Spirobranchus bakau sp. nov. from Singapore: yet another species of S. kraussii-complex (Polychaeta: Serpulidae)

Abstract

The intertidal serpulid polychaete Spirobranchus kraussii was originally described from South Africa and has since been reported in numerous sub (tropical) localities around the world. Recently, however, S. kraussii was uncovered as a complex of morphologically similar and geographically restricted species, raising the need to revise S. cf. kraussii populations. We formally describe S. cf. kraussii from Singapore mangroves as Spirobranchus bakau sp. nov. based on morphological and molecular data. Despite their morphological similarities, Maximum Likelihood and Bayesian Inference analyses of 18S and Cyt b DNA sequence data confirm that S. bakau sp. nov. is genetically distinct from S. kraussii and other known species in the complex. Both analyses recovered S. bakau sp. nov. as part of a strongly supported clade (96% bootstrap, 1 posterior probability), comprising S. sinuspersicus, S. kraussii and S. cf. kraussii from Australia and Hawaii. Additionally, paratypes of S. kraussii var. manilensis, described from Manila Bay in the Philippines, were examined and elevated to the full species S. manilensis. Finally, we tested the hypothesis that fertilisation and embryonic development of S. bakau sp. nov. can occur under the wide range of salinities (19.6–30.9 psu) and temperatures (25–31°C) reported in the Johor Strait. Fertilisation success of ≥70% was achieved across a temperature range of 25–32°C and a salinity range of 20–32 psu. Embryonic development, however, had a narrower salinity tolerance range of 27–32 psu. Clarifying the taxonomic status of S. cf. kraussii populations reported from localities elsewhere in Singapore and Southeast Asia will be useful in establishing the geographical distribution of S. bakau sp. nov. and other members of the S. kraussii-complex.

Transfer of Poly(methyl methacrylate) Nanoparticles from Parents to Offspring and the Protection Mechanism in Two Marine Invertebrates

“…bakau and A. amphitrite were found to thrive at salinity ranges encompassing 27 PSU , and were hence maintained at 27 PSU in this study. They were collected from mangroves along the northwest coast of Singapore, often with brackish water due to rainwater runoff and riverine inputs, predominantly from two major rivers in Johor (Sungei Pulai and Sungei Johor) …”

“…A seawater salinity of 27 PSU was selected to balance both the survival needs of the model organisms used in the study and yet not cause extensive aggregation of the PMMA nanoparticles that they form large flocs that settle out of the water column. Both S. bakau and A. amphitrite were found to thrive at salinity ranges encompassing 27 PSU 25,42 and were hence maintained at 27 PSU in this study. They were collected from mangroves along the northwest coast of Singapore, often with brackish water due to rainwater runoff and riverine inputs, predominantly from two major rivers in Johor (Sungei Pulai and Sungei Johor).…”

“…The PMMA nanoparticle exposure concentration had to be high enough for maternally transferred PMMA nanoparticles to be detectable and yet low enough to not cause any toxicity or interfere with reproduction in the exposed animals. Appropriate numbers of barnacles (25) or tubeworms (8−11) kept inside a glass beaker were exposed to PMMA nanoparticles with a hydrodynamic radius of 167 nm at a concentration of 10 mg/L (effectively 1.32 × 10 13 particles per liter) in 27 PSU seawater to investigate the intake and maternal transfer to their offspring.…”

“…Here, we examined the potential for the transfer of fluorescent poly­(methyl methacrylate) (PMMA) nanoparticles from parents to the offspring of two common mangrove inhabitants, the calcareous tubeworm, Spirobranchus bakau (S. bakau), which was recently described [as S. kraussii (Baird, 1864) in Chan et al, , phylum: Annelida, family: Serpulidae], and the acorn barnacle, Amphibalanus amphitrite (A.…”

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

“…However, such wide, nearly cosmopolitan distributions were recently questioned (Hutchings and Kupriyanova 2018). Genetic studies revealed that this warm temperate intertidal species is restricted to South African coasts and that taxa under this name from other areas belong to a large complex of regionally distributed species (Simon et al 2019;Pazoki et al 2020;Sivananthan et al 2021).…”