Xandaros Maciolek, 1981

Prostomium blunt, anteriorly truncate or rounded, anterior margin with entire anterior margin. Lateral horns absent. Caruncle absent. Occipital antenna absent. Nuchal organ short, at most one segment long. Palps simple, lacking basal sheath. Dorsal ridge connecting bases of branchiae on chaetiger 1 absent. Prominent dorsal collar on setiger 2 absent. Dorsal branchiae present, first present on chaetiger 4. Dorsal branchiae absent from many median and posterior chaetigers, last present on chaetiger 10–13. Dorsal branchiae continuous. Dorsal branchiae free and separate from notopodial lamellae throughout, all simple (but wrinkled). First branchiae without process at base on anterior face. Accessory branchiae arising from posterior part of notopodium absent. Ventral branchiae absent. Chaetiger 3 without filament at base of branchiae. Dorsal crests absent. Ventral crests absent. Chaetiger 1 notopodium absent. Chaetiger 1 notochaetae absent. Neuropodial lobe of chaetiger 2 rounded, approximately symmetrical. Neuropodial lobes of posterior chaetigers a single lobe. Interparapodial pouches absent. Chaetigers 2–4 similar, not strongly differentiated. Chaetiger 5 unmodified, similar to subsequent chaetigers. Posterior modified notochaetae absent. Notopodial hooded hooks absent. Neurochaetae of chaetiger 1 simple capillaries similar to those of subsequent chaetigers. Neuropodial hooded hooks present. Neuropodial hooded hooks with accessory tooth or teeth above the main fang, 1 accessory tooth (bidentate), secondary tooth closely applied to the main fang, about 45º. Shaft of neuropodial hooded hooks of constant thickness, lacking a constriction. Neuropodial sabre chaetae absent. Neuropodial spines present, simple (from chaetiger 3, grading into bidentate hooded hooks by mid-body chaetigers). Embedded bunches of notopodial needle chaetae absent. Pygidium with 4 unequal lobes.

Description generated from: Wilson, RS & McDiarmid, H 2013. Spionidae (Polychaeta)- A DELTA database of genera, and Australian species. Version 2; originally published as In RS Wilson, PA Hutchings & CJ Glasby (eds) Polychaetes: An Interactive Identification Guide. CSIRO Publishing, Melbourne.

Additional references:
Maciolek, NJ. 1981. Spionidae (Annelida: Polychaeta) from the Galapagos Rift geothermal vents. Proceedings of the Biological Society of Washington 94, 826-837.