Psilogamasus decemtrichus Ren & Yi, 2025

Yao, Mao-Yuan, Chen, Jian-Xin, Wu, You-Fang, Ren, Rong, Yi, Tian-Ci & Jin, Dao-Chao, 2025, Three new species of Psilogamasus Athias-Henriot, 1969 (Acari, Parasitiformes, Parasitidae) from Southwest China, ZooKeys 1259, pp. 405-421 : 405-421

Psilogamasus decemtrichus Ren & Yi sp. nov.

Figs 6 , 7 , 8

Diagnosis.

Female. Podonotal and opisthonotal shields with 18 and ten pairs of setae, respectively; setae j 1 and r 3 simple; endogynium tongue-shaped with some small teeth on each side of the leading edge; setae ZV 1 and gland pores gv 2 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. 6 A ). Podonotal and opisthonotal shields separated and with rough reticulation. Podonotal region with 19 pairs of setae, of which 18 pairs on podonotal shield (seta r 5 on podonotal shield) and two pairs (setae r 4 and r 6) off shield. Opisthonotal shield bearing ten pairs of setae. All dorsal setae smooth, setae z 1, s 6, r 2, r 4, r 5 and r 6 tiny. Lengths of dorsal setae: j 1 28–30, j 2 35–38, j 3 47–49, j 4 39–41, j 5 47–49, j 6 40–42, z 1 7–8, z 2 27–28, z 4 47–50, z 5 90–95, z 6 57–62, s 3 31–34, s 4 58–61, s 5 60–62, s 6 15–17, r 2 15–17, r 3 159–165, r 4 15–17, r 5 16–17, r 6 17–18, J 1 50–54, J 2 56–57, J 3 63–65, J 4 55–59, Z 1 50–56, Z 2 62–65, Z 3 58–59, S 1 48–52, S 2 48–50, S 3 58–60.

Venter (Figs 6 B , 7 A ). 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 ( st 1 – st 3), st 1 (66–72) longer than st 2 (58–64) and st 3 (46–50). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st 4 (45–52). Epigynial shield bearing setae st 5 (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. 7 A ). Setae ZV 1 and gland pores gv 2 present. Opisthogastric shield reticulate, bearing six pairs of setae ( JV 1 – JV 4, ZV 1 and ZV 2). 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: JV 1 42–45, JV 2 46–49, JV 3 52–56, JV 4 47–48, ZV 1 12–15, ZV 2 45–48.

Gnathosoma (Fig. 7 B – E ). Movable digit of chelicera with three teeth, fixed digit with five teeth (Fig. 7 B ). Corniculus length 23–28, short and horn-shaped; deutosternal groove with ten denticulate rows. Setae h 1 – h 3 smooth, h 1 25–5026, h 2 21–23, h 3 22–25 in length; pcx slightly pilose, 32–36 in length (Fig. 7 C ). Gnathotectum (Fig. 7 D ) with three prongs, central one bifid apically and lateral ones acuminate distally, emerging from nude base. Palp length 224–232; trochanter with two setae, v 2 slightly pilose; femur with five setae, of which al comblike, d 3 pilose; genu with six setae, of which al 1 and al 2 spatulate distally, remaining setae simple. Trochanter, femur and genu of palp as in Fig. 7 E .

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 av 1 and pv 1 on tarsi II – IV spur-like. Setae pd 2 on tarsus IV, length 95–107, longer than all other setae.

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. YN 2022070601 ), Yunnan Province, Pu’er City, Jingdong Yi Autonomous County, Taizhong Town ; 29°54'33"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 ♀ ( YN 2022070602 – YN 2022070605 ), 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 r 5, ZV 1 and gland pores gv 2.

Figures

Figure 6. Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Dorsum; B. Venter.

Figure 7. Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Endogynium; B. Chelicera; C. Subcapitulum; D. Gnathotectum; E. Trochanter, femur and genu of palp.

Figure 8. Psilogamasus decemtrichus Ren & Yi, sp. nov., female. A. Coxa – tibia of leg I; B. Leg II; C. Leg III; D. Leg IV.