A new species of the Spirobranchus kraussii complex, S. akitsushima (Annelida, Polychaeta, Serpulidae), from the rocky intertidal zone of Japan

Abstract

A new species of Spirobranchus (Annelida: Serpulidae) is described based on specimens collected at the coastal Shonan area of Sagami Bay and the adjacent areas of Honshu, Japan. Spirobranchus akitsushimasp. nov. forms large aggregations in the intertidal rocky zone of warm-temperate Japanese shores. This species was referred to as Pomatoleios kraussii (Baird, 1864) until the monotypic genus Pomatoleios was synonymized with Spirobranchus. This new species is formally described based on morphologically distinct Japanese specimens with supporting DNA sequence data. The calcareous opercular endplate of Spirobranchus akitsushimasp. nov. lacks a distinct talon, but some specimens have a slight rounded swelling on the endplate underside, while in other species of the S. kraussii complex a talon is present, usually extended, and with bulges. We examined sub-fossil tube aggregations of the new species and suggest that such aggregation stranded ashore is a good indicator of vertical land movements (uplift and subsidence) resulting from past events, such as earthquakes, in Honshu, Japan.

A puzzle no more: the identity of Spirobranchus tetraceros (Schmarda, 1861) (Annelida, Serpulidae) is revealed

“…While we designated here a neotype for S. tetraceros based on topotypical material from Sydney, our phylogenetic analyses also provided compelling evidence for the existence of two sympatric well-supported clades within the S. tetraceros sensu stricto morphotype. These two clades show a mean interspecific p-distance of 36%, which actually exceeds those observed for the same cyt b fragment within the Spirobranchus kraussii complex (14.6-26.9%, see Nishi et al, 2022) and other serpulid genera, such as, for example, Ficopomatus (19.2%, Styan et al, 2017), Galeolaria (22.8-24.5%, Halt et al, 2009), and Hydroides (15.8-23.1%, Sun et al, 2016. Thus, although we detected no consistent morphological differences between the specimens of the two clades, we treated them as sympatric cryptic species and in addition to designating the neotype of S. tetraceros, we also described the sister species as S. schmardai sp.…”

Elevated temperatures increase abnormalities in embryos and reduce larval survival in serpulid polychaetes

“…The disappearance of the studied populations would mean changes in the marine environment, leading to a loss of biodiversity in the study region. Spirobranchus species play a key role in marine environments because their calcareous tubes provide substrates for the settlement of other species of marine invertebrate, serving as habitat and refuge ( Gosselin and Sewell, 2012 ; Pazoki et al, 2020 ; Sivananthan et al, 2021 ; Nishi et al, 2022 ). Additionally, there could be changes in the food chain, because serpulids are generally prey to many species of fish, echinoderms, and crustaceans.…”

“…Therefore, they are ecologically important because they feed on particles suspended in the water column ( Jordana et al, 2000 ; Ten Hove and Kupriyanova, 2009 ; Kupriyanova et al, 2019 ). In particular, species of the genus Spirobranchus (Blainville), play a key role in marine environments because some species are gregarious and form large structures known as serpulid reefs, which serve as a habitat and refuge for other marine invertebrate species ( Gosselin and Sewell, 2012 ; Pazoki et al, 2020 ; Sivananthan et al, 2021 ; Nishi et al, 2022 ).…”