Lacydonia quadrioculata Magalhães, Bailey, Brock & Rizzo, 2012, sp. nov.

Lacydonia quadrioculata sp. nov.

Figures 1 (A–D), 2 (A–E) and 3 (A–F)

Material examined. Pacific Ocean – reference stations of Waianae outfall, west shore of Oahu, Hawaii: Holotype: station W1R6, 21° 24' 21.3444" N, 158° 11' 12.3864" W, May /11, 31 m (USNM 1191163); Paratypes: station W2R4, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May/11, 27 m (1, USNM 1191164); station W1R3, 21° 24' 21.3444" N, 158° 11' 12.3864" W, May /11, 31 m (3, USNM 1191165); station W1R1, 21° 24' 21.3444" N, 158° 11' 12.3864" W, May /11, 31 m (1, BPBM R3634); station W2R3, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May/11, 27 m (1, BPBM R3635); station W2R1, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May/11, 27 m (1, USNM 1191166; 4 on stub, USNM 1191167); station W2R5, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May /11, 27 m (1, BPBM R3636); station W1R4, 21° 24' 21.3444" N, 158° 11' 12.3864" W, May /11, 31 m (1, BPBM R3637). Non– type material: station W2R5, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/03, 27 m (3); station W2R6, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/95, 27 m (4); station W2R3, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/95, 27 m (1); station W2R3, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May/93, 27 m (1); station W2R2, 21° 25' 7.2258" N, 158° 11' 18.2574" W, May/93, 27 m (1); station W2R6, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/95, 27 m (3); station W2R6, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/00, 27 m (1); station W2R4, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/97, 27 m (1); station W2R5, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/00, 27 m (2); station W2R4, 21° 25' 7.2258" N, 158° 11' 18.2574" W, Jan/00, 27 m (1). East shore of Oahu, vicinities of Kailua Bay, Mokapu outfall, stations near to the outfall diffuser: station B2R4, 21° 27' 24.8" N, 157° 43' 01.4" W, Mar/92, 34 m (1); station ZR2, 21° 27' 25.9" N, 157° 43' 01.8" W, Mar/98, 34 m (2). South shore of Oahu, Mamala Bay, reference stations of Barbers Point outfall: station HB2R2, 21° 17' 00.1" N, 158° 01' 21.3" W, Mar/07, 60 m (1); station HB1R2, 21° 16' 50.7" N, 157° 59' 19.8" W, Mar/07, 65.5 m (1).

Description. Holotype 2 mm long, 0.2 mm wide for 21 chaetigers. Paratypes and non-type material ranging from 0.8–3.0 mm long, 0.1–0.25 mm wide across parapodia for 12–26 chaetigers. Body dorso-ventrally flattened, widest on anterior chaetigers and smoothly tapering on posterior end (Fig. 2 A). Preserved specimens with varied body color, mostly pale yellow to light olive green but some darker, brownish yellow (Fig. 3 F). Dark brown pigments usually present on prostomium and anterior margin of achaetous segment (Fig. 3 E); dark brown pigment spots present in all chaetigers (rarely on achaetous segments), one spot per parapodium, near to notopodial base (Figs 1 A, 3E); one pair of pigment spots present on pygidium (Fig. 1 D). Pigment spots faded on older preserved specimens and sometimes more than one spot could be present per parapodium. Segmental bands of cilia present throughout, best seen with SEM (Fig. 2 C), but sometimes presented darker coloration in relation to rest of the body, probably due to adhering particles. Pharynx inverted in all specimens but visible through body wall, usually between chaetigers 3–5, with transverse musculature and a pair of large lateral glands (Fig. 1 A). Anterior end of gut beginning on chaetigers 4–5 or 5–6, similar throughout.

Prostomium twice wider than long (Fig. 1 B); three specimens (out of 31) with prostomium just 1.5x wider than long (Fig. 2 B) and one with prostomium as long as wide; rounded anteriorly and with fields of cilia on anterior and posterior end and anteriorly to median antenna (Fig. 2 B). A pair of anterior antennae and a median antenna located on middle of prostomium (Figs 1 A, 2B); all antennae similar in length and shape, short, digitiform to conical; median antenna sometimes shorter than anterior antennae and positioned on posterior half of prostomium (Fig. 2 B). A pair of palps present ventrally on anterior margin of prostomium, similar in shape, length and position to anterior antennae (Figs 1 B, 2C). Dark brown eyespots present in two pairs in most specimens but sometimes only one pair well defined and other scattered dark brown spots present; first pair postero-lateral to median antennae and second pair slightly anterior to central pair but near to edge of prostomium (Figs 1 A, 3E). Peristomium not observed dorsally and presumably limited to lips. Distinct nuchal organs present on dorso-posterior side of prostomium, continuing laterally and ventrally but not forming a complete ring; deep groove with long nuchal cilia observed with SEM, although groove seen in light microscopy (Fig. 2 B, D).

Segment 1 achaetous with a single pair of short, digitiform cirri, well-developed and slightly shorter than following chaetigers. Segments 2–4 uniramous (chaetigers 1–3), with reduced notopodial lobes and a pair of ovoid dorsal cirri with pointed tips. Notochaetae and developed notopodial lobe from segment 5 (chaetiger 4); up to 6 long capillaries with barbed edge (Figs 1 C, 3B). Neuropodium with conical lobe, longer than notopodial lobe; neurochaetae up to 12 composite spinigers with long, serrated cutting edge and long and pointed supracicular lobe (Fig. 3 B); ventral cirrus slightly smaller than dorsal cirrus but with similar shape. Notopodial cirri inserted near to notopodial base on anterior segments but distally on notopodial lobe on posterior segments (Fig. 3 A); neuropodial cirri inserted on last third of neuropodial lobe throughout.

Pygidium with 2 long lateral cirri and an elongated ventral papilla, medially located in relation to paired cirri (Figs 1 D, 3C).

Remarks. By the presence of small eyes, Lacydonia quadrioculata sp. nov., is most similar to L. mikrops from Antarctica. However, L. quadrioculata has two pairs of small eyes with trapezoidal arrangement and L. mikrops has only one pair of eyes that is positioned at the edges of the prostomium (Ehlers 1913; Hartman 1964). The parapodia of both species appear to be very similar with notopodial lobes shorter than neuropodial lobes and notopodial cirri slightly larger than neuropodial cirri. The prostomium is twice wider than long in L. quadrioculata and just a little wider than long in L. mikrops (see Table 1). The pharynx in L. quadrioculata is as long as 3 chaetigers (chaetigers 3–5) while shorter in L. mikrops and limited to chaetigers 3 and 4 only. Anal cirri and papilla are short and spindle-like in L. mikrops and digitiform with ventral papilla slender than cirri in L. quadrioculata. The relevant characters of all described species were taken from the original descriptions or redescriptions and tabulated for comparative purposes (Table 1).

Reproduction. Two female individuals with 19 and 20 chaetigers were observed with large intracoelomic embryos from chaetiger 8 backwards (Fig. 3 F). Embryos were as large as 0.2 mm in diameter, whitish in color. Etymology. The epithet of this new species refers to the presence of four eyes, unique in the genus. Distribution. The type locality is off Waianae at 27 m on the west shore of Oahu, but this species has also been collected at the south (Mamala Bay) and east (Kailua Bay) coasts of Oahu, Hawaii (USA) with a depth range of 27–65.5 m.