Folsomia villosa Potapov & Marusik, 2000

Potapov, Mikhail & Gulgenova, Ayuna, 2013, Isotomidae (Collembola) of Buryat Republic. II. A revision of the genus Folsomia, Zootaxa 3682 (2), pp. 305-330 : 318-319

Folsomia villosa Potapov & Marusik, 2000

Discussion. Our material resembles to the morphology of specimens in populations of F. villosa from Far East Russia. Colour varies from white (more common) to lightly spotted due to scattered pigment grains. Such a variability is present both in Siberia and the Far East. Anterior chaetae on manubrium vary wider than it was given in the first description: from 5+5 to 7+7 (vs. 6+6). In the Far East the species appears to occur in two forms: with 4+4 and 3+3 basolateral chaetae on posterior side of manubrium, the former has thinner chaetae on anterior half of dorsum of Abd.IV. In Buryatia, only the latter form is found.

In the N Barguzin Range and Vitim Plateau a closely related form/species was found which differs from F. villosa by shorter macrochaetae and fewer chaetae on anterior side of manubrium and dens (4–3+4–3 and 8–9, respectively). The difference makes this form very similar to F. re g u l a r i s Hammer and related species which, in contrast, have ocelli. The form is sometimes mixed with common F. v i l l o s a but notably prefers drier sites, including steppes.

Distribution and ecology. So far the species was recorded in three localities of the Far East of Russia and Buryatia (Potapov & Marusik 2000, Chimitova et al. 2010). After the inclusion of our data the distribution of this species area is better understood: it is widely distributed in the south of E Siberia and the Far East of Russia ( Fig. 23 ), the formal gap between Buryatia and Far East probably results from insufficient knowledge on the Chita and Amur regions. In Buryatia the species occurs in northern and eastern areas. No records are known in the west of Buryatia (Khamar Daban and Tunkinskiye Gol'tsy) where it is possibly replaced with F. sensivillosa sp. nov.

This is one of the most common species in Buryatia ( Fig.1 : loc. 1, 2, 3, 5, 7, 8). Prefers different kinds of taiga forest and does not penetrate to steppes and the alpine zone. In the dry Selenga Low Plateau (south) it seems to be limited to damp places while it is more eurytopic in humid mountains. The ecological preferences in Vitim Plateau are described in Chimitova et al. (2010).

Figures

FIGURE 1. The sampling sites in Buryatia: 1 – 2 — Vitim Plateau (1 — Konda Basin, 2 — Eravna Basin), 3 – 5 — Selenga Low Plateau (3 — Zagansky Range, 4 — vicinities of Schuch'ye Lake, 5 — vicinities of Karasinoye Lake), 6 – 8 — Barguzinsky Range (6 — Ust' - Barguzin, 7 — vicinities of Barguzin, 8 — upper flow of Barguzin River), 9 — Khamar-Daban Range, 10 — Tunkinskiye Gol'tsy Range, 11 — vicinities of Ulan-Ude, 12 — estuary of Selenga River, 13 — vicinities of Khorinsk, 14 — vicinities of Unnokent'evka, 15 –– Turka.

FIGURES 20 – 23. F. sensivillosa sp. nov.: 20, habitus and chaetotaxy; 21, lateral part of Abd. III; 22, chaetotaxy of Abd. IV – VI; 23, records, two closely related species also shown.