Epibiotic mites associated with the invasive Chinese mitten crab Eriocheir sinensis – new records of Halacaridae from Poland **This research was supported by grant No. N304 082 31/3219 from the Polish Ministry of Education and Science.

AbstractSeven epibiotic halacarid mites (Caspihalacarus hyrcanus, two species of Copidognathus, Halacarellus petiti, Porohalacarus alpinus, Soldanellonyx monardi and S. chappuisi), two oribatid mites (Hydrozetes lacustris and Trhypochthoniellus longisetus) and one water mite (Piona pusilla) were found on the setae-covered claws of eighteen Chinese mitten crabs (Eriocheir sinensis) collected from fresh and brackish waters in Poland and Germany. The most abundant of the 111 mite individuals recorded was one of the Copidognathus species (N=52); this was followed by H. petiti (N=38) and C. hyrcanus (N=13). This is the first record of H. petiti and of the genus Copidognathus from Polish waters. The possibility of migrating over long distances assisted by catadromous mitten crabs enhances mite dispersal, as well as their introduction to new environments

Zelotes erebeus (Thorell, 1871) (Araneae: Gnaphosidae) in Poland and its distribution in Europe

Zelotes erebeus (Thorell, 1871) is a thermophilic species occurring in southern, western and central Europe. It was excluded from the checklist of Polish spiders because of synonymization issues. This paper corrects the published data and lists new localities in western and central Poland. The sites of Z. erebeus discovered near Swinoujscie, Czarnków and Torun, move northwards the northern range limit of this thermophilous species in Europe. Data on the distribution of this species in eastern Europe and the Caucasus are also corrected - these records relate to the closely related species Z. khostensis Kovblyuk & Ponomarev, 2008. Figures of female and male genitalia of Z. erebeus are presented

Inclusion of juvenile stages improves diversity assessment and adds to our understanding of mite ecology – A case study from mires in Norway

Arachnid orders, Mesostigmata, Trombidiformes, and Sarcoptiformes, commonly known as ‘mites’, are abundant in mires, both as adults and as juveniles. However, due to the challenges of identification, the juvenile forms are often excluded from analyses. This is the first study in mires that included all three mite orders identified to the species level, including juvenile instars. We aimed to compare how diversity and the response to ecological variables differed if only the adults (ad) vs. the total number of specimens (ad+juv) are considered. Samples of 20 Sphagnum species (five subgenera) were collected and mites were extracted using Berlese funnels. Overall, nearly 60,000 mites were analyzed; of these Mesostigmata made up 1.87% of the total, Trombidiformes −0.27%, and Sarcoptiformes −97.86%. The study revealed 154 species (33 Mesostigmata, 24 Trombidiformes, and 97 Sarcoptiformes), the highest diversity of mites ever reported from mires. The inclusion of juveniles increased observed species richness by 6%, with 10 species (one Mesostigmata, six Trombidiformes, and three Sarcoptiformes) represented only by juvenile forms. Seventeen species are new to Norway (four Mesostigmata, one Sarcoptiformes, and 12 Trombidiformes, including five undescribed species of Stigmaeidae and Cunaxidae). Four of these were represented in the samples only by juveniles. Including the juveniles explained a greater amount of the variability of Trombidiformes (explanatory variables account for 23.60% for ad, and 73.74% for ad+juv) and Mesostigmata (29.23% − ad, 52.91% − ad+juv), but had less of an impact for Sarcoptiformes (38.48% − ad, 39.26% − ad+juv). Locality, Sphagnum subgenus and species, wetness, and trophic state significantly affected the mite communities and should be taken into consideration when studying mires. Since juvenile stages contribute significantly to mite diversity in mires, they should also be included in mite studies in other habitats.publishedVersio

The influence of the landscape structure within buffer zones, catchment land use and instream environmental variables on mollusc communities in a medium-sized lowland river

The world’s freshwater molluscan fauna is facing unprecedented threats from habitat loss and degradation. Declines in native populations are mostly attributed to the human impact, which results in reduced water quality. The objectives of our survey were to analyse the structure of the mollusc communities in a medium-sized lowland river and to determine the most important environmental variables at different spatial scales, including landscape structure, catchment land use and instream environmental factors that influence their structure. Our survey showed that a medium-sized river, that flows through areas included in the European Ecological Natura 2000 Network Programme of protected sites, provides diverse instream habitats and niches that support 47 mollusc species including Unio crassus, a bivalve of Community interest, whose conservation requires the designation of a special conservation area under the Habitats Directive Natura 2000. This survey showed that mollusc communities are impacted by several environmental variables that act together at multiple scales. The landscape structure within buffer zones, catchment land use and instream environmental variables were all important and influenced the structure of mollusc communities. Therefore, they should all be taken into consideration in the future restoration of the river, future management projects and programmes for the conservation of biodiversity in running waters. The results of this study may be directly applicable for the rehabilitation of river ecosystems and are recommended to stakeholders in their future decision concerning landscape planning, monitoring species and their habitats, conservation plans and management in accordance with the requirements of sustainable development

Arrenurus inexploratus Viets 1930

Arrenurus inexploratus Viets, 1930 (Fig. 45) Material examined: 10 larvae deriving from 10 females. Larvae large: idiosoma 234–254 µm long. Dorsum: Dp large (DpL: 216–242 µm; DpW: 186–200 µm), egg-shaped, widest at mid-length. Antero-lateral indents slightly obtuse-angled, very small (about 1/6 of plate's length). DpW/Mp1-Mp1 5.3. Lp2, Mh1 smooth. Mp1-Mp1 short (35–38 µm), much shorter than Mp2-Mp2 (50–58 µm); Mp1-Lp2 intermediate (34– 41 µm). Venter: Median margins of CpI, CpII, CpIII 71–76, 34–38, 50– 54 µm long, respectively, their ratio 2:1:1.5. C2, V 3 bipectinate; C1, C3, C4 pectinate. C1-CpIm (19–22 µm) about 2/3 of C4-CpIIIm (26–32 µm). C1-C2 intermediate (42–46 µm). Expp rhomboid, somewhat wider than long. Exp located below plate's midpoint and below E2. Palps: PIII 1 bipectinate. PV3 pectinate, PV6 thick. Chelicerae: First segment elongated (82–90 µm), narrowing anteriorly, margins parallel, distal part slightly curved. Legs: Shorter than body; LI= LII <LIII Fig. 6). ITi8 smooth, short, thick; IIGe2, IIGe4, IIIGe4, IIITi6 bipectinate.Published as part of Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, pp. 1-75 in Zootaxa 1765 (1) on page 62, DOI: 10.11646/zootaxa.1765.1.1, http://zenodo.org/record/512375

Arrenurus conicus Piersig 1894

&lt;i&gt;Arrenurus conicus&lt;/i&gt; Piersig, 1894 &lt;p&gt;(Fig. 35)&lt;/p&gt; &lt;p&gt; &lt;b&gt;Material examined:&lt;/b&gt; 10 larvae deriving from 10 females.&lt;/p&gt; &lt;p&gt;Larvae medium-sized: idiosoma 190&ndash;212 &micro;m long.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Dorsum&lt;/i&gt;: Dp relatively small (DpL: 170&ndash;194 &micro;m; DpW: 146&ndash;170 &micro;m), egg-shaped, widest at about 1/3 distance from anterior margin; distinctly narrowing posteriorly; posterior margin rounded. Antero-lateral indents relatively shallow, obtuse-angled, about 1/5 and 1/4 of Dp length and width, respectively. Microrelief cells elongated. DpW/Mp1-Mp1 5.0. Lp2, Mh1 smooth. Mp1-Mp1 short (30&ndash;34 &micro;m), shorter than Mp2-Mp2 (38&ndash;46 &micro;m); Mp1-Lp2 intermediate (38&ndash;42 &micro;m). &lt;i&gt;Venter&lt;/i&gt;: CpIm (68&ndash;72 &micro;m) clearly longest, CpIIm shortest (22&ndash;28 &micro;m) and CpIIIm intermediate (40&ndash;46 &micro;m). CpIm:CpIIm:Cpm ratio 2.8:1:1.7. Setae on Cp smooth, relatively thick and long. C1-CpIm (21&ndash;26 &micro;m) identical to or somewhat longer than C4-CpIIIm (21&ndash;22 &micro;m). C1-C2 moderately long (40&ndash;45 &micro;m). Expp triangular, margins convex, width almost equal to length. Exp located distinctly below plate&rsquo;s mid-point and slightly below E2. &lt;i&gt;Palps&lt;/i&gt;: PIII 1 bipectinate. &lt;i&gt;Chelicerae&lt;/i&gt;: First segment cylindrical (73&ndash;77 &micro;m), narrowing anteriorly, one margin straight or somewhat concave, other slightly convex. &lt;i&gt;Legs&lt;/i&gt;: Somewhat shorter than body; LI&lt;LII &lt;LIII (Fig. 3). ITi7 thick; ITi8 long; IITi8 long, smooth, thin; IITi10, IIITi10 located at centre of tibia; IIITa3 located near centre of tarsus.&lt;/p&gt;Published as part of &lt;i&gt;Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, pp. 1-75 in Zootaxa 1765 (1)&lt;/i&gt; on page 53, DOI: 10.11646/zootaxa.1765.1.1, &lt;a href="http://zenodo.org/record/5123752"&gt;http://zenodo.org/record/5123752&lt;/a&gt

Arrenurus castaneus Neuman 1880

Arrenurus castaneus Neuman, 1880 (Fig. 40) Material examined: 10 larvae deriving from 5 females. Larva very similar to A. truncatellus. Slight differences in dorsal plate shape. Idiosoma 230–238 µm long. Dorsum: Dp large (DpL: 222–230 µm; DpW: 174–184 µm), egg-shaped, widest at mid-length. Antero-lateral indents small, almost right-angled, reaching to about 1/7 and 1/4 of plate's length and width, respectively. Anterior margin of dorsal plate, relative to its width, slightly wider than in A. truncatellus. DpW/Mp1-Mp1 3.8. Lp2, Mh1 smooth. Mp1-Mp1 (45–52 µm) distinctly shorter than Mp2-Mp2 (54–61 µm); Mp1-Lp2 intermediate (41–45 µm). Venter: Median margins of CpI, CpII, CpIII measure 66–69, 28–31, 50– 54 µm, respectively, their ratio 2:1:1.5. C3, C4 pectinate, C1, C2 smooth. C1-CpIm (18–20 µm) about 3/4 of C4-CpIIIm (24–28 µm). C1-C2 intermediate (44–49 µm). Legs: Shorter than body; LI<LII = LIII (Fig. 4). ITa13 located closer to mid-point of tarsus than in A. truncatellus, IITi10, IIITi10 located closer to distal end of tibia. IITi10, IIITa13 smooth; ITa13 located about 1/3 of distance to proximal end of tarsus.Published as part of Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, pp. 1-75 in Zootaxa 1765 (1) on page 58, DOI: 10.11646/zootaxa.1765.1.1, http://zenodo.org/record/512375

Arrenurus tetracyphus

Arrenurus tetracyphus (O. F. Müller, 1776) (Fig. 21) Material examined: 10 larvae deriving from 10 females. Larvae relatively large: idiosoma 214–260 µm long. Dorsum: Dp relatively large (DpL: 204–228 µm; DpW: 152–176 µm), egg-like and shield-shaped, widest in mid-length, with relatively large, obtuse-angled antero-lateral indents about 1/5 and 1/4 of dorsal plate's length and width, respectively. DpW/Mp1-Mp1 3.1. Lp2, Mh1 pectinate, thicker than remaining setae. Mp1- Mp1 intermediate length (48–56 µm), equal to Mp2-Mp2 (52–56 µm); Mp1-Lp2 relatively short (34–43 µm). Venter: Median margins of CpII very short (29–34 µm), compared to those of CpIII (40–46 µm) and CpI (70– 75 µm). CpI:CpII:CpIII ratio 2.5:1:1.5. C2, C3, C4 bipectinate, C1 smooth. V 3 bipectinate; Lh2, Lh3 pectinate. C1-CpIm (20–23 µm) more than 2/3 of C4-CpIIIm (34–38 µm); C1-C2 intermediate (42–44 µm). Expp pentagonal, clearly wider than long. Exp located slightly above plate's mid-point, above E2. Palps: PIII 1 thick, bipectinate; PV6 short, thick. Chelicerae: First segment shaped like a curved cylinder, slightly tapered anteriorly (67–70 µm). Legs: Somewhat shorter than body; LI<LII = LIII (Fig. 4). ITi8 thin, long, pectinate; ITa13, IITa13, IITi10 long, pectinate. ITa12, IITa12, IIITa11, IIITa12, IIITa7, IIITa9, IIITa10 pectinate. IIITa14 only slightly closer to proximal end of tarsus than IIITa13 or at same level.Published as part of Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, pp. 1-75 in Zootaxa 1765 (1) on page 37, DOI: 10.11646/zootaxa.1765.1.1, http://zenodo.org/record/512375

Arrenurus claviger Koenike 1885

&lt;i&gt;Arrenurus claviger&lt;/i&gt; Koenike, 1885 (219) &lt;p&gt;(Fig. 2, Tables 1, 2)&lt;/p&gt; &lt;p&gt; &lt;i&gt;Arrenurus calycularis&lt;/i&gt; Georg&eacute;vitsch, 1906 (143)&lt;/p&gt; &lt;p&gt; &lt;b&gt;Material examined:&lt;/b&gt; Progeny from a ten females collected from a pool in a ploughed field near Trzebie&nacute;, Dolice district, Poland, 53o17&rsquo;N, 15o27&rsquo;E, among reed&shy;marshes, 1 May 1998.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Diagnosis:&lt;/b&gt; Dorsal plate egg&shy;shaped with small anterior&shy;lateral indentations, Lp2 and Mh1 bipectinate; median margins of CpI 1.5 times longer than the CpII median margins which are a little longer than CpIII margins; Expp pentagonal&shy;shaped, its width equal to its length, Exp located anterior to the centre of Expp and above the E2 setae; IITi10 long, pectinate, and situated almost in the same place as IITi9, IIITa13 pectinate.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Description:&lt;/b&gt; The egg&shy;shaped dorsal plate is widest in the middle of its length and narrows in the posterior part. The anterior margin is slightly convex and the posterior one is pointed. The anterior&shy;lateral indentations are fairly small, with slightly obtuse angles, and reach to about one&shy;fifth of the plate length and one&shy;fifth of its width. Seta Lpl is tripartite, setae Lp2 and Mh1 are bipectinate, the remaining setae are smooth (Fig.2).&lt;/p&gt; &lt;p&gt;The median margins of CpI are 1.5 times longer than the CpII median margins which are a little longer than CpIII ones, the ratio is 1.5/1.1/1. Setae C1, C2, C3 and V3 are bipectinate, C4, Lh2 and Lh3 are pectinate and the remaining setae are smooth. The distance between the C4 seta and the CpIII median margin is 1.5 times longer than the distance between the C1 seta and CpI median margin (Table 1, Fig. 2).&lt;/p&gt; &lt;p&gt;The excretory pore plate is pentagonal&shy;shaped, its width is equal to its length. The excretory pore is located anterior to the centre of the plate and above the E2 setae (Table 1, Fig. 2).&lt;/p&gt; &lt;p&gt; The pedipalps are typical for &lt;i&gt;Arrenurus&lt;/i&gt; species. Seta PIII1 is bipectinate, PIV1 and PV6 are fairly thin and PV8 is fairly long (Table 1, Fig. 2). The first segment of the chelicerae is bottle&shy;shaped, with one margin flat and the other hook&shy;like (Fig. 2).&lt;/p&gt; &lt;p&gt;The proportions of segments are more or less the same on each limb. The shortest segment, the trochanter, constitutes about 2/3 of the femur and genu which are of the same length; the tibia is 1.5 times longer and the tarsus 2 times longer (Table 2). Seta ITi8 is thin and long, IITi10 is long, pectinate, and situated almost in the same place as IITi9. Setae IIIGe2, IIITi7 and IIITi8 are fairly long and bipectinate (Fig. 2).&lt;/p&gt;Published as part of &lt;i&gt;Zawal, Andrzej, 2006, Larval morphology of Arrenurus cuspidifer Piersig, A. claviger Koenike, and A. latus Barrois &amp; Moniez (Acari: Hydrachnidia), pp. 55-68 in Zootaxa 1276&lt;/i&gt; on pages 62-63, DOI: &lt;a href="http://zenodo.org/record/173333"&gt;10.5281/zenodo.173333&lt;/a&gt

Arrenurus knauthei Koenike 1895

Arrenurus knauthei Koenike, 1895 (Fig. 36) Material examined: 5 larvae deriving from 1 female. Larvae very large: idiosoma 260–318 µm long. Dorsum: Dp very large (DpL: 260–302 µm; DpW: 228–240 µm), oval, widest at mid-length. Anterior margin short, almost straight; posterior margin somewhat blunt. Antero-lateral indents very small, somewhat obtuse-angled, about 1/7 and 1/5 of plate's length and width, respectively. DpW/Mp1-Mp1 5.3. Lp2, Mh1 smooth. Mp1-Mp1 intermediate (42–50 µm), shorter than Mp2-Mp2 (70–74 µm); Mp1-Lp2 short (36–40 µm). Venter: Cp very long: CpIm, CpIIm, CpIIIm 86–90, 41–46, 54– 60 µm long, respectively, their ratio 2:1:1.3. Postero-lateral margins of CpIII strongly indented due to large size of excretory pore plate. Setae on Cp pectinate. C1-CpIm (22–26 µm) about 2/3 of C4-CpIIIm (35–38 µm). C1-C2 very long (66–70 µm). Expp oval, somewhat wider than long. Exp located slightly below plate's mid-point, level with or slightly above E2. E1 located relatively far from anterior margin of Expp. Palps: PIII 1 bipectinate; PIV1 long, pectinate; PV6 long. Chelicerae: First segment long, cylindrical (129–140 µm), slightly narrowing anteriorly, one margin somewhat concave, other slightly convex. Legs: Shorter than body; LI= LII = LIII (Fig. 5). ITi8 short, thin; IIGe3, IIIGe3 relatively thick and bipectinate. IIITa11, IIITa12, IIITa13 pectinate. IITi10, IIITi10 smooth, located about 1/3 away from distal end of tibia. Hosts: Culicidae (Münchberg 1936).Published as part of Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, pp. 1-75 in Zootaxa 1765 (1) on page 54, DOI: 10.11646/zootaxa.1765.1.1, http://zenodo.org/record/512375