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THE DARKLING BEETLES (COL., TENEBRIONIDAE) OF THÁSOS

Darkling beetles are a diverse group, comprising over 15,000 species worldwide and inhabiting a wide range of habitats including deserts, sand dunes, caves, and woodlands. Several species are synanthropic and are cosmopolitan pests of stored products. A general trait, at least amongst the European species,  is an affinity for dry, warm habitats and a majority of species are associated either with free-draining open habitats, such as sandy beaches, or with dead wood where several species feed on fungi. This ability to withstand arid conditions makes tenebrionids well-suited to the climate of Thásos and in the lowlands they are usually the commonest ground-active beetles encountered, replacing the Carabidae of more temperate climes. Species such as Tentyria rotundata and Pimelia subglobosa are frequently seen in suitable habitats. Tenebrionids are variable in size, ranging from 3-30mm in length, and are also very diverse in their form. Many (like the cellar beetle Blaps gigas) resemble black ground beetles, whilst others are rotund, shiny and brightly-coloured.

The taxonomic position of the Allelucidae and Lagriidae has been the subject of debate and they are regarded as sub-families of the Tenebrionidae by many authors. They are included here for completeness. Similarly, the taxonomic status of many tenebrionid forms in the Aegean is unclear. A high proportion of the family is flightless and as such island populations frequently exhibit morphological differences. This has led to the description of numerous sub-species (Fattorini, Leo & Salvati 2000), but recent taxonomic revisions have clarified most of the historic confusion. Fattorini & Fowles (2006) summarise these changes as they affect the Aegean fauna and also correct mis-identifications appearing in the published literature for Thásos.

The earliest published records for the island appear to be those of Karnozickij (1959), who recorded 12 taxa (representing 11 species)  in October 1942 and May 1943. Ardoin (1976) added another seven species amongst the twelve species  recorded by M. Cerruti on Thásos in 1973; Whitehead (1999) reported two species collected above Theologos in 1994; whilst Ferrer & Whitehead (2002) announced the important addition of Xanthomus graecus from Limenaria. Fattorini (2002) listed thirteen of these species as occuring on Thásos. During my visits I have recorded twenty species, including eight species that are additions to the island list, and I am grateful to Simone Fattorini, Piero Leo and Paul Whitehead for assistance with identification.  In total, therefore, there have been 25 Tenebrionidae, one Allelucidae and one Lagriidae species recorded from the island. Fattorini & Fowles (2006) report 132 native species of Tenebrionidae (excluding synanthropics) from the Aegean islands so it is likely that there are more species to be found on Thásos. However, species-area analysis of the Aegean fauna suggests that Thásos already has an exceptionally rich fauna for its size. 

Almost two-thirds of the tenebrionid fauna on Thásos has an Eastern Mediterranean distribution, most of which are Balkan in origin, and only a single species, Cephalostenus orbicollis, is of Anatolian distribution. The island has, therefore, probably received most of its species from the adjacent mainland during the Pleistocene when glaciation lowered sea levels and probably connected Thásos to the mainland coast. Present-day habitat diversity may also encourage a comparatively rich fauna, especially with regard to the prevalence of mature broadleaved trees as habitat for xylophilous species such as Bolitophagus reticulatus, Helops rossii and Nalassus plebejus. The survival of undisturbed beaches and sand dunes, as at Cap Prinos and Skala Potamias, is important for psammophilous species like Ammobius rufus, Opatrum obesum and Xanthomus graecus.

Several of the species known from Thásos have been recorded on very few occasions from Greece according to Kühnelt (1965). Bolitophagus reticulatus is a mycophagous species associated with polypore fungi on trees, previously known from Greece only from the Peloponnese. Diaclina fagi, found on Thásos in bracket fungi on fallen poplars, is known from only three other locations in Greece. Platydema europaeum, a mycetophagous species apparently linked to polypores on pine logs and trunks, was previously known from Greece only from Taygetos on the mainland and on Lesvos. Helops rossii and Nalassus plebejus, are additions to the Aegean fauna, previously known for Greece from the mainland and the Ionian Islands. Opatrum sabulosum is known from the islands of Nissiros and Lesvos, and from continental Greece where it appears to be very rare, and Xanthomus graecus is restricted to the Peloponnese and Thásos (Ferrer and Whitehead 2002).

There is no single key available to identify the darkling beetles of Greece, but  many species are widely distributed across Europe and hence covered by a variety of identification guides. Kühnelt (1965) provides a valuable, though taxonomically out-dated, summary of the Greek fauna.

CHECKLIST

Allelucidae

Omophlus lepturoides (Fabricius 1787)

Lagriidae

Lagria hirta (Linnaeus 1758)

Ammobius rufus Lucas 1849

Blaps gigas  (Linnaeus 1767)

Bolitophagus reticulatus  (Linnaeus 1767)

Calyptopsis caraboides (Brullé 1832)

Catomus consentaneus (Küster 1851)

Cephalostenus orbicollis (Ménétriés 1836)

Cylindrinotus (Odocnemis) nigropiceus (Küster 1850)

Dailognatha quadricollis carceli Solier1835

Dendarus messenius (Brullé 1832)

Dendarus moesiacus (Mulsant & Rey 1854)

Diaclina fagi (Panzer 1797)

Dichillus carinatus (Küster 1848)

Gonocephalum granulatum nigrum (Küster 1843)

Graecopachys (Pachyscelis) quadricollis (Brullé 1832)

Helops rossii Germar 1817

Menephilus cylindricus (Herbst 1784)

Nalassus plebejus (Küster 1850)

Opatrum obesum Olivier 1811

Opatrum sabulosum Linnaeus 1758

Pimelia subglobosa graeca Pallas 1781

Platydema europaeum Laporte & Brullé 1831

Tenebrio opacus Duftschmid 1812

Tentyria rotundata angulata (Brullé 1832)

Xanthomus graecus Dajoz 1984

Zophosis punctata Brullé 1832

REFERENCES

Ardoin, P. 1976. Tenebrionidae récoltés par Monsieur M. Cerruti dans diverses iles Grecques. Fragmenta Entomologica, 12: 69-79.

Fattorini, S. 2002. Biogeography of the tenebrionid beetles (Coleoptera, Tenebrionidae) on the Aegean Islands (Greece). Journal of Biogeography, 29: 49-68.

Fattorini, S. & Fowles, A.P. 2006. A biogeographical analysis of the tenebrionid beetles (Coleoptera, Tenebrionidae) of the island of Thasos in the context of the Aegean Islands (Greece). Journal of Natural History, 39: 3919-3949.

Fattorini, S., Leo, P. & Salvati, L. 2000. Levels of endemism in the Aegean tenebrionids (Coleoptera, Tenebrionidae). Biogeographia, 21: 429-440.

Ferrer, J. & Whitehead, P.F. 2002. The genus Xanthomus Mulsant, 1854 (Coleoptera, Tenebrionidae), its evolutionary history and conservation significance. Annales Zoologici (Warszawa), 52: 383-401.

Karnozickij, N. 1959. Materialien zur Koleopteren-Fauna der Agäischen Küste und Insel Thasos. Izv. zool. Inst. Sof., 8: 237-253.

Kühnelt, W. 1965. Tenebrionidae. Catalogus Faunae Graeciae. 1.

Whitehead, P.F. 1999. A second male of Tapinopterus insulicola (Tscitschérine, 1900) (Coleoptera: Carabidae). Entomologist's Gazette, 50: 53-54.