First larval description of the genus Mirabilithrombium Gabryś, 1999(Acari, Microtrombidiidae) from Turkey

Abstract

The genus Mirabilithrombium was founded by Gabryś (1999) to accommodate Georgia mirabilis Willmann, 1950 and Microthrombium sibilatrix Robaux, 1968; both species are known exclusively from postlarval forms. Dorsal opisthosomal setae of Mirabilithrombium show close similarities to the setae of Dactylothrombium. However, while Dactylothrombium carries 1 type of dorsal setae, Mirabilithrombium carries 2 types. This is the first description of the larvae of Mirabilithrombium. In addition, the adult of Mirabilithrombium turcicum sp. nov. is described, and notes on the biology, habitat specificity, and larval developmental time are given. Materials and methodsTwo specimens-active postlarval forms-were collected directly from the soil surface in a humid meadow with copses, in the same field but at different times, close to Ergan Mountain, Erzincan, Turkey (39°38′16″N, 39°31′31″E, 1328 m a.s.l., 21.11.201121.11. /06.11.2012. Larvae were reared from eggs deposited by adults collected in the field. Ovigerous females were placed in glass vials (25 × 30 mm) filled with charcoaled plaster of Paris and closed with tight, semitransparent lids. They were kept at room temperature with a natural light/ dark cycle. In order to maintain the required humidity, water was added to the substratum. After death, adults were preserved in 70% ethyl alcohol and were cleared with 10% KOH prior to mounting. Specimens for light microscope studies (1 female, 1 postlarval specimen, and 6 larvae) were mounted on slides using Hoyer's medium (Krantz and Walter, 2009). Measurements were taken and drawings were made under a Leica DM 4000 microscope with differential interference contrast and phase contrast. Terminology follows Mąkol ( 2007) for larvae and Gąbryś (1999) and Mąkol and Gabryś (2005) for postlarval instars. All measurements are given in micrometers. ResultsFamily Microtrombidiidae Thor, 1935 Genus Mirabilithrombium Gabryś, 1999 Type species Georgia mirabilis Willmann, 1950 Mirabilithrombium Gabryś, 1999 Diagnosis. Adult. Medial face of palp tibia with strong paradont, 1 or 2 ctenidia, and a radula. Radula consists of a few spinelike setae. Lateral face of palp tibia with 1 or 2 long, solid basidonts. Crista metopica with anterior and posterior process; in posterior half, a sensillary area bearing 1 pair of filiform sensillary setae. Accessory posterior process present. Double eyes with large lenses situated on short stalks placed at sides of crista metopica at the level of midpoint of anterior process. Dorsal opisthosomal setae of 2 types, both covered with setules distributed along the stem. Setae of type I (pDS I) more robust, gradually longer and thicker towards idiosoma termination, distal part of the stem slightly bent to idiosoma and bearing 2-5 short lobes at the top. Setae of type II (pDS II) smaller, with slightly thickened, apically narrowing stem. Legs without lamellae, shorter than idiosoma. Tarsus I dilated, longer than high.