Hesperentomon yangi sp. n. from Jiangsu Province, Eastern China, with analyses of DNA barcodes (Protura, Acerentomata, Hesperentomidae)

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.


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 H. xiningense and H. 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). Description. Adult body length 1300-1400 µm (n=13), yellow-brown, and foretarsus with deeper color (Fig. 1).
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).
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).
Remarks. Hesperentomon yangi sp. n. is similar to H. xiningense Yin, 2007 andH. 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 mes- osternum and metasternum (6 and 8 anterior setae in H. yangi sp. n. respectively vs. 4 and 6 anterior setae in H. xiningense and H. nanshanensis), chaetotaxy of head (setae sd4 absent in H. yangi sp. n. vs. present in the later two species), porotaxy of head (frontal pores fp absent and interpseudocular pores ip present in H. yangi sp. n. vs. fp present and ip absent in the later two), porotaxy of sternite VII (3 pores in H. yangi sp. n. vs. 1 pore in the later two). It also differs from H. xiningense in the length of foretarsal sensillum b subequal length to c (b distinctly longer than c in H. xiningense), short sensillum b'-2 which not reaching base of seta α7 (b'-2 surpassing base of seta α7 in H. xiningense), and the presence of regular teeth on hind margin of striate band (with sparse unregular teeth in H. xiningense). It also differs from H. nanshanensis in the chaetotaxy of abdominal segment X (10 and 6 setae on tergite and sternite repectively in H. yangi sp. n. vs. 8 and 4 setae in H. nanshanensis) and shape of maxillary gland (posterior dilation about equal length of the calyx in H. yangi sp. n. vs. about 1/2 length of the calyx in H. nanshanensis).