D. Marcela Bolaños

Reproduction, development and parental care in two direct‐developing flatworms (Platyhelminthes: Polycladida: Acotylea)

Variations in reproductive modes, egg production, and the effects of parental care on hatching success are compared between Pleioplana atomata and Imogine zebra. Pleioplana atomata transfers sperm via true copulation, whereas I. zebra dermally impregnates spermatophores onto the dorsal surface of partners. Pleioplana atomata lays up to 750 large eggs over a 6‐week period, and I. zebra individuals lay up to 1346 small eggs in 12 days. Female fecundity is positively correlated with body size in both species. Developmental time lines are temperature‐dependent, and juvenile worms hatch after 3 and 6 weeks for I. zebra and P. atomata, respectively. Covering of egg masses by the adult is observed for both species and although this parental care is not necessary for egg development or hatching, it plays a significant role in the hatching success of P. atomata. In I. zebra, parental covering of egg masses may play a role in eggshell development. 1Present address: Smithsonian Marine Station, Fort Pierce, FL, USA 2Present address: Childrens Hospital, Boston, MA, USA

When names are wrong and colours deceive: unravelling the Pseudoceros bicolor species complex (Turbellaria: Polycladida)

The polyclad Pseudoceros bicolor derives its name from a distinctive two-coloured dorsal colouration, which consists of a very dark, almost black central area with acute black lobes extending towards a translucent greyish margin. At least three different colour morphs have been described, ranging from a pale speckled brown through an evenly dark brown form, to a morphotype resembling the original species description. Pseudoceros aureolineatus is easily confused with the light brown colour morph of P. bicolor, and P. rawlinsonae resembles both P. bicolor and P. aureolineatus. Using morphological characters of newly collected specimens and nucleotide sequences of the 28S ribosomal DNA gene, the taxonomic validity of P. rawlinsonae and P. bicolor is confirmed and the descriptions of their colouration are emended. The new subspecies, P. bicolor marcusorum subsp. nov. is erected, the genus Cryptoceros is eliminated, and the new combination Maritigrella aureolineata comb. nov. (Euryleptidae) is established for P. aureolineatus.

Embryonic muscle development in direct and indirect developing marine flatworms (Platyhelminthes, Polycladida)

SUMMARY We compared embryonic myogenesis of the direct‐developing acotylean polyclad Melloplana ferruginea with that of Maritigrella crozieri, a cotylean that develops via a larval stage. Fluorescently labeled F‐actin was visualized with laser confocal microscopy. Developmental times are reported as percentages of the time from oviposition to hatching: 7 days for M. crozieri and 22  days for M. ferruginea. The epithelium began to form at 30% development in M. crozieri and at 15% development in M. ferruginea. Random myoblasts appeared in peripheral areas of the embryo at 36% and 22–30% development in M. crozeri and M. ferruginea, respectively. Circular and longitudinal muscle bands formed synchronously at 37–44% development in M. crozieri; yolk obscured observations of early myogenesis in M. ferruginea. An orthogonal muscle grid was established by 45–50% development in both species. Diagonal muscles developed in M. ferruginea at 60–71% development. Hence, juveniles of this species hatch with the same basic body‐wall musculature as adults. Larvae of M. crozieri did not hatch with diagonal muscles; these muscles are acquired postmetamorphosis. Additionally, a specialized musculature developed in the larval lobes of M. crozieri. Oral musculature was complex and established by 72% development in both species. Our results are comparable to the muscle differentiation reported for other indirect‐developing polyclads and for direct‐developing species of macrostomid flatworms. Furthermore, they provide additional support that the orthogonal muscle pattern of circular and longitudinal muscles is a symplesiomorphy of Spiralia.

Evolution of flatworm central nervous systems: Insights from polyclads.

The nervous systems of flatworms have diversified extensively as a consequence of the broad range of adaptations in the group. Here we examined the central nervous system (CNS) of 12 species of polyclad flatworms belonging to 11 different families by morphological and histological studies. These comparisons revealed that the overall organization and architecture of polyclad central nervous systems can be classified into three categories (I, II, and III) based on the presence of globuli cell masses -ganglion cells of granular appearance-, the cross-sectional shape of the main nerve cords, and the tissue type surrounding the nerve cords. In addition, four different cell types were identified in polyclad brains based on location and size. We also characterize the serotonergic and FMRFamidergic nervous systems in the cotylean Boninia divae by immunocytochemistry. Although both neurotransmitters were broadly expressed, expression of serotonin was particularly strong in the sucker, whereas FMRFamide was particularly strong in the pharynx. Finally, we test some of the major hypothesized trends during the evolution of the CNS in the phylum by a character state reconstruction based on current understanding of the nervous system across different species of Platyhelminthes and on up-to-date molecular phylogenies.

New records of cotylean flatworms (Platyhelminthes: Polycladida: Rhabditophora) from coastal habitats of Israel

Seven new records of cotylean flatworms belonging to two families and four genera were identified from Israel collected in the eastern Mediterranean Sea and the northern Red Sea. The family Pseudocerotidae was represented by three genera and six species (Pseudoceros duplicinctus, Pseudobiceros apricus, Pseudobiceros damawan, Pseudobiceros murinus, Pseudobiceros stellae, and Thysanozoon brocchii), followed by the Euryleptidae with a single species (Maritigrella fuscopunctata). Pseudoceros duplicinctus is recognized as a senior synonym of Pseudoceros prudhoei and color and pattern variations are reported for Maritigrella fuscopunctata. In addition, the presence of Pericelis byerleyana in the northern Gulf of Aqaba is confirmed, illustrated, and properly described with morphological and molecular data. Pseudoceros duplicinctus and Pseudobiceros stellae represent new geographic records for the Mediterranean Sea and Pseudobiceros apricus and Pseudobiceros damawan are new for the Red Sea. Detailed morphological analysis with emphasis on the color and pattern was applied for species identifications including high quality photographs of live and fixed animals. Partial sequences of the 28S ribosomal DNA (rDNA) of four of the species were obtained and deposited in GenBank with accession numbers provided with the corresponding species description. Our results represent a significant taxonomic contribution for the diversity and distribution of the Polycladida in Israel pointing out the importance for more integrative and comprehensive surveys in these two regions to advance the knowledge of marine biodiversity worldwide and along both Israeli coasts.