Two new species of Sinella from Guangdong Province, China (Collembola: Entomobryidae)

Abstract Two new blind species of Sinella are described from Guangdong Province, China. Sinella colubra sp. n. possesses minute smooth postlabial chaetae, long mucronal spine, and 4+4(5) lateral mac on Abd. IV, and can be distinguished from two closely related species by the postlabial chaetae and the dorsal macrochaetotaxy. Sinella zhangi sp. n. is also described and can be diagnosed by having minute labial chaeta r and postlabial chaetae X and X4, 5+5 mac on Abd. I, 4+4 central mac on Abd. II, and 4+4 central and 5+5 lateral mac on Abd. IV.


Introduction
The genus Sinella Brook, 1882 is distributed worldwide and is very abundant in China. Deharveng (1990), Chen and Christiansen (1993) and Zhang et al. (2009Zhang et al. ( , 2011 made significant contributions to the modern taxonomy of the genus. Members of the genus have 4-segmented antennae, reduced eye number (0-6 on each side), pigment reduced or absent, polymacrochaetotic chaetotaxy, bidentate mucro, and no dental spines and scales. So far, 39 species, including 14 blind ones, have been recorded from China. Among them, only two eyed species have been recorded from Guangdong Province: Sinella curviseta Brook, 1882 and Sinella longisensilla Zhang, 2013. In this study, two new blind species are described from Guangdong.

Materials and methods
Specimens were cleared in Nesbitt's fluid (Krantz 1978), mounted under a coverslip in Hoyer's solution, and observed using a Nikon E80i microscope. The labial chaetae terminology follows Gisin's system (1967). The dorsal and ventral chaetotaxy of head are described after Chen and Christiansen (1993), completed for the anterior part of head after Jordana and Baquero (2005) and Soto-Adames (2008). Dorsal body chaetae are designated following Szeptycki (1979) and Zhang et al. (2011). The number of macrochaetae is given by half-tergite in the descriptions (left side of tergites drawn in figures). Tergal S-chaetotaxic formula follows Zhang and Deharveng (2015). All descriptions are based on fully developed adults if not otherwise mentioned. Symbols representing chaetal elements used in the figures are as follows: large circle, macrochaeta; small circle, mesochaeta; cross, bothriotrichum; circle with a slash, pseudopore; dotted circle, chaetae present or absent. All materials are deposited in the collections of the Department of Entomology, College of Plant Protection, Nanjing Agricultural University (NJAU), P. R. China. Smooth spiny mic at base of antennae: three dorsal, three ventral on Ant. I; one internal, one external and two ventral on Ant. II. Ant. II distally with one (rarely two) rod-like sens. Ant. III organ with two slightly expanded internal sens. Ant. IV with a knobbed subapical organ. Ant. II. with 2-4 ventral long smooth straight chaetae.
Etymology. Named after the snake Bungarus multicinctus Blyth found in the sampling site.
Trochanteral organ with nine smooth spiny chaetae; five in arms and four internal. Some inner differentiated tibiotarsal chaetae "smooth" with ciliations closely appressed to axis. Tibiotarsi distally with ten chaetae in a whorl. Unguis with three inner teeth; two paired teeth unequal, outer one larger. Unguiculus with a large outer tooth. Tenent hairs clavate (Fig. 20). Abd. IV 3.42 times as long as Abd. III along dorsal midline. Ventral tube anteriorly with seven ciliate chaetae; two of them much larger than oth-ers; posteriorly not clearly seen; each lateral flap with seven smooth and one ciliate chaetae (Fig. 21). Manubrium without smooth chaetae. Manubrial plaque with 2+2 pseudopores and 3+3 ciliate chaetae (Fig. 22). Distal smooth part of dens 1.72 times as long as mucro. Mucro bidentate with apical tooth longer than subapical tooth; basal spine short, reaching tip of subapical tooth (Fig. 23).
Etymology. Named after the Chinese collembologist Dr. Feng ZHANG, who has made great contributions to the taxonomy of Sinella.