Eosentomon hiroshianum Nakamura, 2010

Nakamura, Osami, 2010, Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan 2701, Zootaxa 2701, pp. 1-109 : 42-46

Eosentomon hiroshianum Nakamura sp. nov.

Figs. 23–24; Table 9

Type specimens. Holotype female ( NSMT –Ap 473), Mt. Komaga–take, Kanegasaki–machi, Iwate Prefecture, 39º11'21"N, 140º55'41"E, 920 m elevation, litter of a forest dominated by F. crenata and Q. crispula , 18-VIII-2001, H. Tamura et al. leg. Paratypes: four females ( NSMT –Ap 474–477), same data as for the holotype; two females ( NSMT –Ap 478–479), Mt. Komaga–take, Kanegasaki–machi, Iwate Prefecture, 820 m elevation, litter of a forest dominated by F. crenata , 18-VIII-2001, H. Tamura et al. leg.

Other specimens examined. Nine males, 7 females, 11 maturi juniores, 11 larvae I, same data as for the holotype; 3 males, 2 females, 2 maturi juniores, 2 larvae I, 820 m elevation, 2 females, two maturi juniores, 1020 m elevation, litter of a forest dominated by F. crenata and Q. crispula , 3 males, 6 females, 1130 m elevation, litter of a forest dominated by F. crenata, Mt. Komaga –take, Kanegasaki –machi, Iwate Prefecture, 18-VIII-2001 , H. Tamura et al. leg.; 2 males, 1 female, 39º50'38"N, 141º00'53"E, 1500 m elevation, litter of a forest dominated by Betula ermanii , 6 males, 3 females, 1 maturus junior, 39º50'35"N, 141º01'08"E, 1280 m elevation, litter of a forest dominated by B. ermanii , 3 males, 1 female, 2 maturi juniores, 39º50'29"N, 141º01'22"E, 1080 m elevation, litter of a forest dominated by F. crenata and Q. crispula , 2 males, 1 female, 1 maturus junior, 2 larvae II, 39º50'22"N, 141º01'22"E, 820 m elevation, litter of a forest dominated by Q. crispula and F. crenata, Mt. Iwate –san, Takizawa – mura, Iwate Prefecture, 28-VI-1985, O. Nakamura leg.

Description. Body length 1164 (870–1400) µm. Head 130 (128 –147) µm long, 105 (106–114) µm wide. Setae aa, pa and m4 present, sensilla as and ps present ( Fig. 23A); seta sp 1.9 (1.7–2.0) times longer than p; sensilla pp distinct ( Fig. 23B), (2–3 µm long). Labral setae present ( Figs. 23C, D). Seta rs inflated, shorter than sr ( Figs. 23C, D). On maxillary palpus ( Fig. 23E) sensillum md, 9 (8–10) µm, longer than ml, 7 (7–8) µm. Digits on galea developed and similar to each other ( Fig. 23F). Mandible with three teeth ( Fig. 23G). Clypeal apodemes distinct ( Fig. 23A, C). Pseudoculus almost circular, 12 (10–13) µm long, (10–12 µm wide), without inner structure, but one central spot rarely observed ( Fig. 23H), PR = 11 (10–14).

Foretarsus length ( Figs. 23I, J) 105 (98–112) µm; claw 22 (20–24) µm, TR = 4.9 (4.4–5.4); empodium 21 (20– 22) µm, EU = 0.9 (0.8–1.0); sensillum s as long as or slightly longer than claw, 22 (22–26) µm. Sensillum t1 nearer to α 3' than to α 3, BS = 1.1 (1.1–1.2); t2 thin; t3 thin, not reaching tarsus; a thin, not reaching base of γ 2; b reaching base of e; c not surpassing base of γ 3; d long, surpassing base of α 5; e and g long and spatulate; f1 thin, surpassing tarsus; f2 short; a' surpassing base of t1; b'1 absent; b'2 reaching base of α 5; c' anterior to base of α 6, on the line between α 6 and δ 5, not surpassing tarsus. Length of middle tarsus 53 (51–58) µm, length of claw 16 (13–17) µm; hind tarsus 70 (67–75) µm, claw 18 (17–19) µm; empodia on both tarsi shorter than 1/5 of claw length ( Fig. 23K), 2 (1–3) µm long; on hind tarsus ( Fig. 23K) D2 and D4 thin spine-like, D4 longer and more slender in distal part than D2.

Tracheal camerae long, distally contracted ( Fig. 23L). Central lobe incised ( Fig. 23M). Laterostigmata II–IV large, with no inner structure; those on V–VII small. On female squama genitalis ( Fig. 24A) caput processus swan's head-like, filum processus long, median sclerotization present. Male genitalis with long basiperiphallar setae ( Fig. 24B).

Chaetotaxy as in Table 9. On thoracic tergites II–III, P1a seta-like, slightly longer than P1, posterior to P1–P2, slightly nearer to P1 than to P2; P2a seta-like, shorter than P1, at same level with P2–P3. On abdominal tergites I– VII, P1a sensillum-like and shorter than about one-third length of P1, at hind margin ( Figs. 24C–F); P2a on II–IV filiform and longer than P1 ( Fig. 24D), those on V filiform and as long as P1, those on VI–VII filiform, shorter than P1, but two times longer than P1a ( Figs. 24E, F); on tergite VIII ( Fig. 24G) P1a' without basal dilatation and slightly anterior to P2; P2a linear.

Maturus junior. Body length 904–1034 µm. Head 128–139 µm long, 91–105 µm wide; pseudoculus 10–11 µm long, PR = 13–14. Foretarsus length 90–95 µm, claw 19–20 µm, TR = 4.8–5.0; empodium 18–20 µm, EU = 0.9– 1.0; sensillum s slightly longer than claw, 20–22 µm. Length of middle tarsus 49–51 µm, length of claw 15 µm, empodium 2 µm long; hind tarsus 61–64 µm, claw 16 µm, empodium 2–3 µm. Shape and position of foretarsal sensilla same as those of imago; BS = 1.1.

Larva II. Body length 682–884 µm. Head length 128–136 µm; pseudoculus 8 µm long, 7–8 µm wide, PR = 16. Foretarsus length 80–81 µm; claw 18–20 µm, TR = 4.1–4.5; empodium 17 µm, EU = 0.9; sensillum s 19–20 µm. Length of middle tarsus 42–43 µm, length of claw 14 µm, empodium 3 µm long; hind tarsus 55 µm, claw 15–16 µm, empodium 3 µm. Shape and position of foretarsal sensilla same as those of imago; BS = 1.1. P5 on abdominal tergites II and III displaced anteriorly and at same level with A4 on III ( Fig. 24H).

Larva I. Body length 663–845 µm. Head 104–115 µm long, 79–93 µm wide; pseudoculus indistinct. Foretarsus length 70–80 µm; claw 18–20 µm, TR = 4.0–4.1; empodium 17–18 µm, EU = 0.9–1.0; sensillum s 18–22 µm. Length of middle tarsus 39–45 µm, length of claw 13 µm, empodium 2–3 µm long; hind tarsus 48–54 µm, claw 14– 15 µm, empodium 2–3 µm. Shape and position of foretarsal sensilla same as those of preceding stages.

Diagnosis. The present species is similar in many respects to E. brachychaetum and E. yinae . However, it different from E. brachychaetum in sensillum md longer than ml on the maxillary palpus (md as long as ml in E. brachychaetum ), the shape of distinct sensillum pp (rudimentary in E. brachychaetum ), foretarsal sensillum t3 shorter than c’ (longer than c' in E. brachychaetum ) and five pairs of anterior setae on abdominal tergite VI (four pairs in E. brachychaetum ); and from E. yinae in the shape of inflated seta rs (simple in E. yinae ) and P1a shorter than P1 on the abdominal tergite I–IV (longer than P 1 in E. yinae )

Chaetotaxic variations observed consisted of the asymmetric absences of A3 on abdominal tergite II in two maturi juniores and 1a on the abdominal sternite IX in one maturus junior from Mt. Iwate-san.

Etymology. The specific name is named in honor of Dr. Hiroshi Tamura, who kindly provided opportunities to survey in Mt. Iwate-san and Mt. Komaga–take, Iwate Prefecture, where the specimens examined were collected, and who is my mentor for studies on basal hexapods.

Distribution. Japan (Honshu).