Ascidians collected during the 2013 Singapore Strait International Marine Biodiversity Workshop.

During the 2013 Singapore Strait International Marine Biodiversity Workshop, hundreds of ascidians were collected along with numerous other marine phyla. Collections were made intertidally as well as subtidally by snorkel, SCUBA, trawling and dredging. While many ascidian specimens remain unidentified, 14 aplousobranchs, nine phlebobranchs and 17 stolidobranchs have been identified; a surprising 50% of these comprise 20 new records for Singapore. An additional new record of the phlebobranch Perophora namei collected from the same area in 2014 and 2015 is included here. Of the 21 new records, Aplidium cf. grisiatum, Distaplia regina, Euherdmania cf. digitata, Cnemidocarpa irene, Monandrocarpa monotestis and Polyandrocarpa rollandi are also first records for the entire South China Sea region.

Diversity and abundance of native and non-native ascidians in Puerto Rican harbors and marinas.

Ascidians are an ideal taxon to study invasion processes: they require anthropogenic introduction vectors for long-distance dispersal, are easy to collect and monitor, and are abundant on artificial substrates. In March 2019 we surveyed 11 harbors around Puerto Rico and recorded 47 ascidian species. Eleven of these were only identified to the genus level or above based on morphological or genetic characterization. The remaining 36 species were classified as: 11 introduced (7 with worldwide distributions), 13 cryptogenic, and 12 native. We report the occurrence of Phallusia cf. philippinensis in the Atlantic for the first time. Ascidian community structure did not differ significantly across geographic locations and distances between marinas, while marina size had a significant effect on species richness and composition. Stakeholder involvement and periodic monitoring efforts are essential to detect the arrival of new species and the spread of already introduced ones to natural habitats.

The Ascidiacea collected during the 2017 British Columbia Hakai MarineGEO BioBlitz.

A three-week intensive marine biodiversity survey was carried out at a small remote region of the central British Columbia coast at and near the Calvert Island Marine Station (Hakai Institute) July 21-August 11, 2017. The survey included daily sampling by the staff and a number of visiting taxonomists with specialties covering all the major groups of invertebrates. Many marine habitats were sampled: rocky and sand/gravel intertidal and tidepools, eelgrass meadows, shallow and deeper subtidal by snorkel and Scuba, plus artificial surfaces including the sides and bottom of the large floating dock at the Institute and settlement plates set out up to a year previously at various subtidal sites. Many new species were recorded by all the taxonomists. In this very biodiverse remote area 36 ascidian species were identified: 18 Aplousobranchia, 7 Phlebobranchia, and 11 Stolidobranchia, comprising a total of 15 solitary and 21 colonial species including two undescribed colonial species. This represents almost one third of all the known North American species from Alaska to southern California in this limited very remote area. Remarkably, only two are possible non-natives. Diplosoma listerianum (Milne-Edwards, 1841), was collected mostly on natural substrates including deeper areas sampled by Scuba, and one colony occurred on a settlement plate. A few Ciona savignyi Herdman, 1882 were collected, two from natural substrates and four from artificial surfaces. There were no botryllids, Styela clava Herdman, 1881, Didemnum vexillum Kott, 2002, or Molgula manhattensis (De Kay, 1843), though these are all common and sometimes very abundant non-natives in other parts of BC and along much of the U.S. west coast. Most of the species encountered are known in northern California, Washington, and southern BC, but only a small number are represented among the few known Alaska species.

1,3-dimethyl-8-oxoisoguanine, a new purine from the New Zealand ascidian Pseudodistoma cereum.

A new purine, 1,3-dimethyl-8-oxoisoguanine (2) was isolated from the New Zealand ascidian Pseudodistoma cereum. The structure of 2 was elucidated by the use of standard spectroscopic techniques, including natural abundance 1H-15N 2D NMR.

Kottamides A-D: novel bioactive imidazolone-containing alkaloids from the New Zealand ascidian Pycnoclavella kottae.

Kottamides A-D (1-4), novel 2,2,5-trisubstituted imidazolone-containing alkaloids, were isolated from the New Zealand endemic ascidian Pycnoclavella kottae and structurally characterized using 15N natural abundance 2-D NMR in addition to standard spectroscopic methods. The kottamides exhibited anti-inflammatory and anti-metabolic activity as well as cytotoxicity toward tumor cell lines.

Factors involved in the formation of amorphous and crystalline calcium carbonate: a study of an ascidian skeleton.

The majority of invertebrate skeletal tissues are composed of the most stable crystalline polymorphs of CaCO(3), calcite, and/or aragonite. Here we describe a composite skeletal tissue from an ascidian in which amorphous and crystalline calcium carbonate coexist in well-defined domains separated by an organic sheath. Each biogenic mineral phase has a characteristic Mg content (5.9 and 1.7 mol %, respectively) and concentration of intramineral proteins (0.05 and 0.01 wt %, respectively). Macromolecular extracts from various biogenic amorphous calcium carbonate (ACC) skeletons are typically glycoproteins, rich in glutamic acid and hydroxyamino acids. The proteins from the crystalline calcitic phases are aspartate-rich. Macromolecules extracted from biogenic ACC induced the formation of stabilized ACC and/or inhibited crystallization of calcite in vitro. The yield of the synthetic ACC was 15-20%. The presence of Mg facilitated the stabilization of ACC: the protein content in synthetic ACC was 0.12 wt % in the absence of Mg and 0.07 wt % in the presence of Mg (the Mg content in the precipitate was 8.5 mol %). In contrast, the macromolecules extracted from the calcitic layer induced the formation of calcite crystals with modified morphology similar to that expressed by the original biogenic calcite. We suggest that specialized macromolecules and magnesium ions may cooperate in the stabilization of intrinsically unstable amorphous calcium carbonate and in the formation of complex ACC/calcite tissues in vivo.

Spicule formation in the solitary ascidian, herdmania momus.

Two types of calcareous spicules occur abundantly in Herdmania momus, a solitary pyurid ascidian with a worldwide warm water distribution. The large spindle-shaped body spicules are 1.5-2.5-mm long and are located primarily in the mantle, siphons, and branchial basket. Each body spicule possesses 100 or more rows of overlapping, unidirectional fringing spines. Numerous body spicules occur regularly spaced within a long common sheath of complex structure, and there are many sheaths per animal. Between neighboring body spicules and overlying the fringing spines are the tightly connected pseudopodial sclerocytes. Spine formation is hypothesized to occur within these cells. The body spicules apparently continue to increase in size throughout the animal's life. The tunic spicules are about one tenth the length of the body spicules. They have 20-40 rows of unidirectional nonoverlapping fringing spines and a mace-shaped spiny base that anchors them at the tunic surface. They form quickly in individual spicular envelopes inside the tunic blood vessels over a 4-5-day period. Each tunic spicule then leaves its surrounding envelope and blood vessel, passes into the tunic, and ultimately protrudes through the outer surface of the tunic. An organic covering inside the envelope closely adheres to the tunic spicules and stains with toluidine blue. Dissolution of the CaCO3 mineral phase by EDTA or EDTA-cetylpyridinium chloride-formaldehyde reveals an intricately patterned organic matrix within or upon which the spicules develop.

EARLY POST-METAMORPHIC GROWTH, BUDDING AND SPICULE FORMATION IN THE COMPOUND ASCIDIAN CYSTODYTES LOBATUS.

1. The colonial ascidian Cystodytes lobatus has a long breeding season (at least 6 months) and releases tadpoles sporadically throughout the day, indicating a long period of recruitment. 2. Tadpoles of C. lobatus were settled and reared in the laboratory in order to observe early growth, budding and spicule formation. 3. Budding is preceded by the formation of a new stomach at the posterior end of the esophagus and fits Nakauchi's Type I budding pattern. 4. Spicule formation begins within 5 days after settlement. The spicules appear to form in a particular region at the anterior end of the abdomen and migrate over the abdomen to form a single or slightly overlapping layer embedded in a "tunic spicular lamina." This lamina lies between the common tunic and the zooid cavity and forms a spicular sac in the tunic surrounding but separated from the abdomen of each zooid. It stains especially heavily for sulfated acid mucopolysaccharide; the spicules are concluded to form by cellular action in this organic matrix. 5. There is great variation among zooids in the quantity of spicules formed. These differences are maintained in the buds, resulting in colonies in which all zooids either have few or many spicules, and are therefore probably genetic in origin. 6. During budding the spicular sac becomes disrupted and appears to bud, resulting in a reallocation of the spicules to the buds and formation of separate spicular sacs around the abdomen of each bud. At budding there is apparently no disruption of bladder cell membranes in the tunic and no dissolution of spicules by the acids contained in the bladder cells.

THE GENERAL ECOLOGY AND GROWTH OF A SOLITARY ASCIDIAN, CORELLA WILLMERIANA.

1. A one-year field study of the ecology of the solitary ascidian Corella willmeriana Herdman was conducted between April, 1966, and April, 1967, at the Bremerton Yacht Club, Bremerton, Washington, where two polyvinyl chloride frames containing glass plates were examined at monthly intervals. 2. The results indicate that Corella is a primary colonizer, preferring to settle on clean surfaces. Growth is rapid during the summer, when sexual maturity, corresponding to a size of 12 mm., may be attained in three months and life span is approximately five months. Individuals grow at a slower rate and live longer during the winter; the life span then is seven or eight months. 3. Very young specimens of Corella are frequently overgrown during the winter by the colonial ascidian Diplosoma macdonaldi. The causes of death of adult Corella are not completely known, although a small percentage of them are eaten by the polyclad flatworm Eurylepta leoparda. A luxuriant spring growth of filamentous diatoms may cause death of adult Corella by smothering them.