Psilogamasus bidens 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 bidens Ren & Yi sp. nov.

Figs 9 , 10 , 11

Diagnosis.

Female. Podonotal and opisthonotal shields with 18 and five pairs of setae, respectively; setae j 1 and r 3 slightly pilose; endogynium tongue-shaped with some small teeth on each side of the leading edge; opisthogastric shield bearing six pairs of setae; setae ZV 1 and gland pores gv 2 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. 9 A ). 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 r 6) is off shield. Opisthonotal shield bearing five pairs of setae. Seta J 4 off shield. Setae j 1 and r 3 slightly pilose, j 2, z 1, z 2, r 2, r 4 and r 6 tiny. Lengths of dorsal setae: j 1 50–55, j 2 8–11, j 3 42–46, j 4 48–52, j 5 53–55, j 6 53–58, z 1 13–18, z 2 9–13, z 4 47–50, z 5 67–72, z 6 63–65, s 3 34–38, s 4 53–56, s 5 56–62, s 6 16–20, r 2 13–18, r 3 113–121, r 4 10–13, J 1 66–70, J 2 75–80, J 3 77–82, J 4 45–50, Z 1 65–70, Z 2 61–65.

Venter (Figs 9 B , 10 A ). Tritosternum with two pilose laciniae and a smooth base. Pair of small presternal platelets present. Sternal shield with reticulation, bearing three pairs of setae ( st 1 – st 3), st 1 (42–46) longer than st 2 (34–37) and st 3 (33–37). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st 4 (30–35). Epigynial shield bearing setae st 5 (37–43). Endogynium saccular, tongue-shaped in ventral view, with some small teeth on each side, and anterolaterally with two inner reniform structures (Fig. 10 A ). Setae ZV 1 and gland pores gv 2 absent. Opisthogastric shield reticulate, bearing six pairs of setae ( JV 1 – JV 4, ZV 2 and ZV 3). 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 j 2. Opisthogastric soft cuticle with two pairs of setae. All ventral setae smooth. Lengths of setae on opisthogastric shield: JV 1 37–42, JV 2 40–44, JV 3 44–47, JV 4 47–50, ZV 2 47–51, ZV 3 49–53.

Gnathosoma (Fig. 10 B – E ). Gnathotectum (Fig. 2 B ) 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 h 1 – h 3 smooth, h 1 52–58, h 2 40–43, h 3 57–63 in length; pcx pilose, 70–75 in length (Fig. 10 C ). Movable digit of chelicera with four teeth, fixed digit with five teeth (Fig. 10 D ). Palp trochanter bearing two setae, v 2 pilose; femur with five setae, of which al comblike; genu with six setae, of which al 1 and al 2 spatulate distally, remaining setae smooth. Trochanter, femur and genu of palp as in Fig. 10 E .

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 av 1 and pv 1 on tarsi II – IV spur-like.

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. YN 2024051601 ), 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 ♀ ( YN 2024051602 ), the same data as the holotype . China • 1 ♀ ( YN 2024052901 ), 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 ♀ ( YN 2024051701 ), 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 j 1 and r 3 pilose, vs. simple in the latter; (3) fixed digit of chelicera with four teeth, vs. three in the latter; and (4) setae j 3 about four times longer than j 2 in length, vs. equal in the latter.

Figures

Figure 2. Psilogamasus brachysaccatus Yao & Jin, sp. nov., female. A. Endogynium; B. Gnathotectum; C. Chelicera; D. Subcapitulum; E. Trochanter, femur and genu of palp.

Figure 9. Psilogamasus bidens Ren & Yi, sp. nov., female. A. Dorsum; B. Venter.

Figure 10. Psilogamasus bidens Ren & Yi, sp. nov., female. A. Endogynium; B. Gnathotectum; C. Subcapitulum; D. Chelicera; E. Trochanter, femur and genu of palp.

Figure 11. Psilogamasus bidens Ren & Yi, sp. nov., female. A. Coxa – tibia of leg I; B. Leg II; C. Leg III; D. Leg IV.