Notaulax yamasui, Nishi, Eijiroh, Gil, Joao, Tanaka, Katsuhiko & Kupriyanova, Elena K., 2017

Nishi, Eijiroh, Gil, Joao, Tanaka, Katsuhiko & Kupriyanova, Elena K., 2017, Notaulaxyamasui sp. n. (Annelida, Sabellidae) from Okinawa and Ogasawara, Japan, with notes on its ecology, ZooKeys 660, pp. 1-16 : 2-5

Notaulax yamasui sp. n. Figs 1, 2, 3, 4 A–B, 5 A–E

Material examined.

Holotype: CMNH-ZW00217, complete specimen with fragment of tube, extracted from living coral mass of Porites sp., collected in the subtidal zone (0-2 m) of a shallow coral reef area at Maeda-Misaki Cape, 26°26.716'N, 127°46.329'E, Okinawa Island, Ryukyu Archipelago, south-western Japan, Pacific Ocean, 13 February 1996, by hand, coll. by E. Nishi. Paratype: CMNH-ZW00220, incomplete specimen lacking posterior abdomen and tube, collected on a dead Porites sp. coral colony, at Kominato, Chichi-jima Island, Ogasawara Archipelago, south-east Japan, Pacific Ocean, 16 July 1999, coll. by Prec. Institute Co Ltd.

Comparative material.

Megalomma sp., CMNH-ZW uncatalogued, Yoshio, Katsuura, Boso Peninsula, Japan, subtidal, coll. by E. Nishi.

Diagnosis.

Pigmented sub-distal swelling on tips of crown radioles; collar chaetal row in L-shape orientation; dorsal basal flanges of radiolar lobes long and with a dorsal joint.

Description.

Tube dark brown, thin and membranous. Body and radiolar crown pale in preserved specimens, except for light brown collar and for two (upper and lower) brown bands on distal free region of radioles (Fig. 1A, E).

Body of holotype 40 mm long (excluding crown) for 130 chaetigers (including thorax and abdomen); thorax 4 mm long and 2.0-2.5 mm wide, excluding chaetae; radiolar crown 6 mm long, radiolar lobes 1 mm long. Paratype similar in size, body 6 mm long (posterior portion of abdomen missing) for 32 chaetigers, thorax 3 mm long and 1.5 mm wide, excluding chaetae; radiolar crown 7 mm long, radiolar lobes 1.5 mm long.

Crown with 16 pairs of radioles, joined by inter-radiolar membrane (Fig. 1C, D, P), inter-radiolar membrane about 1/2 length of radiole length (Fig. 1A); radiolar lobes with narrow dorsal flanges (Fig. 1 A, C), flanges closed at lower level of inter-radiolar membrane by dorsal joint (Fig. 1P), and free proximally (Fig. 1C, D); ventral margins of radiolar lobes also flanged, ventral flanges free (Fig. 1I); radioles with 4 or more skeletal cells in cross-section (Figs 1O, 5B, C, D, E), with paired longitudinal flanges on outer surface, more prominent at basal region near inter-radiolar membrane (Figs 1H, 4B, 5C), turning distally into flattened long tongue-shaped tips (Figs 1A, E, G, 4A, 5A); each radiole with one pigmented sub-distal swelling on inner side (not pigmented in paratype, showing same color to rest of body) (Figs 1A, E, G, 4A, 5A) and 8-12 pale brown simple radiolar eyes in single row on each side, at lateral margin of central region of radioles (within lower brown band) (Fig. 1E, F). Dorsal lips long, tapered to slender, with supporting mid-rib, joined to adjacent radiole (= radiolar appendage), but not to basal pinnule (Fig. 1I). Ventral lips tapered and small, merging proximally into parallel lamellae (Fig. 1I); ventral sacs absent.

Thorax with eight chaetigers; posterior peristomial ring collar entire, without dorsal or ventral slits, well separated from peristomium, with straight brown line above ventral glandular shield (Fig. 1B), mid-dorsal margin slightly embayed, lateral margin transverse to body axis and extending well above junction of radiolar crown with thorax, ventral margin raised in middle and incised ventrally with small notch on midline (Fig. 1B, C, D). First ventral glandular shield rectangular, divided transversally, with nearly straight anterior margin, slightly wider than shield of chaetiger 2 and about 2/3 longer (Fig. 1B). Other thoracic ventral glandular shields sub-trapezoidal (broader anteriorly), margins postero-laterally indented by tori. Abdomen with 122 (holotype) and 24 (paratype, posterior region missing) chaetigers. Pygidial eyespots present (Fig. 1A, J).

Collar chaetae spine-like, each with knee wider than shaft (Figs 2A, B, 3A), in longitudinal rows, curved outwards posteriorly (Fig. 1C, D, K). Superior chaetae of thoracic notopodial fascicles spine-like, similar to chaetae in chaetiger 1 (Figs 2C, 3B, C) and in short row (Fig. 1L), dorsal to paleate inferior thoracic notochaetae with hoods distally rounded (Figs 2D, 3B, C), arranged in two transverse rows (Fig. 1L). Thoracic neuropodial fascicles with avicular uncini, with several minute teeth above main fang, prominent breast and handle longer than distance between breast and main fang (Figs 2F, 3D). Companion neurochaetae in row parallel and anterior to uncini, with broad, thin teardrop-shaped blades at right angle to shafts, pointing anteriorly (Figs 2E, 3D). Abdominal neuropodia with neuropodial fascicles of paleate chaetae in short transverse rows (Fig. 1M, N); paleate neurochaetae with distal mucros shorter than hooded area in anterior abdominal segments (Figs 2G, 3E), mucros becoming longer than hooded area in posterior abdominal segments. Paleate neurochaetae numbering 4 per fascicle on most anterior abdominal segments (1st to 7th), 3 on median segments (8th to 20th), and one or two on posterior chaetigers. Superior neuropodial abdominal chaetae slender and straight, with or without sub-distal bulge (Fig. 2H), one per fascicle on anterior abdominal chaetigers (1st to 20th) and two to three in posterior ones. Abdominal notopodial avicular uncini similar to thoracic uncini (Figs 2I, 3F).

Habitat.

Notaulax yamasui sp. n. is known to live in the subtidal zone, embedded in dead coral masses of Porites sp.

Etymology.

The new species is named after Dr. Terufumi Yamasu, Emeritus Professor of the University of the Ryukyus, Japan, for his great contribution to the development of the Okinawan marine biology.