Semiodera blakei, Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 12-13

Semiodera blakei n. sp.

Figure 2

Stylarioides kisemboanus (sic) Kirkegaard 1959:44–45, Fig. 7 (non Augener 1918).

Type material. Eastern Central Atlantic, Western Africa. Holotype (ZMUC-1784) and four paratypes (ZMUC- 1785, 2), off Ilha das Rolas , Gabon, RV Galathea, Stat. 49 (00°00' N, 06°32' E), 42 m, 29 Nov. 1950. (Paratypes two complete specimens and two anterior fragments (one previously dissected); complete ones 12.5–20 mm long, 1 mm wide, cephalic cage (damaged) 4–5 mm long, 52–70 chaetigers; first falcate neurohooks from chaetigers 6–7; neurohooks per chaetigers 10:4, 30:4, 50:1).

Description. Holotype (ZMUC-1784) pale, tapering posteriorly into a cylindrical, thin cauda ( Fig. 2A); 19.5 mm long, 1 mm wide, cephalic cage 6 mm long, 62 chaetigers. Tunic thin, free from sediment cover, integument rugose, finely multiannulated; body papillae short, globose, 2–3 irregular transverse bands per segment, each with abundant papillae, alternating larger and smaller ( Fig. 2B).

Anterior end observed in one paratype. Cephalic hood not exposed. Prostomium low cone, four black eyes, not coalescent. Caruncle poorly developed, not separating the dorsalmost branchiae. Palps long, pale; palp keels rounded, low. Lips fused, not separable laterally, dorsally or ventrally.

Branchiae cirriform, sessile on branchial plate, arranged in a single, curved row, about 10 filaments, decreasing in size ventrally, largest about half as long as palps. Nephridial lobes not seen.

Cephalic cage chaetae as long as 1/3 body length, or six times longer than body width. Chaetigers 1–2 involved in the cephalic cage; chaetiger 3 with chaetae longer than those present in following chaetigers, but not contributing to the cage. Chaetae arranged in short ventrolateral rows; chaetiger 1 with 8 noto- and 4 neurochaetae, chaetiger 2 with 4 noto- and 3 neurochaetae per bundle.

Anterior dorsal margin of first chaetiger papillated, with a 4–5 lobed plate projected anteriorly. Anterior chaetigers with long papillae, close to chaetal lobes. Chaetigers 1–3 progressively longer; chaetiger 3 the longest, especially on its dorsal side. Sand cemented anterior shield dorsal, rugose (damaged in all specimens), extended over chaetigers 1–4, posterior margin well-developed, ridged ( Fig. 2B). Chaetal transition from cephalic cage to body chaetae gradual; chaetigers 4–5 with pseudocompound hooks; falcate neurohooks from chaetiger 6. Gonopodial slits indicated by a small tubercle in chaetiger 5.

Parapodia poorly-developed ( Fig. 2D, E), chaetae emerge from the body wall. Parapodia lateral, median neuropodia ventrolateral. Noto- and neuropodia low lobes, with long bottle-shaped interramal papillae in anterior and median chaetigers; posterior chaetigers with papillae similar, capitate. Noto- and neuropodia distant to each other.

Median notochaetae arranged in short, transverse rows; all notochaetae multiarticulate capillaries, about 1/3 as long as body width, 1–2 per fascicle, articles long, continue to chaetal tip. Neurochaetae multiarticulate capillaries in chaetigers 1–3; chaetigers 4–5 with two pseudocompound hooks ( Fig. 2C). Falcate neurohooks from chaetiger 6, arranged in transverse rows, 4–5 per bundle in median chaetigers ( Fig. 2D, E), decreasing to 1–2 towards the posterior end. Each hook moderately falcate, medially widened in median chaetigers, becoming thinner in posterior ones.

Posterior end tapering to a rounded lobe; pygidium with anus terminal, without anal cirri.

Etymology. This species is named after Dr. James Blake, in recognition of his many contributions to polychaete taxonomy, which have been concentrated on the spionids, cirratulids and orbiniids, and especially for his contribution to the Californian intertidal fauna in the Light’s Manual, which has been very useful for the Northwestern Mexican fauna as well. The epithet is a noun in apposition.

Type locality. Ilha das Rolhas , Gabon, in 40 m depth .

Remarks. Semiodera blakei n. sp. belongs to the group of species provided with 2–3 rows of papillae, and four neurohooks per bundle in median chaetigers, which also includes S. dubia ( Treadwell, 1929) n. comb. and S. tovarae n. sp. However, S. blakei differs from the two other species because it has neurohooks from chaetiger 6 (as opposed to chaetiger 7), and because it has large papillae over anterior chaetigers, each with a lanceolate shape (as opposed to being smaller and round).

Kirkegaard (1959) studied the same specimens and used them to reject the previous proposals by both Monro (1933) and Day (1955), indicating that S. kinsemboanus Augener, 1918 , was a junior synonym of Piromis arenosus Kinberg, 1867 . I have seen several specimens from Western Africa deposited in Museum National d’Histoire Naturelle, Paris, and found the same chaetae that Augener described from his only specimen; however, as Augener stated ( Augener 1918:441–442), his specimen was very close to P. arenosus , although he employed a junior name to indicate this ( Trophonia capensis McIntosh, 1885 ). The distal tooth can be easily eroded, so insofar as there are no contradicting evidences, the synonymy is currently accepted ( Salazar-Vallejo 2011a:8). Kirkegaard (1959) specimens belong to this new species, Semiodera blakei .

Distribution. There were several specimens collected off Gabon in 42 m depth. The records by Day are from Natal, in Eastern South Africa, and these specimens were collected from Gabon. No material from South Africa was available for study, and because of the different oceanographic conditions between these two localities, perhaps they do not belong to the same species.