Agyrtes (Agyrtecanus) bicolor Laporte, 1840

Valcárcel, Javier Pérez & Piloña, Fernando Prieto, 2013, La familia Agyrtidae Thomson, 1859 (Coleoptera) en la Península Ibérica. The family Agyrtidae Thomson, 1859 (Coleoptera) in the Iberian Peninsula., Arquivos Entomolóxicos 8, pp. 1-13 : 5-8

Agyrtes (Agyrtecanus) bicolor Laporte, 1840

PARDO ALCAIDE & YUS (1975) set out a vague note on the occurrence of this species in the Iberian Peninsula in the Enciclopedia de las Ciencias (VV. AA., 1968). FUENTE (1925) includes a record from the Eastern Pyrenees, with no precise location, by Xambeu. Probably he refers to records published by XAMBEU (1891), who recorded this species from the locality of Prades 1, in those French Eastern Pyrenees. We could not find any Iberian material belonging to this species.

Agyrtes bicolor Laporte, 1840 ( fig. 4)

A. bicolor is also distributed along central and western Europe, with eastern boundary in Romania and the western one in France ( SCHAWALLER, 1978; RŮŽIČKA, 2004).

The knowledge of its biology is scarce, as the preceding species, but with distinctive features. It was reported its autumn activity under moss, bark of rotten wood, and decaying fungi and ferns, in the winter in nests of Formica rufa Linnaeus, 1761 ( Hymenoptera, Formicidae) ( ROUBAL, 1947; PECK, 1974; NEWTON, 1997). It has also been found in droppings of solipeds or beating bushes ( XAMBEU, 1891) and, this very winter, in pitfall traps placed near to a rivershore ( COURTIN & CORTI, 2012). The most striking character of its behaviour is the association as larva, pupa or adult with masses of larvae of Bibio marci (Linnaeus, 1758) ( Diptera , Bibionidae ) ( fig. 5 ), that appear on the surface of the soil in winter warm days ( BERCE & BRISOUT DE BARNEVILLE, 1872; PAULIAN, 1945). PAULIAN (1945) also adds that seemingly does not feed on larvae, stating that the nests can be a winter refuge.

Agyrtes bicolor Laporte, 1840 ( fig. 4)

A. bicolor se distribuye también por Europa central y occidental, con límite oriental en Rumanía y occidental en Francia ( SCHAWALLER, 1978; RŮŽIČKA, 2004).

Los conocimientos sobre su biología son escasos, al igual que la especie anterior, aunque con características distintivas. Se ha señalado con actividad otoñal bajo musgo, cortezas de madera podrida, y hongos y helechos en descomposición; en invierno, en nidos de Formica rufa Linnaeus, 1761 ( Hymenoptera, Formicidae) ( ROUBAL, 1947; PECK, 1974; NEWTON, 1997). También ha sido encontrado bajo deyecciones de solípedos o batiendo arbustos ( XAMBEU, 1891) y, este mismo invierno, en trampas de caída situadas a orillas de un río ( COURTIN & CORTI, 2012). El carácter más llamativo de su comportamiento es su asociación como larva, pupa o adulto con masas de larvas de Bibio marci (Linnaeus, 1758) ( Diptera, Bibionidae) ( fig. 5), las cuales aparecen en la superficie del suelo en días templados de invierno ( BERCE & BRISOUT DE BARNEVILLE, 1872; PAULIAN, 1945). PAULIAN (1945) también añade que aparentemente sin alimentarse de las larvas, estableciendo que los nidos puedan ser un refugio invernal.

Mentions to this species, although imprecise, require consider its occurrence in the Iberian Peninsula, even for reasons of geographical proximity, at least in the Pyrenean region. In fact, it should be mentioned the existence of an imprecise old record of Agyrtes castaneus (Fabricius) from the French Eastern Pyrenees. ( COMPANYO, 1856), that might actually belong to this species. As in the previous case, it is strange that despite the samplings taken over the years, and especially due to the attention and the sampling efforts that lately concerns to forestal entomofauna in general and saproxylophague in particular, no captures of this species have been published or these captures remain unnoticed. In this case, however, we do believe that it is not possible to make an assessment on its presence or absence until testing the systematic survey of larval winter accumulations of Bibio sp., a specific technique not implemented in the Iberian Peninsula, as far as could be investigated.

Figures

Fig. 4.- Agyrtes bicolor Laporte, de Slavkovský les (Bohemia Occ., Rep. Checa). Foto de JAn RůžičkA. Fig. 4.- Agyrtes bicolor Laporte, from Slavkovský les (Western Bohemia, Czech Rep.). Photo by Jan RůžičkA.

Fig. 5.-Grupo de larvas de bibionidae. Foto de Chris Raper, de diptera.info. Fig. 5.- Cluster of bibionid larvae. Photo by Chris Raper, from diptera.info.