumbent covering of hair (Foster, 2010), has a pronotum without furrows (although a narrow rim is present), short hair and a size of 4.5-5.5 mm (Friday, 1988).

Adults are often associated with side streams and larvae with temporarily flooded banks. This species is capable of flight (Foster, 2010).

 


Fig01
Figure 1: Pomatinus substriatus (Müller, 1806): a-larva, b-adult.