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1 June 2007 TWO NEW SPECIES OF THE GENUS XENYLLA TULLBERG, 1869 FROM CHINA (COLLEMBOLA: HYPOGASTRURIDAE)
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Abstract

Two new species of Xenylla from Jilin Province, Northeast China are described and illustrated. Xenylla changlingensis, new species clearly differs from the closely related species X. piceeta Stebaeva & Potapov, 1994 in the presence of dorsal la2 of thoracic segments II and III, the absence of ventral seta p2 on abdominal segment II, 1 median ventral seta above the retinaculum on abdominal segment III, and lack of teeth on the mucro. Xenylla changchunensis, new species is similar to the species X. osetica Stebaeva & Potapov, 1994. However, it is separable from the latter by the presence of a furca, a tenaculum, and the ventral chaetotaxy on abdominal segment III.

The genus Xenylla was established by Tullberg for X. maritima Tullberg, 1869 as type species. It is one of the largest and most widespread genera in the family of Hypogastruridae. According to Thibaud et al. (2004), species in the genus Xenylla are mainly characterized by (1) 5+5, rarely 4+4 ommatidia, (2) postantennal organ absent, (3) mandible short with a well developed molar plate, maxillary head with normal lamellae, (4) furca rarely absent, showing a diverse morphology, if mucro separated from the dens, which normally bears 2 setae; mucro, however, fused with the dens or mucro absent, the dens has 1 or 2 setae, (5) empodium absent, and (6) abdominal segment V tergite with p3 as sensilla.

So far, about 126 species of the genus Xenylla have been described worldwide (Christiansen 2006). However, only one, X. boerneri Axelson, 1905, has been reported from East China (Zhao et al. 1997). The taxonomy of the fauna of many Chinese habitats is poorly known, especially those of soil. In the present paper, two new species of the genus Xenylla that were found from Northeast China are described.

Abbreviations

a1, 2, … -- setae 1, 2, … of the anterior row, counted from the “middle line”, m1, 2, … -- setae 1, 2, … of the middle row, counted from the “middle line”, p1, 2, … -- setae 1, 2, … of the posterior row, counted from the “middle line”, c1, 2, … -- cervical setae 1, 2, … of area occipitalis, counted from the “middle line”, La1, 2, …-- setae 1, 2, … of the lateral anterior row in thoracic segments, L1, 2, …-- lateral setae 1, 2, …. in head (Yosii 1960; Gama 1988).

Xenylla changlingensis, new species (Figs. 1-7, 8-10)

Type Materials

Holotype: Female, from the grassland of Leymus chinensis, 44°35’N, 123°30’E, 141 m altitude, Changling county, Jilin Province, Northeast China, 6-5-2005, collected by Dr. Donghui Wu. Paratypes: Two females, 3 males, same data as holotype. Holotype and paratypes deposited in Shanghai Institute of Plant Physiology & Ecology.

Description

Body length up to 0.95 mm. Body color in alcohol dark blue-violet. With 5+5 ommatidia in head (Fig. 1). Antennal segment I with 7 setae, antennal segment II with 12 setae. Sensory organ of antennal segment III consists of 2 microsensilla which are embedded in a tegumentary fold and flanked by 2 longer guard sensillum. Antennae IV with a simple apical bulb and 4 weakly thickened sensillum, of which 3 are dorso-external and 1 dorso-internal, and 2 internal sensillum, which are thinner and shorter than the others (Fig. 8). External maxillary lobe with 2 sublobal hairs.

Tibiotarsi each with 2 capitate, dorsal tenent hairs, which are longer than the inner edge of the claws. Claws with a small, distal internal tooth, 2/3 as long as tibiotarsal hairs (Fig. 9). Mucro well separated from the dens with 2 posterior setae, 1/2 as long as the dens but dens and mucro particularly slender, width of dens at distal seta about an eighth its length, mucro straight and without teeth (Fig. 10). Ventral tube with 4+4 setae. Retinaculum with 3+3 teeth (Fig. 5). Female genital (Fig. 6) and male genital plate (Fig. 7) normal. Anal spines small, on weakly developed papillae separated at the base, 1/4 as long as claws (Fig. 3).

Chaetotaxy, consisting of short setae and longer and fine sensorial setae. Dorsally head without seta c2 (a2 a/c to Babenko), cephalic setae l1 and l3 subequal (Fig. 1), thoracic segments II-III with central setae in 3 rows, on thoracic segments II-III p2 displaced apically relative to p1, and on thoracic segment III a2 displaced distally compared with a1 (Fig. 2), on abdominal segments I-III p5 present, abdominal segments IV with a3. Abd. V with a2 (Fig.3). Ventrally head without seta p1 (Fig. 4), thoracic segments II and III with a pair of medial setae, abdominal segments II without p2 and a5, abdominal segments III with 1 median seta above the retinaculum (Fig. 5).

Comment

The new species is distinguished from all the known species of the genus Xenylla by the absence of mucronal teeth, dorsal side of head without c2 seta, seta p2 on tergite of thoracic segments II-III set in front of p1 seta, head without ventral seta p1, thoracic segments II and III with a pair of ventral medial setae, abdominal segment II without ventral setae p2 and a5, abdominal segment III with 1 median ventral seta above the retinaculum, abdominal segment IV with ventral seta m1, unguis with 1 internal tooth.

Etymology

This species is named after the type locality.

Taxonomic Remarks

This species keys out to X. piceeta Stebaeva & Potapov, 1994 (Babenko et al. 1994), from Far East, southern maritime province, Russia, which was collected in litter of a fir forest (Babenko et al. 1994), but the new species clearly differs from X. piceeta by the presence of dorsal la2 of thoracic segments II and III, which is stable on the tergites, and the absence of ventral seta p2 on abdominal segment II. On abdominal segment III, X. changlingensis has only 1 median ventral seta above the retinaculum, while X. piceeta has a pair of medial setae. In addition, the mucro of X. changlingensis is straight and thin, but lacking teeth.

Xenylla changchunensis, new species (Figs. 11-13, 14-19)

Type Materials

Holotype: Female, from the deciduous-coniferous mixed forest of Jingyuetan Park, 43°45’N, 125°27’E, 242 m altitude, Changchun city, Jilin Province, Northeast China, 3-9-2003, collected by Dr. Donghui Wu. Paratypes: Two females, same data as holotype. Holotype and paratypes deposited in Shanghai Institute of Plant Physiology & Ecology.

Description

Body length up to 0.81 mm. Body color in alcohol red-brown. Antennal segment I with 7 setae, antennal segment II with 12 setae. Sensory organ of antennal segment III consists of 2 microsensilla, embedded in a tegumentary fold and flanked by 2 longer guard sensillum. Antennae IV with a simple apical bulb and 4 weakly thickened sensillum, of which 3 dorso-external and 1 dorso-internal, and 2 internal sensillum, thinner and longer than the others (Fig. 11). External maxillary lobe with 3 sublobal hairs.

Tibiotarsi each with 2 capitate, dorsal tenent hairs, longer than the inner edge of the claws. Claws toothless, 11/15 as long as tibiotarsal hairs (Fig. 12). Dens with 2 posterior setae. Mucro well separated from the dens, straight and fine without teeth, dens broad, at level of distal setae length of dens about 3 times breadth, ratio mucro: dens = 1/2 (Fig. 13). There are 4+4 setae on ventral tube. Retinaculum with 3+3 teeth (Fig. 18). Female genital plate (Fig. 19). Anal spines short, inserted on poorly developed papillae, 1/4 as long as claws (Fig. 16).

Chaetotaxy, consisting of short setae and longer and fine sensorial setae. Dorsally head without seta c1, with both p1 and p2, l1 longer than l3 (Fig. 14), thoracic segments II-III with medial setae in 3 rows, seta p2 on tergite of thoracic segments II-III set in front of p1, on thoracic segments III a2 displaced distally relative to a1 (Fig. 15), on abdominal segments I-III, p5 present, abdominal segments IV without a3, abdominal segments V without a2 (Fig. 16). Ventrally head with seta p1 (Fig. 17), thoracic segments II and III with a pair of medial setae, abdominal segment II without p2 and a5, abdominal segment III with 1 median seta above the retinaculum (Fig. 18), abdominal segment IV without m1 (Fig. 19).

Comment

The new species is distinguished from other species of Xenylla by possessing a mucro without teeth, dorsal side of head with c1 (p1 a/cBabenko et al. 1994) seta absent, seta p2 on tergite of thoracic segments II-III set in front of p1 seta, thoracic segments II and III with a pair of ventral medial setae, abdominal segment II without ventral setae p2 and a5, abdominal segment III with 1 median ventral seta above the retinaculum, abdominal segment IV without ventral seta m1, unguis lacking teeth.

Etymology

Named changchunensis alluding to Changchun, the city where the species was found.

Taxonomic Remarks

The new species resembles X. osetica Stebaeva & Potapov, 1994 in general shape, antenna, tibiotarsi, and claws, especially in dorsal chaetotaxy, but distinctly differs from X. osetica in the following characters: (1) furca and tenaculum present, and (2) ventral chaetotaxy on abdominal segment III.

Key to Species of the Chinese Xenylla Tullberg, 1869

  1. 1.Furca without mucro, retinaculum with 2+2 teeth

  2. Mucro separated from dens that has 2 setae, retinaculum with 3+3 teeth

  3. 2.Dorsal side of head without c2 seta, abdominal segment IV with ventral seta m1, unguis with 1 internal tooth

  4. Dorsal side of head with c1 seta absent, abdominal segment IV without ventral seta m1, unguis lacking teeth

Acknowledgments

Thanks to Mr. Rongdong Xie, Mr. Yiming Yang, Dr. Yunxia Luan, Dr. Yun Bu, and Dr. Yan Gao for help in our taxonomic work. Thanks also to two anonymous reviewers for excellent suggestions. This study is supported by the National Natural Sciences Foundation of China (No. 40601047, 30370169), and China Postdoctoral Science Foundation (20060390643).

References Cited

1.

A. B. Babenko, N. M. Chernova, M. B. Potapov, and S. K. Stebaeva . 1994. Family Hypogastruridae. pp. 259-305, 329 In N. M. Chernova [ed.], Collembola of Russia and Adjacent Countries. Google Scholar

2.

K. A. Christiansen 2006.  http://www.collembola.org.  Google Scholar

3.

M. M da Gama 1988. Filogenia des espécies de Xenylla à escala mundial (Insecta, Collembola). Evolución boilógia 2:139–147. Google Scholar

4.

J. M. Thibaud, H. J. Schulz, and M. M. GAssalino . 2004. Hypogastruridae. In W. Dunger [ed.], Synopses on Palaearctic Collembola 4: 7-10, 217-250. Google Scholar

5.

R. Yosii 1960. Studies on the Collembolan genus Hypogastrura. The American Midland Naturalist 64:257–281. Google Scholar

6.

L. Zhao, A. H. Tamur, and X. Ke . 1997. Tentative Checklist of Collembolan Species from China (Insect). Publications of the Itako Hydrobiological Station 9:15–40. Google Scholar

Appendices

Fig. 1-7. Xenylla changlingensis, new species. 1. Dorsal chaetotaxy of the head. 2. Dorsal chaetotaxy of Th. I-III. 3. Dorsal chaetotaxy of Abd. III-VI. 4. Ventral chaetotaxy of the head. 5. Ventral chaetotaxy of Th. III, Abd. II and III, ventral tube, and retinaculum. 6. Ventral chaetotaxy of Abd. IV and V female genital plate, and anal plate. 7. Male genital plate.

i0015-4040-90-2-378-f01.gif

Fig. 8-10. Xenylla changlingensis, new species. 8. Antenna, dorsal view. 9. Tibiotarsi III with claw. 10. Furca, posterior view.

i0015-4040-90-2-378-f08.gif

Fig. 11-13. Xenylla changchunensis, new species. 11. Antenna, dorsal view. 12. Tibiotarsi III with claw. 13. Furca, posterior view.

i0015-4040-90-2-378-f11.gif

Fig. 14-19. Xenylla changchunensis, new species. 14. Dorsal chaetotaxy of the head. 15. Dorsal chaetotaxy of Th. I-III. 16. Dorsal chaetotaxy of Abd. III-VI. 17. Ventral chaetotaxy of the head. 18. Ventral chaetotaxy of Th. III, Abd. II and III, ventral tube, and retinaculum. 19. Ventral chaetotaxy of Abd. IV and V, female genital plate, and anal plate.

i0015-4040-90-2-378-f14.gif
Donghui Wu and Wenying Yin "TWO NEW SPECIES OF THE GENUS XENYLLA TULLBERG, 1869 FROM CHINA (COLLEMBOLA: HYPOGASTRURIDAE)," Florida Entomologist 90(2), 378-383, (1 June 2007). https://doi.org/10.1653/0015-4040(2007)90[378:TNSOTG]2.0.CO;2
Published: 1 June 2007
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