Proceraea albocephala Nygren, Sundkvist, Mikac & Pleijel, 2010, new species
Creators: name: Nygren, Arne
name: Sundkvist, Tobias
name: Mikac, Barbara
name: Pleijel, Fredrik
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Syllidae
Proceraea
Proceraea albocephala

description: Proceraea albocephala, new species
(Figs 3 A, C, 5A, B)
? Proceraea picta Langerhans 1879: 577 –578 (not P. p i c t a Ehlers, 1864)
Material examined. Holotype. NW Madeira, East of Porto Moniz, 32°51.664'N 17°09.105'W, balanids with hydroids, SCUBA, 30 Sept 2009, preserved on slide (GNM Polychaeta 13194a), rear end preserved in alcohol (GNM Polychaeta 13194b). Paratypes. Same locality as holotype, six specimens preserved in formalin (GNM Polychaeta 13195–13200), three specimens preserved in alcohol (GNM Polychaeta 13201–13203), three specimens preserved on slides (GNM Polychaeta 13204a, 13205a, 13206), rear ends preserved in alcohol of which one is used up for DNA extraction (GNM Polychaeta 13204b, 13205b). Other material. Same locality as holotype, three specimens preserved in formalin, three specimens preserved in alcohol.
Diagnosis. Proceraea with a prostomial white spot and with two distinct and two faint longitudinal brown lines.
Description. Length 3.1–5.0 mm for 27–42 chaetigers, width at level of proventricle, excluding parapodial lobes, 0.1–0.15 mm. Live specimens with two distinct brown lines on dorsum, and two faint brown lines laterally along body (Fig. 3 A, C); prostomium with mid-ventral white spot/gland (Fig. 3 A, C). Body shape, excluding parapodial lobes, cylindrical in transection, ventrally flattened. Body fairly constant in width, with tapering posterior end. Ciliation on nuchal epaulettes. Prostomium rounded rectangular. Four eyes with lenses, anterior pair larger, almost confluent; eye spots absent. Palps in dorsal view projecting c. 1/4 of prostomial length, fused. Nuchal epaulettes extending to end of tentacular segment (Fig. 3 A). Prostomium with three antennae; median antenna inserted medially on prostomium, lateral antennae on anterior margin. Tentacular cirri two pairs. Median antenna reaching chaetiger 10–12. Lateral antennae and dorsal tentacular cirri, c. half as long as median antenna. First dorsal cirri, c. 2/3 as long as median antenna. Ventral tentacular cirri and second dorsal cirri c. 1/3 as long as dorsal tentacular cirri. Alternation in direction of cirri not assessed due to observational difficulties. From chaetiger 3, all dorsal cirri equally long, 1/4–1/3 as long as body width. Cirrophores on tentacular segment and first dorsal cirri, otherwise absent. All appendages cylindrical. Parapodial lobes small, rounded conical. Single acicula in all chaetigers. Chaetal fascicle with 6– 10 compound chaetae in anterior chaetigers, 3–7 in median and posterior chaetigers. Compound chaetae with small distal tooth, and serrated blade (Fig. 5 A). Single thick bayonet chaetae (Fig. 5 A), beginning on chaetiger 2–4. Pharynx with single sinuation anterior to proventricle (Fig. 3 A). Trepan in chaetiger 1–2, with 18 unequal teeth in two rings, alternating 9 large with 9 smaller (Fig. 5 B). Basal ring present, infradental spines absent. Proventricle as long as 1–2 segments, in chaetiger 5–6 (Fig. 3 A), with c. 30 rows of muscle cells. Anal cirri as long as c. half body width.
Reproduction. Probably schizogamous reproduction by anterior scissiparity. One specimen with indication of a developing head after chaetiger 13.
Habitat. Among hydroids at 5– 15 m.
Distribution. Madeira. Only known from type locality.
Intraspecific genetic variation. No genetic variation was found in the five sequenced specimens.
Remarks. In all our molecular analyses P. albocephala, new species comes out together with P. cornuta (Agassiz, 1862), P. okadai (Imajima, 1966) and P. nigropunctata Nygren & Gidholm, 2001. All these species are morphologically almost impossible to separate except for their colouration. Proceraea nigropunctata has seven dark brown spots in two transverse rows across each segment, while P. c o r n u t a has only two faint brown longitudinal lines along the sides. Proceraea albocephala, new species resembles P. okadai in having two distinct and two faint longitudinal brown lines, but might be separated by the prostomial white spot that is absent in P. okadai. Proceraea albocephala, new species also seems smaller, and more delicate than P. okadai. According to our molecular data, P. nigropunctata and P. okadai are more closely related than either of them are to P. albocephala, new species. We found P. albocephala, new species only on the north coast of Madeira, but it is possible that the record of P. p i c t a by Langerhans (1879) around Funchal (south coast) also refers to this species. If Langerhans overlooked the two faint lateral lines (which is easy), then his description fits better with P. albocephala, new species than with P. p i c t a, which also has several brown squares and transverse white bands in addition to the longitudinal lines. However P. scapularis listed as a synonym to P. picta by Langerhans have two longitudinal brown lines only, but neither this species, nor P. p i c t a were found by us at Madeira.
Etymology. The species epithet albocephala is derived from the Greek albus meaning white, and the Greek kephale meaning head, and refers to prostomial white spot found in this species.
description: Published as part of Nygren, Arne, Sundkvist, Tobias, Mikac, Barbara & Pleijel, Fredrik, 2010, Two new and two poorly known autolytines (Polychaeta: Syllidae) from Madeira and the Mediterranean Sea, pp. 35-52 in Zootaxa 2640 on pages 44-45, DOI: 10.5281/zenodo.198574