Eosentomon dubium Nakamura, 2010

Nakamura, Osami, 2010, Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan 2701, Zootaxa 2701, pp. 1-109 : 35-38

Eosentomon dubium Nakamura sp. nov.

Figs. 19–20; Table 7

Type specimens. Holotype female ( NSMT –Ap 467), Jouin –ji, Tsukiya –cho, Ashikaga –shi, Tochigi Prefecture, 36º22'48"N, 139º26'31"E, 225 m elevation, litter of a plantation of Cr. japonica , 12-VII-1997, K. Furuno et al. leg . Paratypes: 2 males ( NSMT –Ap 468–469), same data as for the holotype ; 1 female ( NSMT –Ap 470), Mansho, Yano, Kamiizumi –mura, Saitama Prefecture, 36º07'12"N, 139º01'14"E, litter of a forest dominated by Q. myrsinaefolia , 450 m elevation, 24-VIII-1993, O. Nakamura leg.

Other specimens examined. One male, 1 female, Iwasaki, Toyohashi –shi, Aichi Prefecture, 150 m elevation, 7-XII-1977, K. Niijima leg. ; 1 male, Omoto –dake, Ishigaki Island , Okinawa Prefecture, 24º25'28"N, 124º10'49"E, 450 m elevation, litter of a evergreen broad-leaved forest, 24-V-2000, H. Mizushima leg. ; 1 male, Komi, Iriomote Island , Okinawa Prefecture, 24º19'28"N, 123º54'09"E, 20 m elevation, litter of a evergreen broad-leaved forest, 2- III- 2002, S. Nagashima leg. ; 1 female, Ohara, Iriomote Island , Okinawa Prefecture, 24º16'35"N, 123º52'10"E, 40 m elevation, litter of a forest dominated by Pandnus odoratissimus, 29-V-2000, H. Mizushima leg.

Description. Body length 572 (520–702) µm. Head 85 (86–89) µm long. Setae aa, pa and m4 present, sensilla as and ps present ( Fig. 19A); seta sp 1.5 (1.4–1.5) times longer than p; sensilla pp rudimentary. Labral setae present ( Fig. 19B). Seta rs inflated, equal to sr in length ( Fig. 19B). On maxillary palpus ( Fig. 19C) sensillum md slightly longer than ml. On galea ( Fig. 19D) digit O longer and more slender than M and I; M and I close to each other. Mandible with 3 teeth ( Fig. 19E). Clypeal apodemes distinct ( Fig. 19F). Pseudoculus circular ( Fig. 19G), 11 (12– 14) µm long, PR = 8 (6–8).

Foretarsus length ( Figs. 19H, I) 57 (57–58) µm; claw 13 (12–13) µm, TR = 5; empodium slightly shorter than claw, 13 (12–13) µm, EU = 1.0; sensillum s slightly longer than claw, 14 (13) µm. Sensillum t1 closer to α 3 than to α 3', BS = 0.8 (0.8–0.9); t2 thinly spatulate; t3 long, surpassing base of α 7; a closer to γ 1 than to γ 2; b spatulate; c slightly broadened; d broadened, surpassing base of α 6; e and g roundedly spatulate and long; f1 thinly spatulate; f2 long, reaching base of γ 5; a' at same level with α 3; b'1 slightly broadened and nearer to δ 3' than to δ 4'; b'2 thinly spatulate; c' absent. Length of middle tarsus 26 (26–28) µm, length of claw 9 µm; empodium short and less than 1/ 4 of claw length ( Fig. 19J), 1 (1–2) µm long; hind tarsus 31 (30–35) µm, claw 10 (9–11) µm; empodium about 2/3 of claw length ( Fig. 19K), 7 (5–7) µm; on hind tarsus ( Fig. 19K) D2 and D4 spine-like, somewhat more slender than D5.

Tracheal camerae thin ( Fig. 19L). Central lobe trapezoidal, inner line constricted in middle ( Fig. 19M). Laterostigmata II–III distinct, with no inner structure. On female squama genitalis ( Fig. 19N) S-shaped sclerotization on processus sternalis, caput processus duck’s head-like, filum processus long. Male genitalis with short basiperiphallar setae.

Chaetotaxy as in Table 7. On thoracic tergites II–III, P1a seta-like, posterior to P1–P2; P2a seta-like, nearer to P2 than to P3. P1a on abdominal tergite I, P1a and P2a on II–VI, and P2a on VII filiform and longer than P1 ( Fig. 20A); P1a on VII sensillum-like and about one-third length of P1, posterior to P1–P2 ( Fig. 20B); on tergite VIII ( Fig. 20C) P1a' oblong and anterior to P2; P1a' and P2 nearly the same level with M4; P2a linear.

Diagnosis. This species is similar to E. udagawai Imadaté from Japan ( Imadaté, 1961b, 1974b, 1995), Korea ( Imadaté & Szeptycki, 1976) and Taiwan ( Chao & Chen, 1996) and E. orientalis Yin from China ( Yin, 1965, 1999) in the absent or rudimentary foretarsal sensillum c', possession of a long empodium on hind tarsus, two anterior and seven posterior setae on abdominal tergite VIII, and six setae on abdominal sternites IX–X. However, this new species differs from E. udagawai in the presence of labral setae (absent in E. udagawai ) and the short empodium on middle tarsus (1/3 of claw length in E. udagawai ), and from E. orientalis in pseudoculus with no inner structure (three striae present in E. orientalis ) and five pairs of anterior setae on abdominal tergites V–VI (four pairs in E. orientalis ).

Etymology. The specific name refers to the similarity and long confusion of this species with E. udagawai .

Distribution. Japan (Honshu and Okinawa).