Discoplana malagasensis sp. nov. a New Turbellarian (Platyhelminthes: Polycladida: Leptoplanidae) symbiotic in an ophiuroid (Echinodermata), with a cladistic analysis of the Discoplana/Euplana species

A new species of polyclad flatworm from Papua New Guinea is described. It is found symbiotic in the ophiuroid Ophiothrix purpurea von Martens, 1867 (Echinodermata: Ophiuroidea). Apparently it belongs to the taxon Discoplana Bock, 1913 and can be distinguished from the six previously described Discoplana species by its very short ejaculatory duct and a penial papilla covered with a penial sheath, but without any true sclerotised structures such as a stylet or spines. The cladistic analysis of the Discoplana/Euplana species, based on morphological features and including two outgroups, reveals that all species of Discoplana, except D. pacificola, form a monophyletic taxon, that is not a synonym of Euplana Girard, 1893. Therefore the name Discoplana is conserved and the new species will be described as Discoplana malagasensis sp. nov. A key for the Discoplana/Euplana group is provided. In this key the biogeographical distribution and possible synonyms are given.

Supercontinuum generation in air-silica microstructured fibers with nanosecond and femtosecond pulse pumping

We study the generation of supercontinua in air-silica microstructured fibers by both nanosecond and femtosecond pulse excitation. In the nanosecond experiments, a 300-nm broadband visible continuum was generated in a 1.8-m length of fiber pumped at 532 nm by 0.8-ns pulses from a frequency-doubled passively Q-switched Nd:YAG microchip laser. At this wavelength, the dominant mode excited under the conditions of continuum generation is the LP 11 mode, and, with nanosecond pumping, self-phase modulation is negligible and the continuum generation is dominated by the interplay of Raman and parametric effects. The spectral extent of the continuum is well explained by calculations of the parametric gain curves for four-wave mixing about the zero-dispersion wavelength of the LP11 mode. In the femtosecond experiments, an 800-nm broad-band visible and near-infrared continuum has been generated in a 1-m length of fiber pumped at 780 nm by 100-fs pulses from a Kerr-lens model-locked Ti:sapphire laser. At this wavelength, excitation and continuum generation occur in the LP01 mode, and the spectral width of the observed continuum is shown to be consistent with the phase-matching bandwidth for parametric processes calculated for this fiber mode. In addition, numerical simulations based on an extended nonlinear Schrödinger equation were used to model supercontinuum generation in the femtosecond regime, with the simulation results reproducing the major features of the experimentally observed spectrum. © 2002 Optical Society of America.