Metabelba

van der Hammen, L. & Strenzke, K., 1953, A Partial Revision of the Genus Metabelba Grandjean (Oribatei, Acarina), Zoologische Mededelingen 32, pp. 141-154 : 141-142

[Genus Metabelba ]

The genus Metabelba was created by Grandjean in 1936 for Belbidae of which the solenidions of tibiae II and III are coupled with protective hairs, but of which the solenidion of tibia IV is free, long, and tactile. The genus belongs to the group of rather small species that are never covered with foreign material, but of which the cerotegument is very thick, especially on the moniliform legs, whilst the adults often bear the larval and nymphal skins.

The species have three or four lateral apophyses: one (which is not always present) between leg I and leg II, two between II and III, and one between III and IV. We have been in doubt as to the nomenclature of these apophyses, for although they have generally been regarded as tectopedia, they do not protect the trochanteres. Grandjean (in litt.) recently proposed to us the following notation. The apophysis between I and II is restricted to some members of the Belbidae , and in the present paper it is simply called anterior apophysis (a.a.). The two apophyses between II and III occur in several families; they protect the sejugal stigma; here they are called anterior and posterior parastigmatic apophyses (a.p.a., a.p.p.). It is obvious that the fourth apophysis is a discidium (dis; cf. Grandjean, 1952, p. 31).

There are no Spinae adnatae but there is often one pair of protuberances under the anterior border of the notogaster, opposite to a corresponding pair on the propodosoma; sometimes there is even a second pair of protuberances on the propodosoma, also situated in the posterior part.

The type of the genus is Damaeus papillipes Nicolet, a species that was insufficiently described, but of which Grandjean discovered specimens at the original locality. Whilst creating the genus, Grandjean did not give a redescription of M. papillipes , but in a footnote (1936, p. 56) he wrote that generally the species was considered a synonym of Nothrus pulverulentus Koch . In his opinion, however, the species does not correspond with Koch's original description, because the disposition of the notogastral hairs of pulverulentus Koch points to Porobelba spinosa Sellnick ; Grandjean noted therefore that he preferred to use the name papillipes .

Last year the one of us (van der Hammen, 1952) found that there are two related species of the genus, one of which is pulverulentus auct. non Koch, a species supposed to be synonymous with papillipes , whilst the other was described as a new species ( Metabelba cremersi ).

Recently Grandjean had the kindness to give us topotypes of the Oribatids described by Nicolet from the environments of Paris, species of which the redescription is badly needed; among these there are several specimens of Damaeus papillipes . We expected that papillipes would prove to be identical with pulverulentus auct. non Koch, and we were surprised to find that, on the contrary, the species is identical with cremersi .

It is evident that the difficulties and errors in the genus are numerous, accordingly we decided to give a partial revision, containing a redescription of the type species, a description of pulverulentus auct. non Koch (as pulverosa Strenzke nov. spec.), a critical review of the literature, and notes on the remaining species. The redescription of papillipes was made by the first author, the description of pulverosa by the second, whilst the remaining part has been prepared in co-operation.

We are grateful to Dr. F. Grandjean (Paris) for specimens and for constructive advice; to Dr. G. Owen Evans (London) for the loan of " Damaeus verticillipes " from the Michael Collection; and to Dr. F. A. Turk (Camborne, Cornwall) for the loan of his " Porobelba pulverulenta ".