INTRODUCTION
Fabriciidae is a family composed of small sized polychaetes with a worldwide marine distribution. Most of the species inhabit shallow waters or are intertidal on hard substrates. Few species are known from depths of up to 100 m, and the only species, Raficiba barryi, is known from continental shelf depths (317–335 m).
Until recently, Fabriciidae was regarded as a subfamily, Fabriciinae Rioja (Reference Rioja1923), within Sabellidae Latreille, 1825. Fitzhugh (Reference Fitzhugh1989) conducted the first cladistic analysis of Sabellidae showing series of synapomorphies supporting the monophyly of newly formulated Fabriciinae and Sabellinae Chamberlin, 1919 subfamilies. However, synapomorphies grouping Fabriciinae and Sabellinae together as Sabellidae were limited. Based on molecular data, Kupriyanova & Rouse (Reference Kupriyanova and Rouse2008) subsequently showed that Serpulidae Rafinesque (1815) is the sister group to Fabriciinae, with Sabellinae being the sister group to this assemblage. The inclusion of Serpulidae as a subfamily of Sabellidae would have led to radical changes to the taxonomy within Serpulidae, so these authors removed Fabriciinae from Sabellidae and gave the taxon the rank of family (i.e. Fabriciidae).
Following the systematic revision by Fitzhugh (Reference Fitzhugh1989), the monophyly of Fabriciidae is supported by a series of morphological synapomorphies. The relationships among genera have then been explored using morphological data in a series of papers by Fitzhugh et al. (Reference Fitzhugh, Giangrande and Simboura1994) and Fitzhugh (Reference Fitzhugh1990, Reference Fitzhugh1991, Reference Fitzhugh1995, Reference Fitzhugh1996, Reference Fitzhugh1998, Reference Fitzhugh1999, Reference Fitzhugh2001, Reference Fitzhugh2002). In addition, a further series of potential apomorphies for the taxon was identified by Rouse (Reference Rouse1995a) based on reproductive characters.
The genus Echinofabricia was recently described by Huang et al. (Reference Huanga, Fitzhugh and Rouse2011), who conducted an integrative analysis based on 50 morphological characters and three nuclear sequence markers. This genus is the sister group to Manayunkia and is located in the most plesiomorphic area of the phylogenetic Fabriciidae tree. It is easily recognizable for the presence of four abdominal chaetigers, epidermal emergent spicules on the epithelium surface, and peristomial spermathecae in females.
In the present paper we describe a new species belonging to the Echinofabricia genus which is reported for the first time in the Mediterranean area.
MATERIALS AND METHODS
Examined material was present in the authors' collection and derived from faunistic work conducted at Porto Pozzo (Sardinia) during 1987. Samples were collected with a Van Veen Grab, fixed in 4% formalin and then preserved in 70% alcohol. One specimen was fixed for scanning electron microscopy (SEM) in 2.5% glutaraldehyde, dehydrated in a graded alcohol series, gold coated after critical point drying, and examined with a Phillips 505 scanning microscope. Holotype is deposited at the MNCN (Museo Nacional de Ciencias Naturales, Madrid, Spain). Paratypes are deposited at the PCZL (Polychaete collection at the Zoological Laboratory of Lecce).
SYSTEMATCS
Family FABRICIIDAE Kupriyanova and Rouse Reference Kupriyanova and Rouse2008
Genus Echinofabricia Huang, Fitzhugh and Rouse 2011
Echinofabricia rousei sp. nov.
(Figures 1 and 2)
TYPE MATERIAL
Holotype: a complete specimen preserved in 70% ethanol. Total length 4 mm and 0.4 mm wide, crown 1.00 mm. Porto Pozzo (Sardinia); 41.12′N 9.16′E, 6 m sand with Caulerpa prolifera (MNHN 16.01/14318.); July 1987.
Paratype: a complete specimen preserved in 70% ethanol. Total length 3.8 mm and 0.4 mm wide, crown 0.9 mm. Porto Pozzo (Sardinia); 41.12′N 9.16′E, 6 m sand with Caulerpa prolifera.
ADDITIONAL MATERIAL
One specimen from the same locality, one specimen from the Gulf of Naples collected on hard bottom at 2 m depth. Coll. M. Cristina Gambi, 2004.
DIAGNOSIS
Body with eight thoracic segments and four abdominal segments. Epithelium of most of the body surface with emergent spicules (upon fixation) that may splay out. Branchial crown with three pairs of radioles, each radiole with 5–6 pairs of pinnules terminating at the same height. Branchial hearts present, but poorly developed (Figure 1A, B). Ventral filamentous appendage at ventral margin of each branchial lobe, vascularized, unbranched, about half of the length of radioles (Figure 1A, B). Dorsal lips well developed, triangular ridges with dorsal margins separated from proximalmost pinnules of dorsal radioles (Figure 1D). Anterior peristomial ring dorsally shorter than posterior peristomial ring. Anterior margin of anterior peristomial ring with a wide subsquared ventral lobe (Figure 1B). Superior thoracic notochaetae elongate, narrowly hooded (Figure 1E), three chaetae per fascicle (Figure 2A). Inferior thoracic notochaetae of all chaetigers elongate and narrowly hooded (Figure 1E), six per fascicle (Figure 2A). Pseudospatulate absent. Acicular thoracic uncini in chaetigers 2–8, 8–9 per fascicle (Figure 2B), with dentition above main fang present as a series of uniformly small teeth (Figure 2C), appearing as a hood and difficult to see under light microscope (Figure 1C). Abdominal neuropodia with elongate narrowly hooded chaetae (Figure 1F), 2–3 per fascicle. Abdominal uncini with dentate region with 10–11 teeth in profile, 5–6 teeth per row and with a manubrium about two times as long as dentate region (Figures 1G & 2D). From 21 to 33 abdominal uncini in each torus. Peristomial and pygidial eyes absent.
Fig. 1. Echinofabricia rousei sp. nov. (A) entire worm, lateral view; (B) entire worm, dorsal view, and close-up of ventral view of the anterior end; (C) thoracic uncini; (D) part of radiolar crown showing a dorsal lip and an unbranched vascularized ventral filamentous appendage; (E) superior and inferior thoracic chaetae; (F) abdominal chaeta; (G) abdominal uncinus.
Fig. 2. Echinofabricia rousei sp. nov. Scanning electron microscopy photographs: (A) thoracic chaetae; (B) thoracic uncini; (C) details of thorac uncinus head; (D) abdominal uncini.
ETYMOLOGY
The species was named after Gregory Rouse (Scripps Institution of Oceanography) who made significant contribution to the study on Sabellidae and Fabriciidae.
REMARKS
According to Fitzhugh (Reference Fitzhugh1989), this genus is very distinctive in that its species produces calcareous spicules over the body surface. This feature, however, was not so evident in the Mediterranean material, probably due to the bad preservation. The same can be true for the absence of eyes which usually are visibile only in live material (Huang et al., 2011). The genus is also distinctive in having four abdominal chaetigers. The number of abdominal chaetigers may be size related, with smaller specimens having three chaetigers, while larger ones have four. However, the specimens of E. cf dubia described by Rouse (Reference Rouse1995b) (=A. alata), which were very small sized though sexually mature, showed four chaetigers. Due to the bad preservation of the Mediterranean material it was impossibile to distinguish the spermathecae, or to establish the sex of the specimens. Lastly, another peculiar feature of the genus is the shape of thoracic uncini where teeth above the main fang are very numerous and uniform in size, imparting a very characteristic shape to the distal ends. This feature was considered the plesiomorphic type of thoracic uncinus within the Fabriciidae (Fitzhugh, Reference Fitzhugh1998).
This is the first finding of this genus in the Mediterranean Sea. The presently described material was collected in the Mediterranean about 25 years ago, and due to its peculiarity, it was hypothesized that it was a new genus closely related to Augeneriella dubia described by Hartmann-Schröder (Reference Hartmann-Schröder1965) (Giangrande, personal observation). At that time it was impossible to examine Hartmann-Schröder's material, however Fitzhugh (Reference Fitzhugh1989) confirmed that A. dubia belonged to this new taxon. The genus was partially described by Fitzhugh (Reference Fitzhugh1989) under the name of Genus A and has always been referred to subsequently under this name. After the Fitzhugh revision, another Augeneriella species was described from the Great Barrier Reef (Hartmann-Schröder, Reference Hartmann-Schröder, Hartmann-Schröder and Hartmann1991) as A. alata on the basis of a single specimen, which was proved to belong to the Echinofabricia genus as well (Huang et al., 2011). At present three species belong within the genus: E. goodhartzorum Huang et al., 2011, described for the Caribbean, E. dubia (Hartmann-Schröder, Reference Hartmann-Schröder1965) described for the East Pacific (Hawaii) and E. alata (Hartman-Schöeder, Reference Hartmann-Schröder, Hartmann-Schröder and Hartmann1991) for Australia.
The Mediterranean material differs from E. goodhartzorum and E. dubia in more squared ventral peristomial lobe, in the larger number of abdominal uncini having a shorter manubrium, and in the larger number of inferior thoracic chaetae. It differs from E. goodhartzorum also in the longer unbranched ventral filamentous appendage. Lastly, it differs from E. alata in the distribution of denticles over the main fang of the thoracic uncini, that in the Mediterranean specimens leave only a small portion not covered. Moreover, Mediterranean specimens have a number of thoracic chaete and abdominal uncini different from that reported for E. alata (33 uncini with 10 teeth vs 21 uncini with 7 teeth) and a bigger size.
