Eosentomon spatulatum Nakamura, 2010

Nakamura, Osami, 2010, Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan 2701, Zootaxa 2701, pp. 1-109 : 90-94

Eosentomon spatulatum Nakamura sp. nov.

Figs. 50–51; Table 22

Type specimens. Holotype female ( NSMT –Ap 521), Koguchi, Bato–machi, Tochigi Prefecture, 36°45'57"N, 140°08'52"E, 150 m elevation, litter of a plantation of Cr. japonica , 28-X-2002, Y. Hagiwara leg. Paratypes: 2 males ( NSMT –Ap 522–523), 2 female ( NSMT –Ap 524), same data as for the holotype; 2 female ( NSMT –Ap 525), Ryugu, Oze, Katashina–mura, Gunma Prefecture, 1450 m elevation, 36°55'41"N, 139°14' 20"E, litter of a forest dominated by F. crenata and Q. crispula , 23-X-1994, Sakayori et al. leg.

Other specimens examined. Three males, 4 females, 1 larva II, Mt. Hanagame–yama, Daigo–machi, Ibaraki Prefecture, 36°52'57"N, 140°15'21"E, 670 m elevation, litter of a forest dominated by Abies firma , F. japonica and Q. crispula , 21-VI-2003, H. Hosoda & Y. Hagiwara leg.; one female, Mt. Nandai–san, Iwama–machi, Ibaraki Prefecture, 36º18'16"N, 140º13'20"E, 460 m elevation, litter of a forest dominated by and Carpinus laxiflora and Q. serrata , 20-VI-1998, H. Sakayori et al. leg.; 1 female, 3 larvae II, same data as for the holotype; 1 larva II, same locality, 8- VII- 2002, K. Furuno et al. leg.; 1 female, 1 larva II, Mt. Shirane–san, Sotoyama, Yumoto, Nikko–shi, Tochigi Prefecture, 36°47'53"N, 139°24'20"E, 2130m elevation, litter of a forest dominated by T. diversifolia and R. bracycarpum , 14-IX-1997, Furuno et al. leg.; 1 female, Mt. Nantai–san, Nikko–shi, Tochigi Prefecture, 36°45'55"N, 139°29'27"E, 2480 m elevation, litter of a forest dominated by A. veitchii , 14-X-1983, K. Ishii leg.; 1 female, Yumoto, Nasu–machi, Tochigi Prefecture, 37°05'54"N, 140°00'16"E, 1000 m elevation, litter of a deciduous broad-leaved forest, 31- VII- 1985, O. Nakamura et al. leg.

Description. Body length 630 (533–773) µm. Head 96 (99–104) µm long, 73 (73–76) µm wide. Setae pa and m4 present, but seta aa absent ( Fig. 50A), sensilla as and ps present; seta sp 1.5 (1.6–1.8) times longer than p; sensilla pp distinct ( Fig. 50B). Labral setae present ( Figs. 50C, D). Seta rs inflated, shorter than sr ( Figs. 50C, D). On maxillary palpus ( Fig. 50E) sensillum md, 8 (7–8) µm long, longer than ml of 5 (5) µm. Digits on galea developed, O longer than M and I ( Fig. 50F). Mandible with three teeth ( Fig. 50G). Clypeal apodemes distinct ( Figs. 50A, C). Pseudoculus almost circular with no inner structure ( Fig. 50H), 9–11 µm long, PR = 9–11.

Foretarsus length ( Figs. 50I, J) 70 (70–73) µm; claw 15 (15–16) µm, TR = 5.0 (4.8–5.0); empodium 15 (13–15) µm, EU = 1.0 (0.9–1.0); sensillum s as long as or slightly longer than claw, 15 (15–19) µm. Sensillum t1 nearer to α 3 than to α 3', BS = 0.9 (0.8–0.9); t2 slightly spatulate; t3 surpassing base of α 7; a not reaching base of γ 2; b surpassing base of β 5; c almost reaching base of γ 3; d surpassing base of α 5; e and g spatulate and long; f1 thinly spatulate; f2 almost reaching base of γ 5; a' reaching level of α 3’ and at same level with α 3; b'1 absent; b'2 slightly spatulate; c' not surpassing tarsus. Length of middle tarsus 36 (34–36) µm, length of claw 11 (11) µm; hind tarsus 43 (41–44) µm, claw 13 (11–13) µm; empodia of both tarsi short, about 1/10 of claw length ( Fig. 50K); on hind tarsus ( Fig. 50K) D2 and D4 similar, spine-like.

Tracheal camerae distally contracted ( Fig. 50L). Central lobe weak and incised ( Fig. 50M). Laterostigmata II– IV large, II–III with no inner structures, but IV with a weak spot ( Fig. 50N); those on V and VI small. On female squama genitalis ( Figs. 50A, B) caput processus of duck’s head-type or curved towards median edge, filum processus long, proximo-lateral and median sclerotizations distinct. Male squama genitalis with long basiperiphallar setae ( Fig. 51C).

Chaetotaxy as in Table 22. On thoracic tergites II and III, P1a and P2a seta-like and shorter than P1; P1a posterior to P1–P2 and halfway between P1 and P2; P2a at same level with P2–P3. P1a on abdominal tergite I, P1a and P2a on II–VI and P2a on VII filiform and longer than P1, at posterior margin ( Fig. 51D); P1a on VII sensillum-like, shorter than one-third length of P1, at hind margin ( Fig. 51D); on tergite VIII ( Fig. 51E) P1a' short with basal dilatation and anterior to P2; P2a linear.

Larva II. Body length 494–735 µm. Head 82–98 µm long, 64–74 µm wide; pseudoculus 8 µm long, PR = 10– 13. Foretarsus length 55–66 µm; claw 13–15 µm, TR = 4.3–4.8; empodium 14 µm, EU = 1.0; sensillum s 16–17 µm; BS = 0.7–0.9. Length of middle tarsus 27–33 µm, length of claw 9–11 µm; hind tarsus 33–39 µm, claw 10–12 µm. P5 on abdominal tergites II and III displaced anteriorly and at level of A4 on III ( Fig. 51F).

Diagnosis. This new species is similar to E. kantoense in many respects, but the present species (body and foretarsus length 553–773 and 70–73 µm, respectively) is distinctly smaller than E. kantoense (1098–1339 and 108–123 µm, respectively). Further it differs from the latter in the absence of cephalic seta aa (present in E. kantoense ), the shape of simple seta rs (inflated in E. kantoense ), small spatulate foretarsal sensilla t2 and b'2 (long and narrowly spatulate in E. kantoense ), the position of a' at the same level with α 3 (distal to α 3 in E. kantoense ) and four pairs of anterior setae on abdominal tergite IV (five pairs in E. kantoense ).

Chaetotaxic variations observed consisted of doubled P1 of right side on the abdominal sternite III of one female from Bato–machi, the presence of A3 on the abdominal tergite IV of two females from Bato–machi, and the asymmetric absence of A3 on the abdominal sternite III of one female from Mt. Hanagame –yama .

Etymology. The specific name is derived from the characteristic small "spatulate" sensilla t2 and b'2 on foretarsus.

Distribution. Japan (Honshu).