Paratullbergia Womersley in China: the description of a new species and a key to the genus (Collembola, Tullbergiidae)

Abstract The genus Paratullbergia Womersley, 1930 is recorded for the first time from China. Paratullbergia changfengensis sp. n. from Shanghai is described and illustrated. It is characterized by the presence of 1+1 pseudocelli on thoracic segment I, with two pairs of pseudocelli on each of thoracic segments II and III, presence of seta px on abdominal segment IV, seta a2 and p4 on abdominal segment V as microsetae, and less differentiated sensory seta p3 on abdominal segment V. Both sexes present. The new species can be easily distinguished from its congeners by the presence of pseudocelli on thoracic segment I. An updated key to the world species of the genus Paratullbergia is provided.


Introduction
The family Tullbergiidae Bagnall, 1947 contains a group of tiny euedaphic collembolans with approximately 200 species reported in the world (Bellinger et al. 2015); however, the Chinese Tullbergiidae are poorly known, with only four species recorded to date (Rusek 1967;Tamura and Zhao 1996;Gao 2007;Bu et al. 2013). During the study of the collembolan collections from Changfeng Park of Shanghai, one new species belonging to the genus Paratullbergia Womersley, 1930 was identified and is described in the present paper.
The genus Paratullbergia contains eight species occurring in Holarctic, India, South Africa, and Australia (Prabhoo 1971;Rusek 1991;Dunger and Schlitt 2011;Bellinger et al. 2015). The habitus is similar to that of the genus Mesaphorura Rusek, 1973, with some species being robust, and having an integument with coarse granulation, antennal segment IV with 2 subapical sensory rods, antennal segment III with two large sensory clubs, bent towards one another and two small sensory rods, postantennal organ with 35-68 vesicles in 2-4 rows, and pseudocelli of type IV and type I. Asp stronger, longer than in Mesaphorura.

Materials and methods
Specimens were collected by Berlese-Tullgren funnels and preserved in 80% ethanol. The material was mounted on slides in Hoyer's solution and dried in an oven at 45 °C for identification. Drawings were done with the aid of a phase contrast microscope. The type specimens are deposited in Shanghai Natural History Museum (SNHM), Shanghai, China.
Abbreviations used in the descriptions: Description. Adult body 0.85 mm long in average (0.7-1.0 mm, n = 7). Both females and males were present. Setae well differentiated into micro-and macrosetae ( Fig. 1). Granulations coarse, formed by secondary granules, 2.5-4.0 µm in diameter. Pseudocellar formula: 11/122/11111, 5-8 µm in diameter; on antenna base composed by four ridges from one side only (type IV) (Fig. 2), others star-like (type I); on Th. I between seta m2 and m3, and close to hind margin; on Th. II and III between setae m4/m5 and p3/p4, and close to m5 and p3 respectively; on Abd. I-III posterior to seta p3; on Abd. IV parallel to seta p3; on Abd. V on the border of Abd. VI (Fig. 1).
Antenna (100-135 µm) shorter than head (130-150 µm). Ant. segment IV ( Fig.  3) with five slightly thickened sensilla a-e, without basal heel, sensilla a, c, e long and curved toward inside, b and d short. Small microsensillum, subapical organite and one large apical vesicles present. Antennal organ III (Fig. 3) consists of two small sensory rods concealed behind two papilla and two thick sensory clubs bent toward each other, with four guard setae.
Etymology. The species is named after the Changfeng Park where the type specimens were collected.
Distribution. Known only from the type locality. Considering that all specimens were only found in Changfeng Park, and that no other Paratullbergia has ever been recorded from China, this species has been probably introduced from an other place together with plants and soil.
Diagnosis. Paratullbergia changfengensis sp. n. is characterized by the presence of pseudocelli on thoracic segment I, with two pairs of pseudocelli on each thoracic segment II and III, the presence of seta px on abdominal segment IV, setae a2 and p4 on abdominal segment V as microsetae, and less differentiated sensory seta p3 on abdominal segment V. Bisexual.
Remarks. The presence of pseudocelli on thoracic segment I easily distinguishes Paratullbergia changfengensis sp. n. from other congeners. It is similar to P. trivandrana Prabhoo, 1971 from India in the presence of two pairs of pseudocelli on each of thoracic segments II and III, but differs in the presence of pseudocelli on thoracic segment I (absent in P. trivandrana) and shape of sensory seta p3 on abdominal segment V (setiform vs. flame-like). The nine existing species of the genus Paratullbergia can be distinguished by the following key.