Atypus karschi Dönitz, 1887 (Araneae: Atypidae): An Asian purse-web spider established in Pennsylvania, USA
Fig 2
Chromosomes of A. karschi, Pennsylvania, USA.
A, B. Male (A) and female karyotypes (B), stained by Giemsa, based on mitotic metaphase. 2n♂ = 41, X0; 2n♀ = 42, XX. Empty arrowhead–centromere of submetacentric pair. C. Male pachytene. Note heterochromatic X chromosome on the periphery of the nucleus and prominent knobs on the bivalents. Inset: Scheme of sex chromosome. Note an association of X chromosome arms. Arrow–sex chromosome. D. Male mitotic metaphase, C-banding. Chromosomes exhibit intercalar and terminal heterochromatin blocks. Inset: Magnified submetacentric chromosome containing a large block of heterochromatin (from another mitotic metaphase). Arrowhead–a large block of heterochromatin, empty arrowhead–centromere. E. Male mitotic metaphase, detection of rDNA cluster (FISH). Note chromosomes of a submetacentric pair containing a terminal rDNA cluster at long arm. Arrowhead–rDNA cluster, empty arrowhead–centromere. Scale bars: 10 μm.