ZooKeys 338: 29–37, doi: 10.3897/zookeys.338.6099
Hesperentomon yangi sp. n. from Jiangsu Province, Eastern China, with analyses of DNA barcodes (Protura, Acerentomata, Hesperentomidae)
Yi Bai 1,2,†, Yun Bu 3,‡
1 School of Life Sciences, Taizhou University, Taizhou, 317000, China
2 Institute of Zoology, Shaanxi Normal University, Xi’an, 710062, China
3 Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China

Corresponding author: Yun Bu (ybu@sibs.ac.cn)

Academic editor: L. Deharveng

received 14 August 2013 | accepted 22 September 2013 | Published 2 October 2013


(C) 2013 Yi Bai. This is an open access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


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Citation: Bai Y, Bu Y (2013) Hesperentomon yangi sp. n. from Jiangsu Province, Eastern China, with analyses of DNA barcodes (Protura, Acerentomata, Hesperentomidae). ZooKeys 338: 29–37. doi: 10.3897/zookeys.338.6099

Abstract

Hesperentomon yangi sp. n. is described from eastern China. Its DNA barcodes are sequenced and compared to the similar species of the genus. Hesperentomon yangi sp. n. is characterized by 12 posterior setae on tergites II–VI, 8 posterior setae on sternites IV–VI (seta Pc absent), absence of seta sd4 on head, absence of seta P2a on tergite VII, 6 and 8 anterior setae on mesosternum and metasternum respectively, and few teeth on comb. It differs from Hesperentomon xiningense Bu & Yin, 2007 and Hesperentomon nanshanensis Bu & Yin, 2007 in the chaetotaxy of mesosternum and metanotum, maxillary gland, length and shape of some sensilla on foretarsus, as well as the body porotaxy. The genetic divergences of DNA barcodes sequences between Hesperentomon yangi sp. n., Hesperentomon xiningense and Hesperentomon nanshanensis are 24.1% on average, which is distinctly higher than the divergences between individuals of the new species (0.5%). Molecular data provide a solid evidence of the new species identified by the morphological characters.

Keywords

Protura, Hesperentomon, molecular data, genetic divergence, chaetotaxy

Introduction

The genus Hesperentomon Price, 1960 currently contains 17 species, which with 14 species have been found in China (Bu and Yin 2007a, 2007b, Bu et al. 2011, Shrubovych 2010, Szeptycki 2007, Wu and Yin 2008, Yin 1999). During a collection from Qixia Mountain, Nanjing City, East China (Jiangsu Province), some specimens of the genus Hesperentomon were first found from that area. They were identified as a new species and described as Hesperentomon yangi sp. n. in the present paper. In order to confirm the morphological identification, the DNA barcodes of the new species and two similar congeners Hesperentomon xiningense and Hesperentomon nanshanensis were sequenced and analyzed.

Materials and methods

The specimens were collected with Tullgren funnels. All specimens were mounted on slides in Hoyer’s medium and dried for three days in an oven at 60°C. Specimens were identified and drawn with the aid of a NIKON E600 phase contrast microscope. Type specimens are deposited in the Shanghai Entomological Museum (SEM), Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.

Abbreviations used in the text follow the paper of Bu and Yin (2007b). Head setae and pores are marked according to Rusek et al. (2012).

For DNA barcodes, genomic DNA was extracted from each individual separately by means of a non-destructive method (after Gilbert et al. 2007) with minor modifications. The information for the species is given in Table 1. After the DNA extraction, the cuticles of proturans were retrieved and mounted on the slides as voucher specimens. DNA barcoding sequences of mitochondrial COI gene were amplified and sequenced by primer pair LCO/HCO (Folmer et al. 1994). The barcodes sequences are deposited in GenBank. The genetic divergence and nucleotide composition were calculated using MEGA version 5 (Tamura et al. 2011).

Table 1.

Information for the species used in the study.

Classification Species Locality Number of individuals GenBank Accession Numbers
Protura
Acerentomata
Hesperentomidae
Hesperentomon Hesperentomon yangi sp. n. China: Jiangsu 3 KF530824, KF530825, KF530826
Hesperentomon xiningense China: Qinghai 1 KF530827
Hesperentomon nanshanensis China: Qinghai 1 KF530828
Results
Taxonomy
Material examined.

Holotype, female (No. NJ-8), East China, Jiangsu Province, Nanjing City, extracted from the soil samples under some big trees of Qixia Mountain, 32°09.45'N, 118°57.60'E, elev. 200 m, 29-XI-2012. coll. Y. M. Yang. Paratype, 6 females (Nos. NJ-2, NJ-3, NJ-4, NJ-7, NJ-12, NJ-13), 6 males (Nos. NJ-1, NJ-5, NJ-6, NJ-9, NJ-10, NJ-11), same data as holotype. Other materials, 1 maturus junior (No. NJ-14) and 1 larva II (No. NJ-15). Specimens NJ-13, NJ-14 and NJ-15 are voucher specimens with DNA barcodes sequenced. Type specimens are deposited in Shanghai Entomological Museum (SEM), Institute of Plant Physiology & Ecology, Chinese Academy of Sciences.

Description.

Adult body length 1300–1400 µm (n=13), yellow-brown, and foretarsus with deeper color (Fig. 1).

Head. Oblong, length 125–130 µm, width 85–95 µm. Dorsal setae long, other setae short. Setae d6 and sd6 present, sd4 absent. Seta d6 14–15 µm, d7 6–7 µm in length. Paired pores cp, ip and op present, pore fp absent (Fig. 12). Pseudoculus pear-shaped, with short posterior extension, length 12–15 µm, width 8–9 µm. PR=9–11 (Figs 2, 13). Canal of maxillary gland with sausage-like calyx, posterior dilation about equal to length of calyx. CF=7–9 (Fig. 14). Labial palpus well developed, without basal sensillum (Fig. 15). Maxillary palpus with two tapering sensilla, dorsal one (8–9 µm) distinctly longer than lateral one (5–6 µm) (Fig. 16).

Figures 1–11.

Hesperentomon yangi sp. n. Holotype. 1 Habitus 2 pseudoculus 3 pronotum 4 mesonotum (sl=sublateral pore) 5 metanotum 6 sternite II 7 sternite IV 8 prosternum 9 mesosternum 10 metasternum 11 sternite VII. Arrows show pores. Scale bar: 100 μm in Fig. 1, others, 20 μm.

Figures 12–22.

Hesperentomon yangi sp. n. Holotype. 12 Head, dorsal view (cp=clypeal pores, ip=interpseudocular pores, op =occipital pores) 13 pseudoculus 14 canal of maxillary gland 15 labial palpus 16 maxillary palpus, 17 foretarsus, exterior view 18 foretarsus, interior view 19 tergite VII, left side (al=anterolateral pore, psm=posterosubmedial pore, psl=posterosublateral pore) 20 sternite VII and lateral part of tergite VII 21 Comb 22 female squama genitalis. Arrows show pores. Scale bar: 20 μm.

Foretarsus. Length 73–83 µm, claw length 18–23 µm, without inner flap, TR=3.5–4.4; empodium length 3–4 µm, EU=0.14–0.18. Dorsal sensilla t-1 and t-2 slender and long (14–15 µm), BS=1.1; t-3 slengder, not reaching base of claw. Exterior sensilla all sward-like and in different length, a surpassing base of c, b and c subequal in length, d close to t2, e broad, f short, g long. Interior sensilla also sward-like in different length, a’ short, b’-1 longer than b’-2, c’-2 longer than c’-1. Relative length of sensilla: b’-2 < c’-1 < f< a’< t3< b’-1< (b=c=e) < d<(g= c’-2) < a < t2 < t1 (Figs 17, 18). Length of middle tarsus 35–37 µm, claw length 18–20 µm. Length of hind tarsus 38–40 µm, claw length 20–23 µm.

Thorax. Thoracic chaetotaxy given in Table 2. Setae 1 and 2 on pronotum subequal in length; mesonotum with eight pairs of posterior setae, P5a and P5a’ minute; metanotum with seven pairs of posterior setae, P5a minute; setae P1 and P2 on mesonotum 13–15 µm and 17–20 µm respectively. (Figs 3–5). Prosternum without anterior seta A2, mesosternum and metasternum with 6 and 8 anterior setae respectively (Figs 8–10). All setae on thoracic sternites setiform. Pronotum and prosternum without pores. Mesonotum and metanotum with pores sl (Figs 4, 5). Mesosternum and metasternum each with single median pore, situated anterior to level of setae M (Figs 9, 10).

Table 2.

Adult chaetotaxy of Hesperentomon yangi sp. n.

Segment Dorsal Ventral
Formula Setae Formula Setae
Thorax I 4 1, 2 (2-2)/6 A1, M, P1, 2, 3
II 6/4 A2, 4, M, P1, 2, 2a, 3, 4, 5, 5a, 5a’ (6-2)/5 A1, 2, 3, M, Pc, 1, 2
III 6/14 A2, 4, M, P1, 2, 2a, 3, 4, 5, 5a (8-2)/5 A1, 2, 3, 4, M, Pc, 1, 2
Abdomen I 4/10 A1, 2, P1, 2, 3, 4, 5 4/4 A1, 2, P1, 2
II–III 8/12 A1, 2, 4, 5, P1, 2, 3, 4, 4a, 5 4/5 A1, 2, Pc, 1a, 2
IV–VI 8/12 A1, 2, 4, 5, P1, 2, 3, 4, 4a, 5 4/8 A1, 2, P1, 1a, 2, 3
VII 8/16 A1, 2, 4, 5, P1, 1a, 2, 3, 3a, 4, 4a, 5 4/9 A1, 2, Pc, 1, 1a, 2, 3
VIII 6/14 A1, 2, 5, P1, 1a, 2, 2a, 3, 3a, 5 6 1, 1a, 2
IX 12 1, 2, 2a, 3, 3a, 4 6 1, 1a, 2
X 10 1, 2, 3, 3a, 4 6 1, 1a, 2
XI 8 1, 2, 3, 4 6 1, 1a, 2
XII 9 8

Abdomen. Abdominal chaetotaxy given in Table 2. Tergite I with two pairs of anterior setae (A1, A2) and five pairs of posterior setae. Tergites II–VI with four pairs of anterior setae (A1, A2, A4, A5) and six pairs of posterior setae, P1a, P2a and P3a absent. Tergite VII with 8 posterior setae, P2a absent. Posterior central seta Pc absent on sternites IV–VI (8 posterior setae) (Fig. 7), present on sternite VII (Figs 11, 20). Bases of setae on segments X–XII without surrounding ciliation. Tergites IX–XI, and sternite X with broad, coarsely serrated posterior lamella (Figs 23, 25).

Figures 23–25.

Hesperentomon yangi sp. n. 23 Tergites VIII–XII, left side (pm= posteromedial pore) 24 male squama genitalis 25 sternites VIII–XII (pl=posterolateral pore) 23 and 25 holotype 24 paratype NJ-10. Arrows show pores. Scale bar: 20 μm.

Tergites I–VI with pores psm and al, VII with pores psm, psl and al (Fig. 19), VIII with pores psm and pl, IX, X and XII each with single posteromedial pore (pm), XI without pores (Figs 23, 25). Sternites I–VI each with one medial pore (Fig. 6), VII with one medial pore and one pair of lateral pores (Figs 11, 20), VIII–X each with single medial pore, XI without pores, XII with 3+3 pores.

Abdominal appendages typical of the genus, each with two segments and four setae. Striate band on abdominal segment VIII reduced and only single serrate line present (Fig. 23). Comb on abdomen VIII rectangular, with 7–8 teeth (Fig. 21).

Female squama genitalis robust. Each acrostylus with one slender flap on its outer side (Fig. 22). Male squama genitalis with 2+2 setae on dorsal side and 2+2 setae on ventral side (Fig. 24).

Etymology.

The species is named after Mr. Yi-Ming Yang who collected the specimens and in remembrance of his great contribution to the collection of Protura in China.

Chaetal variability.

Chaetal variations were observed in 5 specimens: on pronotum, with 5 seate, presence of 1 additional seta on left side (No. NJ-2); on prosternum, asymmetrical absence of A1 of right side (No. NJ-3); on sternite I, presence of Pc (Nos. NJ-4, NJ-6, NJ-12); on sternite IV and V, presence of Pc (No. NJ-12).

Distribution.

Jiangsu (Nanjing), China.

Diagnosis.

Hesperentomon yangi sp. n. is characterized by 12 posterior setae on tergites II–VI, 8 posterior setae on sternites IV–VI (seta Pc absent), absence of seta sd4 on head, absence of seta P2a on tergite VII, 6 and 8 anterior setae on mesosternum and metasternum respectively, and few teeth on comb.

Remarks.

Hesperentomon yangi sp. n. is similar to Hesperentomon xiningense Bu & Yin, 2007 and Hesperentomon nanshanensis Bu & Yin, 2007 in having 8 posterior setae on sternites IV–VI (seta Pc absent), 12 posterior setae on tergite IV–VI, and the absence of seta P2a on tergite VII. It can be distinguished from those two species by the chaetotaxy of mesosternum and metasternum (6 and 8 anterior setae in Hesperentomon yangi sp. n. respectively vs. 4 and 6 anterior setae in Hesperentomon xiningense and Hesperentomon nanshanensis), chaetotaxy of head (setae sd4 absent in Hesperentomon yangi sp. n. vs. present in the later two species), porotaxy of head (frontal pores fp absent and interpseudocular pores ip present in Hesperentomon yangi sp. n. vs. fp present and ip absent in the later two), porotaxy of sternite VII (3 pores in Hesperentomon yangi sp. n. vs. 1 pore in the later two). It also differs from Hesperentomon xiningense in the length of foretarsal sensillum b subequal length to c (b distinctly longer than c in Hesperentomon xiningense), short sensillum b’-2 which not reaching base of seta α7 (b’-2 surpassing base of seta α7 in Hesperentomon xiningense), and the presence of regular teeth on hind margin of striate band (with sparse unregular teeth in Hesperentomon xiningense). It also differs from Hesperentomon nanshanensis in the chaetotaxy of abdominal segment X (10 and 6 setae on tergite and sternite repectively in Hesperentomon yangi sp. n. vs. 8 and 4 setae in Hesperentomon nanshanensis) and shape of maxillary gland (posterior dilation about equal length of the calyx in Hesperentomon yangi sp. n. vs. about 1/2 length of the calyx in Hesperentomon nanshanensis).

The DNA barcodes analyses

The standard DNA barcoding sequence (COI gene) from 3 individuals (Nos. NJ-13, NJ-14, and NJ-15) of Hesperentomon yangi sp. n., 1 individual of Hesperentomon xiningense and 1 individual of Hesperentomon nanshanensis were sequenced and deposited in GenBank. The accession numbers given in Table 1. Except a 6 base pairs deletion was found in Hesperentomon xiningense (652 base pairs), other sequences each contains 658 base pairs. The nucleotide compositions as A=34.3%, T=33.6%, C=18.9%, G=13.1% on average in Hesperentomon yangi sp. n., A=27.0%, T=35.5%, C=22.4%, G=15.1% in Hesperentomon xiningense, and A=29.7%, T=35.8%, C=20.2%, G=14.3% in Hesperentomon nanshanensis. The genetic divergence between individuals of Hesperentomon yangi sp. n. is 0.5% on average, between three species is 24.1% on average. The results of molecular data well support the new species identified by morphological characters.

Acknowledgements

We give our cordial gratitude to Mr. Yi-Ming Yang for the collection of specimens and two anonymous reviewers for their valuable comments to our manuscript. This study was supported by the National Natural Sciences Foundation of China (no: 31201706, 31071887) and the Innovative Program for The Excellent Youth Talents of Shanghai Institutes for Biological Sciences (no: 2011KIP305).

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