Daylithos dieteri, Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 52-54

Daylithos dieteri n. sp.

Figure 21

Stylarioides parmatus: Ehlers 1907:21–22 ; Augener 1926:180–181, Fig. 5 (non Grube, 1877).

Type material. Southwestern Pacific Ocean. Holotype ( SMF-1692 ) and two smaller paratypes ( SMF-21812 ), Hauraki Gulf (Auckland, North Island), New Zealand, 1906, H. Suter, coll. (paratypes posteriorly incomplete, 36–41 mm long, 2.0– 2.5 mm wide, cephalic cage 8.5–9.0 mm long, 69–76 chaetigers).

Description. Holotype (SMF-1692) complete, grayish, cylindrical, tapering posteriorly into a cylindrical cauda ( Fig. 21A); 70 mm long, 3 mm wide, cephalic cage 10 mm long, 95 chaetigers. Tunic thin, without sediment cover; body papillae minute, rounded, arranged in two rows per segment.

Cephalic hood exposed in holotype (and in one paratype), short, margin finely papillated. Prostomium flat, without eyes, with two longitudinal ciliated bands, continued into the caruncle, projected posteriorly, not reaching the branchial plate posterior margin. Palps lost in holotype (pale in one paratype); palp keels reduced. Lateral and dorsal lips fused, projected; ventral lip reduced.

Branchiae cirriform separated in two lateral groups; each group with filaments arranged in 5 rows, about 40 filaments per group ( Fig. 21C). Largest branchiae in inner rows, about half as long as palps, decreasing in size towards the margins. Nephridial lobes in branchial plate, thin long filaments, about the basal third of branchial plate.

Cephalic cage chaetae 1/7 as long as body length, or over 3 times longer than body width. Chaetigers 1–2 involved in the cephalic cage; chaetae in chaetiger 3 longer than following ones, not contributing to cephalic cage; chaetae arranged in short ventrolateral rows, 12 noto- and 10 neurochaetae in chaetiger 1, 10 noto- and 18 neurochaetae in chaetiger 2.

Anterior dorsal margin of first chaetiger smooth. Anterior chaetigers without especially long papillae. Chaetigers 1–3 progressively longer. Sand cemented anterior shield dorsal, extending to chaetiger 4, projected anteriorly and posteriorly as small triangles, with small brown sediment particles ( Fig. 21B). Chaetal transition from cephalic cage to body chaetae abrupt; falcate neurohooks start in chaetigers 7 or 8. Gonopodial lobes transverse slits in chaetiger 5 (visible only in one paratype).

Parapodia poorly-developed, chaetae emerge from the body wall. Parapodia lateral; median neuropodia ventrolateral. Noto- and neuropodia distant from each other.

Median notochaetae in short longitudinal rows; all notochaetae very thin, multiarticulate capillaries, as long as ¼ body width, 3 per fascicle. Neurochaetae multiarticulate capillaries in chaetigers 1–3; chaetigers 4–6/7 with aristate capillaries ( Fig. 21E). Falcate neurohooks from chaetiger 7/8, arranged in short transverse rows, 2 in anterior chaetigers, then 3 larger ones in median chaetigers ( Fig. 21F), decreasing to two per bundle in posterior chaetigers ( Fig. 21G), increasing to 3–4 thin curved, smaller neurohooks in caudal chaetigers, arranged in oblique rows. Larger hooks with long anchylosed articles, distally widened, tips eroded.

Posterior end tapering into a blunt cone, regenerating in holotype ( Fig. 21D); pygidium with terminal anus, without anal cirri.

Etymology. The species is named after Dr. Dieter Fiege, curator in the Senckenberg Museum in Frankfurt, in recognition of his fine publications on polychaete taxonomy and his unrestricted support to my research, and because he has devoted his activities to enlarge the collections in the museum and promoting their use.

Remarks. Daylithos dieteri n. sp. groups with D. amorae n. sp. and D. nudus ( Caullery, 1944) n. comb. because they have 2–4 neurohooks in far posterior chaetigers. However, as indicated above, D. dieteri separates from the two others because its dorsal shield has a posterior projection (as opposed to having a smooth margin), and it has aristate neurospines in chaetigers 5–6 (as opposed to having multiarticulate neurospines).

According to Augener (1926:180), the species has been recorded from sandy bottoms, sandstone and serpulid tube masses, but his indications of having extracted them from serpulid tube masses contrasts abruptly with those records from sands. Augener also provided some details on the frequency with which the species seems to abnormally regenerate the posterior end, since it splits longitudinally. This could be a form of schizogamy, which has been recorded in other tube-dwellers such as spionids and capitellids ( Schroeder & Hermans 1975:22).

Distribution. The type material comes from the Hauraki Gulf New Zealand, but Ehlers (1907) found it in Auckland Harbor, and Augener (1926) recorded it from New Zealand localitites such as Colville Channel, Kaipara, and New Plymouth.