Subisotoma asiatica ( Martynova, 1970 )

Potapov, Mikhail, Babenko, Anatoly, Fjellberg, Arne & Greenslade, Penelope, 2009, Taxonomy of the Proisotoma complex. II. A revision of the genus Subisotoma and a description of Isotopenola gen. nov. (Collembola: Isotomidae), Zootaxa 2314, pp. 1-40 : 22

Subisotoma asiatica ( Martynova, 1970)

Figs 58–60 , Tab. 2

Folsomides asiaticus Martynova, 1970: 1876

Material. Paratypes, female and male, Kyrgyz Republic, Issyk–Kul’, Kok–Moinok, 1580 m alt., litter. 23.vi.1969, leg. P. Vtorov ( ZIN)

Redescription. Size 0.80–0.85 mm. According to the original description the colour is light, with diffuse grey pigment, specimens on slides are colourless. Cuticle, especially in middle parts of terga, with unequally sized granulated pattern that gives the appearance of very coarse granulation ( Fig. 59 ). Ocelli 8+8, subequal, G and H ocelli insignificantly smaller than others. PAO large and wide, almost 3 times as long as nearest ocellus (in the original description only 1.5 as long) and clearly longer than inner unguis (1.2–1.3 as long). Maxillary outer lobe with simple palp and 4 sublobal chaetae. Chaetotaxy of labrum not seen on available specimens. Labium with all 5 papillae present, papilla Е at least with two guard chaetae lost (more exact number of e-guard chaetae was impossible to ascertain), proximal and basomedian fields of labium with 3 and 4 chaetae as usual. Ventral side of head with 4+4 postlabial chaetae. Ant.1 with 2 basal microsensilla (bms, dorsal and ventral), and 2 ventral sensilla (s) differing in size. Ant.2 with 3 bms and 1 laterodistal s. Ant.3 with 5 distal s ( AO and one lateral s), inner sensilla of AO roundish and much shorter than outer ones, bms and additional sensilla absent (as on Fig. 61 ). Ant.4 with many poorly differentiated sensilla, subapical organite small, microsensillum present.

Dorsal axial chaetom of Th.II–Abd.III as 8, 7/5, 5–6, 6. Thorax without ventral axial chaetae. Macrochaetae not developed, ordinary chaetae slightly broadened, especially on abdominal tip. Largest chaetae on Abd.V about 0.2 times as long as tergal length. Sensilla short, clearly differentiated from ordinary chaetae. Sensillar formula 33/22224 (s) and 10/001 (ms). Sensilla on Abd.I–III set near the p-row of chaetae, ms on Abd.III situated between sensilla and in front of them ( Fig. 58 ). On Abd.V the sensilla of the lateral pair shorter and slightly wider than medial sensilla.

Unguis simple, without inner tooth. Unguiculus lanceolate, inner lamella poorly developed. Ti.1–3 with 21, 21, 25 chaetae. Tibiotarsal tenent chaetae hardly differentiated. Ventral tube with 4+4 laterodistal and 5 caudal chaetae. Tenaculum with 3+3(2) teeth and one chaeta. Sterna of Abd.III with a pair of medial chaetae isolated from the main setaceous part of segment ( Fig. 60 ). Anterior furcal subcoxae with 7–8(10) chaetae, posterior ones with 6 chaetae. Manubrium without anterior chaetae, posterior side with 9–10+9–10 chaetae, laterobasal lobes with 4(3) additional chaetae. Dens with only 3–4 posterior chaetae, no anterior chaetae. Mucro short, with two subequal teeth, weekly set off from dens. Ratio of manubrium: dens: mucro as about 10: 5: 1. Anal lobes with three minute setulae.

Affinity. Broadened chaetae and coarse granulation are unique characters among known members of Subisotoma but could indicate that type material is affected by ecomorphosis. Apart from these unreliable characters, S. asiatica is well defined by microsensillar set (10/001), the absence of basal ms on Ant.3 and anterior chaeta on dens (the two latter are shared with S. cruda sp. nov.).

Distribution. The known distribution of the species is restricted to the Issyk–Kul’ lake basin, where it is rather common in desert, semi–desert and mesophytic communities on plain and foothills ( Vtorov & Martynova 1976).

Figures

FIGURES 58 – 60. Subisotoma asiatica (paratype): 58, chaetotaxy of Abd. III; 59, area of posterior part of head (high magnification); 60, ventral side of Abd. III (pair of isolated chaetae encircled), sock. –– chaetal socket.

FIGURES 61 – 63. Subisotoma cruda sp. n.: 61, Ant. 3, dorsal view; 62, ventral chaetotaxy of posterior part of abdomen and furca; 63, chaetotaxy of Abd. V.