Three new species of Psilogamasus Athias-Henriot, 1969 (Acari, Parasitiformes, Parasitidae) from Southwest China

405 Three new species of Psilogamasus Athias-Henriot, 1969 (Acari, Parasitiformes, Parasitidae) from Southwest China Mao-Yuan Yao1, Jian-Xin Chen1, You-Fang Wu1, Rong Ren2,3 , Tian-Ci Yi2,3 , Dao-Chao Jin2,3 1 College of Agriculture, Anshun University, Anshun, China 2 Provincial Special Key Laboratory for Development and Utilization of Insect Resources of Guizhou, Guizhou University, Guiyang, China 3 Institute of Entomology, Guizhou University, Guiyang, China Corresponding author: Dao-Chao Jin ([email protected]) Copyright: © Mao-Yuan Yao et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract The present study reports three new species of Psilogamasus. Among them, one species, Psilogamasus brachysaccatus Jin & Yao, sp. nov. from the Xizang Autonomous Region, China, was described and illustrated based on adult females and males. Two species, Psilogamasus decemtrichus Ren & Yi, sp. nov. and Psilogamasus bidens Ren & Yi, sp. nov. from Yunnan Province, China, were described and illustrated based on females. Parasitus truncatus Tseng is transferred from the genus Parasitus to Psilogamasus. A key to the known species of Psilogamasus is provided. Key words: Decomposing leaves, description, key, mites, new species, Parasitinae, taxonomy Introduction The family Parasitidae comprises more than 500 species and 47 genera in two subfamilies, Parasitinae Oudemans, 1901 and Pergamasinae Juvara-Bals, 1972 (Hrúzová and Fenďa 2018; Makarova 2019; Juvara-Bals 2019; Yao et al. 2020, 2024). The genus Psilogamasus, belonging to the subfamily Parasitinae, was erected by Athias-Henriot (1969) with Psilogamasus hurlbutti Athias-Henriot, 1969 as its type species. It was a monotypic genus when first described. The genus Taiwanoparasitus was erected by Tseng in 1995 with Taiwanoparasitus pentasetosus as its type species. Hrúzová and Fenďa (2018) transferred two species from the Chinese mainland, Vulgarogamasus brachysternalis Ma & Lin, 2005 and V. longascidiformis Ma & Lin, 2005, to Taiwanoparasitus (Tseng 1995; Ma and Lin 2005). Recently, Yao et al. (2020) indicated that Taiwanoparasitus is newly synonymized with Psilogamasus, and four species from the Chinese mainland, namely T. pentasetosus T. brachysternalis, T. longascidiformis, Vulgarogamasus lingulatus Bai & Ma, 2013, have been transferred to Psilogamasus. To date, six species of Psilogamasus, P. brachysternalis (based on female), P. hurlbutti (female and male), P. lingulatus (female), P. longascidiformis (female), P. pentasetosus Tseng, 1995 (female), and P. pentatideus Yao & Jin, 2020 (female and male), have been described worldwide (Yao et al. 2020). Except for P. hurlbutti which has been recorded in Tanzania and America, the mites of the genus have Academic editor: Farid Faraji Received: 3 September 2025 Accepted: 21 October 2025 Published: 12 November 2025 ZooBank: https://zoobank. org/7CDB90F7-C0F7-4A30-A96AC0C327598026 Citation: Yao M-Y, Chen J-X, Wu Y-F, Ren R, Yi T-C, Jin D-C (2025) Three new species of Psilogamasus AthiasHenriot, 1969 (Acari, Parasitiformes, Parasitidae) from Southwest China. ZooKeys 1259: 405–421. https://doi. org/10.3897/zookeys.1259.171008 ZooKeys 1259: 405–421 (2025) DOI: 10.3897/zookeys.1259.171008 406 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China only been reported in China (Athias-Henriot 1969; Hennessey and Farrier 1989; Tseng 1995; Ma and Lin 2005; Bai and Ma 2013; Yao et al. 2020). During a survey of Chinese Parasitidae, three new species of Psilogamasus were discovered. Herein, we describe these new species and provide an identification key to the known species of Psilogamasus. Material and methods Mites were extracted from decomposing leaves by Berlese-Tullgren funnels for 12–24 hours and stored in 75% alcohol. Mites were cleared in Nesbitt’s solution and then mounted on slides in Hoyer’s medium. Specimens were observed and illustrated under a Nikon DS-Ri2 microscope, and figures were edited with Adobe Photoshop CC2021. All measurements are given in micrometers (μm). The system of idiosomal setal nomenclature follows Hyatt (1980). Terminology for leg chaetotaxy follows Evans (1963a); palp chaetotaxy follows Evans (1963b); adenotaxy and poroidotaxy follow Athias-Henriot (1971, 1975); and measuring follows Yao et al. (2022). Results Family Parasitidae Oudemans, 1901 Subfamily Parasitinae Oudemans, 1901 Genus Psilogamasus Athias-Henriot, 1969 Type species. Psilogamasus hurlbutti Athias-Henriot, 1969 Diagnosis. Both sexes. Dorsal idiosoma with less than 30 pairs of setae; setae z5 of dorsal hexagon similar to j5 and j6 in form (smooth), while different in length (z5 longer); tritosternum biramous; opisthogastric shield bearing five to six pairs of setae; setae ZVI and gland pores gv2 absent (present in P. decemtrichus sp. nov.); seta al of palp femur comblike, all and al2 of palp genu entire and spatulate distally; corniculi small; epistome trispinate. Female with separated podonotal shield with 16–18 pairs of setae, and opisthonotal shield with five to six pairs of setae (ten pairs in P. decemtrichus sp. nov.); genital shield triangular or subtriangular; peritrematal shield anteriorly fused to podonotal shield and posteriorly free; movable digit of chelicerae with three or four teeth; setae avl and av2 on femur II, avl on genu II and tibia II acicular. Male with holodorsal shield and transverse suture in central region; movable digit of chelicera with five or six teeth; setae avl and av2 on femur II modified into spurs fused at base; seta avl on genu II and tibia II each modified into spur. Psilogamasus brachysaccatus Yao & Jin, sp. nov. https://zoobank.org/59A8B989-D6F9-491A-8FAB-4EEA5E6D0C7B Figs 1–5 Diagnosis. Female. Podonotal and opisthonotal shields with 18 and five pairs of setae, respectively; setae j1 slightly pilose, r3 simple; endogynium comprised of a short semi-circular sac with three to five small teeth on each side of the 407 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China leading edge; opisthogastric shield bearing six pairs of setae; setae ZV1 and gland pores gv2 absent; Peritrematal groove extending anteriorly to beyond coxa II; movable digit of chelicera with four teeth. Male. Seta j1 slightly pilose; opisthogastric region with seven pairs of setae; central prong of gnathotectum serrated apically and lateral prongs acuminate distally; movable digit of chelicera with four teeth; dorsal seta on fixed digit of chelicera smooth; femur II with a main spur (proximal) and an axillary process (distal), genu II and tibia II each with a small spur (Fig. 5E). Other characteristics as in female. Description. Female (N = 4). Idiosoma weakly sclerotized, length 672–710, width 481–498. Dorsum (Fig. 1A). Podonotal and opisthonotal shields separated and with rough reticulation. Podonotal region with 19 pairs of setae, of which 18 pairs on podonotal shield and a pair (seta r6) off shield. Opisthonotal region bearing seven pairs of setae, of which J1–J3 and Z1, Z2 on opisthonotal shield, J4 and J5 off shield. Seta j1 stout and slightly pilose, other dorsal setae smooth. Seta r3 longer than others, setae j2, j3, z1, z2, s3, s6, r2, r4, r6 and J4 tiny and short. Lengths of dorsal setae: j1 74–78, j2 15–17, j3 32–35, j4 66–70, j5 58–62, j6 58–61, z1 26–28, z2 16–18, z4 47–50, z5 90–95, z6 57–62, s3 31–34, s4 58– Figure 1. Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Dorsum; B. Venter. A B 408 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China 61, s5 60–62, s6 15–17, r2 15–17, r3 159–165, r4 15–17, r6 15–17, J1 79–82, J2 78–82, J3 80–84, J4 16–17, J5 92–95, Z1 57–61, Z2 65–69. Venter (Figs 1B, 2A). Tritosternum with two pilose laciniae (111–120) and a smooth base (42–45). Presternal platelets absent. Sternal shield reticulated, bearing three pairs of setae (st1–st3), st1 (48–52) longer than st2 (38–41) and st3 (42–43). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st4 (39–42). Epigynial shield bearing setae st5 (40–42). Anterior margin of epigynial shield with glassy angulation apex. Endogynium comprised of a short semi-circular sac with three to five small teeth on each side of the leading edge, and anterolaterally with two inner spindle-shaped structures underneath metasternal shields (Fig. 2A). Setae ZV1 and gland pores gv2 absent. Opisthogastric shield reticulate, bearing six pairs of setae (JV1–JV4, ZV2 and ZV3). Setae pa and po equal in length (27–30). Peritrematal groove length 219–238, extending to anterior level of coxa II. Peritrematal shield fused with podonotal shield anteriorly and separated at level of seta j2. Opisthogastric soft cuticle with three pairs of setae. All ventral setae smooth. Lengths of setae on opisthogastric shield: JV1 42–45, JV2 46–49, JV3 47–49, JV4 47–50, ZV2 32–34, ZV3 42–43. Gnathosoma (Fig. 2B–E). Gnathotectum (Fig. 2B) with three prongs, serrated apically and emerging from base with one to three small teeth on each side. Movable digit of chelicera with four teeth, fixed digit with six teeth (Fig. 2C). Corniculus length 27–34, short and horn-shaped; deutosternal groove with 11 denticulate rows. Setae h1–h3 smooth, h1 46–50, h2 40–43, h3 47–50 in length; pcx pilose, 48–52 in length (Fig. 2D). Palp length 228–239; trochanter Figure 2. Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Endogynium; B. Gnathotectum; C. Chelicera; D. Subcapitulum; E. Trochanter, femur and genu of palp. AB CD E 409 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China with two pilose setae, v1 stouter than v2; femur with five setae, of which al comblike, d3 pilose; genu with six setae, of which al1 and al2 spatulate distally, remaining setae smooth. Trochanter, femur and genu of palp as in Fig. 2E. Legs (Fig. 3). Lengths of legs I–IV: I 865–910, II 572–634, III 565–642, IV 907–990. Most leg setae smooth and setae on genu IV and tibia IV usually longer than others. Seta al on trochanter I stout and pilose. Most setae on tarsi II and tarsi III slightly pinnate. Setae av1 and pv1 on tarsi II–IV spur-like. Seta pd2 (282–301) on tarsus IV longer than all other leg setae. Male (N = 3; Figs 4, 5) Idiosoma length 476–495, width 306–317. Dorsum (Fig. 4A). Reticulate holodorsal shield covering entire dorsum, with a suture closely anterior to setae J1, not reaching lateral margin of idiosoma. Podonotal region with 18 pairs of setae. Opisthonotal region bearing eight pairs of setae. All setae inserted on reticulate holodorsal shield. Seta j1 slightly pilose, other dorsal setae smooth. Setae j2, j3, z1, z2, s3, s6, r2, r4, r6 finer than others. Lengths of dorsal setae: j1 47–50, j2 17–19, j3 27–30, j4 40–44, j5 35– 38, j6 35–39, z1 19–21, z2 16–19, z4 29–33, z5 50–55, z6 36–40, s3 24–26, s4 31–33, s5 35–39, s6 21–23, r2 18–20, r3 128–132, r4 14–15, r6 14–15, J1 48–53, J2 55–58, J3 63–67, J4 74–76, Z1 47–48, Z2 51–53, Z3 37–40. Venter (Fig. 4B). Tritosternum with two pilose laciniae (42–50), and a smooth base (17–20). Presternal shields absent. Genital lamina poorly visible, anteriorly extending to form a hyaline and smooth protrusion. Sternogenital shield bearing five pairs of setae (st1–st5). Anterior margin of sternogenital Figure 3. Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Coxa–tibia of leg I; B. Leg II; C. Leg III; D. Leg IV. A B C D 410 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China shield concave, posterior margin fused to opisthogastric region. Opisthogastric region with seven pairs of smooth setae. Setae pa and po equal in length (22–25). Peritrematal groove as in female, length 191–224. Lengths of setae on sternogenital region: st1 35–37, st2 32–34, st3 26–28, st4 26–28, st5 30– 32, as well as on opisthogastric one: JV1 30–32, JV2 36–39, JV3 38–40, JV4 47–50, JV5 48–50, ZV2 32–34, ZV3 42–43. Gnathosoma (Fig. 5). Gnathotectum (Fig. 5A) with three prongs, central one serrated apically and lateral ones acuminate distally, emerging from nude base. Movable and fixed digit of chelicera with four teeth, respectively (Fig. 5B). Palp 189–205 in length, as in female, trochanter, femur and genu as shown in Fig. 5C. Subcapitulum (Fig. 5D) with setae pcx (30–31) pilose, h1 (36–38), h2 (32–35) and h3 (40–43) smooth; deutosternal groove with ten rows, corniculus (23–25) and internal mala acute as in female. Legs. Lengths of legs I–IV: I 799–812, II 531–544, III 512–539, IV 838–880. Leg II stouter than others. Femur II with a main spur (proximal) and an axillary process (distal), genu II and tibia II each with a small spur (Fig. 5E). Other characteristics as in female. Other stages. Unknown. Etymology. This species is named after its endogynium, which is composed of a short, semi-circular sac structure. Material examined. Holotype. China • 1 ♀ (slide no. XZ2019071901), Xizang Autonomous Region, Linzhi City, Bome County; 29°54'33"N, 95°29'36"E; 2624 m a.s.l.; 19 Jun. 2019; collected from decomposing leaves by Jian-Xin Chen, Paratypes. China • 3 ♀ and 3 ♂ (XZ2019071902–XZ2019071902), the same data as the holotype. Figure 4. Psilogamasus brachysaccatus Yao & Jin, sp. nov., male. A. Dorsum; B. Venter. AB 411 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China The holotype and paratypes are deposited in the Institute of Entomology, Guizhou University, Guivang, China (GUGC). Remarks. The female of the newly described species is morphologically similar to P. bidens Ren & Yi, sp. nov. in the setal numbers on the podonotal, opisthonotal and opisthogastric shields, and the shape of seta j1. However, the female P. brachysaccatus Yao & Jin, sp. nov. is different from P. bidens Ren & Yi, sp. nov. as follows: (1) dorsal seta r3 simple, vs. pilose in the latter; (2) presternal platelets absent, vs. a pair of presternal platelets present in the latter; (3) three prongs of gnathotectum each apically serrated and emerging from base with 1–3 small teeth on each side, vs. bifid and emerging from nude base in the latter; (4) endogynium with a semi-circular sac, vs. tongue-shaped in the latter; and (5) seta v1 on palp trochanter pilose, vs. simple in the latter. Psilogamasus decemtrichus Ren & Yi, sp. nov. https://zoobank.org/B627FA48-0110-410B-B562-379A6094572B Figs 6–8 Diagnosis. Female. Podonotal and opisthonotal shields with 18 and ten pairs of setae, respectively; setae j1 and r3 simple; endogynium tongue-shaped with some small teeth on each side of the leading edge; setae ZV1 and gland pores Figure 5. Psilogamasus brachysaccatus Yao & Jin, sp. nov., male. A. Gnathotectum; B. Chelicera; C. Trochanter, femur and genu of palp; D. Subcapitulum; E. Femur, genu and tibia of leg II. AB C D E 412 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China gv2 present; opisthogastric shield with six pairs of setae; Peritrematal groove extending anteriorly to beyond coxa II; movable digit of chelicera with three teeth. Description. Female (N = 5). Idiosoma weakly sclerotized, length 428–468, width 259–278. Dorsum (Fig. 6A). Podonotal and opisthonotal shields separated and with rough reticulation. Podonotal region with 19 pairs of setae, of which 18 pairs on podonotal shield (seta r5 on podonotal shield) and two pairs (setae r4 and r6) off shield. Opisthonotal shield bearing ten pairs of setae. All dorsal setae smooth, setae z1, s6, r2, r4, r5 and r6 tiny. Lengths of dorsal setae: j1 28–30, j2 35–38, j3 47–49, j4 39–41, j5 47–49, j6 40–42, z1 7–8, z2 27–28, z4 47–50, z5 90–95, z6 57–62, s3 31–34, s4 58–61, s5 60–62, s6 15–17, r2 15–17, r3 159– 165, r4 15–17, r5 16–17, r6 17–18, J1 50–54, J2 56–57, J3 63–65, J4 55–59, Z1 50–56, Z2 62–65, Z3 58–59, S1 48–52, S2 48–50, S3 58–60. Venter (Figs 6B, 7A). Tritosternum with two pilose laciniae (64–73) and a smooth base (24–29). Presternal platelets absent. Sternal shield without reticulation, bearing three pairs of setae (st1–st3), st1 (66–72) longer than st2 (58–64) and st3 (46–50). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st4 (45–52). Epigynial shield bearing setae st5 (35–37). Endogynium tongue-shaped with some small teeth on each Figure 6. Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Dorsum; B. Venter. A B 413 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China side of the leading edge, and anterolaterally with two inner roller-shaped structures underneath metasternal shields, connected by a ribbon structure (Fig. 7A). Setae ZV1 and gland pores gv2 present. Opisthogastric shield reticulate, bearing six pairs of setae (JV1–JV4, ZV1 and ZV2). Setae pa and po equal in length (17–23). Peritrematal groove length 356–379, extending anteriorly to level of coxa II. Opisthogastric soft cuticle with three pairs of setae. All ventral setae smooth. Lengths of setae on opisthogastric shield: JV1 42–45, JV2 46–49, JV3 52–56, JV4 47–48, ZV1 12–15, ZV2 45–48. Gnathosoma (Fig. 7B–E). Movable digit of chelicera with three teeth, fixed digit with five teeth (Fig. 7B). Corniculus length 23–28, short and horn-shaped; Figure 7. Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Endogynium; B. Chelicera; C. Subcapitulum; D. Gnathotectum; E. Trochanter, femur and genu of palp. A B C D E 420 ZooKeys 1259: 405–421 (2025), DOI: 10.3897/zookeys.1259.171008 Mao-Yuan Yao et al.: Three new species of Psilogamasus from Southwest China Acknowledgements We sincerely thank the editor and reviewers for their time, effort, and valuable suggestions during the review process. Their insightful comments and constructive suggestions greatly improved the quality and clarity of our manuscript. Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Use of AI No use of AI was reported. Funding This work was supported by the Guizhou Provincial Science and Technology Projects (QKHJC [2024] youth 289 and 410, Qiankehe Basic-ZK[2023] General 023), National Natural Science Foundation of China (No. 31872275 and 32160118), Key Laboratory of Plants Protection Informatization for Featured and Efficient Agriculture in Central Guizhou Province (Qianjiaoji KY [2022] No. 052). Author contributions Data curation: RR, JXC. Investigation: RR, YFW. Supervision: TCY. Writing – original draft: MYY. Writing – review and editing: MYY, DCJ. Author ORCIDs Mao-Yuan Yao https://orcid.org/0000-0002-5475-046X Jian-Xin Chen https://orcid.org/0000-0001-8787-6678 You-Fang Wu https://orcid.org/0000-0001-7968-5345 Rong Ren https://orcid.org/0009-0003-5331-3887 Tian-Ci Yi https://orcid.org/0000-0002-9953-3709 Dao-Chao Jin https://orcid.org/0000-0003-2727-5621 Data availability All of the data that support the findings of this study are available in the main text. 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