Pseudanisentomon nasuense, Nakamura, 2021

Nakamura, Osami, 2021, Three New Species of the Family Eosentomidae (Protura) from the Nasu Imperial Villa, Central Japan, Species Diversity 26 (1), pp. 111-125 : 115-118

Genus Pseudanisentomon Zhang and Yin, 1984 Pseudanisentomon nasuense sp. nov.

( Figs 3 , 4 ; Table 2)

Pseudanisentomon sp. : Nakamura 2019: 18 (partim).

Diagnosis. Foretarsal sensillum b ′ 1 absent, d fairly broad, and t3 long, reaching base of tarsal claw; long empodia on both middle and hind tarsi; abdominal tergites II–IV with five pairs of anterior setae, V–VII with four pairs of anterior setae (A1, 2, 4, 5); sternites IX–X with six setae.

Specimens examined. Holotype (NSMT-Ap 540): female, the Nasu Imperial Villa, Nasu-machi, Tochigi Prefecture, 37.1102°N, 140.0152°E, elev. 928 m, secondary forest dominated by Q. crispula and P. densiflora , 5 September 2012, K. Furuno et al. leg. Paratypes (n=21): one female (NSMT-Ap 541), same data as for the holotype; same locality as for the holotype, two males (NSMT-Ap 542, 543), 11 June 2012, one male and one female (NSMT-Ap 544, 545), 7 November 2012, one male and one female (NSMT-Ap 546, 547), 15 October 2013, K. Furuno et al. leg.; 37.1105°N, 140.0150°E, elev. 929 m, one male and one female (NSMT-Ap 548, 549), 11 June 2012, one male (NSMT-Ap 550), 7 November 2012, K. Furuno et al. leg.; 37.1102°N, 140.0161°E, elev. 918 m, one male and three females (TPM-IV-14025–14028), 11 June 2012, one male (TPM-IV-14029), 15 October 2013, one male (TPM-IV-14030), 27 October 2015, K. Furuno et al. leg.; 37.1100°N, 140.0158°E, elev. 919 m, one female (SMNH-Ap-36640), 7 October 2011, one female (SMNH- Ap-36641), 11 June 2012, one female (SMNH-Ap-36642), 7 November 2012, two males (SMNH-Ap-36643, 36644), 15 October 2013, K. Furuno et al. leg.

Other material examined (n=17): same locality as for the holotype, one female, 7 November 2012, one male and one female, 15 October 2013, one female and one maturus junior, 27 October 2015; 37.1105°N, 140.0150°E, elev . 929 m, one male and one female, 7 October 2011, one male and one female, 11 June 2012, one maturus junior, 7 November 2012, one maturus junior, 15 October 2013; 37.1102°N, 140.0161°E, elev. 918 m, two males, one female and one maturus junior; 37.1100°N, 140.0158°E, elev. 919 m, one male, 7 November 2012, one female, 27 October 2015.

Description. Body length. 722 (592–780) µm.

Head. 99 (95–100) µm long, 67 (66–74) µm wide. Posterior additional setae and seta m4 present, anterior additional seta absent; anterior and posterior sensilla present ( Fig. 3A ); median subposterior seta length 8 (7–9) µm, 1.1 times longer than median posterior seta, 7 (6–8) µm; a pair of rudimentary sensilla posterior to pseudoculus rudimentary. Labral setae present ( Fig. 3B ). Rostral seta length 11 (10–12) µm, tapering, subequal to subrostral seta, 11 (10–14) µm in length ( Fig. 3B ). On maxillary palpus ( Fig. 3C ) dorsal sensillum length 6 (5–7) µm, longer than lateral sensillum, 4 (4–6) µm. On galea ( Fig. 3D ), digit O longer than M and I. Mandible with two teeth ( Fig. 3E ). Clypeal apodeme distinct ( Fig. 3B ). Pseudoculus with three lines, central one long and other two short ( Fig. 3F ), 7 (7–9) µm long, PR=15 (12–15).

Legs. Foretarsus length ( Fig. 3G, H ) 64 (61–67) µm; claw 12 (11–13) µm, TR=5.0 (4.7–5.5); empodium 12 (11–13) µm, EU=1.0 (0.9–1.1); sensillum s length about equal to claw, 11 (11–13) µm. Sensillum t1 nearer to α3 than to α3 ′, BS=0.9 (0.9–1.0); t2 thin; t3 broad, reaching base of tarsal claw; a linear; b linear, reaching base of β6; c linear, reaching base of γ3; d fairy broad, reaching base of α5; e absent; f1 narrowly spatulate; f2 linear; g rounded spatulate and large; a ′ linear; b ′ 1 absent; b ′ 2 and c ′ thin, almost same length. A pore posterior to seta y. Length of middle tarsus 27 (26–30) µm, length of claw 10 (8–11) µm; hind tarsus 33 (33–37) µm, claw 11 (8–10) µm; both empodia long, about 2/3 of claw length on middle tarsus, 7 (5–8) µm long ( Fig. 3I ); empodium longer than 2/3 of claw length on hind tarsus ( Fig. 3J ), 9 (7–9) µm long; on hind tarsus ( Fig. 3J ), D2 seta-like; D4 spine-like, but more slender than D5.

Chaetotaxy. Chaetotaxy as in Table 2 and Fig. 4A–D . On thoracic tergites II–III ( Fig. 4A ), P1a and P2a seta-like; P1a posterior to P1-P2; P2a on II slightly nearer to P2 than to P3; P2a on III halfway between P2 and P3; P1a and P2a on II–III shorter than P1; on II P1a 8 (7–10) µm, slightly longer than P2a, 7 (5–7) µm; on III P1a 7 (9–11) µm, length subequal to or slightly longer than P2a, 7 (7–9) µm. Abdominal tergites II–IV with five pairs of anterior setae (A1 to 5), V–VII with four pairs (A1, 2, 4, 5); P1a on I, P1a and P2a on II–VI and P2a on VII delicate, longer than P1; P1a on VII short, about 1/3 of P 1 in length, 5 (4–7) µm long, at hind margin ( Fig. 4B ); on VIII ( Fig. 4C ) P1a ′ with basal dilatation and slightly anterior to P2, P2a ′ falcate. Setae on thoracic and abdominal sternites all seta-like; VIII with two anterior and seven posterior setae; IX–X with six setae ( Fig. 4D ).

Porotaxy. Abdominal tergites I–V with posterosubmedial pore between A2 and P2; IX–X with one medial pore ( Fig. 4C ). Abdominal sternites VIII–X with one medial pore ( Fig. 4D ). Telson with one dorsal medial pore and two ventral medial pores.

Genitalia. Female squama genitalis ( Fig. 4E ), with caput processus shaped like a duck’s head, filum processus short; proximo-lateral sclerotization present; posterior sclerotization of stylus apex present. Male squama genitalis with short basiperiphallar setae ( Fig. 4F ).

Maturus junior (n=4). Body length 580–618 µm. Head 91–94 µm long, 63–74 µm wide; pseudoculus 7–8 µm long, PR=11–14. Foretarsus length 56–59 µm; claw 10–11µm, TR=5.0–5.6; empodium 9–10 µm, EU=0.8–1.0; sensillum s 9–11 µm; shape and position of foretarsal sensilla same as those of imago, BS=0.8–0.9. Length of middle tarsus 27 µm, length of claw 8–10 µm, empodium 5–6 µm; hind tarsus 29–33 µm, claw 10–11 µm, empodium 7–10 µm. Chaetotaxy as in imago, but lacking P1a on abdominal sternite IX and 2 and 4 on sternite XI.

Chaetotaxic variation. Pc on abdominal sternite VIII absent in one female; A2 on abdominal tergite III asymmetrically absent in one male; P2a ′ on abdominal sternites VI and VII absent and asymmetrically absent in one maturus junior, respectively.

Remarks. The genus Pseudanisentomon is distributed in China and Japan, and consists of 22 species, of which 18 are from China and four are from Japan ( Yin 1999; Nakamura 2010; Bu et al. 2020). The new species resembles P. songkiangensis (Yin, 1977) , P. guangxiensis (Yin and Zhang, 1982) , P. huichouense Zhang and Yin, 1984 , and P. jiangxiensis Yin, 1987 from China by the absence of foretarsal sensillum b ′ 1 and long empodia on both the middle and hind tarsus. However, the new species differs from P. songkiangensis , P. huichouense , and P. jiangxiensis by the five pairs of anterior setae on abdominal tergite IV (four pairs of anterior setae in the three established species), and from P. guangxiensis and P. huichouense by having six setae on abdominal sternites IX–X (four setae in these two established species). Moreover, the new species is distinguished from P. songkiangensis by having five pairs of anterior setae on abdominal tergites II–III (four pairs of anterior setae in P. songkiangensis ), from P. jiangxiensis by the length of foretarsal sensilla a and c (short in P. jiangxiensis ), from P. guangxiensis by the length of sensilla t2 and f2 on the foretarsus (not short in P. guangxiensis ), and from P. huichouense by the shape and length of foretarsal sensillum t3 (not broad and short in P. huichouense ).

Distribution. Japan, known only from the Nasu Imperial Villa.

Etymology. The specific name is derived from the name of the district, Nasu-machi, where Nasu Imperial Villa of the type locality is located.

Figures

Fig. 3. Pseudanisentomon nasuense sp. nov., holotype, female (NSMT-Ap 540). A, Dorsal view of the head; B, labrum and rostral region; C, maxillary palpus; D, galea; E, mandible; F, pseudoculus; G, interior view of foretarsus; H, exterior view of the foretarsus; I, distal part of the middle tarsus; J, dorsal view of the hind tarsus. Abbreviations: as, anterior sensillum; I, inner digit; lb, labral seta; M, median digit; md, dorsal sensillum; ml, lateral sensillum; O, outer digit; p, median posterior seta; pa, posterior additional seta; pp, a pair of sensilla posterior to pseudoculus; ps, posterior sensillum; rs, rostral seta; sp, median subposterior seta; sr, subrostral seta. Arrow shows pore. Scale bars: 20µm in A; 10µm for all other images.

Fig. 4. Pseudanisentomon nasuense sp. nov. A, Dorsal view of thorax III, right side; B, dorsal view of abdomen VI–VII, left side; C, dorsal view of abdomen VIII–XI, left side; D, ventral view of abdomen VIII–X, right side; E, female squama genitalis; F, male squama genitalis. Arrows show pores. A–D, Holotype, female (NSMT-Ap 539); F, paratype, male (SMNH-Ap-36643). Scale bars: 20µm.