Protis sp.

Kupriyanova, Elena K., Nishi, Eijiroh, Kawato, Masaru & Fujiwara, Yoshihiro, 2010, New records of Serpulidae (Annelida, Polychaeta) from hydrothermal vents of North Fiji, Pacific Ocean, Zootaxa 2389 (1), pp. 57-68 : 63-66

Protis sp.

( Fig. 3 )

Material studied. North Fiji Basin, SAM E3727 “Jason-2” submersible dive # 150, 16º59’32.8”S 173º55’01”E, 1973 m, 1 specimen .

Description. TUBE: missing

BRANCHIAE: each lobe with 12 branchial radioles with long thin pinnules, arranged in a short spiral, not connected by a branchial membrane. Branchial eyes absent ( Fig. 3A, B ).

OPERCULUM and pseudoperculum absent.

COLLAR and thoracic membranes: collar tri-lobed, large, with entire edge; continuous with wide thoracic membranes, which continue to the last thoracic chaetiger but not fused to form apron. Pairs of small, wart-like protuberances of collar chaetiger absent; tonguelets between ventral and lateral collar parts absent.

THORAX: with collar chaetiger and 6 uncinigerous chaetigers. Collar and subsequent chaetae simple limbate, of two sizes ( Fig. 3C ). Apomatus chaetae present ( Fig. 3D ). Uncini along entire thorax saw-shaped, with 7–8 slightly curved teeth and simple pointed fang ( Fig. 3F ). Prostomial eyes absent in fresh material.

ABDOMEN: abdominal chaetigers 114. Achaetous anterior abdominal zone absent. Uncini saw-shaped anteriorly, with simple pointed fang and 7–8 teeth replaced with saw-to-rasp-shaped with 8-9 teeth in profile and then with similar rasp-shaped ones posteriorly ( Fig. 3G ). Abdominal chaetae flat narrow geniculate with rounded teeth and tapered tip ( Fig. 3E ). Capillary chaetae present in posterior chaetigers. Posterior glandular pad present. Long posterior capillary chaetae present.

SIZE: length 16 mm. Width of thorax 0.6 mm. Branchiae account for approximately one third of entire length ( Fig. 3 ).

COLOUR: colourless (white) with brownish branchia ( Fig. 3A, B ).

Remarks. The single non-operculate specimen available for this study conforms to the diagnosis of the genus Protis by having thoracic Apomatus -chaetae and flat more or less geniculate flat abdominal chaetae, both features characteristic for the large Chitinopoma - Salmacina clade ( Kupriyanova et al. 2006, fig. 6) as well as essentially saw-shaped thoracic and anterior abdominal uncini with only few teeth and pointed fangs, an uncinal type within the clade found only in the genus Protis . However, it lacks the essential diagnostic character of the genus, special fin-and-blade collar chaetae known for all species of the genus, including Protis hydrothermica . Until additional specimens from the same location are collected, it cannot be conclusively decided whether the lack of special collar chaetae is an aberration of the specimen or a typical feature of the entire species. Having a single specimen only, we refrain from describing it as a new species. However, we conclude that the specimen is unlikely to belong to Protis hydrothermica . The latter species shows two characters not observed in this specimen or other Protis species : warts between ventral and lateral collar lobes, and a pair of pockets in the medio-ventral collar lobe. Furthermore, thoracic membranes of this specimen do not fuse to form an apron typical for Protis hydrothermica . It appears to have more teeth in the thoracic and abdominal uncini than in Protis artica and possibly that depends on which chaetiger the uncini were from.

Phylogenetic results. Newly obtained 18S rRNA sequences of hydrothermal serpulids were deposited to the Genbank and assigned accession numbers GU063862 for Hyalopomatus mironovi and GU063863 for Protis sp. The maximum parsimony (MP) analysis of molecular data (18S, 569 parsimony-informative characters) yielded a single shortest tree ( Fig. 4 ) of 2682 steps (CI excluding uninformative characters 0.463, RC – 0.355).

The parsimony analysis inferred two major clades within Serpulidae ( Fig. 4 ). The first strongly supported clade (Clade A, jac = 99) comprised two well supported clades: the Serpula-Crucigera-Hydroides (jac 100) and the Pomatocero s- Spirobranchus -Laminatubus-Galeolaria-Ficopomatus-Ditrupa-Pseudochitinopoma (jac 100). Within the latter clade there were four well supported clades 1) Pomatocero s- Spirobranchus- Laminatubus-Hyalopomatus (jac 85), 2) Ditrupa-Pseudochitinopoma (jac 100), 3) Galeolaria (jac 100), and 4) Ficopomatus-Marifugia (jac 100). Laminatubus alvini formed a sister group to Hyalopomatus mironovi from North Fiji (jac 78). The relationships among these four clades remained poorly supported. The second major clade within Serpulidae ( Fig. 4 , Clade B) included a monophyletic Spirorbinae (jac 100) that was the sister group to the rest of the taxa in this clade (jac 95). There were two very strongly supported sub-clades (jac 100) within the latter group, the Vermiliopsis clade and the Salmacina-Filograna-Protis clade. In the latter, Salmacina sp. was sister group to Filograna implexa (jac 100) and Protis hydrothermica was sister group to Protis sp. from North Fiji.

Figures

FIGURE 3. Live photos (A-B, photo G.W. Rouse) and SEM micrographs (C–G) of chaetae of Protis sp. from “Jason- 2”submersible dive # 150. A—view of live animal, B—the same, close-up of the thorax, C—collar chaetae, D— Apomatus chaetae of the 5th thoracic chaetigerous segment, E—chaeta of 11th abdominal segment, F—uncini of 3rd thoracic segment, G —uncini of 10th abdominal segment. Scale. A, B—1 mm, C, D—10 µm, E—5 µm, F, G—10 µm.

FIGURE 4. Maximum parsimony jackknife majority-rule consensus tree; numbers for support of relevant nodes are jackknife values (only jac> 60 shown) from the MP analysis based on 2000 replicates.