﻿Two new species of the genus Samarangopus and the first record of Eurypauropusjaponicus (Arthropoda, Myriapoda, Pauropoda, Eurypauropodidae) from China

﻿Abstract Two new species, Samarangopustestudineussp. nov. from Hunan, South China and S.rotundifoliussp. nov. from Zhejiang, East China, are described and illustrated. Samarangopustestudineussp. nov. is characterized by unusual testudinal patterns on the dorsal side of the body and well-differentiated marginal protuberances on tergites. Samarangopusrotundifoliussp. nov. features large, round, leaf-shaped marginal protuberances and small, candle-like dorsal protuberances on tergites. Both of these species are compared to similar species in detail. In addition, Eurypauropusjaponicus Hagino & Scheller, 1985 is newly recorded from China.


Introduction
Pauropoda are tiny arthropods living in litter or soil. They are among the leastknown myriapods in the world, with only about 990 species described worldwide (https://www.itis.gov/, accessed May 2023). The Chinese pauropod fauna is poorly known, with only 50 species reported so far (Bu 2020a(Bu , 2020b(Bu , 2020c(Bu , 2021Qian et al. 2018). In recent years, several interesting species of pauropods have been discovered in China: Psammopauropus macrospinus Bu, 2020, family Hansenauropodidae Remy, 1954, was found in sand on the seashore and is characterized by the presence of a pair of large spines on the pygidial tergum (Bu 2020a); Colinauropus chinensis Bu, 2020, C. chongzhoui Bu, 2020, and C. foliosus Bu, 2020, family Colinauropodidae Scheller, 1985 can be recognized by having their tergites divided into sclerotized coarse plates (Bu 2020b), and Dasongius liupanensis Bu 2021 andD. spatulatus, family Pauropodidae Lubbock, 1867 both have a specialized engraved, honeycomb-like surface on the pygidial tergum, which is diagnostic of the endemic genus Dasongius (Bu 2021).
The family Eurypauropodidae Ryder, 1879 currently includes about 70 valid species (https://www.itis.gov/). It is characterized by a flattened body, strongly sclerotized tergites with a coarsely ornamented surface, modified setae, and specialized marginal protuberances (Scheller 2011). It was first reported in China with a preliminary description of one undetermined species Eurypauropus sp. from Zhejiang Province (Zhang and Chen 1988). After a long gap without new discoveries in China, three species of the genus Samarangopus Verhoeff, 1934 have been reported: S. dilatare Qian, 2014 from Jiangxi Province (Qian et al. 2014), and S. zhongi Bu, 2020 andS. canalis Scheller, 2009 from Tibet (Bu 2020c). During an extensive soil-fauna investigation in eastern and southern China from 2012 to 2020, some specimens of the family Eurypauropodidae were obtained. Two of them are new species of the genus Samarangopus and one belongs to the genus Eurypauropus, which is recorded here for the first time in China. Here, S. testudineus sp. nov. and S. rotundifolius sp. nov. are described and illustrated, and Eurypauropus japonicus Hagino & Scheller, 1985 is described and illustrated based on Chinese specimen.

Materials and methods
All pauropods were obtained by extraction of soil and litter samples from broadleaf or mixed forests using Berlese-Tullgren funnels. 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 are deposited in the collection maintained by the Shanghai Natural History Museum (SNHM), Shanghai, China. Abbreviations used in the descriptions follow Qian et al. (2018). Absolute lengths of all body parts are given in mm and μm. Remaining measures in the text refer to relative lengths. In the description of the new species, measurements and indices of paratypes are given in brackets. Diagnosis. Samarangopus testudineus sp. nov. is characterized by testudinal pattern (tortoise shell-like) on the dorsal side of the body, marginal protuberances on tergites well-differentiated into four kinds of shapes, and one pair of sausage-shaped bladders on the anal plate.

Taxonomy
Description. Adult body length 1.95 mm; body dark brown in alcohol, brown to reddish after mounted on slides, dorsally with distinct testudinal pattern (Figs 1A,B,2A).
Head setae strongly reduced, dorsally with setae a 0 and one pair of lateral setae l 1 , other setae absent. Temporal organs rectangular in tergal view, length 0.7 of shortest interdistance, glabrous. Tiny pistils present laterally.
Legs. All legs 5-segmented. Setae on coxa and trochanter of leg 9 similar to each other; thin, glabrous, bifurcate, with length of secondary branch 0.6 times of primary one (Fig. 4I). Tarsi tapering, those of leg 9 1.9 times as long as greatest diameter; proximal seta glabrous, pointed, 35 μm, 0.4 times of the length of tarsus (75 μm) and 2.9 times as long as distal pubescent seta (12 μm) (Fig. 4G). Tarsus of leg 1 with only pubescent distal seta (Fig. 4F). Setae on coxa and trochanter of leg 1 both bifurcate, glabrous, length of secondary branch 0.2 times of primary one (Fig. 4H). All legs with large main claw and small setose anterior secondary claw (Fig. 4F, G).
Etymology. From the masculine Latin word "testudineus" meaning "with the pattern of tortoise shell" that refers to the testudinal pattern on the tergites of the new species.
Distribution. China (Hunan). Known only from the type locality.
Remarks. Samarangopus testudineus sp. nov. can be easily distinguished from all other congeners by the unique dorsal testudinal pattern on the body and the shape of protuberances on the body, as well as the anal plate. The dark-brown ridges composed of different structures and protuberances on tergites were only observed in S. amplissimus Scheller, 2009 from Indonesia, but their patterns are apparently different between the two species (vertically located on posterior part of tergites I-V in S. testudineus sp. nov. vs located on anterior part of tergite I and lateral part of tergites II-VI, curved). The species also differ in the shapes of marginal protuberances on tergite I (differentiated in three kinds, with pattern 1 tiny-3 large-41 small-3 large-1 tiny in S. testudineus sp. nov. vs with 38 similar leaf-shaped, large protuberances in S. amplissimus), the shape of leaf-shaped protuberances (with reticulations in S. testudineus sp. nov. vs without reticulations in S. amplissimus), the shape of globulus g on antenna (1.4 times as long as greatest diameter in S. testudineus sp. nov. vs 2.4 times as long as greatest diameter in S. amplissimus), the shape of the setae on the pygidial sternum (cylindrical in S. testudineus sp. nov. vs slender and pointed in S. amplissimus), and the anal plate (with sausage-shaped, granulated bladders in S. testudineus sp. nov. vs with ovoid, pubescent bladders in S. amplissimus). Diagnosis. Samarangopus rotundifolius sp. nov. is characterized by large, round, leaf-shaped protuberances on the anterior margin of tergite I and the lateral margins of tergites I-VI, small, candle-like protuberances with distal, flame-like structures and entire protuberance surrounded by a circular collar Figure 5. Samarangopus rotundifolius sp. nov. (holotype) A habitus, tergal view, on slide B anal plate C setae on coxa (cx) and trochanter (tr) of leg 1 D tergite I E tergite II, right side F tergite III, right side G tergite IV, right side H tergite V right side I tergite VI and pygidum J middle part of tergite II, showing protuberances K left side of tergite IV, with round, leaf-shaped protuberance and T 3 L setae on coxa (cx) and trochanter (tr) of leg 9. Scale bars: 100 μm (A); 20 μm (B-L).

Samarangopus rotundifolius
mainly situated in the caudal halves of all tergites, trifurcated setae on coxa and trochanter of leg 1, and a pair of triangular bladders on the anal plate.
Anal plate (Figs 5B, 7F) 1.6 times as long as broad, slightly tapering posteriorly; lateral margins with a pair of thin, diverging, pubescent branches, 0.5 times of the length of plate, distal part faintly inflated; posterior 1/2 of plate divided into two tapering branches by a deep, V-shaped incision, each branch with two apical appendages: a submedian short, straight, glabrous one and a stalked bladder of triangular shape in sternal view. Bladder 0.6 times of length of plate. Plate glabrous, bladder densely granulated.
Etymology. From the Latin "rotundus" = "round" and "folium" = "of leaf". The species name "rotundifolius" is masculine that refers to the round, leaf-shaped protuberances on the margin of tergites in the new species.
Distribution. China (Zhejiang). Known only from the type locality. Remarks. Samarangopus rotundifolius sp. nov. can be easily distinguished from all other congeners by the round, leaf-shaped marginal protuberances on its tergites. It is similar to S. umbonifer Scheller, 1995 andS. doiinthanonaeus Scheller, 1995 from Thailand in the shape of the anal plate and setae on the pygidium. They differ in the shape of marginal protuberances on tergite I (all rounded leaf-shaped in S. rotundifolius sp. nov. vs fungiform at anterior and anterolateral margins and some wedge-to leaf-shaped at posterolateral corners in S. umbonifer, and all wedge-to leaf-shaped in S. doiinthanonaeus), the shape of setae on the collum segment (furcate and the secondary branch about half length of primary one in S. rotundifolius sp. nov. vs furcate with a rudimentary secondary branch in S. umbonifer and S. doiinthanonaeus), shape of setae on tergum of pygidium (a 1 and a 2 short, clavate, pubescent, subequal in S. rotundifolius sp. nov. vs a 1 cylindrical and longer than clavate a 2 , both glabrous in S. umbonifer, and a 1 and a 2 both cylindrical, pubescent in S. doiinthanonaeus), and the shape of the plate on the anterior side of the femur of leg 1 (conical in S. rotundifolius sp. nov. vs linguiform and slightly pointed in S. umbonifer, linguiform and round in S. doiinthanonaeus).

Genus Eurypauropus Ryder, 1879
Type species. Eurypauropus spinosus Ryder, 1879. Diagnosis. Fourth antennal segment with four well-developed setae; globulus g of ventral antennal branch long-stalked; third antennal segment with a globulus g 2 ; setae of tergites inserted in rounded crater-shaped structures; first and last pair of legs 5-segmented, other pairs 6-segmented; anal plate V-shaped with straight lateral margins; interdistance of pygidial setae a 1 nearly twice as long as distance a 2 -a 3 (Scheller 2011).
Distribution. Nearctic, Palaearctic. Diagnosis. Eurypauropus japonicus is characterized by the shape of the anal plate with one pair of small, pointed lateral appendages, subcylindrical setae b 2 on the sternum of the pygidium, tergites with large, curved, ciliated spines and small, nipple-shaped tubercles with conical bases.

Eurypauropus japonicus Hagino & Scheller, 1985, new record to China
Description of new material. Length 1.28 mm, light brown (Fig. 8A). Head covered by tergite I and chaetotaxy not observed in detail.
Anal plate. 1.1 times as long as broad; narrow at base; distal part of plate cleft by narrow, V-shaped incision, depth about half of plate length, incision forming two posterior branches, each carrying two pairs of appendages: submedian pair leaf-shaped, about half length of plate, 2.1 times as long and wide; lateral ones short, pointed and pubescent. Plate glabrous, distal appendages pubescent (Fig. 8C).
Distribution. China (Zhejiang), Japan (Honshu, Kyushu). Remarks. Eurypauropus japonicus was originally described and known from Honshu and Kyushu, Japan (Hagino and Scheller 1985;Hagino 1992). The antenna, protuberances, and bothriotricha on tergites, the setae on legs and pygidium, and the shape of the anal plate of Chinese specimens are very similar to E. japonicus, which corroborates the species identity. The main difference observed are: (1) the protuberances on the lateral margin of tergites which are thin and pointed (thick and blunt in types); (2) tergites I-V each with 6 open fields have circular tubercles (eight in types); (3) the bothriotricha T 1 and T 2 are medially with erect, short pubescence and the distal 4/5 have distinct, branched hairs arranged in whorls (distal 1/3 with short pubescence in types). Other minor differences are body size, lengths of setae, bothriotricha, and flagella, which might be due to the variation between populations. In addition, one pair of large spines located on the posterior corner of tergite VI observed in Chinese specimens was not mentioned in the original description of type materials.
The genus is rich in species in South and East Asia, with 28 species recorded: five species in China, four in Thailand, two in Philippines, seven each in Malaysia and Indonesia, and one each in Vietnam, Singapore, and Nepal. The remained 12 species are described from New Caledonia (four species), Madagascar (three), New Zealand (two), Papua New Guinea (one), Australia (one), and Rwanda (one). They usually living in upper layer of soil or in litter of forests, but with lower density compared with pauropods of the family Pauropodidae. They can be easily separated from other groups of pauropods by the strongly sclerotized tergites and relatively flattened body.
The genus Eurypauropos includes about 10 species recorded from USA and Japan (Scheller 2011; https://millibase.org/). It is a group belong to Nearctic and Palaearctic regions and also have strong sclerotized tergites and a robust habitus. In China, only one undetermined species, Eurypauropus sp., was ever reported from Zhejiang Province (Zhang and Chen 1988). The present paper determines the first species of the genus from China, E. japonicus, which was only found in Japan before.