Biologia 63/1: 100—103, 2008 Section Zoology DOI: 10.2478/s11756-008-0004-4

Redescriptions of Arctoseius minutus (Halbert, 1915) and Arctoseius pulvisculus (Berlese, 1920) (: )

Dariusz J. Gwiazdowicz

August Cieszkowski Agricultural University, Department of Forest Protection, ul. Wojska Polskiego 71c, PL-60625 Pozna´n, Poland; e-mail: [email protected]

Abstract: Arctoseius pulvisculus has been so far treated in literature as a synonym of A. minutus. However, on the basis of the analysis of the type material (A. pulvisculus), the Halbert’s descriptions and figures and the material from the specimens that conform to this description (A. minutus) it was discovered they were two distinct species. The study presents the female description of both species and the differences between them, and also includes figures. Key words: Acari; ; Ascidae; ; Arctoseius

Introduction elongated or curved (Fig. 1B). This was the basis for the assignment of both species to the genus Arctoseius. In one of his studies, Berlese described the species Lasioseius (Lasioseius) pulvisculus (Mesostigmata: As- Arctoseius minutus (Halbert, 1915) cidae) for which, however, no figures were presented (Berlese 1920). In subsequent acarological studies this Synonyms: Arctoseius cf. minutus sensu Athias-Henriot species was treated as a synonym of the previously de- (1973), Arctoseius minutus sensu Karg (1973, 1993). scribed Seiulus minutus Halbert, 1915 (Bernhard 1963; Bregetova 1977; Karg 1993). Therefore, the type ma- Description. Female. Oval idiosoma with approx. terial (microslides no. 201/8–11) in Berlese Acaroteca 300 µm of length and approx. 190 µmofwidth. from the Experimental Institute for Agricultural Zool- Holodorsal shield with 31 pairs of setae, 14 of them in ogy in Florence (Italy) was a subject of the examina- the posterior region (Fig. 2A) on dorsal side. All setae tion. However, attempts to obtain the material from simple with approx. 13 µm of length. Only j1 and J5 Halbert’s collection were unsuccessful. Thus, the de- setae are shorter (9–10 µm). Sometimes, lack of some scriptions and figures made by Halbert (1915), Evans of setae or irregular arrangement of setae. For instance (1954) and Karg (1993), the specimens from the au- Fig. 2A shows the lack of z3 seta on the right-hand side. thor’s collection and also mites from the Sogn og Fjor- Sculpture is diverse; between j1–j4 setae the sculpture dane University collection (Norway) were taken into is reticulate and in the region below granulate. consideration. A number of differences were found be- A sternal shield with three pairs of setae on the tween these species. Therefore the aim of this study ventral side (Fig. 2B). All sternal setae are simple and is to redescribe both species and to present the basic of the same length (12 µm). Setae st4 on the mem- morphological differences between them. brane and st5 outside the genital shield. Endopodal The systematic assignment of these mites also shields between st4 setae and coxae III and IV. Metapo- proved to be a controversial issue. Evans (1954) as- dal shields are oval with approx. 18 µmoflength. signed this species to the genus Arctoseiopsis Evans, Anal shield 70 µminlengthand70µminwidth, 1954, whereas Bernhard (1963) assigned it to the genus with puncticulate sculpture. Circum-anal setae sube- Leioseius Berlese, 1916, subgenus Arctoseius Thor, qual (12 µm). Long peritremes on peritremal shield. 1930. Bregetova (1977) and Gwiazdowicz (2003) con- Stigmata in the region of coxae IV. cluded that this species belongs to the genus Iphidozer- The hypostome has horn-like corniculae. The con Berlese, 1903, whereas Karg (1993) suggested the longest setae are C1, while the shortest are C2. The assignment of this species to the genus Arctoseius. hypostomal groove with seven rows of hypognathal den- Hypostome and chaetotaxy of legs in both species ticles (5–18 denticles in row) (Fig. 1A). Tectum tri- were analyzed on the basis of the available material. ramous with bifurcate tips (Fig. 4A). Fixed digit with Deutosternum with rows of denticles confined by well- three teeth, a movable digit with two teeth. formed lateral lines (Fig. 1A) was found. Tarsi II to IV Length of legs variable: pair I is the longest each with the dorsoproximal setae (ad-2 and pd-2) not (250 µm), pairs II (200 µm) and IV (230 µm) are

c 2008 Institute of Zoology, Slovak Academy of Sciences Redescriptions of two Arctoseius species 101

Fig. 1. Female of Arctoseius minutus: A – hypostome; B – tarsus IV. Scale 50 µm

Fig. 2. Female of Arctoseius minutus: A – dorsal view; B – ventral view. Scale 100 µm shorter, and pair III (170 µm) is the shortest. Adult Description. Female. Oval idiosoma with approx. setation of legs I-II-III-IV, trochanter 6-5-5-5; femur 12- 285–325 µm of length and approx. 155–170 µmofwidth. 9-5-5; genu 12-9-7-7; tibia 12-9-7-7. Holodorsal shield with 32 pairs of setae, 14 of them in the posterior region on dorsal side (Fig. 3A). All setae Material examined. Microslides from the Sogn og Fjor- simple with approx. 12 µm of length. Only j1 and J5

dane University Collection (Norway): 2 ¾ (no. 14/18.10.01), setae are shorter (8 µm). J3–J5 and Z3–4 setae on tu-

1 ¾ (no. 24/18.10.01); microslides from A. Cieszkowski Agri- bercles. Sculpture on holodorsal shield is colliculate. A

cultural University, Department of Forest Protection in Poz- well-defined pair of tubercles between J4 and J5 setae.

¾ ¾ nan (Poland): 1 ¾ (no. A089), 2 (no. A318), 1 (no. A sternal shield with three pairs of setae on the

A338), 2 ¾ (no. A479). ventral side (Fig. 3B). All sternal setae are simple and subequal (12 µm). Setae st4 on the membrane and st5 outside the genital shield. A pair of endopodal shields Arctoseius pulvisculus (Berlese, 1920) between sternal and genital shields. Extended metapo- dal shields (15 µm) below coxae IV. Anal shield oval, Synonyms: Leioseius (Arctoseius) minutus sensu Bernhard 70 µm in length and 60 µm in width, with lineate sculp- (1963), Iphidozercon minutus sensu Bregetova (1977). ture and three setae. Post-anal seta is longer than para- 102 D.J. Gwiazdowicz

Fig. 3. Female of Arctoseius pulvisculus: A – dorsal view; B – ventral view. Scale 100 µm

Idiosoma size (285–325 µm for females) is comparable for both species. However, there are crucial differences in the ornamentation of the idiosoma dorsum. In A. minutus, the anterior part of the dorsal shield, i.e. be- tween setae j1–j4, is characterized by reticulate orna- mentation, whereas posteriorly j4 the sculpture is gran- ular (Fig. 2A); dorsal setae are simple, approx. the same length, and located simply on the shield. In contrast, the dorsal shield of A. pulvisculus is covered with collic- Fig. 4. Tectum of females: A – Arctoseius minutus;B–Arctoseius pulvisculus.Scale30µm ulate ornamentation; a well-defined pair of tubercles are found between setae J4–J5; all dorsal setae are simple, although some of them, i.e., J3–J5, Z3, Z4 are located on small tubercles (Fig. 3A). The differences are also anal setae. Long peritremes and stigmata in the region clear in the analysis of the venter. The sternal shield of of coxae IV. A. minutus is wide in its anterior part, i.e. in the region The hypostome has horn-like corniculae. Setae C1 of st1, with branching arms (Fig. 2B), whereas it gets are the longest, C3 and C4 are shorter and C2 are the narrower in the case of A. pulvisculus (Fig. 3B). More- shortest. The hypostomal groove with seven rows of over, it is clearly visible that the ornamentation on the hypognathal denticles (7–16 denticles in row). Tectum anal shield is different. A. minutus has a clearly visible tri-ramous and the central tip is the longest (Fig. 4B). punctate ornamentation, whereas A. pulvisculus has a Fixed digit with three teeth, a movable digit with two delicate linear-reticulate ornamentation. teeth. The chelicerae of both species are similar and con- Length of legs variable: pair I is the longest sist of two teeth on the movable digit and three teeth (270 µm), pair IV are shorter (240 µm) and pairs II on the fixed digit. The hypostome is also similar, al- (200 µm) and III (185 µm) are the shortest. Chaeto- though one can observe differences in the morphology taxy of legs is the same as in A. minutus. of the tectum. A. minutus has a tri-ramous tectum, Material examined. Microslides from Berlese Acaroteca, with branching or denticulate tips (Fig. 4A), whereas A. pulvisculus

Experimental Institute for Agricultural Zoology in Florence has only three single tips (Fig. 4B).

¾ ¾ (Italy): 1 ¾ (no. 201/8–11), 1 (no. 201/9), 1 (no. Both species inhabit similar microenvironments

201/10), 1 ¾ (no. 201/11). such as soil, forest litter, moss, rotting wood, nests of small mammals and bark beetle galleries (Gwiazdowicz Distinction between Arctoseius minutus and A. 2007). pulvisculus Redescriptions of two Arctoseius species 103

Acknowledgements Bregetova N.G. 1977. Sem. Aceosejidae Beker et Wharton, 1952 (sensu Evans, 1958), pp. 169–226. In: Gilarov M.S. & The author wishes to thank Dr. M. Castagnoli and G. Sab- Bregetova N.G. (eds), Opredelitiel’ obitayushchikh v pochve batini Peverieri from the Experimental Institute for Agri- kleshche˘ı (Mesostigmata), Nauka, Leningrad. Evans G.O. 1954. Some new and rare species of Acarina. Proc. cultural Zoology in Florence, Italy, for making the Berlese Zool. Soc. Lond. 123: 793–811. collection microslides available. I am also grateful to Dr. P. Gwiazdowicz D.J. 2003. Description of Iphidozercon poststigma- Mašán for the consultations and comments on the subject tus sp. n. (Acari, Ascidae) with a key to Palearctic species of matter. This paper is the result of a grant sponsored by the the genus Iphidozercon. Biologia 58: 151–154. Ministry of Education (No 2 P06L 048 28), Poland. Gwiazdowicz D.J. 2007. Ascid mites (Acari, Mesostigmata) from selected forest ecosystems and microhabitats in Poland. Wydawnictwo Akademii Rolniczej, Pozna´n, 248 pp. References Halbert J.N. 1915. Arachnida II, Terrestrial and marine acarina. Clare Island Survey, part 39. Proc. R. Ir. Acad. 31: 45–136. Athias-Henriot C. 1973. Arctopsis inexpectatus n. gen., n. sp., Karg W. 1973. Zur Kenntnis der Ascidae Oudemans, 1905 (Ara- Gamaside litiéricole nouveau de Normandie (Arachnides, rina, Parasitiformes). Dtsch. Entomol. Z. 20: 329–338. Dermanyssina, Ascidae). Bull. Soc. Entomol. Fr. 78: 226– Karg W. 1993. Acari (Acarina), Milben Parasitiformes (An- 236. actinochaeta), Cohors Gamasina Leach. Raubmilben. Die Berlese A. 1920. Centuria quinta di Acari nuovi. Redia 14: 143– Tierwelt Deutschlands, 59 Teil. Gustav Fischer Verlag, Jena, 195. 523 pp. Bernhard F. 1963. Die Familie Ascaidae (Oudemans 1905) Bern- hard nov. comb., pp. 33–177. In: Stammer H.J. (ed.), Beitr¨age Received February 14, 2007 zur Systematik und Okologie¨ mitteleurop¨aischer Acarina II: Accepted September 4, 2007 Mesostigmata, Leipzig.