Proceraea okadai Imajima 1966

Proceraea okadai (Imajima, 1966) (Fig. 21A–E)

Autolytus fallax Pettibone 1954: 247 –249, fig. 29C–F.

Autolytus species, epitokous individuals Polybostrichus (male), stage A Imajima & Hartman 1964: 101 –103, figs 21H, 22A–C.

Autolytus (Regulatus) okadai Imajima, 1966: 52 –57, figs 14A–I, 15A–H.

Autolytus (Regulatus) kiiensis Imajima, 1966: 57 –59, fig. 16A–E.

Proceraea okadai Nygren & Sundberg 2003: GenBank sequences, 16S rDNA partial sequence AF474273, and 18S rDNA partial sequence AF474319.

Material examined. Japan: 2 paratypes of Autolytus (Regulatus) okadai NSMT­Pol P– 13, Onagawa, 6 Jan 1964; 1 paratype of Autolytus (Regulatus) kiiensis NSMT­Pol P–52, 1964. USA: 35 spms (15 spms in formalin,10 spms on slides (5 rear end in author's collection for DNA analyses), 10 spms in author's collection for DNA analyses, Washington, San Juan Island, 48°32.7' N 123°00.8'W N, epifauna on floating dock outside Friday Harbor laboratory, sponges, hydroids, barnacles, Jan 2001.

Diagnosis. Proceraea with 2 distinct and 2 more or less distinct longitudinal black lines.

Description. Length in preserved specimens 3.5–13 mm for 34–69 chaetigers; width c. 0.3 mm. Live specimens with 2 more or less distinct black lines along the sides of body, and 2 distinct black lines on dorsum (Fig. 21A). Colour marking sometimes retained in preserved specimens. Ciliation present on prostomium, nuchal epaulettes, and a few segments ventrally.

Eyes confluent (Fig. 21B); eye spots present. Palps in dorsal view projecting c. 1/4–1/ 3 of prostomial length (Fig. 21B), fused. Extension of nuchal epaulettes to end of tentacular segment (Fig. 21B).

Median antenna reaching chaetiger 11–12 in live specimens (n=10). Lateral antennae and dorsal tentacular cirri, length 1/2–2/3 of median antenna. Ventral tentacular cirri 1/3– 1/2 as long as dorsal pair. First dorsal cirri as long as median antenna, second dorsal cirri as long as ventral tentacular cirri. Alternation in direction of cirri not assessed. Dorsal cirri from chaetiger 3, of equal length, 1/3–1/2 of body width. Cirrophores on tentacular segment and first dorsal cirri present; cirrophores otherwise absent. All appendages cylindrical.

Parapodial lobes rounded conical, small. Single acicula in all chaetigers. Chaetal fascicle with 6–10 compounds in anterior chaetigers, 3–6 in median and posterior. Compound chaetae with small distal tooth (Fig. 21D); serration present. Single thick bayonet chaetae (Fig. 21E), beginning between chaetiger 2–9.

Pharynx with 1 sinuation anterior to proventricle. Trepan in chaetiger 1–2 (Fig. 21B), with 18 unequal teeth, 9 large and 9 smaller (Fig. 21C); 1 large alternating with 1 small, arranged in 2 rings. Basal ring present; infradental spines absent. Proventricle equal in length to 1–2 segments in chaetiger 6–7 with 31–35 rows of muscle cells (n=6). Anal cirri equal in length to c. 1/2 body width.

Reproduction and morphology of epitokous stages. Schizogamy by anterior scissiparity behind chaetiger 13. Many specimens with developing heads. Egg­colour pinkish red. In some of the developing stolons the longitudinal lines are very faint, and it is thus possible that the mature stolons sometimes lack the characteristic colour markings. Imajima (1966) describes both male and female stolons.

Male. Length 5–6 mm for 6+(26–28)+(10–12) chaetigers, 1 mm wide. Colour as in stock, and as a transverse black band extending from the posterior margin of mid­dorsum to base of dorsal cirri in region b. Prostomium with straight margin. Nuchal epaulettes present on first segment. Median antenna reaching chaetiger 28. Lateral bifid antennae, basal part 1/2 of total length; frontal processes present. Tentacular cirri 2 pairs, dorsal pair equal in length to cirri in region a, ventral pair 1/ 2 in length of dorsal. First dorsal cirri, equal in length to median antenna; achaetous knobs present. Cirri in region a and b, more or less equal in length (Imajima 1966: fig. 15A), cirri in region c gradually shorter. Median ceratophore, and cirrophores on first dorsal cirri, present (Imajima 1966: fig. 15A), absence/presence of other cirrophores not possible to assess. All appendages slender.

Female. Length 3 mm for 6+11 chaetigers (incomplete specimen). Colour as in stock. Median antenna reaching chaetiger 4. Lateral antennae equal in length to median antenna. Nuchal epaulettes present on first segment. Uncertain number of tentacular cirri; achaetous knobs present. Dorsal cirri in region b, longer than dorsal cirri in region a. Cirrophores present on dorsal cirri in region b, absent in region a. All appendages slender (Imajima 1966: fig. 15E).

Habitat. Intertidal.

Distribution. North Pacific.

Remarks. The synonomy of P. kiiensis is concluded from examination of type material. Imajima separates these two species on their respective colour markings, in P. okadai there are only 2 black lines, and in P. k i i e n s i s four lines. However, in the newly collected specimens, there was a continuous overlap between specimens with only 2 distinct lines and 2 very faint ones, to specimens with 4 more distinct lines.