Emanuela Di Martino

A DIVERSE PATCH REEF FROM TURBID HABITATS IN THE MIDDLE MIOCENE (EAST KALIMANTAN, INDONESIA)

ABSTRACT The Kutai Basin (East Kalimantan, Indonesia) contains a rich and well-preserved Miocene fossil record of small patch reefs that developed under the influence of high siliciclastic input associated with the progradation of the Mahakam Delta. In this study, we reconstruct the biodiversity and paleoenvironments on one of these delta-front, mixed carbonate-siliciclastic systems that developed at the Serravallian–Tortonian boundary near the city of Samarinda. In two newly exposed sections, we analyzed the sedimentology and distribution of the main fossil biota including corals, foraminifers, coralline algae, and bryozoans. Seven facies are herein defined, including two dominated by platy corals and two by larger benthic foraminifera. Facies distributions were driven by changes in depth and variations in terrigenous input within a range of delta-front habitats. Despite the turbid conditions, fossil assemblages are highly diverse, including 69 coral species and 28 bryozoan species that occur in coral-dominated facies. Crustose coralline algae were mainly associated with the coral-dominated facies. Larger benthic foraminifera showed broader ecological tolerance within the range represented in the studied sections and thus are common in most facies. These diverse patch reef ecosystems were able to cope with high siliciclastic input during the early development of the Miocene coral reef biota.

Bryozoan Communities and Thanatocoenoses from Submarine Caves in the Plemmirio Marine Protected Area (SE Sicily)

Living and dead bryozoan communities from three caves in the “Plemmirio Marine Protected Area” (SE Sicily, Italy) were studied. Species richness from each cave and from the area as a whole (72 species) are comparable to those observed in other regions and caves within the Mediterranean. Communities consist largely of cave dwellers, sciaphilic and cryptic species, often related to coralligenous habitats, but include also some generalist species components. Bryozoans from hard surfaces (vaults, walls and floor) and bottom sediments were studied separately taking into account both living specimens and thanatocoenoses. According to previous data, communities of hard surfaces exhibit a trend of decreasing species richness towards the inner area and a clear patchiness, unlike those in sediments whose distribution appears strongly related to local sediment texture. Dead colonies and fragments from both hard surfaces and bottom sediments contribute valuable information concerning the pool of species potentially inhabiting caves. The usefulness and limits of different sampling methods for the study of cave bryozoans are discussed.

Interspecific interactions through 2 million years: are competitive outcomes predictable?

Ecological interactions affect the survival and reproduction of individuals. However, ecological interactions are notoriously difficult to measure in extinct populations, hindering our understanding of how the outcomes of interactions such as competition vary in time and influence long-term evolutionary changes. Here, the outcomes of spatial competition in a temporally continuous community over evolutionary timescales are presented for the first time. Our research domain is encrusting cheilostome bryozoans from the Wanganui Basin of New Zealand over a ca 2 Myr time period (Pleistocene to Recent). We find that a subset of species can be identified as consistent winners, and others as consistent losers, in the sense that they win or lose interspecific competitive encounters statistically more often than the null hypothesis of 50%. Most species do not improve or worsen in their competitive abilities through the 2 Myr period, but a minority of species are winners in some intervals and losers in others. We found that conspecifics tend to cluster spatially and interact more often than expected under a null hypothesis: most of these are stand-off interactions where the two colonies involved stopped growing at edges of encounter. Counterintuitively, competitive ability has no bearing on ecological dominance.

BRYOZOAN DIVERSITY IN THE MIOCENE OF THE KUTAI BASIN, EAST KALIMANTAN, INDONESIA

ABSTRACT Miocene bryozoans from the Indonesian Archipelago have seldom been investigated in the past. Several factors combine to explain their poor fossil record, including rare exposures in a lushly vegetated terrane, dominance of inconspicuous encrusting species, and the adverse effects of diagenesis on fossil preservation. A large collection of samples from the Kutai Basin (East Kalimantan) has allowed new insights into the diversity of Miocene bryozoans in this region. The bryozoan assemblage as a whole consists of 123 species; a remarkable increase in known diversity. Substrate availability appears to be the main factor controlling bryozoan distribution. The majority of encrusting species are associated with plate-like scleractinian corals. Collecting curves allow sampled sites to be divided into three groups characterized by high, medium, and low species richness. The site of highest diversity is a mesophotic reef slope, an environment influenced by high input of terrigenous sediment. Ordination plots show no clear patterns of distribution among sites, with putatively endemic species accounting for most of the discrimination. A similar level of endemism and habitat heterogeneity characterizes modern, tropical bryozoan faunas. However, many more intermediate sites need to be sampled to achieve a fuller understanding of the true pattern of bryozoan species distribution in the Miocene of the Kutai Basin.

Differences in extinction rates drove modern biogeographic patterns of tropical marine biodiversity

Diversity contrasts between the Caribbean and Coral Triangle arose from differential extinction rates in the last 5 million years. Marine biodiversity in the Coral Triangle is several times higher than anywhere else, but why this is true is unknown because of poor historical data. To address this, we compared the first available record of fossil cheilostome bryozoans from Indonesia with the previously sampled excellent record from the Caribbean. These two regions differ several-fold in species richness today, but cheilostome diversity was strikingly similar until the end of the Miocene 5.3 million years ago so that the modern disparity must have developed more recently. However, the Miocene faunas were ecologically very different, with a greater proportion of erect and free-living species in the Caribbean compared to the less well-known Coral Triangle. Our results support the hypothesis that modern differences in diversity arose primarily from differential extinction of Caribbean erect and free-living species concomitant with oceanographic changes due to the uplift of the Isthmus of Panama, rather than exceptional rates of diversification in the Indo-Pacific.

Morphology and palaeobiogeography of Retelepralia , a distinctive cheilostome bryozoan new to the fossil record

A new species of ascophoran cheilostome bryozoan, Retelepralia macmonagleae sp. nov., is described from Malaysian Borneo (Sabah). Dated as Late Oligocene, it is the oldest known and the first recognized fossil species of Retelepralia. A second fossil species of this genus, originally described as Hippodiplosia voigti DaviD, MongErEau & PouyEt, 1972, occurs in the Miocene of France and Morocco. Synonymy of H. voigti with the Recent type species of Retelepralia, Lepralia mosaica KirKPatricK, 1888, is tentatively proposed. Included in the Cheiloporinidae, Retelepralia is characterized by a lepralioid frontal shield with a distinctive median gymnocystal strip. The presence of two hypostegal coelomic compartments in living zooids is inferred, and the palaeobiogeography of Retelepralia is discussed.

Non-indigenous bryozoan species from natural and artificial substrata of Mediterranean submarine caves

Numerous non-indigenous bryozoan species or NIBs (= non-indigenous bryozoans) have been recorded in the Mediterranean Sea, some in marine cave habitats. Recent surveys, mostly of submarine caves, led to the discovery of new NIBs and documented the spreading of NIBs already known from the basin. Cradoscrupocellaria hirsuta, Catenicella paradoxa, and Smittina nitidissima were recorded at several localities of central sectors of the Mediterranean. Only Ca. paradoxa was previously known from the area, while S. nitidissima had previously been recorded only from the Eastern Mediterranean, and Cr. hirsuta is new to the area. Within the examined area, Cr. hirsuta has a wide distribution, occurring on artificial panels and natural substrates. S. nitidissima and Ca. paradoxa were detected only on artificial panels, except for a few Ca. paradoxa colonies from a single locality, which had settled on algae. Artificial substrates offer additional surfaces available for colonisation, often more suitable than natural substrates. As such, they can be rapidly exploited by new settlers and particularly by opportunistic taxa as most alien species are. Although artificial substrates can be advantageous tools for the early detection of non-indigenous species (NISs), submerged anthropogenic substrates, such as artificial reefs and coastal protection structures, may selectively attract non-indigenous species favouring their spreading alongshore. Shipping appears to be one of the main pathways for species introduction and the main vector for dispersion.

First bryozoan fauna from the Eocene-Oligocene transition in Tanzania

Records of Cenozoic tropical bryozoan faunas are sparse, particularly from Africa. Here we describe a previously unknown bryozoan ‘sand fauna’ from a drill core across the Eocene–Oligocene boundary from a hemipelagic clay succession in Tanzania. Although low in diversity, this well-preserved fauna includes four cheilostome species, all new to science: Heteractis tanzaniensis sp. nov., Bragella pseudofedora gen. et sp. nov., Lacrimula kilwaensis sp. nov. and L. crassa sp. nov. The four species vary in mineralogy, with H. tanzaniensis having an entirely aragonitic skeleton, B. pseudofedora being bimineralic and the two species of Lacrimula calcitic. These species have either free-living ‘lunulitiform’ (H. tanzaniensis) or rooted ‘conescharelliniform’ (B. pseudofedora, L. kilwaensis and L. crassa) colonies adapted to life on a soft, unstable seafloor. The peak occurrence of bryozoans in the core coincides with the Eocene–Oligocene Glacial Maximum (EOGM), characterized by global environmental change from a greenhouse to an icehouse world, sea-level fall, cooling of the oceans and changes in water circulation that may have led to enhanced nutrient levels favourable to bryozoans both in Tanzania and elsewhere. http://zoobank.org/urn:lsid:zoobank.org:pub:6E49FB4A-EB50-4BCE-9D3D-B139CB5D4C5A

Revision of the bryozoan genus Gephyrotes Norman, 1903 (Cheilostomata, Cribrilinidae) with the description of two new taxa

The finding of a new species of Gephyrotes, G. moissettei n. sp., in Miocene deposits of southern Italy, prompted a revision of this distinctive cribrimorph taxon, leading to the redescription and first SEM documentation of the type material of nine species. Five of them are retained in Gephyrotes, namely the type species, G. nitidopunctatus, and G. fortunensis, G. spectabilis, G. quadriserialis, and G. convexus, to which G. moissettei n. sp. is added. The only Recent species is the genotype, while all the others are fossils from North America, Europe and northwest Africa. Two further species are transferred to the genus Tricephalopora, namely T. saillans and T. levigata, whereas Spiniflabellum n. gen., is established to accommodate a species from the Caribbean area, S. spinosum, previously assigned to Gephyrotes.

Early Pleistocene and Holocene bryozoans from Indonesia

This paper describes 40 bryozoan species, comprising one cyclostome and 39 cheilostomes (8 anascan- and 31 ascophoran-grade), obtained from early Pleistocene and Holocene samples from two localities in Indonesia. Five of the cheilostomes are described as new species: Acanthodesia variegata n. sp., Pleurocodonellina javanensis n. sp., Calyptotheca sidneyi n. sp., Characodoma wesselinghi n. sp., and Turbicellepora yasuharai n. sp. All of the remaining species are extant and characterized by a tropical to subtropical Indo-West Pacific distribution.