Bryozoans are common on gastropod shells inhabited by the hermit crab Pagurus comptus in the southern southwest Atlantic. The aim of this study was to test whether bryozoan biodiversity was higher on larger and more complexly sculptured gastropod shells, as well as to analyze spatial and bathymetric changes in bryozoan assemblages. Forty-four bryozoan species were recorded on 59 gastropod (morpho) species. Larger shells tended to host a higher number of bryozoan species than smaller ones. Bryozoan species richness differed significantly among gastropods with different shell ornamentation, but richness did not increase along a predicted qualitative scale of increasing ornamentation complexity. Almost smooth but large shells had a much higher bryozoan richness than expected, and small shells with prominent ornamentation had unexpectedly the lowest richness, suggesting that shell size may be more important than ornamentation in determining bryozoan richness. Most of the shells hosted two bryozoan species, although up to 11 species per shell were observed. Maximum bryozoan richness occurred between 99 and 137 m. Bryozoan species richness on gastropod shells occupied by P. comptus was higher in the Burdwood Bank than around Tierra del Fuego and Isla de los Estados. Epibiont assemblage composition and species richness differed among the six most abundant gastropods (Trophon ohlini, Pareuthria atrata, Cerithiopsis caelatum, Fuegotrophon pallidus, P. fuscata, Argeneuthria cerealis). The two most abundant bryozoans, Burdwoodipora paguricola and Odontoporella adpressa, do not overlap in their occupation of shell surfaces. This is the first study analyzing the relationships among bryozoans, gastropod shells, and hermit crabs in subantarctic waters.

寄居蟹Pagurus comptus栖息的腹足动物贝壳上常见苔藓虫在西南大西洋的南部。这项研究的目的是检验在较大且更复杂的腹足动物壳上，苔藓虫的生物多样性是否更高，以及分析苔藓虫组合的空间和水深变化。在59个腹足类（形态）物种上记录了44种苔藓动物。较大的壳往往比较小的壳拥有更多的苔藓动物。不同外壳装饰的腹足类动物中，苔藓虫的丰富度差异显着，但丰富度并没有随着装饰复杂度的增加而按预定的定性尺度增加。几乎光滑但大的贝壳具有比预期更高的苔藓虫丰富度，而具有突出装饰的小贝壳出乎意料地具有最低的丰富度，这表明壳大小可能比装饰物对确定苔藓虫的丰富度更为重要。尽管观察到每个壳最多11种，但大多数壳中都存在两种苔藓动物。最大的苔藓动物丰富度发生在99至137 m之间。腹足动物壳所占据的苔藓动物物种丰富度。Burdwood银行的P. comptus高于Tierra del Fuego和Isla de los Estados附近。Epibion​​t组合组成和物种丰富的六个最丰富的腹（间差异Trophon ohlini，Pareuthria蝉，Cerithiopsis caelatum，Fuegotrophon苍白球，P. fuscata，Argeneuthria禾谷）。两种最丰富的苔藓动物，Burdwoodipora paguricola和Odontoporella adpressa在它们对壳表面的占领中不重叠。这是首次研究亚极南极水域的苔藓动物，腹足动物的壳和寄居蟹之间的关系的第一项研究。