Scutisotoma potapovi, Xie, Gui-Lin & Chen, Jian-Xiu, 2008

Xie, Gui-Lin & Chen, Jian-Xiu, 2008, A new species of Scutisotoma Bagnall (Collembola: Isotomidae) from China, Zootaxa 1766, pp. 46-52 : 47-51

Scutisotoma potapovi sp. nov.

Figs 1–22, Table 1

Type material. HOLOTYPE female: China, Jiangsu Province, Nanjing, northern slope, near the peak of Qingliang Mt., in deadwood, litter, tussocks, under bricks or tiles under a maple and Pterocarya , 2.iii.2006, collection number 9324. PARATYPES: 16 females and 12 males, same data as holotype. Deposited in the Department of Biology, Nanjing University.

Description. Body length of holotype: 2.47 mm, of paratypes: 1.76–2.50 mm, color bluish-gray, eye patches dark, legs and furca pale.

Head. Each antennal segment with many common setae. Ant. I with 2 basal microsensilla (bms) in dorsal and ventral position, and 2 ventral sensilla (s). Ant. II with 3 bms and 1 laterodistal s. Ant. III with 1 bms and 6 distal s (4 in AO and 2 lateral of similar length). Lateral guards of AO longer than inner pair of sensilla. Additional sensilla on Ant. II-III present in males. Ant. IV with 1 bms and 50–80 setae, sensilla (s) poorly differentiated. Pin-seta on Ant. IV simple (Fig. 1). Eyes 8+8, G and H smaller, eye patch with 3 setae e1–3 (=oc3– 1). Postantennal organ (PAO) elliptical, not constricted, surrounded by 5 guard setae, length 2.2–2.8 times the diameter of nearest eye (Fig. 2). Labrum with two apical folds, anterior one larger than posterior. Labral setae formula 2/554, each seta in anterior 3 rows on subequal papilla (Fig. 3). Maxillary palp simple, outer maxillary lobe with 4 sublobal hairs and 1 basal seta (Fig. 4). Head of maxilla with short lamellae (Fig. 5). Labial palp with all 5 papillae (A-E) and 1 lateral process (lp). Totally, 5 papillae with 13 setae (a1, b1-4, d1-4, e1-4), papilla E without guards e4, e5 and e7 (Fig. 6). Hypostomal setae thick and blunt, h1 and H subequal slightly shorter than h2 (Fig. 7). Labium with 3+3 proximal (px), 5+5 basomedian (bm), 5+5 basolateral (bl) setae. Ventral side of head with 4–5+4–5 postlabial (plb) setae along ventral groove (Fig. 8).

Body chaetotaxy. Common setae (c) smooth, in different sizes. Common setae along median line on each side (axial setae––ax) of Th. II–Abd. III as 17–15, 13–14 / 8–10, 9–10, 10. Th. III with 34–36 setae in p-row. Thorax without ventral setae. Sensillum (s) thin-walled, shorter and more translucent than common seta. Microsensillum (ms) thick-walled and smaller than sensillum (Fig. 9). Sensillar and microsensillar formulae 33/22224 (s) and 11/111 (ms), respectively (Fig. 10). Sensilla on Abd. I–III in mid-tergal position. Microsensillum on Abd. III set close to lateral sensillum. Accp sensilla 2 and 3 clearly thicker, accp sensilla 1, 2 and 3 moved forward anteriorly on Abd.V (Fig. 11).

Appendages. Unguis simple without teeth. Unguiculus toothless, long and narrow reaching beyond half of unguis. Ti.1–3 with numerous common setae (about 38, 41 and 58 setae), with 0, 2, 2 clavate tenent hairs, shorter than unguis. A-row and B-row with 7 setae each. Setae on Ti. 3 in males with different setae x and B5. Upper and lower subcoxa with 1 and 1 (leg I), 11 and 14 (leg II), 14–17 and 19–22 (leg III) setae (Figs 12–15), respectively. Ventral tube with 9+9 latero-distal and 10–11 posterior setae ( Fig. 21 ). Retinaculum with 3+3 teeth and with 1–4 setae arranged as 1, 0–1, 0–2 (Fig. 15). Anterior and posterior parts of furcal subcoxa respectively with 38–44 and 17–25 setae ( Fig. 16 ). Manubrium anteriorly with 1+1 setae, posteriorly with about 57–68 setae. Dens anteriorly with 4 (1, 1, 2) setae, posteriorly with 7–8 (2–3, 1,1,1,1,1) setae. Mucro with 3 teeth. ( Figs 17, 18 ). Length ratio of manubrium:dens:mucro as 7–10.7:6.5–7.3:1.

FIGURES 1–8. Scutisotoma potapovi sp. nov.: 1, antennal sensilla; 2, eyes and PAO, PAO––postantennal organ, g1-5––guard setae associated with PAO, e1–3 (=oc3–1)––setae in eye patch; 3, labrum; 4, maxillary outer lobe, mxp––maxillary palp, slh––sublobal hairs, bc––basal seta; 5, maxillary head; 6, labial palp, A-E––main papillae and sensilla, lp––lateral process, e1–6—sensilla of papillae E; 7, hypostomal setae, H––main hypostomal setae, h1 –2––accessory hypostomal setae; 8, labium, showing groups of setae, px—proximal group, bm––basomedial group, bl––basolateral group, plb––postlabial group.

FIGURES 9–15. Scutisotoma potapovi sp. nov.: 9, variations of setae, from left to right: common setae (c), sensilla (s), microsensillum (ms); 10, body sensilla (s) and microsensillum (ms), lateral view; 11, dorsal & lateral chaetotaxy of Abd. V; 12, leg III in male (B5, x: male modified chaetae); 13, leg I; 14, legII; 15, leg III.

Genital plate. Male with 9+9 outer setae. 6+7 setae in peripheral area ( Fig. 19 ). Female with 2+2 outer setae and 6+7 setae in peripheral area ( Fig. 20 ).

Etymology. The new species is named after Mikhail Potapov (Moscow State Pedagogical University) for his kind help and suggestions.

Remarks. The new species could be easily separated from all known species in the genus by the combination of the following characters: large body, number of prelabral setae (only 2 what is exceptional in this genus), numerous common setae on Ti.1–3 (about 38, 41 and 58 setae; only S. titusi Folsom, 1937 posses more than 21, 21, 25 setae) and 0, 2, 2 clavate tenent hairs, Abd. V with thick accp sensilla 2 and 3, labial papilla E with 4 setae, e4, e5 and e7 absent, setae B5 and x on Ti. 3 in males different from other setae, ventral tube with 9+9 laterodistal and 10–11 posterior setae.

The new species is similar to S. subarctica ( Gisin, 1950) and S. indigirka Potapov, Babenko & Fjellberg, 2006 in mucro with 3 teeth, manubrium anterior setae 1+1, simple maxillary palp, dens crenulated, sensilla on abdomen set in mid-tergal position, eyes 8+8, G and H smaller, outer maxillary lobe with 4 sublobal setae, labium with 3+3 proximal setae, B-row on Ti.1–3 with 7 setae, thorax without ventral setae. The differentiating characters are presented in the Table 1.

Figures

FIGURES 16 – 22. Scutisotoma potapovi sp. nov.: 16, anterior and posterior parts of furcal subcoxa; 17, furca, anterior view; 18, furca, posterior view; 19, male genital plate; 20, female genital plate; 21, ventral tube, posterior view; 22, retinaculum, anterior view.