Osientomon japonicum Nakamura, 2010

Nakamura, Osami, 2010, Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan 2701, Zootaxa 2701, pp. 1-109 : 6-10

Osientomon japonicum Nakamura sp. nov.

Figs. 1–3; Table 1

Type specimens. Holotype female ( NSMT –Ap 450), Kushiishi –yama, Ajigasawa –machi, Aomori Prefecture, 40°31'06"N, 140°06'17"E, 520 m elevation, litter of a forest dominated by Fagus crenata , 2-X-1999, H. Tamura et al. leg . Paratypes: 1 male ( NSMT –Ap 451) , 1 female ( NSMT –Ap 452), same data as for the holotype .

Other specimens examined. One male, Mt. Komaga–take, Kanegasaki–machi, Iwate Prefecture, 39°11'09"N, 140°56'40"E, 620 m elevation, litter of a forest dominated by Quercus crispula , with a ground cover of Sasa kurilensis , 18-VIII-2001, H. Tamura et al. leg.; 1 male, Mt. Kodake, Fujisato–machi, Akita Prefecture, 40°25'58"N, 140°11'51"E, 1040 m elevation, litter of a forest dominated by Q. crispula var. horikawae and Rhododendron brachycarpum , 28-VIII-1994, O. Nakamura leg.; 1 male, Akanagi–san, Tochigi Prefecture, 36°48'33"N, 139°34'07"E, 1670 m elevation, Sasa field, 21-IX-1996, K. Furuno et al. leg.; 1 female, Yamanohana, Katashina– mura, Gunma Prefecture, 36°54'08"N, 139°11'50"E, 1450 m elevation, litter of a forest dominated by F. crenata and Q. crispula , 22-X-1994, H. Tamura et al. leg.; 1 male, Tochimoto, Otaki, Chichibu–shi, Saitama Prefecture, 35°56'58"N, 138°53'57"E, 900 m elevation, 9- VII- 1991, Y. Kuwabara leg.; 1 female, Setokura, Oyama–machi, Toyama Prefecture, litter of a forest dominated by F. crenata, 1280 m elevation, 11-VI-1995, Y. Hirauchi leg.

Dorsal Ventral

Formula Composition of setae Formula Composition of setae Thorax I 4 1, 2 6-2 A1, 2, 3, M

6 P1,2,3

II 6 A2,4, M 6-2 A1,2,3, M

16 P1,1a, 2,2a, 3,3a, 4,5 6 P1,2,3

III 6 A2, 4, M 6-4 A1, 2, 3, M1, 2

20 P1,1a, 2,2a, 3,3a, 4,4a, 5,6 8 P1,2,2a, 3

Abdomen I 4 A1, 2 4 A1, 2

12 P1,1a, 2,2a, 3,4 4 P1,2

II-III 10 A1, 2, 3, 4, 5 6 A1, 2, 3

16 P1,1a, 2,2a, 3,4,4a, 5 4 P1,2

IV-VI 10 A1, 2, 3, 4, 5 6 A1, 2, 3

16 P1,1a, 2,2a, 3,4,4a, 5 10 P1,2,2a, 2a’, 3

VII 6 A2, 4, 5 6 A1, 2, 3

16 P1,1a, 2,2a, 3,4,4a, 5 10 P1,2,2a, 2a’, 3

VIII 6 M2, 4, 5 2 A

9 Pc, 1a, 1a’, 2,2a 7 Pc, 1,1a, 2

IX-X 8 1, 2, 3, 4 6 1, 1a, 2

XI 8 1,2,3,4 8 1,2,3,4

Telson 9 12

Description. Body length 670 (598–819) µm. Head length 110 (97–113) µm. Setae aa, pa and m4 present, sensilla as and ps present ( Fig. 1A); seta sp equal to p in length; sensilla pp rudimentary. Labral setae present ( Fig. 1B). Seta rs simple, equal to sr in length ( Fig. 1B). On maxillary palpus ( Fig. 1C) sensillum md slightly longer than ml. On galea ( Fig. 1D) digit O slightly longer than M and I. Mandible with three apical and one subapical teeth ( Fig. 1E). Clypeal apodemes distinct ( Fig. 1B). Pseudoculus circular, 10 (7–9) µm, with two depressions ( Fig. 1F), PR = 11 (13–15).

Foretarsus length ( Figs. 1G, H) 73 (63–78) µm; claw 14 (13–14) µm, TR = 5.2 (5.6–5.8); empodium equal to claw in length, 14 (13–14) µm, EU = 1.0; sensillum s slightly longer than claw, 17 (14–15) µm. Sensillum t1 closer to α 3 than to α 3', BS = 0.8; t2 thin; t3 broadened and long, surpassing tarsus; a slightly broadened; b reaching base of β 5; c slightly broadened, reaching base of γ 3; d broadened, surpassing base of α 6; e absent; f1 spatulate; f2 thin; g short and setiform; a' thin; b'1 absent; b'2 thin; c' absent. Length of middle tarsus 32 (28–35) µm, length of claw 11 (10–11) µm, empodium short and about 1/4 of claw length ( Fig. 1I), 2 µm long; hind tarsus 41 (36–43) µm, claw 11 (10–11) µm, empodium longer than 2/3 of claw length ( Fig. 1J), 8 (7–9) µm; on hind tarsus ( Fig. 1J) D2 and D4 spine-like, D4 more slender than D2.

Tracheal camerae short ( Fig. 2A). Central lobe trapezoidal ( Fig. 2B). Laterostigmata II – III distinct ( Fig. 2C); II without inner structure; III with a weak curved line. On female squama genitalis ( Fig. 2D) S-shaped sclerotization on processus sternalis, caput processus of duck's head type, proximo-lateral sclerotization present, filum processus long, median sclerotization present. Male squama genitalis with short basiperiphallar setae ( Fig. 2E) .

Chaetotaxy as in Table 1. On thoracic tergites II–III, P1a and P2a seta-like, P1a posterior to P1–P2, P2a slightly closer to P2 than to P3 ( Fig. 3A). Setae 1 and 2 on abdominal tergite XI microchaetae. P1a on abdominal tergite I, P1a and P2a on I–VI and P2a on VII filiform and longer than P1 ( Figs. 3B, C, E); P1a on VII sensillumlike and shorter than one-fourth length of P1, at hind margin ( Fig. 3E); on tergite VIII ( Fig. 3D) P1a’ oblong and anterior to P2, P2a linear. Sternite VIII with two anterior and seven posterior setae ( Fig. 3F); IX–X with three pairs of setae ( Fig. 3F). On telson, a pair of anterior sternal setae small and sensillum-like ( Fig. 3F).

Diagnosis. This new species is similar to O. linoculum (Zhang & Yin) from China ( Yin, 1999; Zhang & Yin, 1981), but differs in pseudoculus structure (two depressions on the disc, rather than five longitudinal striae and three minute globules in O. linoculum ), long empodium on hind tarsus (short in O. linoculum ), and five pairs of anterior setae on abdominal tergites IV–VI (four pairs in O. linoculum ), the presence of anterior setae on sternite VIII (no anterior setae in O. linoculum ), and six setae on sternites IX–X (four setae in O. linoculum ). One female from Setokura possesses four pairs of anterior setae on the abdominal tergite VII.

Etymology. The specific name is named for its country of origin.

Distribution. Japan (Honshu).