Folsomia uniramia , Potapov, Mikhail & Gulgenova, Ayuna, 2013

Potapov, Mikhail & Gulgenova, Ayuna, 2013, Isotomidae (Collembola) of Buryat Republic. II. A revision of the genus Folsomia, Zootaxa 3682 (2), pp. 305-330: 323-325

publication ID

publication LSID

persistent identifier

treatment provided by


scientific name

Folsomia uniramia

sp. nov.

Folsomia uniramia  sp. nov.

Figs 32View FIGURES 31 – 32, 34–38View FIGURES 33 – 38. F

Type material. Holotype: Adult female. Russia (East Siberia), Buryat Republic, Ust'-Barguzin, shore of Baikal Lake, pine wood on dunes, flotation of sand on beach (5 m from water edge), 21.viii. 2008, 5 paratypes from the same locality, leg. A. Gulgenova & M. Potapov. Holotype and 3 paratypes in MSPU; 2 paratypes in BSU.

Other material. Shore of Baikal Lake, ca. 30 km S estuary of Selenga River, Posol'sky Sor Bay, near Baikal'sky Priboy station, lake debris near the water, 23.viii. 2011. leg. A. Gulgenova and L. Vanyavina.

Description. Body size 0.4–0.5 mm. Without pigmentation, ocelli absent. Cuticle with thin hexagonal primary granulation ("smooth"). PAO broadly elliptical, not constricted, about as long as width of Ant I (0,8–1,1) and 1,4– 1,6 as long as inner unguis length ( Fig. 37View FIGURES 33 – 38. F). Maxillary outer lobe with 4 sublobal hairs, maxillary palp simple. Labral formula as 3 /5,5,4. Labral edge reduced and distal row of labral chaetae placed in apical position ( Fig. 37View FIGURES 33 – 38. F). Labium with 5 papillae (А –Е), guard chaetae e 7 present, 3 proximal and 4 basomedian chaetae. Ventral side of a head with 4 (3)+ 4 (3) chaetae. Ant.I with 2 ventral sensilla (s) and 2 small basal microsensilla (bms), dorsal and ventral, the former set together with long chaeta-form microsensillum, Ant.II with 3 bms and 1 latero-distal s, Ant.III without bms and with 5 distal s (including one lateral), without additional sensilla. Sensilla on Ant. 4 weakly differentiated. Organite small.

Sensillary formula as 3,3 /2,2,2,3,5 (s), 1,0/0,0,0 (ms) ( Fig. 32View FIGURES 31 – 32). Corner sensilla on Th.II absent. Tergal sensilla as long as or longer than common chaetae and hardly distinguishable ( Fig. 34View FIGURES 33 – 38. F). Medial sensilla on Th.II –Abd.III situated in mid-tergal position, on Abd.I –III between Mac 1 and Mac 2. Abd.V with 5 sensilla arranged with 3 dorsal ones (al, accp 1, accp 2) being long and slender and 2 lateral middle-sized thickened and pointed sensilla ( Figs 34, 35View FIGURES 33 – 38. F). Shape of lateral sensilla varies ( Fig. 36View FIGURES 33 – 38. F). Macrochaetae smooth and short, 1,1 /3,3,3 in number, medial ones on Abd.V 1.6–2.0 times shorter than dens and 3.7–4.6 times longer than mucro ( Fig. 36View FIGURES 33 – 38. F). 7 foil chaetae at the tip of abdomen (fa 1, fa 2, fp0, and fp 2). Axial chaetotaxy as 7–8,4 /3,3,3 (only one specimen was studied). Thorax without ventral chaetae.

Unguis of normal shape, without lateral and inner teeth. Empodial appendage about half as long as unguis (0.5–0.6). Tibiotarsi without additional chaetae on Leg I and II (21 chaetae), and with some ones on Leg III (up to 27 in all). Tibiotarsal tenent chaetae pointed. VT with 4 + 4 laterodistal and 5 posterior chaetae, anteriorly without chaetae. Tenaculum with 4 + 4 teeth and a chaeta. Anterior furcal subcoxae with 6, posterior one with 4–5 chaetae. Anterior side of manubrium with 2 + 2 chaetae ( Fig. 34View FIGURES 33 – 38. F). Posterior side of manubrium with 8 + 8 chaetae on main part: 2 apical chaetae (ap), 2 + 2 chaetae in distal transversal row (M 1 and L 1), and 5 + 5 in central part ( Fig. 38View FIGURES 33 – 38. F). 4 + 4 laterobasal chaetae, a pair of laterocentral chaetae present or absent (see the discussion part). Dens with 16–18 anterior chaetae ( Fig. 34View FIGURES 33 – 38. F). Posterior side of dens crenulated and with 4 chaetae (2 basal and 2 at the middle), without minute chaeta at the base of mucro. Mucro short, bidentate. Ratio of manubrium:dens:mucro = 5.6–6.8: 7.5–7.9: 1.

Discussion. The species belongs to ' heterocellata ' group. It is a rather peculiar member of the genus due to reduced edge of labrum, absence of corner sensilla on Th.II and microsensilla on Abd.I. In the characters of the furca, F. uniramia  sp. nov. takes an intermedate position between F. kurushica Potapov, Abdurakhmanov & Aitekova, 2001  and F. vitimica  sp. nov. One specimen from Eastern Buryatia (Eravna Basin, pine wood) differ from the type population by the presence of microsensilla on Abd.I and a lateral pair of chaeta on manubrium and probably belongs to another undescribed species. Two specimens from an estuary of the Selenga River also have lateral chaetae on the manubrium, which are treated as a variation within F. uniramia  sp. nov. by us.

Distribution and ecology. Two distant records from the sandy shore of Baikal Lake ( Fig. 1View FIGURE 1: loc.: 6, 12).

Etymology. The species has a simple maxillary palp with only one branch.


Belgorod State University