All members of the syllid genus
Trypanosyllis show distinctive flattened, ribbon-like bodies and a pharynx armed with a trepan; however, the phylogenetic relationships within this genus remain unsettled, especially with respect to the genera
Eurysyllis and
Xenosyllis (morphologically similar). To resolve this systematic uncertainty we analysed the phylogenetic relationships of a worldwide sampling of specimens of
Trypanosyllis and three related genera using multiple molecular markers. We show that
Trypanosyllis as presently construed is paraphyletic, and identify a clade of striped species that were previously all considered to be
Trypanosyllis zebra (Grube, 1860). We outline the case to consider
Trypanosyllis krohnii Claparède, 1864 as the type species of the genus, instead of
Trypanosyllis zebra.
Trypanosyllis krohnii (interpreted as
Trypanosyllis zebra by recent authors) was previously believed to be cosmopolitan, but we show that it includes at least seven cryptic and pseudocryptic species, five of which are described herein:
Trypanosyllis kalkin sp. nov.,
Trypanosyllis californiensis sp. nov.,
Trypanosyllis luquei sp. nov.,
Trypanosyllis leivai sp. nov., and
Trypanosyllis taboadai sp. nov. In addition,
Trypanedenta gemmipara (Johnson, 1901) comb. nov. and
Trypanedenta gigantea (McIntosh, 1885) comb. nov., previously included in
Trypanosyllis, are here transferred to
Trypanedenta Imajima & Hartman, 1964, and
Pseudosyllis brevipennis Grube, 1863 [previously named
Trypanosyllis coeliaca (Claparède, 1868)] is transferred to the resurrected genus
Pseudosyllis Grube, 1863. Overall our results show a complex scenario of speciation, with cases of pseudocryptic species that correspond to geographically restricted lineages.
