Description of a new Promastobranchus species (Annelida, Capitellidae) from Chinese coasts, with molecular evidence for intraspecific variation in the number of thoracic chaetigers

By

Lin, Jun-hui
García Garza, María Elena
Mou, Jian-Feng
Lin, Heshan

Type

Article

Date of Publication

2023

Original Publication

ZooKeys

Volume

1174

Pages

1--14

Subjects

Mitochondrial markers , nuclear markers , Polychaete , South China Sea , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.1174.106624

 

Abstract

Promastobranchus Gallardo, 1968 is a small genus in the polychaete family Capitellidae, and the available records are largely reported from the Indo-West Pacific region. Although Gallardo (1968) and Green (2002) noted that Promastobranchus species had intraspecific variation in the number of thoracic chaetigers when they described the two previously known species, this variation has not been corroborated using molecular evidence. In this study, a new Promastobranchus species, Promastobranchus variabilissp. nov., is described based on 29 specimens collected from the Beibu Gulf, South China Sea. The new species is mainly characterized by having a tessellated epithelium in the anterior thorax, nine teeth in three rows above the main fang in the abdominal hooks, four pairs of genital pores located on the intersegmental grooves between chaetigers 9 and 13, and its unique methyl green staining pattern. Comparisons of multiple gene markers (16S, 18S, 28S, and H3) revealed no genetic divergence (K2P < 0.003) among these type specimens with 9–13 thoracic chaetigers. In other words, the new species exhibited morphological variability in the number of thoracic chaetigers during ontogeny, and this character was unsuitable to differentiate Promastobranchus species as the ranges overlap among Promastobranchus species. This is the third Promastobranchus species known in the world, and it is now recorded along the Fujian coast.