Study on the Pauropoda (Myriapoda) from Tibet, China – Part II: New species and new record of the genus Samarangopus

Abstract The pauropod family Eurypauropodidae Ryder, 1879 is recorded from Tibet, China for the first time. In this study, a new species Samarangopus zhongisp. nov. is described and illustrated from Motuo County, southeastern Tibet of China. It is distinguished from other species in this genus by having one pair of spiniform appendages on the sternum of the last trunk segment, 28–34 marginal protuberances on tergite I, the distal quarter of bothriotricha T3 golf-club-shaped, and the leaf-shaped seta st on tergum of pygidium. In addition, Samarangopus canalis Scheller, 2009 is newly recorded from China.

The purposes of this study are 1) to record the occurrence of family Eurypauropodidae Ryder, 1879 in Tibet;2) to describe a new species of the genus Samarangopus Verhoeff, 1934;3) to record the presence of Samarangopus canalis Scheller, 2009 in southeastern Tibet for the first time.

Materials and methods
All pauropods were collected using a Tullgren's funnel. The specimens were sorted under a stereomicroscope and preserved in 80% alcohol. They were mounted on slides using Hoyer's solution and dried in an oven at 50 °C. Observations were performed under a phase contrast microscope (Leica DM 2500). Photos were taken using a digital camera (Leica DMC 4500). Line drawings were made using a drawing tube. All specimens were deposited in the collection maintained by the Shanghai Natural History Museum (SNHM).
Abbreviations used in the descriptions follow Qian et al. (2018). Absolute lengths of all other body parts are given in mm and μm. Otherwise, the text refers relative lengths. For the description of the new species, measurements and indices of paratypes are given in brackets.
Anal plate (Figs 2D, 3B) (2.1-) 2.2 times as long as broad, tapering posteriorly; lateral margins with a pair of thin, diverging, cylindrical, distal part faintly inflated, pubescent branches which are (0.3-) 0.4 of the length of plate; posterior 2/5 of plate divided into 2 tapering branches by a narrow V-shaped incision, each branch with 2 appendages: a submedian short, straight, tapering, glabrous one and a stalked bladder of triangular shape in sternal view. Bladder-shaped appendages (0.6-) 0.7 of length of plate. Plate glabrous, bladder-shaped appendages with short erect pubescence.
Etymology. The new species is dedicated in honor of the late Professor Zhong Yang  who was an eminent botanist from Fudan University and Tibet University, for his great contribution to the knowledge of flora and biodiversity of Tibet. This study is also to express my great gratitude to his help.
Distribution. Known only from the type locality. Remarks. Samarangopus zhongi sp. nov. can be easily distinguished from all other congeners by the presence of the one pair of spiniform appendages on the sternal side of last trunk segment. It is most similar to S. campanulatus Scheller, 2004 from Vietnam in the shape of anal plate, the chaetotaxy of pygidium and the protuberances on the body. It can be distinguished from S. campanulatus by: the spiniform appendages on the sternum of last trunk segment (present in S. zhongi sp. nov. vs absent in S. campanulatus), shape of bothriotricha T 3 (distal quarter golf-club-shaped, densely pubescent in S. zhongi sp. nov. vs distal 2/5 part clavate, end-swelling in S. campanulatus), shape of seta st on tergum of pygidium (leaf-shaped in S. zhongi sp. nov. vs lanceolate in S. campanulatus), the shape of proximal seta on tarsus 9 (striated in S. zhongi sp. nov. vs glabrous in S. campanulatus), and the shape of appendage on the femur of leg 1 (broad triangular in S. zhongi sp. nov. vs blunt cylindrical in S. campanulatus ). The shape of posterior appendage on anal plate of the new species is also similar to S. tuberosus Scheller, 2007 from Singapore andS. cylindratus Scheller, 2009 from Indonesia. The new species differs from S. tuberosus in the shape of setae b 2 on pygidium (slender and pointed in S. zhongi sp. nov. vs large and lanceolate in S. tuberosus). It differs from S. cylindratus in the shape of appendages of the collum segment (barrel-shaped in S. zhongi sp. nov. vs cylindrical and large in S. cylindratus).  Description of new materials. Length 0.90 mm (n = 2), yellow to brown in color (Fig. 4A). Head covered by tergite I and chaetotaxy not studied in detail.
Legs. All legs 5-segmented. Setae on coxa and trochanter of leg 9 similar to each other, thin, furcate, densely annulated, length of secondary branch 0.7-0.8 of primary one (Fig. 4I). On more anterior legs these setae with rudimentary secondary branches (Fig. 4H). Tarsi of leg 9 short and thick, tapering, 2.2 times as long as greatest diameter; tergal setae pointed, glabrous. Proximal seta length 9-10 μm, 0.3 of the length of tarsus (33 μm) and 1.2-1.3 times as long as distal seta (7-8 μm). Cuticle of tarsus with minute granules. No proximal seta on tarsus of leg 1. All legs with large main claw and small setose anterior secondary claw, the former on those of leg 9 0.5 of tarsi. Anterior side of femur of leg 1 with one blunt appendage with short pubescence, length = 4-5 μm (Fig. 4H).
Anal plate. 1.2 times as long as broad; lateral margins straight anteriorly, concave posteriorly; distal part of plate cleft by narrow U-shaped incision, depth 0.3-0.4 of the length of plate, incision forming two posterior branches with subparallel sides, each with two appendages: a submedian short, straight, glabrous one and a thin folioform stalked appendage protruding backward. Folioform appendage about 0.6 of length of plate. Plate glabrous, distal appendages with somewhat granular surface.
Distribution. China (Tibet), Indonesia (Sulawesi). Remarks. Samarangopus canalis was originally described and only known from Sulawesi Island, Indonesia (Scheller 2009). The anal plate, the male genital papillae as well as the protuberances on the body of Chinese specimens are nearly the same with S. canalis which proved the species identity. The main difference is that the posterior branches of anal plate of Chinese specimens each have two appendages, with a submedian, short, straight, glabrous appendage present, but absent in the types from Sulawesi. Other minor differences are the body size, numbers of protuberances on the body and the lengths of setae, bothriotricha, and flagella, which might belong to the variances between populations of different localities. In addition, the anal plate of S. canalis and S. zhongi sp. nov. both having two appendages, but the shape of posterior one is different: bladder is triangular in S. zhongi sp. nov. but folioform in S. canalis.