Porobelba weigmanni, Miko, Ladislav, 2008

Miko, Ladislav, 2008, Taxonomy of European Damaeidae (Acari: Oribatida) II. Porobelba weigmanni n. sp. (Oribatida, Damaeidae), from East Slovakia, with comments on other known species of the genus, Zootaxa 1844, pp. 55-62 : 59-61

Comments on Porobelba parki Jacot, 1937

During the study of damaeid mites from the collection of Karl Strenzke in the Senckenberg Museum, Frankfurt, Germany, I had an opportunity to study one mounted adult individual, probably sent to Strenzke directly by A. P. Jacot. The slide is labelled "SMF 16926: Porobelba , 350, Belbidae . Old Tawney’s Cave, Twilight zone; Thulss – Mt.Lake; Hoyer-H.G.S". It is not part of the type series, which was from forest floor near Mammoth Cave, Kentucky. The specimen is in comparatively good condition, but the notogaster is crushed.

This species differs from European species of Porobelba by several important characters. The body is strongly narrowed in the sejugal area ( Fig. 4 B). The prodorsum has a well developed propodolateral apophysis P. The parastigmatic apophyses are differently shaped: S a is strong, long, perpendicular to the body, pedotectum-like; S p is much smaller, triangular, oblique, well separated from S a. The discidium is small, thorn-like, oriented anterolaterad. Notogastral setae are similar in size anteriorly (c1 = c2), but diminish posteriad. In all European species of Porobelba , notogastral setae are arranged and oriented radially, whereas in P. p a r k i they are inserted in two paraxial rows, as found in some other genera of Damaeidae (eg. some Metabelba species). I did not find differences in leg setation formula; nevertheless, dorsal setae of the femora are much stronger than other setae, covered by distinct spinuli ( Fig. 5 ). The most characteristic synapomorphy of Porobelba — single area porosa on posterior part of notogaster—is absent. This observation was confirmed by Norton (pers. comm.), who studied quite extensive American material. The most typical character of the species is very long sensillus, slightly but distinctly broadened (lanceolate) towards the end.

It is clear that P. parki does not share characters of Porobelba as given in the diagnosis above. Differences are quite numerous even if general appearance and some characters are similar (size, legs and their setation). Some of the differences observed have been commonly used for establishing genus-level taxa within Damaeidae . The generic or specific value of leg setae characters and shape of the sensillus is unclear, but the presence of apophysis P, shape of parastigmatic apophyses and position of notogastral setae in two parallel rows are collectively of generic significance. Therefore, a new genus, closely related to Porobelba will be proposed in the subsequent paper of this series, together with a detailed redescription of P. p a r k i.

Based on the above descriptions and discussion, the three known species of Porobelba may be identified using the following key:

1 First pair of prodorsal setae (c1) very long, typically lyriform shape. Other notogastral setae minute, thin. Prodorsum with one pair of tubercles behind insertions of interlamellar setae. Body length 390–405 µm.. ....................................................................................................................................... P. weigmanni n. sp.

- Setae c1 longer than other notogastral setae, but straight, parallel, oriented forwards. Remaining notogas- tral setae shorter and thinner, but well visible. Without tubercles on prodorsum .......................................2

2(1) Spinae adnatae present, body length 345–420 µm ............................................ P. spinosa ( Sellnick, 1920)

- Spinae adnatae absent, body length 380–400 µm .......................................... P. grandjeanica Subías, 1977

Figures

FIGURE 4. Porobelba spinosa (Sellnick): A—prodorsum and anterior part of notogaster, C—sensillus and bothridial complex; Porobelba parki Jacot: B—prodorsum and anterior part of notogaster, D—sensillus and bothridial complex. Abbreviations: P— propodolateral apophysis; for the rest see Fig. 1 and Fig. 3

FIGURE 5. Porobelba parki Jacot: A— leg I (antiaxial view), B—leg IV (paraxial view)