Pseudolaelaps schweizeri, Mašán, 2017

Mašán, Peter, 2017, Two new species of the genus Pseudolaelaps Berlese, 1916 (Acari: Mesostigmata: Pseudolaelapidae) from Europe, with an updated key to known species, Journal of Natural History 51 (21 - 22), pp. 1183-1195 : 1187-1193

Pseudolaelaps schweizeri sp. nov.

( Figures 2 and 3 (b))

Pseudolaelaps doderoi – Evans and Till, 1966: 266; Arroyo et al., 2015: 17. New misidentifications.

not Laelaps (Hoplolaelaps) doderoi Berlese, 1910: 259 (= Pseudolaelaps sensu Berlese 1916: 30 ).

Specimens examined

Northwestern Switzerland, Basel City and its surrounding area, coll. P. Mašán: holotype female – Riehen Municipality, Wenkenhof Park, leaf litter and soil, under solitary old beeches ( Fagus sylvatica ) growing on grassy area, altitude 315 m, 1 June 2016; paratypes – four females, Riehen Municipality, Wenken Settlement, old beech forest with limes ( Tilia sp. ) and maples ( Acer sp. ), leaf litter and soil, altitude 380 m, 1 June 2016; one female, Bettingen Municipality, St Chrischona Mountain, broad-leaved deciduous forest, moss and soil, altitude 500 m, 1 June 2016; three females, Birsfelden Municipality, Hard Forest, broad-leaved deciduous forest (mainly Fagus sylvatica , Quercus sp. , Carpinus betulus , Fraxinus sp. , Acer sp. , Ulmus sp. , Tilia sp. ), leaf litter and soil, altitude 285 m, 3 June 2016; one female, Muttenz Municipality, Wartenberg Hill, beech forest, leaf litter and soil, altitude 450 m, 3 June 2016.

Diagnosis

The new species may be distinguished from the other congeners by the combination of the following characters: (1) dorsal shield with 24 pairs of relatively longer and thicker setae; (2) dorsal setae S5 little longer than postanal seta; (3) inner anterior margin of presternal shields markedly crenulate or denticulate; (4) lines of sternal and genitiventral reticulation undulate; (5) ventral setae JV3 shorter than dorsal setae J5; (6) setae JV2 and ZV2 inserted on genitiventral shield; (7) tibia I and genu I each with only two ventral setae, av1 and pv1 (av2 absent); genu II with only one ventral seta, pv1 (av1 absent); genu III with only one ventral seta, av1 (pv1 absent).

Description

Female. Dorsal idiosoma ( Figure 2 (a)). Dorsal shield 405 – 480 µm long and 285 – 330 µm wide, suboval (length/width 1.4 – 1.52), rounded anteriorly, micropunctate and reticulate throughout its surface; reticulate sculpture of the shield weak on anteromedial area but more distinct on posterior area, outlines of polygonal cells undulate. Dorsal shield with 24 pairs of setae; the setae long, slightly thickened, smooth, lanceolate; length of selected setae as follows: j1 18 – 22 µm, j5 30 – 34 µm, J4 46 – 56 µm, J5 40 – 50 µm, S5 18 – 23 µm.

Ventral idiosoma ( Figure 2 (b)). Presternal shields separate but closely contiguous medially, with inner anterior margin conspicuously crenulate or denticulate. Sternal shield quadrate, subequal in length and width (83 – 96 µm long, 84 – 96 µm wide), with reticulate ornamentation on surface; outlines of medial polygonal cells undulate ( Figure 3 (b)). Metasternal platelets subtriangular, relatively middle-sized (20 – 28 µm wide). Genitiventral shield mostly longer than wide (length 180 – 215 µm, width 173 – 203 µm, length/width 1 – 1.15), well widened posteriorly, slightly concave laterally and posteriorly, with rounded posterolateral angles, finely punctate, and with undulate reticulation throughout. Opisthogastric setae JV2 and ZV2 inserted on genitiventral shield. Length of setae JV3 24 – 33 µm. Anal shield subtriangular, 55 – 75 µm long and 83 – 107 µm wide (length/width 0.56 – 0.76); length of postanal seta 14 – 20 µm. Peritrematal shields punctate, with weak undulate sculptural lines; peritremes smooth or with finely crenulate inner margin. Metapodal platelets small and narrow, elongate.

Epistome ( Figure 2 (c)). Tricuspid, with delicately serrate anterolateral margins; cusps with smooth margins, medial cusp slightly longer than lateral cusps or all cusps subequal in length.

Leg chaetotaxy (as in Figure 1 (d)). Tibia I and genu I with 12 setae (2 – 3/1, 3/1 – 2); genu II with 10 setae (2 – 3/0, 2/1 – 2); genu III with eight setae (2 – 2/1, 2/0 – 1).

Male and developmental stages. Unknown.

Etymology

This species is named in honour of Swiss acarologist Josef Schweizer, who did many years of patient work in acarology and made many valuable contributions to the diversity of mites living in Switzerland.

Remarks

The new species may be easily distinguished from other congeners by the characters presented in Table 1, and with the help of the identification key provided below.

In his review of the genus Pseudolaelaps, Mašán (2014) considered the re-description and implied concept of Pseudolaelaps doderoi by Evans and Till (1966), widely followed by other authors ( Bregetova 1977; Karg 1993), to be incorrect and based on misidentified specimens from Great Britain (London and Winchester). The British material was not examined by him so its true identity could not be definitely resolved in that review and remained doubtful.

Now, the identity of the British material of Pseudolaelaps can be elucidated here because I could study some individuals from Ireland, together with several photos taken from the English specimens deposited in the Natural History Museum, London, and redescribed by Evans and Till (1966). Arroyo et al. (2015) referred the name doderoi to the specimens collected in ant hills built by Lasius flavus (Fabricius, 1782) in an Irish grassland. I have examined a slide with three clearly conspecific females reported by Arroyo et al. (2015). These females are in perfect agreement with the primary description given for Pseudolaelaps schweizeri sp. nov. in this paper, and considered to be identical with the types of this species. Also I could find no important morphological differences between photographed specimens and those available from Switzerland and Ireland. Accordingly, I have concluded that both the above-mentioned reports from the British Isles should be considered as misidentifications of P. schweizeri sp. nov.

Key to species of the genus Pseudolaelaps (females)

All known species of Pseudolaelaps are included in the following key, except two that are not sufficiently described, P. doderoi ( Berlese 1910) and Pseudolaelaps paulseni ( Berlese 1910) . Some diagnostic characters of P. doderoi and P. paulseni have been previously described by Mašán (2014).

1. Tibia I and genu I with two ventral setae: av1 and pv1 (with 12 setae: 2 – 6/2 – 2) ....... 2

– Tibia I and genu I with three ventral setae: av1, av2 and pv1 (with 13 setae: 2 – 6/3 – 2) .......................................................................................................................................... 9 2. Genu II with one ventral seta: pv1 (with 10 setae: 2 – 5/1 – 2).......................................... 3

– Genu II with two ventral setae: av1 and pv1 (with 11 setae: 2 – 5/2 – 2) ..................... 6

3. Lines of sternal reticulation straight; dorsal setae S5 shorter than or subequal to postanal seta........................................................................................................................................ 4

– Lines of sternal reticulation undulate; setae S5 apparently longer than postanal seta........................................................................................................................................................... 5

4. Dorsal setae long: setae J3 with tips reaching beyond insertions of following setae J4 (≈ 60 – 65 μm); sternal shield sculpture with sparse spicule-like elements............... ........................................................................................ Pseudolaelaps barbatus Mašán, 2014

– Dorsal setae very short, with their tips markedly distant from insertions of following setae, setae J4 7 – 10 μm long; sternal shield sculpture smooth, lacking spiculelike elements.................................................................... Pseudolaelaps calvescens sp. nov.

5. Inner anterior margin of presternal shields smooth; idiosomal setae JV3 and S5 longer, equal or slightly differing in length (JV3 33 ‒ 37 μm, S5 23 ‒ 30 μm)................. ................................................................................... Pseudolaelaps propinquus Mašán, 2014

– Inner anterior margin of presternal shields distinctly crenulated or denticulate; idiosomal setae JV3 and S5 shorter, apparently differing in length (JV3 24 ‒ 33 μm, S5 18 ‒ 23 μm)................................. ................................. Pseudolaelaps schweizeri sp. nov.

6. Posterior dorsal shield with five pairs of J-setae, J1−J5......................................................... ....................................................................................... Pseudolaelaps mirandus Mašán, 2014

– Posterior dorsal shield with four pairs of J-setae (J2 absent)......................................... 7

7. Ventral setae ZV2 inserted on soft integument........................................................................ ........................................................................................ Pseudolaelaps brevipilis Mašán, 2014

– Setae ZV2 inserted on genitiventral shield............................................................................. 8

8. Lines of sternal reticulation with minute spicule-like elements densely arranged in rows; dorsal setae S5 10 ‒ 16 μm long, shorter than or subequal to postanal seta (15 ‒ 17 μm)...................................................................... Pseudolaelaps scaber Mašán, 2014

– Lines of sternal reticulation with rounded tubercles, lacking spicule-like elements; setae S5 27 ‒ 33 μm long, longer than postanal seta (14 ‒ 19 μm)...................................... ............................................................................................ Pseudolaelaps lepidus Mašán, 2014

9. Genu III with one ventral seta: av1 (with eight setae: 2 – 4/1 – 1) ................................. 10

– Genu III with two ventral setae: av1 and pv1 (with nine setae: 2 – 4/2 – 1) .............. 15

10. Anterior dorsal shield with five pairs of j-setae (j1, j3−j6 present; j2 absent) and four pairs of r-setae (r3 ‒ r6); sternal shield smooth, lacking specific sculptural pattern.... ........................................................................................ Pseudolaelaps rotundus Mašán, 2014

– Anterior dorsal shield with six pairs of j-setae (j1−j6) and two pairs of r-setae (r3, r6 present; r4, r5 absent); sternal shield with reticulate pattern...................................... 11

11. Lines of sternal reticulation undulate; presternal shields separate; exopodal platelets III – IV free ..................................................................................................................................... 12

– Lines of sternal reticulation straight; presternal shields medially fused; exopodal platelets III – IV fused to exopodals II – III.................................................................................. 13

12. Metasternal platelets expanded laterally (22 ‒ 30 μm in width), with adjacent medial margins............................. ............................. Pseudolaelaps gamaselloides Berlese, 1920

– Metasternal platelets small (12 ‒ 16 μm in width), with well-separated medial margins........................................... ........................................... Pseudolaelaps jozefi Mašán, 2014

13. Lines of genitiventral reticulation undulate; dorsal shield with distinct reticulation throughout........ Pseudolaelaps venustulus Mašán, Hajizadeh and Ramroodi, 2014

– Lines of genitiventral reticulation straight; dorsal shield without reticulation, or weakly and unevenly reticulated .............................................................................................. 14

14. Polygonal cells of sternal reticulation with straight lines and anterior corners usually obtuse; idiosomal setae shorter: J4 23 ‒ 28 μm, J5 24 ‒ 29 μm, S5 21 ‒ 25 μm; sternal shield subequal in length and width (length 83 ‒ 90 μm, width 84 ‒ 91 μm)........................ ................................ Pseudolaelaps laevidorsatus Mašán, Hajizadeh and Ramroodi, 2014

– Polygonal cells of sternal reticulation with some lines concave and anterior corners acuminate; idiosomal setae longer: J4 29 ‒ 33 μm, J5 29 ‒ 34 μm, S5 24 ‒ 28 μm; sternal shield slightly oblong (length 90 ‒ 95 μm, width 80 ‒ 84 μm)................................ ........................ Pseudolaelaps semiduplicans Mašán, Hajizadeh and Ramroodi, 2014

15. Setae JV2 and ZV2 inserted on genitiventral shield................................................................ ........................................................................................... Pseudolaelaps stellifer Mašán, 2014

– Setae JV2 and ZV2 inserted on soft integument............................................................... 16

16. Lines of sternal reticulation undulate.......... .......... Pseudolaelaps pallidus Mašán, 2014

– Lines of sternal reticulation straight...................... Pseudolaelaps regularis Mašán, 2014

Acknowledgments

I am deeply grateful to Marco Valle, Paolo Pantini and staff of Institute of Zoology, the Natural History Museum (Museo Civico di Scienze Naturali “ Enrico Caffi ”) in Bergamo, Italy for kind hospitality, all-round assistance during field trip and providing laboratory space, equipment and help while in Bergamo. I express my sincere appreciation to Thomas Bolger (School of Biology and Environmental Science, University College Dublin, Ireland) for providing me with his Pseudolaelaps specimens from Ireland. My sincere thanks also go to Matthew Shaw (Canterbury Museum, Christchurch, New Zealand) who kindly helped me by providing detailed photographs of Pseudolaelaps specimens, from a depository at the Natural History Museum, London.

Funding

This study was supported by the Scientific Grant Agency of the Ministry of Education of Slovak Republic and the Academy of Sciences [VEGA Grant No. 2/0091/14: Arboricolous mites (Acari: Mesostigmata ) associated with wood-destroying insects and fungi, with consideration on taxonomy, ecology and chorology of individual species.].

Figures

Figure 1. Pseudolaelaps calvescens sp. nov., female. (a) Dorsal idiosoma; (b) ventral idiosoma; (c) epistome, variant forms; (d) diagrammatic representation of chaetotaxy of selected leg segments (tibia I, genua I−III).

Figure 2. Pseudolaelaps schweizeri sp. nov., female, with setal notation of some idiosomal setae. (a) Dorsal idiosoma; (b) ventral idiosoma; (c) epistome.

Figure 3. Pseudolaelaps spp., sternal shields of females. (a) Pseudolaelaps calvescens sp. nov.; (b) Pseudolaelaps schweizeri sp. nov.