Redescription of a rarely encountered species Travisa chinensis Grube, 1869 (Annelida, Travisiidae), including a description of a new species of Travisa from Amoy, China

Abstract

The original description of Travisia chinensis Grube, 1869 was incomplete, leading to confusion with other species. To clarify the status of this species, we provide a redescription of, and remarks on, T. chinensis based on an examination of the type specimen. We also describe Travisia amoyanussp. nov., collected from Xiamen (Amoy), China, and originally identified as T. chinensis by Monro (1934). The new species can be distinguished from its congeners by a combination of the following characters: the total number of segments (34 or 35) and chaetigers (33 or 34), parapodial lappets first from chaetiger 15, and a pygidium with a large ventral triangular cirrus and about six encircling lateral cirri. Genetic distances and phylogenetic analyses based on the mitochondrial (16S rRNA) and nuclear (18S rRNA) genes support the identity of the new species.

New species of Travisia Johnston, 1840 (Annelida, Travisiidae Hartmann-Schröder, 1971) from south-eastern Australia

“…Investigation of this issue is beyond the scope of this study but remains a concern, especially as only 13 of the 38 species of Travisia are based on descriptions of more than six specimens, and 17 species descriptions are based on one or two specimens (based on published data in original descriptions). Yang et al (2022) do show that numbers of chaetigers and branchiae and position of first parapodial lobes do not vary with length for T. amoyanus Yang, Wu, Wang, Zhao, Hwang and Cai, 2022, but size-related variation of other characters and in other species remains poorly understood.…”

“…Coding of morphological characters in this study follows recent literature (Blake and Maciolek, 2016;Yang et al, 2022 Table S5) except where noted below. Our complete list of characters and states is available from Wilson and Avery (2023).…”

“…Remarks. Ten species and subspecies of Travisia have chaetiger 1 biannulate, chaetiger 2 triannulate and mouth in the usual position between chaetigers 1 and 2: T. amoyanus Yang, Wu, Wang, Zhao, Hwang and Cai, 2022;T. araciae Rizzo and Salazar Vallejo, 2020;T.…”

“…Travisia is assigned to the family Travisiidae Hartmann-Schröder, 1971 in most recent treatments (Blake and Maciolek, 2016;Rizzo and Salazar-Vallejo, 2020;Yang et al, 2022;Read and Fauchald, 2023). Recent molecular studies show Travisia to be sister group to Scalibregmatidae Malmgren, 1867 (Persson and Pleijel, 2005;Paul et al, 2010;Law et al, 2014;Rouse et al, 2022).…”