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L'artcile en entier iciThe genus Andrena Fabricius, 1775 in the Iberian Peninsula (Hymenoptera, Andrenidae) - T Wood 2023 // pp. 266-267 a écrit :
Andrena (Melandrena) nitida (Müller, 1776), Andrena (Melandrena) thoracica (Fabricius, 1775), and Andrena (Melandrena) limata Smith, 1853
Remarks.
The specific differences between these taxa is unclear across southern Europe. In some northern countries, only two taxa are present (A. nitida and A. thoracica, e.g. the United Kingdom), with no introgression observed. Andrena nitida flies only in the spring, whereas A. thoracica is bivoltine, flying in both the spring and the summer. In Central Europe, A. limata can be found, this taxon also being bivoltine. Differentiation between the three taxa in Central Europe has often utilised hair colouration characters, as in this region the three taxa are separable with reference to the hairs on the sides of the mesosoma (light in A. nitida and A. limata, dark in A. thoracica) and the hairs of the face and the tibial scopal (light and dark in A. nitida, uniformly dark in A. limata and A. thoracica). There are additional characters such as the colour of the hind tibial spur and the density of the punctures T1, but these are less commonly referred to; both A. nitida and A. limata have dense punctures on T1 (separated by up to 1 puncture diameter), whereas they are more clearly spaced in A. thoracica (punctures separated by 1–2 puncture diameters). It is important to note that A. limata is a replacement name for A. lucida Lepeletier, 1841 nec. A. lucida Panzer, 1798 which is nominally a synonym of A. bicolor Fabricius, 1775 but this must be established (see section on subgenus Euandrena). Andrena lucida Lepeletier was described from ‘France’, without further details. I have not been able to inspect the type which should be in the MNHN collection, but which I could not locate.
The situation in southern Europe is much more challenging. In south-western Europe, A. limata becomes much darker, and therefore closely resembles the colour form of A. thoracica, with extensive black pubescence on the mesosoma laterally. This colour form was described as A. limata mixtura Warncke, 1967 (illustrated by Wood et al. 2020a). This form can be recognised by the dense punctures of T1, separating it from Iberia A. thoracica; the colour of the hind tibial spur is variable and of little consistent utility. Because of this variation, Warncke later adopted a much broader concept of A. nitida, with A. nitida s. str., A. nitida limata, and A. nitida mixtura (e.g. Warncke 1974). This position was not followed by Gusenleitner and Schwarz (2002) who followed a three distinct species interpretation (nitida, limata including mixtura, thoracica).
Analysis of barcodes does not provide clarity (Fig. 10). Whilst A. thoracica and A. nitida form reciprocally monophyletic clades, three different clades are formed for A. limata. There is no geographic pattern to these clades; clade #1 contains individuals from Austria, Poland (KJ837115; specimen identified as A. nitida but associated photograph on BOLD shows A. limata colour pattern), Spain, and Portugal; clade #2 contains individuals from Morocco, Spain, and Portugal; and clade #3 contains individuals from Finland (MZ625969; specimen identified as A. nitida but associated photograph on BOLD shows A. limata colour pattern), France, and Spain. Confusingly, sequences IBIHM501-21 and WPATW086-21 come from two different female specimens collected from the same field near Pedret i Marzà in north-eastern Spain. As Iberian individuals fall into three of these clades and the power of COI analysis is clearly insufficient to deal with potential hybridisation and introgression, no further action can be taken on the basis of these results. A dedicated study using more powerful
genetic markers is necessary to resolve this issue. For now, I maintain the position of Gusenleitner and Schwarz (2002) in that there are three species in this group (nitida, limata including mixtura, and thoracica). It will probably be necessary for a future study to designate a neotype for A. limata if Lepeletier’s original specimens cannot be definitively located.