Scutisotoma longisensilla, 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 : 30-31

Scutisotoma longisensilla sp.n.

Figs. 72–79

Material. Holotype: ♀, Russia, Far East, Southern Primor’e , entrance of a cave, date unknown, leg. N. Myuge. Paratypes: 23 exx., same sample ( MSPU) .

Description. Size 0.8–1.0 mm. Colour blue or blue-violet with numerous paler spots, ventral side and extremities light. Cuticle with very fine primary granulation. Ocelli 8+8, G and H slightly smaller. PAO wide elliptical, not constricted, about 2.0–2.5 as long as ocellus diameter and 1.1–1.5 as long as U 3. Maxillary outer lobe with 4 sublobal hairs, maxillary palp bifurcate. Maxillary head with short, unmodified lamellae. Labral formula 4/554. Labium with a full set of papillae and guards, proximal field with 3, basomedian field with 4 chaetae. Ventral side of head usually with 4+4 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 6 distal s (AO and two lateral s of different length). Lateral guard sensilla of AO more than twice as long as inner pair ( Fig. 75 ). A few additional sensilla on Ant. 2–3 in males hardly differ in size from ordinary chaetae. Sensilla on Ant.4 hardly differentiated, subapical organite small.

Dorsal axial chaetom of Th.II–Abd.III as 8–9,7–8/5,5,5–6. Thorax without ventral axial chaetae. Macrochaetae differentiated laterally on Th.II–III and on tip of abdomen, medial ones on Abd.V are 0.2–0.3 as long as tergite. Sensilla on tergites long, hardly differing in length from ordinary chaetae. Sensillar formula 33/22224 (s) and 11/111 (ms). Sensilla on Abd.I–III in almost mid-tergal position (medial sensillum on Abd.III set in posterior 1/3 of the tergite). Microsensillum of Abd.III close to lateral sensillum ( Figs. 76–78 ). On Abd.V one sensillum of the medial pair (accp2) clearly displaced anteriorly ( Fig. 79 ).

Unguis slender, without inner tooth. The number of chaetae on Ti.1–3 is 21-21-25 (like the basal set), rarely with 1–2 additional proximal chaetae. B-row on Ti.1–2 with 7 chaetae. Chaetae x and B 5 on Ti. 3 in males stick-like, slightly expanded at tip. Tibiotarsal tenent chaetae (1-2-2) on Ti.1–3 usually pointed, about as long as unguis (U 3: t.ch. = 0.9–1.3: 1). Ventral tube with 4+4 laterodistal and 5–7 posterior chaetae. Tenaculum with 4+4 teeth and one chaeta. Anterior furcal subcoxa with 18–22 chaetae, posterior with 9–11 chaetae. Anterior side of manubrium with a pair of distal chaetae, posterior side with 17–24+17–24 on the main part and with 4+4 chaetae on its laterobasal lobes ( Fig. 72 ). Dens distally with 8–11 anterior chaetae, basal 1/2 without chaetae. Posterior side of dens crenulated, with 10–11 chaetae (usually with 5 basal, 2–3 outer, 2 inner and 1 subapical near mucro, Figs. 73–74 ). Mucro with 3 subequal teeth set close together. Ratio of manubrium: dens: mucro = 5.0–7.3: 3.9–5.3: 1. Each anal lobe with 3 minute chaetae of similar length.

Affinity. Furcal structures are similar to S. schisti sp.n., but S. longisensilla sp.n. may be distinguished by the presence of two lateral sensilla on Ant.3, long “guard” sensilla in AO and the chaeta-like tergal sensilla. The positions of Abd.V sensilla also differ and tenaculum has 4+4 distinct teeth. See also the remarks to S. kolymica above.

Distribution. Known only from the type-locality in the Russian Far East.

Name derivation. The new species is named after the long sensilla.

Figures

FIGURES 72–79. Scutisotoma longisensilla sp.n. 72, posterior side of manubrium; 73, 74, posterior and anterior sides of dens; 75, Ant.3, lateral view (ls – lateral sensilla); 76–78, variants in position of sensillum and microsensillum on Abd.III (p-chaetae connected by a line, s: sensillum, ms: microsensillum); 79, chaetotaxy of Abd.V (s1–4: accp1–4 sensilla).