Timarcha a blood spitting magistrate

Timarcha is a leaf beetle (Chrysomelidae), doubtfully placed under the subfamily Chrysomelinae. In view of its peculiar and primitive features, some chrysomelidologists prefer to place in a subfamily of its own, Timarchinae.

Why is this large black beetle given the name Timarcha? The name is in view of its shape, its deliberate and noble walk, and its majestic bearing. Timarcha is generally black, sometimes bluish or cupreous, and a very archaic beetle, with very primitive characters, such as an old style aedeagus and tegmen, a very simple and primitive nervous system, besides some apomorphic characters (i.e. of recent origin), like fused elytra. It is totally apterous, and this character seems ancient, as its pupa is also without developing wings; very few beetles, as Meloe spp., share that characteristic. Loss of wings, early in its evolutionary history, has given it features like a small metasternum, loss of wing muscles and nerves, and other related changes.

Once in Greece, in Athens, on the side of the Acropolis, PJ saw in a café, a painting representing a man followed by a lot of kids. He asked what the meaning of the picture was, and he learnt that it was an early last century painting, showing a man, who used to walk two steps forward and one step behind. The boys, following him, used to imitate his way of walking. Timarcha is a beetle, not walking like the gentleman of Athens, but slowly, peacefully, majestically, and constantly looking around as if searching for something of value.

Timarque, in Greek Timarchos, was, as is said, an Athenian politician, from the fourth century BC. In 347 BC he tried to stop the selling of arms to Philippos, the father of Alexander the Great, and he repaired the Athens wall. Pushed by Demosthene, he became the main accuser of Eschyne, during the embassy affairs in 346 BC. Unfortunately, his dissolute morals, even at that time, offered to Eschyne a good way to counter attack. Due to the seriousness of the revelations, Demosthene could not defend Timarque, who was then deprived of his civilian and political rights. After this trial, Timarque is said to have commited suicide. It is also said that "timarchia" is used to characterize a government founded on the love of honours. In Roma, later on, Timarchia became the name of the Censure or Judiciary. It is said by the etymologists that the slow and majestic walking of the Timarcha beetles reminded Latreille, the French entomologist, of the nobility of the Athenian judges, and thus he coined the generic name for the beetle.

The genus Timarcha comprises four subgenera, two of them not much different, Timarcha s. str. and Timarchostoma, and two others well separated: Metallotimarcha and Americanotimarcha. There are around 125 species and 30 subspecies, spread in eastern North America and around the Mediterranean basin (Jolivet, in Capinera, 2004). Timarcha species are present in central Anatolia, but they are missing in Syria, Lebanon, Israel, and Egypt where they have been probably eradicated during the Pleistocene desertification. They are missing also in Sinai, and, in Lybia; they survive along the coast on the western side and in Cyrenaica. In Lybia they occur also in certain oases, 80 km south. Timarcha did not survive in Hoggar, in the middle of Sahara, where some species of Chrysolina still live. When Sahara was green, not more than 5,000 years ago, probably Timarchas distribution was much wider than today, but it never crossed totally the desert since it did not reach Mauritania and Senegal in the west, extreme south of Algeria, and south of Tunisia in the east. Some Moroccan species were shared with Spain once, in the Betico-Riffan massif, before the opening of Gibraltar strait. Western islands of the Mediterranean were, most of them, colonized, except for instance Iviga and Malta, and Timarcha never reached the eastern islands: Creta, Corfu, Rhodos and Cyprus. Iviga seems to have a different geological history than the rest of the Baleares. Malta must have had its Timarcha, but they were probably lost with the intense urbanization, dating from the Greeks and the Romans.

Fossil Timarcha, before the Peistocene, are unknown, but Timarcha is a very ancient genus, probably related to the Upper Jurassic Timarchopsis, a fossil from Siberia. It is very probable that the genus originated in Central Asia, where it could have been eradicated by the glaciations. From there it migrated to Europe, where it adapted to cold in Europe, due to a complex cycle of egg and adult diapauses, and to North Africa, where it became a steppic species or it adapted to local mountains. It also migrated to North America, probably through North-Atlantis, but a trans-Beringhian migration has also been seriously envisaged (Poinar and Jolivet, 2004; Poinar et al, 2002). Strange enough, for supporting the hypothesis, no traces of the beetle are there in Japan, in Russian mountains, like the Altai, or in southern China. The subgenus Metallotimarcha has adapted to mountain life, but, as are the American species, it is entirely nocturnal. Several species in Morocco seem to be crepuscular, a way to escape the heat or the luminosity in the Atlas mountains. The steppic species remain totally diurnal. It is a fact that in America, as in Europe, the northern distribution of Timarcha coincides with the meridional extension of the quaternary glaciers: south of Baltic states, Denmark, Southern Scotland, island of Vancouver, in Canada, Montana in USA.

Apterism and fused elytra, with a subelytral cavity below, is a form of protection against heat and water loss in steppic areas, and also a protection against the cold in middle Europe. These modifications reduce transpiration and compensate the loss of liquid through reflex bleeding. Timarcha ejects actual blood through prebuccal openings and femoral articulations, and was nicknamed the bloody nose beetle in England. Its blood is very toxic, being rich in anthraquinones, and, as a result, practically there are no vertebrate predators, birds or lizards. Their colour, generally black, is aposematic and contrast with the green of the food-plants. Let us note that the nocturnal species have lost partly ('Metalloúmarcha) or totally (Amencanotimarcha) the reflex bleeding, and even the fusion between the two elytra becomes rather loose. Protection against big predators seems unnecessary during the night. Normally Timarcha species are totally black, but a Balearic species, T. balearica, several Spanish ones, show a bluish color, and the nocturnal Metallotimarcha spp. are cupreous, a colour possibly detected during night by potential predators like birds and others, which learn to avoid them. It seems that in North Africa, where Timarcha and Pimelia (Tenebrionidae) cohabit, there is a Müllerian mimicry between both, since Pimelia regurgitates liquid when disturbed.

Timarcha has no predators, and also few parasites. There are, however, several parasitoids (Hymenoptera chiefly) and intestinal commensals (Gregarines) and phoretic mites under the elytra, in the subelytral cavity (Canestriniidae).

Timarcha feed mostly in Europe, on Rubiaceae (Gaium, Rubia, Crucianella, Asperula, Sherardia) and in North Africa on Rubiaceae and Plantaginaceae (Plantago). However, Plantago selection starts in Southern Europe, with several other plant families, mostly in Spain and North Africa, e.g. Veronica (Scrophulariaceae), Scabiosa, Knautia (Dipsacaceae), Launea (Asteraceae), Carrichtera, Iberis, Alyssum (Brassicaceae). Metallotimarcha species feed on Vaccinium (Ericaceae) and Asperula (Rubiaceae) and Americanotimarcha species feed on Rosa, Rubus and Fragaria (Rosaceae) and on Vaccinium, Gaultheria and Rhododendron (Ericaceae). Perhaps it is correct to regard Vaccinium as its original food-plant, as this plant is widely distributed in the Holarctis.

Size of Timarcha varies from 5 mm (T. cerdo) to 23 mm (T. tangeriana). The chromosomal meioformula varies slightly among its species, but remains in average as 2n = 12 in Europe and 2n = 44 in America.

Finally the bloody nose beetle remains rather enigmatic, and, more or less, a living fossil among the leaf-beetles. It varies enormously in the Pyrenees and along the Moroccan coast. It seems to be still in continued evolution, probably due to some interbreeding between the races. Otherwise, there is no crossing between the species, or, if that happens accidentally, it does not produce viable offspring.

Extinction of this beetle is fast approaching; it is being caused by urbanization, fragmentation of the habitat, use of insecticides and herbicides, general pollution and many other reasons. Being wingless, the beetle cannot recolonize new habitats.

There is a folkloric aspect of the bloody-nosed beetle. Kids in western Europe used to play with them frequently as with coccinellids. They were abundant everywhere during PJ's youth, but they are no more common now, except perhaps along the dunes, on halophytic plants. One wonders how long they are going to survive. When we build a golf or a racing course, a bungalow, they just disappear in that area forever. It is a Jurassic survivor which is vanishing away and needs protection.

— Fig. 30.1. Timarcha tenebricosa Fabricius, male on Galium verum L. (Rubiaceae). Normandy.

— Fig. 30.2. Timarcha tenebricosa larva, 3rd instar on Knautia arvensis Coult. (Dipsacaceae). Aveyron, 850 m (photos Jolivet).

References

Capinera, J. L. (ed.). 2004. Encyclopedia of Entomology. 3. Kluwer Academic Press,

Dordrecht, Boston, London: 2265-2269. Poinar, G. and Jolivet, P. 2004. Origin of Timarcha: Trophic relationships in the old and new world. In: Jolivet, P, Santiago-Blay, J.A. and Schmitt, M. (eds.) 2004. New Developments in the Biology of Chrysomelidae. SPB Academic Publishing, Tha Hague, The Netherlands: 281-290. Poinar, G., Jolivet, P. and Grafteaux, A. 2002. New food-plants provide clues for the origin and distribution of Timarcha (Col. Chrysomelidae Chrysomelinae). Lambillionea 102 (1):103-109.

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