Family SYLLIDAE

Pionosyllis (Malmgren)

© Copyright © Michael Marmach, Museum Victoria, Vic

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Introduction

Syllids are found in most marine and estuarine habitats from the intertidal to the deep sea and at all latitudes. They are often among the most diverse, and even sometimes the most abundant of polychaete families found in benthic samples from both soft substrates and from fouling communities, though different taxa tend to be present in different substrates. Many syllids, especially members the subfamilies Autolytinae and Syllinae, apparently consume the internal fluids of bryozoans, sponges, hydrozoans and other invertebrates. The toothed pharynx is used to puncture the prey and the proventricle is a pump that sucks out the fluids. Members of the Eusyllinae include species which feed on diatoms and detritus, and others that are carnivores. Members of the diverse and taxonomically challenging Exogoninae are most common on soft sediments; these are apparently selective deposit feeders.

Syllids are generally small, slender worms with three antennae and (usually) conspicuous dorsal cirri. They are easily distinguished from all other polychaetes by the proventricle, a cylindrical muscularised region of the anterior digestive tract; the regular, almost mesh-like structure of the proventricle is often visible through the body wall.
Syllids range in size from interstitial species only a few mm in length to species as long as several cm.

Figures of 32 genera and 77+ species were given by Beesley et al. (2000: App. 1) for representation of the family in Australian waters, and 66 genera and 819+ species worldwide. The Australian fauna is incompletely studied and undoubtedly many more taxa remain to be described. This database includes 165 species from 34 genera.

See Glasby (2000) for detailed treatment of the family.

Database Notes

checked against DELTA CD, 2003 by RTJ

Diagnosis

General features. Body shape vermiform, or grub-shaped; dorsoventrally flattened, or not dorsoventrally flattened; segments numerous (more than about 15); regionation absent. Epidermis more-or-less smooth, or papillate, irregularly arranged papillae (rarely). Pygidium simple ring or cone. Pygidial appendages present; one pair of cirri, or one pair of cirri and single medial papilla.
Head & head structures. Head discrete and compact, dorsal to mouth. Prostomium rounded to oval (anteriorly truncate). Eyes present; two pairs, or three pairs; situated on prostomium; without lenses, or compound with lenses. Prostomial antennae present; include paired anterolateral ones and single medial one (median one rarely absent); smooth, or articulated. Palps paired (may be reduced or fused); unarticulated; ventrolateral. Nuchal organs indistinct paired dorsolateral patches, or paired posterior projections. Peristomial ring absent.
Pharynx & pharyngeal apparatus. Foregut a muscular axial pharynx; without jaws (although fused teeth may resemble jaws); without teeth, or with a single tooth, or with a trepan (fused teeth); surface smooth (chitinous); distal ring of papillae present; proventricle present.
Body segments & parapodia. First segment with tentacular cirri (rarely absent). Tentacular cirri 1–2 pair(s); arise on a single segment; internal aciculae absent. First chaetiger with neurochaetae only. Parapodia uniramous throughout; notopodial lobes absent; neuropodial lobes represented by at least one chaetal lobe. Dorsal cirri more-or-less cirriform. Ventral cirri absent, or present, cirriform or tapering. Branchiae absent.
Chaetae. Notochaetae absent. Aciculae present; in ventral position (=neuroaciculae). Capillary chaetae present; hair-like; smooth. Spines absent, or present in most or all chaetigers; in neuropodia only; slightly curved and more-or-less smooth (may be bifid distally). Hooks absent. Compound chaetae absent, or present; appendage distally tapering to slender tips (=spinigerous), or distally curved (=falcate); appendage not canaliculated; appendage without hoods or guards; joint distinctly asymmetrical (=heterogomph); joint effected by ligament(s); shaft tapering slightly or evenly thick from emergence to joint; shaft without distinct core. Compound falcigers present in most or all chaetigers.
Tube & burrow. Tube absent or unconsolidated. Burrow traces absent.

The above description was generated from: 'C.J. Glasby & K. Fauchald (2002 onwards). POLiKEY. An information system for polychaete families and higher taxa: Version 1: September 2002.'
(See ABRS website: Online Resources: Polikey, for Version 2, released June 2003)

General References

Beesley, P.L., Ross, G.J.B. & Glasby, C.J. (eds) 2000. Polychaetes & Allies: The Southern Synthesis. Fauna of Australia Vol. 4A Polychaeta, Myzostomida, Pogonophora, Echiura, Sipuncula. Melbourne : CSIRO Publishing Vol. 4 Part A xii 1-465 pp.

Glasby, C.J. 1993. Family revision and cladistic analysis of the Nereidoidea (Polychaeta: Phyllodocida). Invertebrate Taxonomy 7: 1551-1573

Glasby, C.J. 2000. Family Syllidae. pp. 161-167 in Beesley, P.L., Ross, G.J.B. & Glasby, C.J. (eds). Polychaetes & Allies: The Southern Synthesis. Fauna of Australia Vol. 4A Polychaeta, Myzostomida, Pogonophora, Echiura, Sipuncula. Melbourne : CSIRO Publishing Vol. 4 Part A xii 1-465 pp.

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