Cosmochthonius plumatus Berlese, 1910

Cosmochthonius plumatus Berlese, 1910, p. 221, pl. 20 fig. 48; Lombardini, 1936, p. 39; Grandjean, 1950, p. 78, fig. 2.

C. plumatus is bidactylous at I and tridactylous at II, III, and IV, just as C. lanatus . The microsculpture of the dorsal surface is different from lanatus because it is not reticulate but consists of small irregular points.

The localities recorded by Berlese are: M. Giovi, Mugello (Tuscany), and Palermo (Sicilia). In the Collection I found indeed a slide (no. 80/7) that bears the indication "Monte Giovi, muschio, tipico". Further there are 4 slides (nos. 80/4, 5, 6, 8) with specimens from Palermo. On slide no. 22/30 from Florence, Berlese wrote with a question-mark the names lanatus as well as plumatus (the preparation is recorded in the catalogue under both names); the extremely bad condition does, however, not allow of a definite conclusion.

C. plumatus appears to be a rare species. The notes given by Grandjean (1950) are founded on one of Berlese's specimens. In the Oudemans Collection (present in the Leiden Museum) I found a preparation of a nymph from Salatiga (Java), which Oudemans identified with plumatus (cf. Oudemans, 1916a, p. 266; Buitendijk, 1945, p. 374); although this nymph generally reminds of the adults of plumatus, genuine nymphs are required to arrive at a positive proof 1).

1) Hammer (1958, p. 23, pl. 4 fig. 18) describes a " variety " of the species, collected in South America ( Cosmochthonius plumatus var. suramericanus). The single specimen is rather small (0.22 mm) so that it is perhaps a nymph. The number of claws is not mentioned.