Eosentomon bracychaetum Nakamura, 2010

Nakamura, Osami, 2010, Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan 2701, Zootaxa 2701, pp. 1-109 : 27-30

Eosentomon bracychaetum Nakamura sp. nov.

Figs. 14–15; Table 5

Type specimen. Holotype female ( NSMT –Ap 464), Mt. Hayachine –san, Monma, Kawai –mural, Iwate Prefecture; litter of a forest dominated by Picea glehnii ; 6-XI-2000; T. Fujikawa leg.

Description. Body length 1287 µm. Head 139 µm long, 120 µm wide. Setae aa, pa and m4 present, sensilla as and ps present ( Fig. 14A); seta sp 1.6 times longer than p; sensilla pp rudimentary. Labral setae present ( Fig. 14B). Seta rs inflated, shorter than sr ( Fig. 14B). On maxillary palpus ( Fig. 14C) sensillum md similar to ml in shape and length. On galea ( Fig. 14D) digit O longer than M and I. Mandible with three teeth ( Fig. 14E). Clypeal apodemes distinct ( Figs. 14A, B). Pseudoculus with very faint lines, 15 µm long, PR = 10.

Foretarsus length ( Figs. 14F, G) 105 µm; claw 22 µm, TR = 5.0; empodium 22 µm, EU = 1.0; sensillum s slightly longer than claw. Sensillum t1 closer to α 3' than to α 3, BS = 1.1; t2 thin; t3 thin, not surpassing tarsus; a not reaching base of γ 2; b linear; c linear, not reaching base of γ 3; d thin, surpassing base of α 5; e and g spatulate and long; f1 long, surpassing base of γ 5; f2 small; a' linear; b'1 absent; b'2 thin; c' small. Pores close to α 3' and y, respectively. Length of middle tarsus 53 µm, length of claw 14 µm; hind tarsus 67 µm, claw 18 µm; empodia on both tarsi short and about 1/5 of claw length ( Fig. 14H). On hind tarsus ( Fig. 14H) D2 and D4 spine-like.

Tracheal camerae distally contracted ( Fig. 15A). Side parts of central lobe visible, but central part indistinct ( Fig. 15B). Laterostigmata II–IV distinct and large, with a central pore ( Fig. 15C); that on V small. On female squama genitalis of swani-group ( Fig. 15D) caput processus being curved towards median edge of stylus at a sharp angel, corpus processus slender and continuing forward to the sharp angle of caput processus, filum processus long; median and proximo-lateral sclerotization present. Male unknown.

Chaetotaxy as in Table 5. On thoracic tergites II–III, P1a seta-like, posterior to P1–P2; P2a seta-like, between P2 and P3. P1a on abdominal tergites II–V sensillum-like, about a half length of P1 ( Fig. 15E), those on VI about one-third length of P1 ( Fig. 15F), those on VII about one-fourth length of P1 ( Fig. 15G); P2a on II–V filiform and longer than P1 ( Fig. 15E); those on VI filiform and as long as P1 ( Fig. 15F); those on VII filiform, but shorter than P1 ( Fig. 15G); on tergite VIII ( Fig. 15H) P1a' without basal dilatation and anterior to P2; P2a linear.

Diagnosis. Among the swani -group of Tuxen (1964), this species resembles E. imadatei Tuxen , E. swani Womersley from Australia ( Tuxen, 1964, 1967; Womersley 1932, 1939) and E. yinae Szeptycki & Imadaté from North Korea ( Szeptycki & Imadaté, 1987) in lacking foretarsal sensillum b'1 and possessing two anterior and seven posterior setae on the abdominal sternite VIII. The present species and E. yinae are different from other two species in the positions of foretarsal sensilla t1 posterior to α 3' (at same level with α 3' in E. imadatei and E. swani ) and a' at same level with α 3 (distal to α 3 in E. imadatei and E. swani ), five pairs of anterior setae on abdominal tergite IV (less than five pairs in E. imadatei and E. swani ), six setae on sternites IX–X (four setae in E. imadatei and E. swani ), and the length of P1a shorter than P1 on the abdominal tergites V–VI (longer than P 1 in E. imadatei and E. swani ). This new species is distinguished from E. yinae in the shapes of inflated seta rs (not inflated in E. yinae ) and of P1a shorter than P1 on the abdominal tergites I–IV (longer than P 1 in E. yinae ).

Etymology. The specific name is derived from the short P1a on abdominal tergites II–VII.

Distribution. Japan (Honshu, known only from the type locality).