Scutisotoma muriphila ( Grinbergs, 1968 ) Potapov & Babenko & Fjellberg, 2006

Potapov, Mikhail, Babenko, Anatoly & Fjellberg, Arne, 2006, Taxonomy of the Proisotoma complex. Redefinition of genera and description of new species of Scutisotoma and Weberacantha (Collembola, Isotomidae), Zootaxa 1382 (1), pp. 1-74 : 19-21

Scutisotoma muriphila ( Grinbergs, 1968) , comb.n.

Figs. 36–39

Proisotoma (Dimorphiella) muriphila Grinbergs, 1968: 139

Material studied. 10 exx., Russia, Rostov-on-Don Province, Orlovsky area, Manychsky village , saline land. 20.v.2003, leg. A. Kremenitsa. 8 exx., Russia, Siberia, Novosibirsk Province, Kargatsky area , 5 km S Sarykamyshska (55 o 37’N, 80 o 42’E), on pools, 10.viii.1992, leg. S. Chernyshev. 14 exx., same region near Karasuk village (53 o 44’N, 78 o 02’E), wet depression near salt lake, 15.ix.1979, leg. S. Stebaeva. 26 exx., Russia, Tuva Republic, near Khol-Oozhu (50 o 44’N, 94 o 24’E), way to Kara-Khol lake , stony steppe, 16.vii.1993, leg. S. Stebaeva. 1 ex. , same region, 20 km from settl. Khol-Oozhu , 2100 m alt., 16.vii.1993, leg. S. Stebaeva. 4 exx., same region, near Ubsu-Nur salt lake, in grass on lake shore, 18.vii.1993, leg. S. Stebaeva. 18 exx., Kazakhstan, Pavlodar Province, near Matogul village , submerged depression with sedge, 17.v.1978, leg. S. Stebaeva ( MSPU) .

Redescription. Size 1.1–1.6 mm. Colour dark, blue-violet with paler spots, antennae and extremities paler. Cuticle with fine but visible primary granulation. Ocelli 8+8, G and H slightly smaller. PAO not very big, narrow elliptical, not constricted, about 1.5 as long as ocellus diameter. Maxillary outer lobe with bifurcate palp and 4 sublobal hairs. Labral formula 4/554. Labium with a complete set of papillae (A–E) and guards. Labium with 3 proximal and 4 basomedian chaetae. Ventral side of a head usually with 4+4(5) postlabial chaetae. Ant.1 with 2 basal microsensilla (bms), dorsal and ventral, and 2 ventral sensilla (s). Ant.2 with 3 bms and one laterodistal s. Ant.3 with one bms and 5 distal s (including one lateral), “guards” sensilla of AO small, almost as long as the two inner sensilla. Additional sensilla on Ant. 2–3 in males fine, chaeta-like. Sensilla on Ant.4 hardly differentiated, subapical organite small.

Dorsal axial chaetom of Th.II–Abd.III as 9–11,7–8/6,5–7,5–6. Thorax without ventral chaetae. Mature males armed with strong, spine-like dorsal macrochaetae (also developed on Ant.1–2). Macrochaetae in immature males only slightly thicker than microchaetae. In females macrochaetae are of normal shape (see original figure in Grinbergs (1968) and Figs. 28–30). The macrochaetae do not differ significantly between sexes: on Abd.V they 0.3–0.4 and 0.5–0.6 as long as the tergite length in females and epitokous males, respectively. Sensilla on tergites short, clearly different from microchaetae. Sensillar formula 33/22224 (s), 11/111 (ms). Sensilla on Abd.I–III in mid-tergal position. On Abd.V two median sensilla (accp1 and accp2) situated along posterior edge of tergite, lateral sensilla accp3 and accp4 set more anteriorly ( Fig. 39 ).

Unguis thin and long, without inner tooth. Tibiotarsi with additional chaetae in proximal parts (corresponding to more than 21-21-25 chaetae). B-row on Ti.1–2 with 7 chaetae. Male spurs (x and B 5) on Ti.3 thinner and shorter than ordinary chaetae. Tibiotarsal tenent chaetae (1-2-2 on Ti.1–3) clavate, slightly longer than unguis (U 3: t.ch. = 0.9–1.0: 1, Fig.38 ). Ventral tube usually with 4+4 laterodistal and 5 posterior chaetae. Tenaculum with 3+3 teeth and 1 chaeta. Anterior furcal subcoxae with 25–34 chaetae, posterior ones with 10–11. Furca long ( Figs. 36–37 ). Anterior side of manubrium with a pair of distal chaetae, posterior side on each side of the midline with 23–29 chaetae on the main part and 4–5 on the laterobasal lobes. Dens with 25–29 anterior chaetae, basal 1/4 without chaetae. Posterior side of dens crenulated, with 20–26 chaetae (7–10 basal, 7–10 outer, 5–7 inner and one subapical near mucro). Mucro strong, with 3 subequal teeth, subapical and proximal set close together. Ratio of manubrium: dens: mucro = 5.8–7.8: 6.4–8.8: 1. Medial preanal chaeta on each of the anal lobes longer than lateral ones.

Taxonomic remarks. Mature males of the species are easily identified by the strong spine-like macrochaetae on the tergites. Females and immature males are very similar to the partly sympatric S. ladaki . For separation of the two species, see key and remarks to S. ladaki .

Distribution. Steppe regions of Eastern Palaearctic (SE Russian Plain, S Siberia, Tuva, N Kazakhstan). Originally described from the Novosibirsk area, SW Siberia. The species prefers damp saline sites.

Figures

FIGURES 36–39. Scutisotoma muriphila. 36, 37, anterior (36) and posterior (37) sides of furca; 38, tip of leg 3 in male; 39, sensillary chaetotaxy of Abd.V (s1–4: accp1–4 sensilla).