Scutisotoma nicksmeti, 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 : 52-54

Scutisotoma nicksmeti sp.n.

Figs. 143–148

Material. Holotype: ♀, Kazakhstan, Tian-Shan Mts. , Zailiiskyi Alatau Range , Chinturgen valley, 30 km south-east from Issyk (43 o 14’N, 77 o 45’E), alpine belt, 3100–3200 m alt., moss on rocks, 21.viii.1991, leg. M. Potapov. Paratypes: 1 ex., same sample. 10 exx., same valley, from mosses and lichens on stones at lower altitudes (2000–2900 m). 5 exx., same region, from Sovet Mt. , alpine meadow, 23.vii.1992, leg. T. Taran ( MSPU) .

Description. Size 0.9–1.1 mm. Colour dark grey with paler spots, extremities paler. Cuticle with visible primary granulation. Ocelli 8+8, G and H smaller. PAO elliptical, rather wide, about 2.0–2.5 as long as ocellus diameter and 0.7–1.1 as long as U 3 ( Fig. 145 ). Maxillary outer lobe with 4 sublobal hairs and bifurcate maxillary palp. Labral formula 4/ 554. Labium with all five papillae present, papilla E without guard e 7. Proximal field with 3 chaetae, basomedian field with 4. Ventral side of a head with (3)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 1 laterodistal s, Ant.3 with 1 bms and 5 distal s (AO and one lateral s). Additional sensilla on Ant.2–3 present in males, usually short. Sensilla on Ant.4 hardly differentiated, subapical organite small.

Dorsal axial chaetom of Th.II–Abd.III as 6–8,5–7/4–5,4–5,4–5. Thorax without ventral axial chaetae. Clearly differentiated macrochaetae only present laterally on Th.II–III and on abdominal tip. Medial macrochaetae on Abd.V are 0.4–0.5 as long as tergite. Sensilla on tergites clearly shorter than ordinary chaetae. Sensillary formula 33/ 22224 (s) and 11/111 (ms). Sensilla on Abd.I–III in mid-tergal position (medial sensillum on Abd.III set in posterior 1/4–1/3 of the tergite). The microsensillum on Abd.III set close to the lateral sensillum ( Fig. 147 ). On Abd.V the lateral pair of sensilla (accp3 and accp4) clearly shorter and thicker than medial ones ( Fig. 146, 148 ).

Unguis simple without inner tooth. Number of chaetae on Ti.1–3 similar to the basic set (21-21-25), but Ti.3 often 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 undifferentiated. Tibiotarsal tenent chaetae (1-2-2) pointed, rarely truncate, about as long as unguis length (U 3: t.ch. = 0.9–1.1: 1). Ventral tube with 4+4 laterodistal and 5–8 posterior chaetae. Tenaculum with 4+4 teeth and 1(2) chaetae. Anterior furcal subcoxa with 10–15 chaetae, posterior one with 6–7 chaetae. Anterior side of manubrium with a pair of distal chaetae, posterior side with 9–10+9–10 on the main part and with (3)4+4 chaetae on laterobasal lobes ( Fig.143 ). Dens with 6 anterior chaetae in the distal half, arranged as 3-2-1. Posterior side crenulated, with 4 chaetae (3 basal and 1 subapical near mucro) ( Fig.143, 144 ). Mucro with two teeth. Ratio of manubrium: dens: mucro = 4.8–6.0: 2.7–3.3: 1.

Affinity. Related to S. tianshanica (Martynova) , which was originally described from the same mountain system (paratypes and some other material have been checked). Both species share the absence of guard e 7 on labial papilla E, which is untypical for the genus. The only significant difference between tianshanica and nicksmeti is the reduced number of chaetae on posterior side of dens in the latter (6 in tianshanica , 4 in nicksmeti ) (cf. Fig. 144 and 149 ). Also nicksmeti has slightly shorter macrochaetae and the tergal sensilla are thicker (cf. Fig. 148 and 150 ).

Distribution. Known from two localities in the northern Tian-Shan Mountains. Field observations from Sailiskoe Alatau indicate that nicksmeti prefers the alpine sites whereas tianshanica lives within the mountain forest belt.

Name derivation. Named after Nickolai Smetana, who studied Collembola communities of Tian-Shan Mts.

Figures

FIGURES 143–150. 143–148, Scutisotoma nicksmeti sp.n. 143, posterior side of furca; 144, dens, lateral; 145, PAO and ocelli; 146, chaetotaxy of Abd.V; 147, lateral sensillum and microsensillum on Abd.III (p-chaetae connected); 148, medial and lateral pairs of sensilla on Abd.III (s: sensillum, ms: microsensillum); 149–150, S. tianshanica. 149, dens, lateral; 150, medial and lateral pairs of sensilla on Abd.V (s1–4: accp1–4 sensilla).