A new gregarious sabellid worm from the Gulf of California reproducing by spontaneous fission (Polychaeta, Sabellidae)

Abstract

A new species of the sabellid genus Pseudobranchiomma is described from 50 cm depth in dock fouling from the southern Gulf of California. Pseudobranchiomma schizogenica sp. nov., belongs to a group of six species characterized by having radiolar serrations extending for most of the radiolar length. The new species is characterized by the presence of a unique set of features related to the covering of the peristomium by lateral collar margins, the shape of the first ventral shield, the size of interramal eyespots, and the width of the hood of thoracic and abdominal spinelike chaetae. Information about live and post-fixed colour, glandular pattern and reproduction is also provided. The new species described here is compared with all species in the former group. The presence of paired patches of cilia without heads (kinocilia-type) on ventral lappets and ventral shields of the collar, thorax and abdomen is documented for the first time in the genus Pseudobranchiomma. Dense aggregations of Pseudobranchiomma schizogenica sp. nov., on docks from the southern Gulf of California are predominantly a result of asexual reproduction taking place during summer, when 82% of the population reproduces by architomy.

A taxonomic guide to the fanworms (Sabellidae, Annelida) of Lizard Island, Great Barrier Reef, Australia, including new species and new records

“…This species resembles Pseudobranchiomma schizogenica Tovar-Hernández & Dean, 2014, described from the Gulf of California, Eastern Pacific, in the colour pattern, the presence of serrated radiolar flanges along radioles, the absence of radiolar eyes, the shape of the collar -with lateral collar margins oblique and covering the anterior peristomial ring -and the conspicuous interramal eyespots. However, some observed differences include the number of serrations along the flanges, 3-6 in specimens described herein and 6-11 in P. schizogenica, as well as the shape of the radiolar serrations, step-like in the Australian specimens and circular in cross-section in P. schizogenica (Tovar-Hernández & Dean 2014 Description of material examined. Specimens up to 20 mm long, 1 mm wide, 8-12 thoracic and numerous abdominal chaetigers.…”

Combined morphological and molecular data unveils relationships of Pseudobranchiomma (Sabellidae, Annelida) and reveals higher diversity of this intriguing group of fan worms in Australia, including potentially introduced species

“…It is characterised by a combination of features: up to ten pairs of short flat serrations along each radiole, 5–6 rows of teeth over the main fang in thoracic uncini, a branchial crown that has narrow irregular bands of purple colour (or “splotches”), with often a reduced number of thoracic segments (as few as four, indicating evidence of imperfect regeneration after asexual reproduction), large interramal eyespots, and a collar ventral shield that is trapezoidal in shape (according to Tovar-Hernández and Dean 2014). The Australian specimen, when stained with methyl green, displayed a similar staining pattern on the collar ventral shield as that described for Pseudobranchiomma schizogenica Tovar-Hernández and Dean, 2014, although the authors state that this feature differentiates Pseudobranchiomma schizogenica from Pseudobranchiomma emersoni and Pseudobranchiomma orientalis (Tovar-Hernández & Dean, 2014).…”

“…According to: † Tovar-Hernández and Dean 2014; ‡ Knight-Jones and Giangrande 2003; § Nogueira et al 2006; ¶ Geoff Read, pers. comm.…”

“…Their tubes are made of muddy sediment embedded into a mucous matrix usually attached to hard substrates. Some species of Pseudobranchiomma are considered fouling organisms, settling on artificial surfaces and in some cases are common in harbour environments (Russell and Hewitt 2000, Swami and Udhayakumar 2010, Tovar-Hernández and Dean 2014). At least six species have been described as reproducing asexually, by fission of posterior segments, also known as scissiparity (Nogueira and Knight-Jones 2002, Knight-Jones and Giangrande 2003, Tovar-Hernández and Dean 2014).…”

“…There are 16 species currently circumscribed within the genus (Nogueira and Knight-Jones 2002, Knight-Jones and Giangrande 2003, Tovar-Hernández and Dean 2014). The most conspicuous morphological interspecific differences within Pseudobranchiomma are the absence or presence of serrated radiolar flanges (paired lappets along the radioles lateral margins that may be few in number or extend along the full radiolar length), absence or presence of paired compound radiolar eyes, shape of the ventral collar glandular shield (rectangular, M-shaped, trapezoidal or divided in two), absence or presence of pinnular appendages, number of thoracic segments (Knight-Jones and Giangrande 2003), together with a broad variety of colour-morphs (Nogueira and Knight-Jones 2002, Knight-Jones and Giangrande 2003, Tovar-Hernández and Dean 2014).…”