Psilogamasus brachysaccatus Yao & Jin, 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

publication ID	https://doi.org/10.3897/zookeys.1259.171008
publication LSID	lsid:zoobank.org:pub:7CDB90F7-C0F7-4A30-A96A-C0C327598026
DOI	https://doi.org/10.5281/zenodo.17594033
persistent identifier	https://treatment.plazi.org/id/049A404C-F402-591C-BC0B-DFBACCB15EAC
treatment provided by	ZooKeys by Pensoft
scientific name	Psilogamasus brachysaccatus Yao & Jin
status	sp. nov.

Treatment

Psilogamasus brachysaccatus Yao & Jin sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Diagnosis.

Female. Podonotal and opisthonotal shields with 18 and five pairs of setae, respectively; setae j 1 slightly pilose, r 3 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 ZV 1 and gland pores gv 2 absent; Peritrematal groove extending anteriorly to beyond coxa II; movable digit of chelicera with four teeth.

Male. Seta j 1 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. 5 E View Figure 5 ). Other characteristics as in female.

Description.

Female ( N = 4). Idiosoma weakly sclerotized, length 672–710, width 481–498.

Dorsum (Fig. 1 A View Figure 1 ). 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 r 6) off shield. Opisthonotal region bearing seven pairs of setae, of which J 1 – J 3 and Z 1, Z 2 on opisthonotal shield, J 4 and J 5 off shield. Seta j 1 stout and slightly pilose, other dorsal setae smooth. Seta r 3 longer than others, setae j 2, j 3, z 1, z 2, s 3, s 6, r 2, r 4, r 6 and J 4 tiny and short. Lengths of dorsal setae: j 1 74–78, j 2 15–17, j 3 32–35, j 4 66–70, j 5 58–62, j 6 58–61, z 1 26–28, z 2 16–18, 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 6 15–17, J 1 79–82, J 2 78–82, J 3 80–84, J 4 16–17, J 5 92–95, Z 1 57–61, Z 2 65–69.

Venter (Figs 1 B View Figure 1 , 2 A View Figure 2 ). Tritosternum with two pilose laciniae (111–120) and a smooth base (42–45). Presternal platelets absent. Sternal shield reticulated, bearing three pairs of setae ( st 1 – st 3), st 1 (48–52) longer than st 2 (38–41) and st 3 (42–43). Metasternal shields separated from sternal shield by medially arched groove, bearing setae st 4 (39–42). Epigynial shield bearing setae st 5 (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. 2 A View Figure 2 ). 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 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 j 2. 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 47–49, JV 4 47–50, ZV 2 32–34, ZV 3 42–43.

Gnathosoma (Fig. 2 B – E View Figure 2 ). Gnathotectum (Fig. 2 B View Figure 2 ) 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. 2 C View Figure 2 ). Corniculus length 27–34, short and horn-shaped; deutosternal groove with 11 denticulate rows. Setae h 1 – h 3 smooth, h 1 46–50, h 2 40–43, h 3 47–50 in length; pcx pilose, 48–52 in length (Fig. 2 D View Figure 2 ). Palp length 228–239; trochanter with two pilose setae, v 1 stouter than v 2; 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 smooth. Trochanter, femur and genu of palp as in Fig. 2 E View Figure 2 .

Legs (Fig. 3 View Figure 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 av 1 and pv 1 on tarsi II – IV spur-like. Seta pd 2 (282–301) on tarsus IV longer than all other leg setae.

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

Dorsum (Fig. 4 A View Figure 4 ). Reticulate holodorsal shield covering entire dorsum, with a suture closely anterior to setae J 1, 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 j 1 slightly pilose, other dorsal setae smooth. Setae j 2, j 3, z 1, z 2, s 3, s 6, r 2, r 4, r 6 finer than others. Lengths of dorsal setae: j 1 47–50, j 2 17–19, j 3 27–30, j 4 40–44, j 5 35–38, j 6 35–39, z 1 19–21, z 2 16–19, z 4 29–33, z 5 50–55, z 6 36–40, s 3 24–26, s 4 31–33, s 5 35–39, s 6 21–23, r 2 18–20, r 3 128–132, r 4 14–15, r 6 14–15, J 1 48–53, J 2 55–58, J 3 63–67, J 4 74–76, Z 1 47–48, Z 2 51–53, Z 3 37–40.

Venter (Fig. 4 B View Figure 4 ). 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 ( st 1 – st 5). 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: st 1 35–37, st 2 32–34, st 3 26–28, st 4 26–28, st 5 30–32, as well as on opisthogastric one: JV 1 30–32, JV 2 36–39, JV 3 38–40, JV 4 47–50, JV 5 48–50, ZV 2 32–34, ZV 3 42–43.

Gnathosoma (Fig. 5 View Figure 5 ). Gnathotectum (Fig. 5 A View Figure 5 ) 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. 5 B View Figure 5 ). Palp 189–205 in length, as in female, trochanter, femur and genu as shown in Fig. 5 C View Figure 5 . Subcapitulum (Fig. 5 D View Figure 5 ) with setae pcx (30–31) pilose, h 1 (36–38), h 2 (32–35) and h 3 (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. 5 E View Figure 5 ). 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. XZ 2019071901 ), 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 GoogleMaps , Paratypes. China • 3 ♀ and 3 ♂ ( XZ 2019071902 – XZ 2019071902 ), the same data as the holotype GoogleMaps .

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 j 1. However, the female P. brachysaccatus Yao & Jin , sp. nov. is different from P. bidens Ren & Yi , sp. nov. as follows: (1) dorsal seta r 3 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 v 1 on palp trochanter pilose, vs. simple in the latter.