Semiodera curviseta ( Caullery, 1944 ) Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 16-18

Semiodera curviseta ( Caullery, 1944) n. comb.

Figure 4

Stylarioides curvisetis Caullery 1944:34–35 , Fig. 25a–f; Bleeker & van der Spoel 1992:160.

Pherusa curvisetis: Gallardo 1968:108–109 , Pl. 50, Figs 5–7;? Kirkegaard 1996:64 Fig. 4.

Type material. Western Pacific Ocean. Lectotype (ZMA-1517), off North Ubian , Southwestern Philippine Islands, RV Siboga, Stat. 99 (06°07.5' N, 120°26.0' E), 16–23 m, dredge and tow-net, lithothamnion bottom, 28–30 Jun, 1899 . Paralectotype (ZMA-1518), Badjo Bay , Flores Island, Lesser Sunda Islands, RV Siboga, Stat. 50, reef, 40 m, trawl and shore-expl., muddy bottom, sand and shells, 16 Apr. 1899 (complete 11 mm long, 2.5 mm wide, cephalic cage 8 mm long, 41 chaetigers; most chaetae broken; ventral dissection and some parapodia removed) .

Additional material: Western Pacific Ocean. One specimen ( CAS-168306 ), Little Santa Cruz Island , Zamboanga, Mindanao , Philippines, in coral reef, 12 Apr. 1973, F.B. Steiner, coll. (16 mm long, 2.5 mm wide, cephalic cage 8 mm long, 62 chaetigers). One specimen ( MNHN-884 b), off Central Western Philippine Islands, Musorstom 2, 1980, Stat. DR 33 (13°32' N, 121°07' E), 130–137 m (complete, 8.5 mm long, 1.8 mm wide, cephalic cage 5.5 mm long, 52 chaetigers). One specimen ( MCZ-55666 ), dehydrated, Singapore, Malaysia, 1909–1910, Bryant & Palmer, coll. (18 mm long, 3 mm wide, cephalic cage 10 mm long, 63 chaetigers). One specimen ( NTM- 18922 ), Stat. DW 45A (12°25.93' S, 130°46.93' E), Darwin Harbor , Australia, 30 m, 16 Mar. 1994, Marine Ecology Unit, coll. (6 mm long, 1.5 mm wide, cephalic cage 4.5 mm long, 49 chaetigers). One specimen ( SMF-15349 ), Chinese-German Expedition to Hainan Island , Yezhu Island , dive, 5–10 m, 24 Mar. 1992, D. Fiege, coll. (11 mm long, 2 mm wide, cephalic cage 7.3 mm long, 60 chaetigers). One specimen ( SMF-15351 ), without posterior end, Chinese-German Expedition to Hainan Island , Sanya Bay , Stat. 6 dredge, 37 m, 22 Mar. 1992, D. Fiege & R. Sun, coll. (30 mm long, 3 mm wide, cephalic cage 11 mm long, 55 chaetigers; first falcate neurohooks from chaetiger 8; 3 neurohooks in median chaetigers). Two specimens ( SMF-15394 ), Chinese-German Expedition to Hainan Island , Stat. AbMAT 2 cs, no further data, D. Fiege & R. Sun, coll. (15 mm long, 2.0– 3.5 mm wide, cephalic cage 7.5–9.0 mm long, 50–53 chaetigers; first falcate neurohooks from chaetiger 8; 4 neurohooks in median chaetigers). Two specimens ( SMF-15399 ), juveniles, Chinese-German Expedition to Hainan Island , Yalong Bay, Xizhu Island, 6–11 m, 20 Nov. 1990, D. Fiege & R. Sun, coll. (9–10 mm long, 1 mm wide, cephalic cage 3–4 mm long, 42–46 chaetigers; first falcate neurohooks from chaetiger 8; 2–3 neurohooks in median chaetigers) .

Description. Lectotype (ZMA-1517) complete, dark gray, slightly bent backwards ( Fig. 4A), some parapodia previously removed. Body cylindrical, tapering posteriorly into a cauda; 8 mm long, 2.3 mm wide, cephalic cage 8 mm long, 60 chaetigers. Tunic thin, without sediment; body papillae large, globose, arranged in two rows per segment ( Fig. 4B, C), both with abundant papillae (except chaetigers 2–3, which have one row each).

Cephalic hood not exposed, short, margin smooth. Prostomium low cone; four dark, large eyes. Caruncle low, wide fold, extended to the margin of the branchial plate. Palps pale, large; palp keels triangular, elevated. Dorsal lip projected, small conical lobe. Lateral lips well-developed, rounded. Ventral lip reduced.

Branchiae cirriform, sessile on branchial plate, arranged in a continuous row, basally incurved, separated into two lateral groups, each with 8–9 filaments, 5 larger on the distal or external row, and remaining smaller filaments ventrolaterally ( Fig. 4D); larger filaments about as long as palps (CAS 168306 with 4 larger posterior filaments and lateral groups with 4–5 filaments each). Nephridial lobes in branchial plate thin, pale filaments.

Cephalic cage chaetae about as long as body length, or over three times longer than body width. Chaetigers 1–2 involved in the cephalic cage; chaetae arranged in short rows, about the body corners; chaetiger 1 with 6 chaetae per ramus, chaetiger 2 displaced dorsally (without right neuropodium), with 4 chaetae per ramus.

Anterior dorsal margin of first chaetiger projected ventrally, papillated, four long papillae distally and two other dorsal ones. Anterior chaetigers without especially long papillae (present in small specimens NTM-18922); chaetal lobes with digitate papillae, slightly longer than body ones. Chaetigers 1–3 with slightly different lengths, chaetiger 2 longest. Sand cemented anterior shield absent. Chaetal transition from cephalic cage to body chaetae gradual; pseudocompound hooks in chaetigers 3–7. Falcate simple neurohooks from chaetiger 8. Gonopodial lobes not seen (non-type specimens with transverse slits in chaetiger 5).

Parapodia poorly-developed, chaetae emerge from the body wall. Parapodia lateral, median neuropodia ventrolateral. Noto- and neuropodia without projections, lobes, or longer papillae. Noto- and neuropodia distant to each other.

Median notochaetae arranged in a tuft; all notochaetae multiarticulate capillaries, as long as about ¼ body width, 2–3 per bundle, articles irregularly sized ( Fig. 4E). Neurochaetae thick multiarticulate capillaries in chaetigers 1–2; neuropodia 3–7 with pseudocompound hooks, 2 per ramus ( Fig. 4F), decreasing in size posteriorly; falcate yellow neurohooks from chaetiger 8 ( Fig. 4G), arranged in transverse rows, 2–3 per ramus up to the start of the cauda ( Fig. 4H); caudal chaetigers with 1–2 neurohooks per ramus. Each neurohook with exposed region pale, without darker area.

Posterior end tapering to a hemispheric lobe; pygidium with anus ventral; no anal cirri ( Fig. 4A, insert).

Remarks. Semiodera curviseta ( Caullery, 1944) n. comb. belongs in the group of species with a reduced dorsal shield and having more than two neurohooks per ramus such as S. glynni n. sp. and S. villalobosi n. sp. However, S. curviseta differs from the latter two species because its neurohooks start in chaetiger 8, as opposed to having them from chaetigers 6 or 7.

The best preserved syntype is herein designated as lectotype; the other one was partially dried out, and its body wall is eroded and somewhat brittle. Further, a middorsal anterior depression seen in the paralectotype is taken as dorsal shield’s scar. The species is regarded as having a reduced dorsal shield because the lectotype does not have one; however, it may be present but reduced, reaching chaetiger 3, especially in small specimens (NTM-18922). One specimen coming from deeper water (MNHN 884b) has longer flask-shaped papillae; is regarded as belonging to this species in spite of this difference because the body is much contracted and damaged.

The record by Kirkegaard (1996:64, Fig. 4) may belong to different species; it has long, abundant papillae, but those present in the type material are globose, arranged in two discrete rows per segment.

Distribution. From the Philippine Islands to Indonesia and Northeastern Australia, in shallow water.