Two new species of Lobellini from Tianmu Mountain, China (Collembola, Neanuridae)

Abstract Three species of the subfamily Neanurinae (Collembola: Neanuridae) are recorded from Tianmu Mountain, Zhejiang Province, east China. Two of them, Lobellina fusa sp. n. and Paralobella tianmuna sp. n., are new to science and described in this paper. Lobellina fusa sp. n. can be recognized by the presence of six teeth on mandible and the fusion of dorsointernal tubercles on the head. Paralobella tianmuna sp. n. is characterized by a mandible with seven teeth, the lateral tubercle of Abd. II–III respectively with 7 (6+s) chaetae. Crossodonthina bidentata Luo & Chen, 2009 is widely distributed in the mountain from 300 to 1500 m a.s.l.


Introduction
To date, on a worldwide scale, the tribe Lobellini consists of 17 genera (including two subgenera) and approximately 157 species mainly from South-East Asia and the Australian-Oceania region (Bellinger et al. 2017). Up to now, only six genera and 12 species were reported from mainland China (Denis 1929;Stach 1964;Yue and Yin 1999;Wang 2003;Xiong et al. 2005;Ma and Chen 2008;Luo and Chen 2009;Jiang and Zhang 2012;Luo and Palacios-Vargas 2016;Wang et al. 2016). The tribe is diversified in all regions sampled so far, but huge areas have never been sampled and the knowledge of Chinese fauna of Lobellini can be considered as very incomplete.
Tianmu Mountain, located in Lingan City, Zhejiang Province, east China, covers an area of 4300 hectares. The elevation of the highest peak of the mountain is more than 1500 meters. It belongs to the subtropical humid monsoon climate zone. The flora is a typical subtropical evergreen broad-leaved forest. One of the main targets of the Zhejiang Tianmu Mountain National Nature Reserve is the protection of rare and endangered plants, such as Ginkgo biloba, Cercidiphyllum japonicum, and Liriodendron chinensis. Till now, more than 4000 species (including 657 type species) of insects were reported from the mountain (Wu and Pan 2001). However, the Collembolan fauna of the mountain is poorly known, and only very few neanurid species were reported from it Chen 2009, Jiang et al. 2012). In 2011, organized by The Management Bureau of Zhejiang Tianmu Mountain National Nature Reserve, we carried out field work in this mountain. Three species of the tribe Lobellini were identified and two of them are described as new.

Terminology
The terminology and layout of the tables used in this paper follow Deharveng (1983), Deharveng and Weiner (1984), and Smolis and Deharveng (2006).

Materials and methods
All specimens were collected with the aid of Tullgren funnels or aspirators, and preserved in 95% ethanol. They were cleared in Nesbitt's fluid and mounted on slides in Hoyer's medium. Preparations were dried for 7-10 days in oven at 55 °C, and then ringed with lacquer. The morphological characters were observed and figures were drawn using a phase contrast microscope Nikon 80i. Material is deposited in the Key Laboratory of Zoology, Hunan University of Arts and Science, Changde, Hunan Province, China. Labrum chaetotaxy as 0/2, 2. Mandible with six teeth. Maxilla consisting of two crochet-like lamellae and two teeth. Chaetae formula of tubercle Di on Th. I-Abd. V as 1, 3, 3/2, 2, 2, 2, 3. S-chaetae and s-microchaeta formula on Th. I-Abd. V as 0, 2+ms, 2/1, 1, 1, 1, 1. Ventral tube with 4+4 chaetae, furcular vestige with 3 chaetae. Unguis with an inner tooth and without lateral tooth.
Ecology. Under leaves in forest.
Remarks. The taxon Lobellina was erected by Yosii in 1956 as a subgenus of the genus Lobella Börner, 1906. It was raised to generic status by Cassagnau (1983) and redefined by Deharveng and Weiner (1984): body without blue pigment, 3+3 black eyes. Tubercles on the head and the tergites well developed, marked by a bump of the tegument and /or by differentiated tertiary grain, or some more strong secondary grains. Body without reticulation. Chaetotaxy of labrum as 0/2, 2. Maxilla styliform, mandible tridentate to multidentate. The sgd of Ant. III organ not shifted to ant. IV. Dorsal macrochaetae thickened and double lined, rounded to the apex. Chaetotaxy of type s normal (2+ms, 2/1, 1, 1, 1, 1). Abd. I without supplemental s-chaeta on lateral tubercle. Posterior chaetotaxy of head of cross-type. Chaetotaxy of tubercles Di of Th. II and III characteristic, with two macrochaeta (Di1 and Di2) and a small microchaeta, sometimes indistinct (Di3). Abd. V with 2+2 or 3+3 tubercle, tubercle De is isolated from the tubercle Dl, or fused to tubercle Dl.
To date, 12 valid species are known in the genus Lobellina (Deharveng andWeiner 1984, Ma andChen 2008). The new species can be distinguished from others by having six teeth on the mandible and fused tubercle Di on head. A key for all species of the genus is given below.   Etymology. The new species is named after the type locality, Tianmu Mountain. Diagnosis. Habitus typical of the genus Paralobella. Dorsal tubercles round or oval and well developed. 3+3 unpigmented eyes. Labrum round, chaetotaxy as 0/ 2, 2. Mandible with seven teeth. Maxilla nearly styliform, apex with two hook-like teeth. Cephalic tubercle Fr with chaeta O. Tubercle An with four chaetae, chaetae C and D free from the tubercle. Tubercle Oc with three chaetae. Cephalic tubercle Di, De, Dl respectively with 1, 3, 4 chaetae. Tubercle De of Th. II-III each with four (3+s) chaetae. Unguis with an inner tooth, and without lateral tooth. VT with 4+4 chaetae. Furcular vestige with three chaetae and no microchaetae.

Key to species of genus Lobellina
Description. Body length: male 2.0-2.5 mm; female 2.1-3.5 mm. Body entirely red while alive and white in alcohol.
Body tubercles round or oval (Fig. 8-9). Chaetae Di3 free on the tubercles Di on Th. II-III. Abd. I-IV each with four tubercles. Abd. V with three tubercles, tubercle De only with an S-chaeta. The tubercles of Abd. VI with seven chaetae each. Body tubercles and chaetotaxy as in Appendix 1, table 2a and 2b.
Remarks. At present, 12 species belong to the genus Paralobella, all from Asia (Jiang et al. 2012, Luo andPalacios-Vargas 2016). In general appearance, Paralobella tianmuna sp. n. strongly resembles P. perfusa (Denis, 1934) from Indochina in the structure of maxilla, the number of mandible teeth, the arrangement of body tubercles, the presence of chaeta O of tubercle Fr, the tubercle Di of Th. I with one chaeta, and the tubercle De and Dl of Abd. V separate. However, Paralobella tianmuna sp. n. can be distinguished from the latter by number of chaetae on body, the former has 3 chaetae on each tubercle Di of Th. II-III, 7 (6+s) chaetae on each tubercle L of Abd. II-III; the latter has 2 chaetae on each tubercle Di of Th. II-III, 4 (3+s) chaetae on each tubercle L of Abd. II-III. The new species is also similar to Chinese species P. breviseta Palacios-Vargas, 2016 andP. palustris Jiang, Luan &Yin, 2012 in the arrangement of body tubercles, the presence of chaeta O of tubercle Fr, tubercle Di of Th. I with one chaeta, and the separate tubercle De and Dl of Abd. V. The new species can be separated from its congeners by the following key.