(Fig. 1 A–K)
Material examined. Holotype: Adult female from Ponta do Cabo Branco beach (07°09' 16 ''S; 34 ° 47 '00''W), João Pessoa, Paraíba Brazil (CIM-POL-UFPB 238). Paratypes: two specimens from same locality (CIM- POL-UFPB 26, 255).
Diagnosis. Prostomium rounded anteriorly, forming a high, arched cephalic keel; nuchal grooves elliptical, opening posteriorly. A dorsal peristomial furrow extends from either side of mouth behind the prostomium. Colour dark beige on setigers 4–17. Four to 7 acicular spines on setigers 1–3 (1: 4; 2: 5; 3: 7). Posterior end terminating in cup-shaped anal funnel, with triangular, equal-sized anal cirri and concave sides.
Description. Body complete, with 22 setigers and two pre-anal asetigerous segments; total length 110 mm; segments become gradually larger. Setiger 1-4 with 2 mm wide, setiger 5 and subsequent setigers 4 mm wide, continuing until first asetigerous segment. Posterior region 4 mm long, formed by two asetigerous segments and anal funnel. Prostomium fused to peristomium, forming a well-defined head. Prostomium rounded anteriorly, forming a high arched keel (Fig. 1 A). Short curved nuchal organs opening posteriorly (Fig. 1 B). Peristomium with several transverse folds, extending beyond posterior edge of prostomium; ocelli and pigment spots absent. Mouth ventral, with two well-developed lips, anterior lip larger, slightly pigmented, with numerous dark spots anteriorly, overlapping unpigmented posterior lip.
Setigers 1–3 light-yellow, with anterior borders inflated. Neuropodia of setigers 1–3 with honey-coloured, strongly pointed acicular spines (1: 4, 2: 5, 3: 7) (Fig. 1 C). Posterior half of setigers 4–17 with dark beige pigment, after which colour changes to light yellow. Parapodial lobes light yellow throughout. Posterior to setiger 4, neuropodia with a simple row of rostrate uncini. Each uncinus with a main fang and 7–8 accessory teeth; long, thin fibrils below main fang (Fig. 1 D, 1 E); each uncinus perpendicular to body wall; long anterior shaft, manubrium prominent on center of uncinus; shorter and curved posterior shaft; each uncinus with darkly coloured patch. After setiger 4, neuropodia with a variable number of uncini: 4: 30, 5: 36, 6: 43, 7: 49, 8: 49. Notopodia of setigers 1–22 with fascicles of long and narrow capillary setae. These capillaries arise from a short torus and are of three kinds: long, thin, and smooth (Fig. 1 F); long, bristled, with or without bifurcate tips, shaft yellow, transparent and smooth (Figs. 1 G, 1 H); and smooth unilimbate, with margins hatched, and with very narrow apices, shaft strong, yellow, transparent (Fig. 1 I).
Scales bars: 1 (J) 2 mm; 1 (A, B, K): 1mm; 1 (C, D, E, F, G, H, I): 0,5 mm.
Two short, equal, pre-anal asetigerous segments present, anterior one with a posterior border overlapping posterior segment. Anal funnel cup-like, bearing 21 sub-triangular equal-sized anal cirri (Fig. 1 J); anus terminal, located in center of funnel, pillow-shaped, bordered by numerous digitiform papillae of different sizes (Fig. 1 K).
Tube up to 200 mm long, 10 mm wide, composed of grains of sand, fragments of sea-urchin spines, and pieces of mollusk shells pasted to a fine and resistant yellowish membrane. The tubes form galleries extending below one or several rocks.
Habitat. Specimens live under intertidal rocks.
Etymology. The species name is for Dr. Paulo da Cunha Lana, Professor of the Universidade Federal do Paraná, who has contributed much to the knowledge of Brazilian polychaetes.
Remarks. Nicomache (Nicomache) antillensis Augener, 1922 differs from N. (Nicomache) lanai sp. nov. by having the prostomium forming a rounded and little prominent dorsal keel, the nuchal grooves almost perpendicular to the keel and slightly curved near the apex with the shape of an inverted V, for presenting a variable number of setigers (22–23), by having 3–5 acicular spines on setigers 1–3, and for having an anal funnel with convex sides bordered by numerous similar cirri (Augener 1922; Treadwell 1924; Jiménez-Cueto & Salazar-Vallejo 1997). Nicomache (Nicomache) lumbricalis (Fabricius, 1780) differs from N. (Nicomache) lanai sp. nov. by having a hook-like prostomial projection overhanging the mouth, nuchal grooves long and parallel slits with their anterior ends curved outwards, by having one acicular spine on setigers 1–3, and by always having 23 setigers. The two species are similar in the concave, cup-shaped anal funnel (Arwidsson 1907; Fauvel 1928; Monro 1930; Treadwell 1948; Pettibone 1954; Day 1967; Imajima & Shiraki 1982; Branch 1994; Imajima 1997, 2000). Nicomache (Nicomache) monroi Hartman, 1967 differs from N. (Nicomache) lanai sp. nov. by having reddish anterior segments, a prostomium forming a high cephalic keel, straight and parallel nuchal grooves, and by having 1–2 acicular spines on setigers 1–3. The two species are similar in the nature of the cup-shaped anal funnel, but differ in the shape of the anal cirri (Monro 1930; Hartman 1967). Nicomache (Nicomache) plimmertonensis Augener, 1926 differs from N. (Nicomache) lanai by having straight nuchal grooves that form an angle of 90 anteriorly, 24 setigers, one spine on setigers 1–3, and a long anal funnel with sides strongly curved outwards (Augener 1926). Nicomache (Loxochona) canadensis McIntosh, 1913 differs from N. (Nicomache) lanai sp. nov. by having an obliquely truncate prostomium that forms a nose-shaped keel in lateral view, hooked nuchal grooves with one of the tips parallel to the keel, curved posteriorly and with the anterior part forming a sharp angle, and no more than two acicular spines on setigers 1–3. The two latter species are similar in having a concave anal funnel, but in N. (Loxochona) canadensis the borders are asymmetric (McIntosh, 1913; Treadwell, 1948).