Lacydoniidae Bergström, 1914
Lacydonia Marion & Bobretzky, 1875
Lacydonia sp. 1
Voucher. VINSON WEST: station 5MFB.
Diagnosis. Voucher specimen complete; 4mm long and 1.2 mm wide (including parapodia) for 33 chaetigers. Body dorso-ventrally flattened; preserved specimens pale yellow without pigmentation. Pharynx inverted in all specimens but visible through body wall. Prostomium about three times wider than long; rounded anteriorly; with a pair of anterior antennae and a median antenna located on middle of prostomium, all antennae similar in length and shape, short, globular to digiform. A pair of palps present ventrally on anterior margin of prostomium, slender and slightly longer than antennae. Segment 1 achaetous with a single pair of short, ovoid to digiform tentacular cirri. Chaetigers 1–3 uniramous. Notopodia and neuropodia similar in shape and size, both long and cylindrical with well developed lobes; dorsal and ventral cirri not observed. Notochaetae present from chaetiger 4; about 20 long capillaries with serrated edge, serration widely spaced. Neurochaetae about 30 composite spinigers (4 of those much shorter than others), with long unidentate blades with finely serrated edge. The last three chaetigers very reduced. Pygidium rounded lobe, no cirri observed (missing?).
Remarks. Genus Lacydonia contains 10 valid species (see comparative table in Magalhães et al. 2012), broadly divided into occulate and annoculate groups. Three species are known from the area: L. mikrops Ehlers, 1913; L. oculata Hartman, 1967 (=synonym of L. antarctica) and L. gorda Hartmann-Schröder, 1993. Of these only the last species lacks eyes and is therefore most similar to Falkland Island specimen. Falkland Island specimen appear to differ from L. gordia in development of notopodia (these are long in FI specimen not truncated). However as Magalhães et al. (2012) noted that most known species of Lacydonia are known only through a single or few type specimens and ontogenetic variation is unknown. Hartmann-Schröder’s (1993) description is also rather brief. Without molecular data it is difficult to currently establish if these constitute the same species. Given the morphological differences observed here, we assign Falkland Island specimens to morphospecies Lacydonia sp. 1 until more evidence becomes available.
REFERENCES
Ehlers, E. 1913. Die Polychaeten-Sammlungen der deutschen Südpolar- Expedition, 1901-1903. Deutsche Südpolar-Expedition 1901-1903 im Auftrage des Reichsamtes des innern herausgegeben von Erich von Drygalski Leiter Expedition, 13(4): 397-598, plates XXVI-XLVI., available online at http://www.biodiversitylibrary.org/item/18731#page/461/mode/1up*
Hartman, O. 1967. Polychaetous annelids collected by the USNS Eltanin and Staten Island cruises, chiefly from Antarctic Seas. Allan Hancock Monographs in Marine Biology, 2: 1-387
Hartmann-Schröder, G. (1993). Die Polychaeten der "Polarstern" -Reise ANTX/1b zur Antarktischen Halbinsel und Isla de los Estados (Feuerland, Argentinien) 1991. Teil 1: Polynoidae bis Iphitimidae. Mitteilungen aus den Hamburgischen Zoologischen Museum und Institut. 90: 127-150.
Magalhães, Wagner F.; Bailey-Brock, Julie H.; Rizzo, Alexandra E. 2012. Lacydonia quadrioculata, a new lacydoniid (Polychaeta: Phyllodocida) from Oahu, Hawaii. Zootaxa (3589): 65-76
