Assemblages of intertidal bryozoans are proving to be more species-rich than generally previously appreciated. This study found 31 species of cheilostome bryozoans at three rocky-intertidal sites at Ketchikan, Alaska, USA. Species richness varied considerably among the three collecting sites: 28 at East Tongass Narrows, 18 at Higgins Point, 10 at Settlers Cove. Each site had species not occurring at the other sites (12, two, and one species, respectively). The number of species per site was within the range of values previously observed in a more extensive study at Kodiak, Alaska, suggesting both similar intertidal species richness at the two localities, and that sampling of other intertidal sites at Ketchikan would detect additional species. Descriptions and scanning electron microscopy (SEM) illustrations are provided for the species found at Ketchikan, and SEM illustrations are included for

This study examines the diversity of bryozoans found at four rocky intertidal sites (Kiholo Bay, Whittington Beach Park, Kealakekua Bay, and Kapa'a Beach Park) on the Island of Hawaii, USA. Bryozoans were patchily distributed, with few or no bryozoans, or low species diversity, at three protected or semi-protected sites, and unexpectedly high diversity at one exposed site. Species richnesses at the four sites were zero, one, five, and 32 species, respectively. Species diversity at the richest site was within the range of single-site diversities previously reported from optimal sites in temperate latitudes. We provide descriptions and SEM illustrations for 32 species recorded, which include a new genus (Junerossia) in the Family Stomachetosellidae and 10 new species (Alderina flaventa, Corbulella extenuata, Puellina septemcryptica, Junerossia copiosa, Calytpotheca kapaaensis, Bryopesanser serratus, Cribellopora souleorum, Metacleidochasma verrucosa, Disporella compta, and Favosipora adunca). The species encountered included 23 (72%) ascophorans, four (13%) anascans, two (6%) cribrimorphs, three (9%) cyclostomes, but no ctenostomes. All species were encrusting and essentially two-dimensional in growth form. Most species occurred on a substratum of lava rock, though not exclusively so. Of 23 species distributed outside the Hawaiian Islands, five (22%) have putatively cosmopolitan distributions and 18 (78%) Indo-West Pacific distributions; 19 (83%) are new records for the Hawaiian Islands. We briefly discuss freshwater influence and predation as possible factors in the patchy distribution of the intertidal bryozoans, and stress tolerance and larvalsettlement specificity as factors in the composition of the intertidal assemblage.

The degree to which evolutionary outcomes are historically contingent remains unresolved, with studies at different levels of the biological hierarchy reaching different conclusions. Here we examine historical contingency in the origin of two evolutionary novelties in bryozoans, a phylum of colonial animals whose fossil record is as complete as that of any major group. In cheilostomes, the dominant living bryozoans, key innovations were the costal shield and ascus, which first appeared in the Cretaceous 85 -95 Myr ago. We establish the parallel origin of these structures less than 12 Myr ago in an extant bryozoan genus, Cauloramphus, with transitional stages remarkably similar to those inferred for a Cretaceous clade. By one measure, long lag times in the first origins of costal shield and ascus suggest a high degree of historical contingency. This, however, does not equate with dependence on a narrow set of initial conditions or a low probability of evolution. More than one set of initial conditions may lead to an evolutionary outcome, and alternative sets are not entirely independent. We argue that, although historically contingent, the origin of ascus and costal shield was highly likely with sufficient possibilities afforded by time.

We found 39 cheilostome species among more than 7000 specimens collected at 10 intertidal sites in rocky habitats along the shore of Akkeshi Bay, eastern Hokkaido Island, Japan. These species are herein described in detail and illustrated by scanning electron microscopy. Nine species (23% of total) are described as new (Electra asiatica, Callopora sarae, Conopeum nakanosum, Cauloramphus cryptoarmatus, Cauloramphus multispinosus, Cauloramphus niger, Stomachetosella decorata, Microporella luellae, and Celleporina minima), and 21 species (54%) are reported for the first time from Japan. Species richness ranged from eight to 29 species per study site. A TWINSPAN analysis showed the species fell into nine groups defined by the local pattern of distribution. A cluster analysis of study sites based on similarity of species composition showed three faunistic groups distributed geographically: in Akkeshi Lake, along the eastern-central shore of the bay, and at the mouth of the bay. Species richness in estuarine Akkeshi Lake was low, with a species composition very different from the outer bay. Most cheilostomes were found on rock and shell substrata, but uncommonly occurred on concrete walls, algae, hydroids, tubes of polychaetes, other bryozoans, and anthropogenic debris. Of the 39 species found, 33 (85%) contained embryos during the collecting periods, 2-7 June and 3-6 July 2004. The biogeographical composition of intertidal cheilostomes at Akkeshi Bay included species with Arctic-Boreal (28%), Boreal (59%), and Boreal-Subtropical (13%) distributions. The overall species richness of intertidal cheilostomes was two-thirds that documented intertidally in a comparable study at Kodiak, Alaska, a locality 15u higher in latitude. We attribute the lower richness at Akkeshi to differences in the nearshore marine environment between the two localities.

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