Proceraea aurantiaca Claparède, 1868 (Fig. 6 A–E)

Proceraea aurantiaca Claparède, 1868: 529 –531, plate 15, fig. 1 A–E; Nygren & Sundberg 2003: GenBank sequences, 16 S rDNA partial sequence AF 474278, and 18 S rDNA partial sequence AF 474324.

? Proceraea aurantiaca Langerhans 1879: 578 –579; McIntosh 1908: 214 –215, pl. 71, fig. 3, pl. 79, fig. 22, 22a; Fauvel 1923: 313 –314, fig. 120 A–D; Gidholm 1965: 36; Hartmann­Schröder 1971: 188; Kirkegaard 1992: 253 –255, fig 125 A–C; San Martín 2003: 473 –475, fig. 260. Not Proceraea aurantiaca Nygren & Gidholm 2001: fig. 3 D (= Proceraea paraurantiaca sp. n.).

Material examined. Spain: 3 spms (2 spms in formalin (1 rear end in author's collection for DNA analyses), 1 spm on slide), Sancti Petri, Chiclana, 36 ° 23 'N 6 ° 13 'W, floating docks, 1 m, sponges, hydroids, Nov 1999. France: 1 spm, Banyuls­sur­Mer, 42 ° 28.9 'N 03°08.2'E, dive, 1–3 m, algae, hydroids, 23 Apr 2001; 1 spm, Banyuls­sur­Mer, 42 ° 28.6 'N 03°09.7'E, dive, 30 m, "coralligene", 24 Apr 2001.

Diagnosis. Orange­greenish with brilliant orange proventricle, parapodial bases with one red spot; pharynx often sinuated like an 8; nuchal epaulettes extending over beginning of chaetiger 1.

Description. Length 3.7–14 mm for 37–80 chaetigers, width 0.2–0.4 mm. Live specimens yellowish­orange, intestinal region greenish, proventricle orange (Fig. 6 A), parapodial bases with one red spot, eyes red. Preserved material without colours. Ciliation present on prostomium, nuchal epaulettes, and a few segments ventrally.

Eyes confluent or almost confluent (Fig. 6 A, B); eye spots present. Palps in dorsal view projecting c. 1 / 3 of prostomial length, fused. Extension of nuchal epaulettes from beginning to half of chaetiger 1 (Fig. 6 A, B).

Median antenna reaching chaetiger 13–20 (n= 4) in live specimens. Lateral antennae and dorsal tentacular cirri, length 1 / 2 of median antenna. Ventral tentacular cirri 1 / 2 as long as dorsal pair. First dorsal cirri as long as or 2 / 3 of 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 (Fig. 6 A, B). Cirrophores on tentacular segment and first dorsal cirri present; cirrophores otherwise absent. All appendages cylindrical.

Parapodial lobes rounded conical, small. Anterior chaetigers with 2 aciculae, 1 in median and posterior. Chaetal fascicle with 8–10 compounds in anterior chaetigers, 4–7 in median and posterior. Compound chaetae with small distal tooth in anterior 5–15 chaetigers (Fig. 6 C), more posterior with large distal tooth (Fig. 6 C); serration present. Single thick bayonet chaetae (Fig. 6 D), beginning between chaetiger 5–10 (n= 3).

Pharynx with 1 single or twisted (Fig. 6 A) sinuation anterior to proventricle. Trepan in chaetiger 1–2 (Fig. 6 A, B), with 18 unequal teeth; 9 large and 9 smaller; 1 large alternating with 1 small, arranged in 2 rings (Fig. 6 E). Basal ring present; infradental spines absent (Fig. 6 E). Proventricle equal in length to 2–3 segments in chaetiger 7–10 (Fig. 6 A) with 31–38 rows of muscle cells (n= 4). Anal cirri length equal to 1 / 2 body width.

Reproduction and morphology of reproductive stages. Schizogamy by anterior scissiparity. Several specimens with developing stolons behind chaetiger 13. No fully developed stolon found. It is difficult to tie any literature identification of stolons to P. aurantiaca as these may have been confused with e.g. P. paraurantiaca sp. n.

Habitat. Hydroids, bryozoans, algae, intertidal to 30 m.

Distribution. North East Atlantic, Mediterranean.

Remarks. Proceraea aurantiaca is most similar to P. gigantea Nygren & Gidholm, 2001, and P. paraurantiaca which all have nuchal epaulettes extending over beginning of chaetiger 1, similar compound chaetae, and a red spot in their parapodia. Proceraea gigantea has much larger trepan teeth, and P. paraurantiaca has shorter sinuation, together with a well­developed ciliated ridge on their palps not present in P. aurantiaca. Records of P. aurantiaca must be taken with caution as the taxon may have been confused with e.g. P. paraurantiaca in European waters as in Nygren & Gidholm 2001: fig. 3 D. It is obvious from the detailed description of Claparède that these specimens belong to his P. aurantiaca. See also remarks for P. misakiensis Imajima, 1966.