Ameroseius plumigera ( Oudemans, 1930 )

Narita, João Paulo Z., Bernardi, Leopoldo F. O., Ferreira, Rodrigo L. & de Moraes, Gilberto J., 2013, A new species of Ameroseius Berlese from Brazil, redescriptions of Ameroseius plumosus (Oudemans) and Ameroseius plumigera (Oudemans) (Acari: Mesostigmata: Ameroseiidae) based on the examination of type material, Journal of Natural History 47 (35 - 36), pp. 2311-2326 : 2321-2325

Ameroseius plumigera ( Oudemans, 1930)

Kleemannia plumigera Oudemans, 1930: 140 .

Primoseius gracei Hughes, 1948: 149 , synonymy by Hughes (1961): 244.

( Figure 4 )

Diagnosis of adult

Dorsal shield with 29 pairs (seta z6 present) of setae, all leaf-shaped and serrate. Most dorsal setae reaching the base of the subsequent seta. Setae J2 and J4 long, 100 and 123 long, respectively. Sternal shield longer than wide. Seta st3 on a platelet, opisthogaster with six pairs of setae, two of which on the ventrianal shield. Nothing can be said about leg chaetotaxy from the examination of the holotype, because the legs are broken.

Adult female ( Figure 4 A–D)

Gnathosoma . Fixed cheliceral digit 29 long, apparently with four relatively large teeth near the base of the digit and apparently one tiny tooth near the apex; movable cheliceral digit 25 long, teeth not discernible. Antiaxial and dorsal lyrifissures not distinct. Epistome, palp apotele, deutosternum and corniculi not distinct, because the gnathosoma is damaged.

Dorsal idiosoma ( Figure 4 A–C). Dorsal shield entire, totally reticulate; reticula formed by simple lines; 450 long and 295 wide at level of s6; apparently with two pairs of pores (posteromediad of r4, posterolaterad of S3) and seven pairs of lyrifissures (anterolaterad of j3, posteromediad of r4, laterad of j6, posteromediad of s6, posteromediad of S3, laterad of j4, posteromediad of S4). Lengths of dorsal setae: j1 29; j2 41; j3 55; j4 50; j5 broken; j6 broken; J2 100; J4 123; z2 45; z4 53; z5 53; z6 broken; Z1 65; Z2 broken; Z4 95; Z5 broken; s1 49; s2 60; s4 broken; s5 63; s6 55; S2 70; S3 70; S4 75; S5 broken; r2 50; r3 50; r4 65; r5 55. Distance between the bases of setae J4 about 0.8 times as long as distance between J4 and Z4 of each side. All setae leaf-shaped and serrate, j1 wider distally than other setae.

Ventral idiosoma ( Figure 4D ). Base of tritosternum 13 long and 9 wide, total length was not possible to measure, because this structure is damaged. Sternal shield reticulate; 90 long at midline and 69 wide at widest level, bearing setae st1 and st2. Seta st3 on a platelet and seta st4 on unsclerotized cuticle. Genital shield reticulate, bearing st5, 108 wide at widest level, sided posteriorly by a pair of lyrifissures. Ventrianal shield reticulate, with reticula much wider than long anterior to the anal opening and roughly longer than wide or as long as wide posteriorly, 130 long at the midline and 180 wide at the widest level, bearing Jv2 and Jv3, with a pair of lyrifissures posteromediad of Jv5. Unsclerotized cuticle of opisthogaster with setae Jv1, Jv5, Zv1 and Zv2, two pairs of lyrifissures (anteromediad of Zv2, anterolaterad of Jv5) and a pair of elongate metapodal platelets sided posteriorly by other two pairs of lyrifissures. Lengths of ventral setae: st1 14; st2 broken; st3 8; st4 6; st5 25; Jv1 10; Jv2 10; Jv3 10; Jv5 broken; Zv1 10; Zv2 17. Unbroken ventral setae setiform and smooth. Endopodal shield fused to sternal shield except for a triangular remnant platelet between coxae II and III. Exopodal shield distinguishable as a narrow band with projections between coxae II and III and coxae III and IV.

Peritreme and peritremal shield. Peritreme reaching level of j2. Peritremal shield fused to exopodal shield behind stigma; with a large pore at level between coxae II and III (gd3 of Athias-Henriot 1975; gp2 of Lindquist and Moraza 2009).

Legs. Broken in the examined specimen.

Material examined

Holotype female collected from seagrass, in Helder , the Netherlands, by Dr Redeke misit [sic; sent by Dr Redeke], September 1910, deposited at The Netherlands Centre for Biodiversity Naturalis, Leiden, the Netherlands ( RMNH Acari P 4301).

Remarks

In the original description of A. plumigera, Oudemans (1930) reported the corniculus to be three-tined, and the dorsal shield to bear 30 pairs of setae. The number of tines of the corniculus could not be determined in our examination of the holotype, because the gnathosoma is damaged; however, the number of dorsal shield setae is clearly 29 pairs rather than 30. Specimens from Germany redescribed by Rack (1963) also had 29 pairs of dorsal shield setae; the author made no reference to the number of tines of the corniculus. Hughes (1961) redescribed A. plumigera based on specimens from the UK, reporting the corniculus to be two-tined and the dorsal shield to bear 28 pairs of setae (apparently missing one S seta). In the same publication, she synonymized Zercoseius gracei Hughes, 1948 under A. plumigera . Hughes (1976) showed the same illustrations as in her publication of 1961, but mentioned in the text the presence of 29 pairs of setae on the dorsal shield. A re-examination of the specimens studied by Hughes would be necessary to confirm the identity of the specimens that she identified as A. plumigera and to confirm whether Z. gracei is really a synonym of A. plumigera .

Key to species of the “ plumosus ” group based on adult females

In addition to the similarity of the new species to A. plumosus , A. potchefstroomensis and A. eumorphus mentioned previously, the new species here described is also similar to four other species that have corniculus bifurcate or trifurcate; dorsal shield reticulate and without pit-like depressions; 26 or 28 pairs of dorsal shield setae, most of which are lanceolate to leaf-shaped; and five or six pairs of opisthogastric setae, two pairs of which are on ventrianal shield. All of these species are here referred to as the plumosus species group.

The following key is provided to help their separation. It was constructed taking into account our examination of the holotypes previously mentioned in this paper and the original descriptions of the other species. Ameroseius lanceosetis Livshitz and Mitrofanov (1975) was not included in the key because of the controversial information concerning the number of dorsal shield setae in this species; while 28 pairs are shown in the illustration, 29 pairs are mentioned in the text. It is assumed that a pair of setae is missing in the illustration.

Key to separate the species of the plumosus species group

1. Dorsal shield setae with 26 pairs of setae; except for j1, dorsal shield setae as well as Jv5 leaf-shaped and smooth; genital shield with an anteromedian horseshoe-shaped structure; with five pairs of opisthogastric setae............................................. A. dipankari Bhattacharyya, 2004 , India Dorsal shield with 28 pairs of setae; dorsal shield setae as well as Jv5 ranging from lanceolate to leaf-shaped, smooth or serrate; genital shield with or without an anteromedian horseshoe-shaped structure; with five or six pairs of opisthogastric setae..................................................... 2

2. Dorsal shield setae smooth; with five pairs of opisthogastric setae (Jv1, Jv2, Jv3, Jv5 and Zv1)....................................................... 3 Dorsal shield setae very lightly serrate to distinctly serrate; with six pairs of opisthogastric setae (Jv1, Jv2, Jv3, Jv5, Zv1 and Zv2)..................... 4

3. Seta z6 present and s6 absent; j1 with about triangular contour; metapodal shield subtriangular... A. reticulatus ( Kruger and Loots, 1980) , South Africa

Seta z6 absent and s6 present; j1 feather-shaped; metapodal shield bacilliform........................ A. wahabi ( Ibrahim and Abdel-Samed, 1992) , Egypt

4. Genital shield with an anteromedian horseshoe-shaped structure................................... A. parplumosus ( Nasr and Abou-Awad, 1987) , Egypt Genital shield without anteromedial horseshoe-shaped structure.......... 5

5. Seta Jv5 at least eight times as long as wide and about as long as distance between its base and that of of postanal seta............................. 6 Seta Jv5 at most five times as long as wide and at most 0.7 as long as distance between its base and the base of postanal seta............................ 7

6. Sternal shield centrally smooth....... A. eumorphus Bregetova, 1977 , Russia Sternal shield scantly reticulate.......................................................... A. potchefstroomensis ( Kruger and Loots, 1980) , South Africa

7. Distance between the bases of setae J4 about 0.7 times as long as distance between J4 and Z4 of each side; among j-J series, j1 and j3 reaching the base of subsequent seta; sternal shield with an inverted “U” shaped anteromedial structure..................... A. plumosus ( Oudemans, 1902b) , Netherlands Distance between the bases of setae J4 about 1.3 times as long as distance between J4 and Z4 of each side; among j-J series, j1, j2, j3 and j4 reaching the base of subsequent seta; sternal shield scantly reticulate........................................ A. mineiro Narita, Bernardi and Moraes sp. nov., Brazil

Figures

Figure 4. Ameroseius plumigera (Oudemans) female. (A) Dorsal view of idiosoma; (B) detail of seta j1; (C) detail of seta j4; (D) ventral view of idiosoma.