Trhypochthonius tectorum, : Berlese, 1904

Weigmann, Gerd & Raspotnig, Günther, 2009, Comparative morphological and biometrical studies on Trhypochthonius species of the tectorum species group (Acari: Oribatida: Trhypochthoniidae), Zootaxa 2269 (1), pp. 1-31 : 20

Comparison of Trhypochthonius tectorum populations

The biometrical data numbers of genital setae, notogastral setal lengths (%) and notogaster lengths (µm) were measured from each specimen of six Trhypochthonius tectorum populations (3: n=5), (6: n=4), (7: n=5), (8: n=5), (9: n=5) and (10: n=3), as listed in the section “Material examined”.

The number of genital setae pairs varies within the populations and obviously also among the populations of T. tectorum ( Fig. 10b ). The total observed range of setae pairs is 7–11; the median value in populations (9) and (10) is nine, in (3) is ten, in (6), (7) and (8) is eleven.

There were no significant differences of notogaster lengths among the tested six populations ( Fig. 10a ). Only in three of fifteen notogastral setae sets were significant differences found: regarding setae d 2, population (3) is significantly different from all others which are otherwise not different from each other. The significant differences regarding d 1 and p 1 are indicated in figures 11c and 11d: the relative lengths of seta d 1 are partly different between populations and show moderate variability within populations. Population (10) is represented only by three specimens that probably are not fully representative. As two examples, figures 11a and 11b show the non-significant variability between the populations for setae c 2 and c 3; the means are partly different, but the ranges overlap.

Remarks. The observed but limited biometrical differences among populations of Trhypochthonius tectorum are not surprising, considering that the species is strictly parthenogenetic; populations consist of clone lines without genetic interchange, which would balance variability within populations as occurs in bisexual species. Similar differences between populations are observed in other biometrically analysed parthenogenetic species, e.g. in Tectocepheus and Trhypochthoniellus species ( Weigmann 1999, 2002).

Figures

FIGURE 10. Biometrical data of different Trhypochthonius tectorum populations. a—notogaster length data; b— numbers of genital setae pairs.—Population (6) from Italy; (3), (7) and (8) from Austria; (9) and (10) from Germany.