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

Mao-Yuan Yao; Jian-Xin Chen; You-Fang Wu; Rong Ren; Tian-Ci Yi; Dao-Chao Jin

doi:10.3897/zookeys.1259.171008

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 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, 2, 3, 4, 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 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 58–61, 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.

Figure 1.

Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Dorsum; B. Venter.

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.

Figure 2.

Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Endogynium; B. Gnathotectum; C. Chelicera; D. Subcapitulum; E. Trochanter, femur and genu of palp.

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 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.

Figure 3.

Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Coxa–tibia of leg I; B. Leg II; C. Leg III; D. Leg IV.

Male (N = 3; Figs 4, 5) Idiosoma length 476–495, width 306–317.

Figure 4.

Psilogamasus brachysaccatus Yao & Jin, sp. nov., male. A. Dorsum; B. Venter.

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.

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 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.

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, 7, 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 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.

Figure 6.

Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Dorsum; B. Venter.

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 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.

Figure 7.

Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Endogynium; B. Chelicera; C. Subcapitulum; D. Gnathotectum; E. Trochanter, femur and genu of palp.

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; deutosternal groove with ten denticulate rows. Setae h1–h3 smooth, h1 25–5026, h2 21–23, h3 22–25 in length; pcx slightly pilose, 32–36 in length (Fig. 7C). Gnathotectum (Fig. 7D) with three prongs, central one bifid apically and lateral ones acuminate distally, emerging from nude base. Palp length 224–232; trochanter with two setae, v2 slightly pilose; femur with five setae, of which al comblike, d3 pilose; genu with six setae, of which al1 and al2 spatulate distally, remaining setae simple. Trochanter, femur and genu of palp as in Fig. 7E.

Legs (Fig. 8). Lengths of legs I–IV: I 470–481, II 294–326, III 305–320, IV 465–485. Most leg setae smooth. Setae av1 and pv1 on tarsi II–IV spur-like. Setae pd2 on tarsus IV, length 95–107, longer than all other setae.

Figure 8.

Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Coxa–tibia of leg I; B. Leg II; C. Leg III; D. Leg IV.

Other stages.

Unknown.

Etymology.

The name of the species is derived from “ decem-”, meaning “ten”, and–trichus, meaning “setae”. It refers to the opisthonotal shield with ten pairs of setae in females, which is diagnostic for this species.

Material examined.

Holotype. China • 1 ♀ (slide no. YN2022070601), Yunnan Province, Pu’er City, Jingdong Yi Autonomous County, Taizhong Town; 24°32'28"N, 101°1'25"E; 2466 m a.s.l.; 6 Jun. 2022; collected from moss by Ye-Yi Shuai and Gui-Ming Mu. Paratypes. China • 4 ♀ (YN2022070602–YN2022070605), the same data as the holotype.

The holotype and paratypes are deposited in the Institute of Entomology, Guizhou University, Guivang, China (GUGC)

Remarks.

Psilogamasus decemtrichus Ren & Yi, sp. nov. can be easy distinguished from other species of the genus due to the setal number on the opisthonotal shield, which bears ten pairs rather than five or six pairs, and the presence of setae r5, ZV1 and gland pores gv2.

Psilogamasus bidens Ren & Yi, sp. nov.

https://zoobank.org/769DEA9D-2AD9-4DCC-80D6-3FEF7C974193

Figs 9, 10, 11

Diagnosis.

Female. Podonotal and opisthonotal shields with 18 and five pairs of setae, respectively; setae j1 and r3 slightly pilose; endogynium tongue-shaped with some small teeth on each side of the 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.

Description.

Female (N = 4). Idiosoma weakly sclerotized, length 575–668, width 408–425.

Dorsum (Fig. 9A). Podonotal and opisthonotal shields separated and with reticulation. Podonotal region with 19 pairs of setae, of which 18 pairs are on podonotal shield and a pair (seta r6) is off shield. Opisthonotal shield bearing five pairs of setae. Seta J4 off shield. Setae j1 and r3 slightly pilose, j2, z1, z2, r2, r4 and r6 tiny. Lengths of dorsal setae: j1 50–55, j2 8–11, j3 42–46, j4 48–52, j5 53–55, j6 53–58, z1 13–18, z2 9–13, z4 47–50, z5 67–72, z6 63–65, s3 34–38, s4 53–56, s5 56–62, s6 16–20, r2 13–18, r3 113–121, r4 10–13, J1 66–70, J2 75–80, J3 77–82, J4 45–50, Z1 65–70, Z2 61–65.

Figure 9.

Psilogamasus bidens Ren & Yi, sp. nov., female. A. Dorsum; B. Venter.

Venter (Figs 9B, 10A). Tritosternum with two pilose laciniae and a smooth base. Pair of small presternal platelets present. Sternal shield with reticulation, bearing three pairs of setae (st1–st3), st1 (42–46) longer than st2 (34–37) and st3 (33–37). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st4 (30–35). Epigynial shield bearing setae st5 (37–43). Endogynium saccular, tongue-shaped in ventral view, with some small teeth on each side, and anterolaterally with two inner reniform structures (Fig. 10A). Setae ZV1 and gland pores gv2 absent. Opisthogastric shield reticulate, bearing six pairs of setae (JV1–JV4, ZV2 and ZV3). Setae pa (22–25) and longer than po (15–17). Peritrematal groove length 178–188, 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 two pairs of setae. All ventral setae smooth. Lengths of setae on opisthogastric shield: JV1 37–42, JV2 40–44, JV3 44–47, JV4 47–50, ZV2 47–51, ZV3 49–53.

Figure 10.

Psilogamasus bidens Ren & Yi, sp. nov., female. A. Endogynium; B. Gnathotectum; C. Subcapitulum; D. Chelicera; E. Trochanter, femur and genu of palp.

Gnathosoma (Fig. 10B–E). Gnathotectum (Fig. 2B) with three prongs, each apically bifid and emerging from nude base. Corniculus length 32–38, short and horn-shaped; deutosternal groove with ten denticulate rows. Setae h1–h3 smooth, h1 52–58, h2 40–43, h3 57–63 in length; pcx pilose, 70–75 in length (Fig. 10C). Movable digit of chelicera with four teeth, fixed digit with five teeth (Fig. 10D). Palp trochanter bearing two setae, v2 pilose; femur with five setae, of which al comblike; genu with six setae, of which al1 and al2 spatulate distally, remaining setae smooth. Trochanter, femur and genu of palp as in Fig. 10E.

Legs (Fig. 11). Lengths of legs I–IV: I 783–850, II 518–576, III 508–580, IV 937–970. Most leg setae smooth and setae on femur IV, genu IV, tibia IV and tarsi IV usually longer than setae on other legs. Most setae on tarsi II and tarsi III slightly pinnate. Setae av1 and pv1 on tarsi II–IV spur-like.

Figure 11.

Psilogamasus bidens Ren & Yi, sp. nov., female. A. Coxa–tibia of leg I; B. Leg II; C. Leg III; D. Leg IV.

Other stages.

Unknown.

Etymology.

This new species is named based on the three prongs of the gnathotectum, where each prong exhibits an apical bifurcation (bidens).

Material examined.

Holotype. China • 1 ♀ (slide no. YN2024051601), Yunnan Province, Honghe Hani and Yi Autonomous Prefecture, Pingbian County, Daweishan National Nature Reserve; 22°54'48"N, 103°41'47"E; 2038 m a.s.l.; 16 May, 2024; collected from decomposing leaves by Hu-Die He and Rong Ren. Paratypes. China • 1 ♀ (YN2024051602), the same data as the holotype. China • 1 ♀ (YN2024052901), Yunnan Province, Baoshan City, Longyang District, Mangkuan Yi and Dai Ethnic Township, Gaoligong Mountain National Nature Reserve; 25°17'28"N, 98°46'17"E; 2392 m a.s.l.; 29 May, 2024; collected from decomposing leaves by Hu-Die He and Rong Ren. China • 1 ♀ (YN2024051701), Yunnan Province, Honghe Hani and Yi Autonomous Prefecture, Mengzi City; 23°11'25"N, 103°22'54"E; 1649 m a.s.l.; 17 May, 2024; collected from moss by Hu-Die He and Rong Ren.

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. longascidiformis in the setal number on the opisthonotal shield, dental number of the fixed digit on chelicera, and the endogynium with a tongue-shaped suck. However, the female P. bidens Ren & Yi, sp. nov. is different from P. longascidiformis as follows: (1) opisthogastric shield bearing six pairs of setae, vs. five pairs in the latter; (2) dorsal setae j1 and r3 pilose, vs. simple in the latter; (3) fixed digit of chelicera with four teeth, vs. three in the latter; and (4) setae j3 about four times longer than j2 in length, vs. equal in the latter.

Discussion

The placement of the species Parasitus truncatus Tseng, 1995 needs some discussion. This species was known only from the adult females collected from litter in Taiwan province, China (Tseng 1995). The genus Parasitus was established by Latreille in 1795 with Parasitus coleoptratorum Latreille, 1758 as its type species (Latreille 1795). The main characteristics of females of this genus are the separated podonotal and opisthonotal shields; dorsum with more than 40 pairs of setae; setae z5 of dorsal hexagon markedly different in form from j5 and j6, usually thicker, long and pilose distally; opisthogastric shield bearing rarely more than 30 pairs of setae; seta al of palp femur bifid, and setae al1 and al2 of palp genu entire, setiform or spatulate distally (Hyatt 1980). Parasitus truncatus is different from the mites of Parasitus, especially the type species P. coleoptratorum, in the following characteristics: dorsum with 22 pairs of setae; setae z5 similar to j5 and j6 in form (smooth); opisthogastric shield bearing five pairs of setae; setae ZV1 and gland pores gv2 absent; seta al of palp femur comblike (Tseng 1995). The common features of female P. truncatus with Psilogamasus are: dorsum with less than 30 pairs of setae, which of podonotal shield with 16–18 pairs of setae and opisthonotal shield with five to six pairs of setae (ten pairs only P. decemtrichus); setae z5 similar to j5 and j6 in form (smooth); opisthogastric shield bearing five to six pairs of setae; setae ZV1 and gland pores gv2 absent (present only in P. decemtrichus sp. nov.); seta al of palp femur comblike, al1 and al2 of palp genu entire and spatulate distally; peritrematal shields free posteriorly; and peritrematal groove extending to anterior level of coxa II (Tseng 1995; Yao et al. 2020). Moreover, the endogynium of P. truncatus has a long, tongue-shaped structure, which is similar to those of six species (namely, P. decemtrichus sp. nov., P. hurlbutti, P. lingulatus, P. longascidiformis, P. pentatideus and P. bidens sp. nov.) in Psilogamasus. Furthermore, Table 1 compares the main morphological features of P. truncatus with those of the six species.

Table 1.

Download as

CSV

XLSX

Morphological variations in females of Psilogamasus decemtrichus Ren & Yi, sp. nov., Psilogamasus hurlbutti (Athias-Henriot, 1969), Psilogamasus lingulatus (Bai & Ma, 2013), Psilogamasus longascidiformis (Ma & Lin, 2005), Psilogamasus pentatideus (Yao & Jin, 2020), Psilogamasus bidens Ren & Yi, sp. nov. and Psilogamasus truncatus (Tseng, 1995), comb. nov.

Mite	P. decemtrichus sp. nov.	P. hurlbutti	P. lingulatus	P. longascidiformis	P. pentatideus	P. bidens sp. nov.	P. truncatus comb. nov.
Setal number on podonotal shield	18 pairs	18 pairs	16–18 pairs	17 pairs	18 pairs	18 pairs	16 pairs
Setal number on opisthonotal shield	10 pairs	6 pairs	6 pairs	5 pairs	5 pairs	5 pairs	6 pairs
Setal number on opisthogastric shield	6 pairs	5 pairs	5 pairs	5 pairs	5 pairs	6 pairs	5 pairs
Dental numbers of movable digit on chelicera	3	4	4	3	4	4	4
Dental numbers of fixed digit on chelicera	5	7	5	5	7	5	9
Shape of setae j1	smooth	smooth	pilose	smooth	smooth	pilose	smooth
Base of gnathotectum	nude	nude	denticles	denticles	denticles	nude	denticles
Small teeth in endogynium	present	present	present	absent	present	present	absent

Therefore, we conclude that P. truncatus must be included in Psilogamasus.

Psilogamasus truncatus (Tseng, 1995), comb. nov.

Original designation. Parasitus truncatus Tseng, 1995: 32.

The mites of Psilogamasus occur in litter, moss, decomposing leaves, soil and humus. The geographical distribution of Psilogamasus has, until now, been limited to Tanzania, America, and China. This limited distribution may be related to the host species, collection times, and collection methods (Athias-Henriot 1969; Hennessey and Farrier 1989; Tseng 1995; Ma and Lin 2005; Yao et al. 2020). Therefore, in future taxonomic studies, more attention should be paid to host ranges and the use of diverse collection methods over different periods to better understand their geographical distribution.

Key to adults of Psilogamasus species (updated from Yao et al. (2020))

Females
1	Opisthonotal shield with ten pairs of setae; setae ZV1 and gland pores gv2 present	P. decemtrichus sp. nov.
–	Opisthonotal shield with five pairs of setae; setae ZV1 and gland pores gv2 absent	2
2	Opisthonotal shield with six pairs of setae	3
–	Opisthonotal shield with five pairs of setae	5
3	Dorsal setae j1 pilose	*P. lingulatus*
–	Dorsal setae j1 smooth	4
4	Endogynium with small teeth; base of gnathotectum nude	P. truncatus comb. nov.
–	Endogynium without teeth; base of gnathotectum denticular	*P. hurlbutti*
5	Peritrematal groove extending anteriorly to posterior of coxa III; movable digit of chelicera with three teeth	6
–	Peritrematal groove extending anteriorly to beyond coxa II; movable digit of chelicera with four teeth	7
6	Podonotal shield with 18 pairs of setae; the base of epistome smooth; epigynium serrate on both sides	*P. brachysternalis*
–	Podonotal shield with 17 pairs of setae; the base of epistome with small denticles; epigynium smooth on both sides	*P. longascidiformis*
7	Opisthogastric shield with six pairs of setae	8
–	Opisthogastric shield with five pairs of setae	*P. pentatideus*
8	Podonotal shield with 16 pairs of setae; dorsal setae j1 smooth	*P. pentasetosus*
–	Podonotal shield with 18 pairs of setae; dorsal setae j1 pilose	9
9	Dorsal setae r3 smooth; endogynium with a short semi-circular sac structure	P. brachysaccatus sp. nov.
–	Dorsal setae r3 pilose; endogynium with a long tongue-shaped structure	P. bidens sp. nov.
Males
1	Dorsal setae j1 pilose; gnathotectum emerging from nude base and lateral prongs acuminate distally	P. brachysaccatus sp. nov.
–	Dorsal setae j1 simple; gnathotectum emerging from small teeth base and lateral prongs split distally	2
2	Dorsal seta on fixed digit of chelicera smooth; central prong of gnathotectum apically divided into 2–3 branches	*P. pentatideus*
–	Dorsal seta on fixed digit of chelicera forked; central prong of gnathotectum serrated apically	*P. hurlbutti*

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.

References

Athias-Henriot C (1969) Psilogamasus hurlbutti, n. g., n. sp., gamaside nouveau de Tanzani (Acariens Anactinotriches, Parasitidae). Annales de la Société Entomologique de France 5(2): 439–449. https://doi.org/10.1080/21686351.1969.12277783

Athias-Henriot C (1971) La divergence néotaxique des Gamasides (Arachnides). Bulletin Scientifique de Bourgogne 28: 93–106.

Athias-Henriot C (1975) Nouvelles notes sur les Amblyseiini II. Le relevé organotaxique de la face dorsaleadulte (Gamasides, Protoadenique, Phytoseiidae). Acarologia 17: 20–29.

Bai XL, Ma LM (2013) A new species of Vulgarogamasus and supplementary description of female Neogamasus crispus (Acari: Parasitidae). Acta Zootaxonomica Sinica 38(1): 70–74.

Evans GO (1963a) Observation on the chaetotaxy of the legs in the free-living Gamasina (Acari: Mesostigmata). Bulletin of the British Museum, Natural History. Zoology 10: 275–303. https://doi.org/10.5962/bhl.part.20528 [Natural History]

Evans GO (1963b) Some observations on the chaetotaxy of the pedipalps in the Mesostigmata (Acari). Annals & Magazine of Natural History 6(69): 513–527. https://doi.org/10.1080/00222936308651393

Hennessey MK, Farrier MH (1989) Mites of the Family Parasitidae (Acari: Mesostigmata) Inhabiting Forest Soils of North and South Carolina. North Carolina Agricultural Research Service, 52–53.

Hrúzová K, Fenďa P (2018) The family Parasitidae (Acari: Mesostigmata)–history, current problems and challenges. Acarologia 58(Suppl): 25–42. https://doi.org/10.24349/acarologia/20184280

Hyatt KH (1980) Mites of the subfamily Parasitinae (Mesostigmata: Parasitidae) in the British Isles. Bulletin of the British Museum, Natural History. Zoology 38(5): 237–378. https://doi.org/10.5962/p.12620 [Natural History]

Juvara-Balş I (1972) Mixogamasus, un nouveau genre de Parasitidae (Acarien: Anactinotriches) de Roumanie. Acarologia 14: 3–14.

Juvara-Bals I (2019) Occigamasus, a new genus of pergamasine mites, with description of two new species from the west coast of North America (Parasitiformes: Gamasina: Parasitidae). Acarologia 59(4): 551–570. https://doi.org/10.24349/acarologia/20194354

Latreille PA (1795) Observations sur la variété des tiques, et distribution méthodique des insectes de cette famille d’après les caractères établis sur la conformation de ces organes. Magazin Encyclopédique 4(13): 15–20.

Ma LM, Lin JZ (2005) Four new species of the family Parasitidae (Acari, Gamasina). Dong Wu Fen Lei Xue Bao 30(1): 73–80.

Makarova OL (2019) North Pacific versus North Atlantic: A case with species of the amphiboreal littoral mite genus Thalassogamasus gen. nov. (Parasitifomes, Mesostigmata, Parasitidae). Zootaxa 4647(1): 457–485. https://doi.org/10.11646/zootaxa.4647.1.29

Oudemans AC (1901) Notes on Acari. Ser. 3. Tijdschrift van de Nederlandse Dierkundige Vereeniging, Leyden 7: 50–88.

Tseng YH (1995) A taxonomical study of free-living gamasine mite family Parasitidae Oudemans (Acari, Mesostigmata) from Taiwan Journal of Taiwan Museum 48: 11–81.

Yao MY, Yi TC, Jin DC, Guo JJ (2020) A new species of Psilogamasus Athias-Henriot, 1969 from China and redefinition of the genus (Parasitiformes: Parasitidae). Acarologia 60(4): 1–11. https://doi.org/10.24349/acarologia/20204404

Yao MY, Chen JX, Yi TC, Guo JJ, Jin DC (2022) Morphological description of ontogenetic stages in Parasitus yuensis Ma & Lin (Acari: Parasitiformes: Parasitidae). Systematic and Applied Acarology 27(11): 2269–2282. https://doi.org/10.11158/saa.27.11.12

Yao MY, Chen JX, Yi TC, Jin DC (2024) Cerogamasus, a new genus of Parasitinae mites, with description of four new species from China (Acari: Parasitiformes: Parasitidae). Animals (Basel) 14(15): 2260. https://doi.org/10.3390/ani14152260

﻿Abstract

Key words:

﻿Introduction

﻿Material and methods

﻿Results

﻿Family Parasitidae Oudemans, 1901

﻿Genus Psilogamasus Athias-Henriot, 1969

Type species.

Diagnosis.

﻿ Psilogamasus brachysaccatus Yao & Jin, sp. nov.

Diagnosis.

Description.

Other stages.

Etymology.

Material examined.

Remarks.

﻿ Psilogamasus decemtrichus Ren & Yi, sp. nov.

Diagnosis.

Description.

Other stages.

Etymology.

Material examined.

Remarks.

﻿ Psilogamasus bidens Ren & Yi, sp. nov.

Diagnosis.

Description.

Other stages.

Etymology.

Material examined.

Remarks.

﻿Discussion

﻿Psilogamasus truncatus (Tseng, 1995), comb. nov.

﻿Key to adults of Psilogamasus species (updated from Yao et al. (2020))

﻿Acknowledgements

﻿Additional information

Conflict of interest

Ethical statement

Use of AI

Funding

Author contributions

Author ORCIDs

Data availability

﻿References

Abstract

Introduction

Material and methods

Results

Family Parasitidae Oudemans, 1901

Genus Psilogamasus Athias-Henriot, 1969

Psilogamasus brachysaccatus Yao & Jin, sp. nov.

Psilogamasus decemtrichus Ren & Yi, sp. nov.

Psilogamasus bidens Ren & Yi, sp. nov.

Discussion

Psilogamasus truncatus (Tseng, 1995), comb. nov.

Key to adults of Psilogamasus species (updated from Yao et al. (2020))

Acknowledgements

Additional information

References