A contribution to the study of the Lower Volga center of scarab beetle diversity in Russia: checklist of the tribe Aphodiini (Coleoptera, Scarabaeidae) of Dosang environs

Abstract The field sampling of the Aphodiini scarab beetles in Dosang environs (Astrakhan Province, European Russia) in 2006–2012 resulted in the collection of 44 species. All but one of them belong to Aphodius Hellwig (sensu lato). This is apparently the richest recorded local Aphodiini fauna in Russia. The high Aphodiini diversity in the area can be explained by the long vegetative season with high effective heat sum, large livestock providing abundant food resources throughout the year, and location in the transition belt between Volga-Akhtuba Floodplain and Desert floristic districts. The core fauna consists of mesophilous species widely distributed in the Palearctic region and confined to the intrazonal habitats. Other species have ranges mostly limited to the steppe, semidesert, and desert zones.


Introduction
The tribe Aphodiini is the most diverse and widespread among the scarab beetles of the Northern Palearctic, including Russia. The members of this group dominate dung beetle communities and a few species can be found as far north as 65 degree of the northern latitude. However, like the majority of other scarabs, Aphodiini are the most diverse in the southern regions of the country. In Russia, major centers of aphodiine diversity are chiefly found in mountainous regions -Caucasus, Altai Mountains, Southern Primorye (Akhmetova 2011). The exception to this is the Caspian lowland desert with rich scarab beetle fauna (Nikolajev 1987, Shokhin 2007. Lower Volga, and especially Caspian lowland desert has long been recognized as a center of scarab beetle diversity in Russia. A number of first country records of aphodiines have originated from this area (Akhmetova and Frolov 2008b, Akhmetova and Frolov 2008a, Akhmetova and Frolov 2009) yet its fauna is still inadequately explored.
We have summarized the data of multi-year survey in Astrakhan Province and provided a check-list of the tribe Aphodiini of the Dosang environs. The list includes 44 species for which all but one of which belong to the mega-diverse genus Aphodius Hellwig (= Aphodius Illiger) ( sensu lato). Notes on the distribution of the species and feeding preferences, if known, are given. The biogeographic composition of the fauna and possible reasons of high local species richness are discussed.

Study area
The study area is situated оn the Akhtuba River (fork of Volga River) about 90 km upstream of Volga estuary, Astrakhan Province, European Russia. We were based in Dosang Railway Station (N 46°54' E 47°55'). All species listed below and the majority of specimens were collected within 1 km from the station i.e. within an area of about 3 km .
A contribution to the study of the Lower Volga center of scarab beetle ... 3

Material
The material used in this work was collected by the authors from 2006 to 2012 in different seasons but primarily in spring and fall. Additional specimens were received from colleagues listed in the acknowledgement section. All the material mentioned is deposited in the collection of Zoological Institute of Russian Academy of Sciences, Sankt-Petersburg (ZIN).  Left side of Akhtuba River, riverine secondary forest near Dosang, Astrakhan Province, Russia.

Methods
The beetles were collected by the following methods: washing of fresh horse and cow dung, hand collecting from fresh and old dung, mercury lamp traps, soil sifting with a sieve, hand collecting from marmot holes. The larvae were collected from old dung and soil and some specimens from each lot were reared to adults in the laboratory.
Classification and nomenclature of taxa follow Nikolajev (1987), Kabakov and Frolov (1996), Frolov (2002) and Akhmetova and Frolov (2008b). Classification of distribution ranges of Aphodiini species follows Akhmetova (2011) and is based on the zoogeographical divisions of the Palearctic Region (Emeljanov 1974). Aphodius species are arranged alphabetically by epithet.  Distribution: Central and Eastern Europe, Western Asia up to East Kazakhstan in the east. The species is mostly occur in forest-steppe and steppe zones.  Feeds on: Adults and larvae feed on horse dung.

Distribution: Caspian lowland desert, Middle Asian deserts
Distribution: Caspian lowland desert.   Feeds on: Rodent nest dweller, adults and apparently larvae feed on rodent excrement (Fig. 9).

Aphodius (Orodaliscus) zangi
Distribution: Distributed mostly in the steppe and semidesert zones from Lower Volga in the west to West Siberia in the east.  Distribution: This species is thought to be widely distributed in the Holarctic Region. However, Wilson and Angus (2006)

Discussion
To date, 44 species of the Aphodiini have been recorded from Dosang and its environs. This is apparently the richest recorded local Aphodiini fauna in Russia (by "local fauna" here we understand the fauna occurring in a small area and consisting of sympatric and parapatric populations of different species). The large number of the Aphodiini species found in the area can be explained by a combination of the following factors: 1. Long vegetative season with high effective heat sum. The beetles were found active from March to November and it is possible that some species may be active during winter months, especially during mild winters. The climate in the area is arid in general but the high level of groundwater in sands, even in the driest months, provides suitable conditions for psammophilous taxa. 2. Large livestock including horses and cows provide abundant food resources throughout the year. In the hottest months however, much of the fresh dung is consumed by the Scarabaeinae dung-beetles, notably Scarabaeus typhon Fischer-Waldheim, and Gymnopleurus mopsus (Pallas).