Psilogamasus Athias-Henriot, 1969

Yao, Mao-Yuan, Yi, Tian-Ci, Jin, Dao-Chao & Orginal, Jian-Jun Guo, 2020, A new species of Psilogamasus Athias-Henriot, 1969 from China and redefinition of the genus (Parasitiformes: Parasitidae), Acarologia 60 (4), pp. 831-841 : 832-834

Genus Psilogamasus Athias-Henriot, 1969

Type species: Psilogamasus hurlbutti Athias­Henriot, 1969

Diagnosis

Both sexes. Dorsal idiosoma with less than 30 pairs of setae, of which seven or eight pairs of podonotal setae very short; setae z5 of dorsal hexagon similar to j5 and j 6 in form (smooth),

while different in length z5 (longer); presternal platelets absent; tritosternum biramous;

opisthogaster bearing five to six pairs of setae; setae ZV1 and gland pores gv2 absent; seta al of palp femur comblike, al1 and al2 of palp genu entire and spatulate distally; corniculi small;

epistome trispinate, central prong apically with two to five branches or multidentate, lateral prongs spiculate with bifid apex or two to four apical branches.

Female with separated podonotal shield that with 16–18 pairs of setae, and opisthonotal shield that with five to six pairs of setae; 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 av1 and av2 on femur II, av1 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; two ventral setae on femur II modified into spurs fused at base;

one ventral seta on genu II and tibia II each modified into spur.

Remarks

In Hrúzová & Fenďa (2018), the genera Psilogamasus and Taiwanoparasitus were separated by the number of setae on the opisthonotal shield (six and five pairs, respectively) and the presence of trichocystic seta pd2 on telotarsus IV (present and absent, respectively). However,

they also discussed the lack of data on the latter character, leaving the number of opisthosomal shield setae as the critical feature for defining the genera.

In regards to the number of opisthosomal shield setae, we explored the constituent species of both genera and found no other character states that were linked with this feature ( Table 1). Therefore, we concluded this was best considered an intrageneric feature, as suspected by Hrúzová & Fenďa (2018). Therefore, we consider Taiwanoparasitus a junior synonym of Psilogamasus .

The above action of synonymizing Taiwanoparasitus under Psilogamasus leads to several new combinations, i.e., T. brachysternalis , T. longascidiformis and T. pentasetosus are now included in the genus Psilogamasus .

Psilogamasus brachysternalis ( Ma & Lin, 2005) n. comb.

Original designation and recent revision: Vulgarogamasus brachysternalis Ma & Lin, 2005 :

p. 73–74; Taiwanoparasitus brachysternalis (Ma & Lin) Hrúzová & Fenďa, 2018: p. 39

Psilogamasus longascidiformis ( Ma & Lin, 2005) n. comb.

Original designation and recent revision: Vulgarogamasus longascidiformis Ma & Lin,

2005: p. 74–75; Taiwanoparasitus longascidiformis (Ma & Lin) Hrúzová & Fenďa, 2018 :

p. 39.

Psilogamasus pentasetosus ( Tseng, 1995) n. comb.

Original designation: Taiwanoparasitus pentasetosus Tseng, 1995: p. 34 –35

Based on the previous records of Athias­Henriot (1969), Tseng (1995), Ma & Lin (2005),

Bai & Ma (2013), and newly found collections in this study, the geographical distribution of Psilogamasus is limited to Tanzania and China, with the possible adventive presence P of. hurlbutti in North America (Hennesey & Farrier 1989).

We conclude that the species Vulgarogamasus lingulatus Bai & Ma, 2013 may also be moved into the genus Psilogamasus .

Psilogamasus lingulatus ( Bai & Ma, 2013) n. comb.

Original designation: Vulgarogamasus lingulatus Bai & Ma, 2013: p. 71 –73

The genus Vulgarogamasus , established by Tichomirov (1969), markedly differs from Psilogamasus by having setae z5 of the dorsal hexagon very similar to j5 and j 6 in length, and both podonotal and opisthonotal shields with more than 20 pairs of setae. The female V. of lingulatus differs from the other species of Vulgarogamasus by the following characteristics:

z5 longer than j5 and j6, opisthonotal shield with only 6 pairs of setae, peritrematal shield free posteriorly and central prong of epistome multidentate distally and lateral ones spiculate or bifid apically. The features of female V. lingulatus conform with Psilogamasus : peritrematal shield anteriorly fused to podonotal shield, posteriorly free; 16–18 pairs of acicular setae on the podonotal shield, of which 8 pairs are tiny; six pairs of acicular setae on opisthonotal shield;

opisthogaster bearing 5 pairs of setae, setae ZV1 and gland pores gv2 absent; central prong of epistome multidentate distally and lateral ones spiculate or bifid apically; endogynial sac large.

The description of P. pentatideus n. sp. and the additions of P. brachysternalis n. comb.,

P. longascidiformis n. comb. and P. lingulatus n. comb., P. pentasetosus n. comb. permit a revision of the genus diagnosis. Within this genus, the number of setae on the idiosomal shields,

dental numbers of cheliceral digits, and the length of the peritrematal groove are variable (Table

1).

However, we add further character states to define the female Psilogamasus of. On the venter, setae ZV1 is absent (erroneously named ZV1 by Tseng (1995) was ZV2) and peritrematal shield free posteriorly; on the dorsum the total number of dorsal setae is less than 30 pairs, and of which z5, j5, j6 are smooth; and setae av1 and av2 on femur II, av1 on genu II and tibia II are acicular.

The diagnostic definition of Psilogamasus male, with the most conspicuous features, can also now be proposed as: the holodorsal shield bears less than 30 pair of setae; the movable digit of the chelicera has five or six teeth, which is rare in Parasitidae ; setae av1 and av2 on femur II, av1 on genu II and tibia II are spur­like.