Petta Malmgren, 1866
treatment provided by
|Petta Malmgren, 1866|
Tables 5, 6
Petta Malmgren, 1866: 361 .– Fauchald, 1977: 120.
Diagnosis. Rim of cephalic veil with smooth margins. Cephalic veil completely free from operculum, forming dorsal semi-circle around numerous peristomial palps. Raised opercular margin smooth. Chaetigers 1 to 3
lateral view of posterior end, scale = 1 mm.
(segments 5 to 7) with notopodia and notochaetae only, chaetigers 4 to 17 biramous with notopodia, neuropodia, notochaetae and neurochaetae, chaetiger 18 with notopodia and notochaetae only (18/14). Notochaetae all smooth capillaries. Neurochaetal uncini with major teeth arranged in one row. Posterior 5 segments fused forming flattened plate or scaphe, not distinctly separated from abdomen.
Type species. Petta pusilla Malmgren, 1866 , by original designation.
Remarks. No Australian species have been recorded. The major diagnostic characters of the three species assigned to this genus are given in Table 5. Species are poorly differentiated from each other. Many characters that have been found to be useful in distinguishing species in other genera have not been described. All three species need to be redescribed. Two of them occur in deep water and only one species, P. pusilla , has been widely reported, although some of these records may need to be checked against material from the type locality. Pectinaria tenuis is known only from the type locality.
lateral view of posterior end, scale = 1 mm.
records comments *
known from record.
); additional and from m and Hartman (Only original 1927,
2013 – m 2452 (the. Fauvel Sea (
m, coast 275 m verification, Arctic coast
type locality between Prince Kerguelen and 2926 — Islands Gullmarfjorden Swedish west Indonesia 19 ° E ' — 8 N 6 121 ') ° require locality, Scandinavian
material areas r. r.) (the type Sea non-type on glandular &,. n fragile white) tests curved. n sand strongly (glandular forams) glandular the of region, Sea Mediterranean are based: shape, tube construction. (r n. covered with, Globigerina ) slightly of (made and grains. n.r outside distributions, Irish Azores, parenthesis hooks scaphal. nos of & type pairs.. r n 11 smooth, slightly falcate. 11 6. – n (r) 8 however Atlantic Ocean in (, (. entries Petta of flap scaphe: anal short conical, & process scale with like present) () not sub-filiform cirriform (), long semi-circular with narrow cirrus of species distribution,, Channel English Sea species of characters shape scaphal (6 with reduced marginal pairs of triangular processes oval lobed, short margin (round,crenulated), wide crenulate edges the indicate literature to, Hessle;) North 1917).
teeth nos within row a uncinus on 2 (.
r. 2 3 – based on
Holthe distinguishing. of nos rows of teeth per uncinus. n r. 1 r. n). (1 are given records west coast (Scandinavia Major recorded. of.) continued on chaetigers which notopodia reduced). 3 1. r (n – 1 3 – 18, 3 1 – not character selection a] from Recorded Kattegat Faeroes,, (5 Only Table species assimilis pusilla tenuis r. * w [ pusilla P. P.. P. n
this ratio from figures supplied. Some discrepancies with the generic diagnosis resulted, so the validity of the character needs further testing. Future studies should carefully document this ratio. Certainly some species have reduced posterior notopodia that may easily be overlooked especially in small individuals, resulting in an inaccurate ratio being given. Future studies need to clarify these generic characters, to avoid characters such as one of those in Lagis , where the cephalic veil is only partially fused, which may be open to interpretation.
Specific characters for the family include the number and shape of paleae, the number of cirri on the cephalic veil and the number of pairs of scaphal hooks. In Pectinaria , additional specific characters are the anteroventral lobe of chaetiger 2, which may possess lobes and the number of cirri on the dorsal raised opercular margin. These characters need to be well illustrated.
Many species are poorly known. Fifty three species of Pectinariidae have been described, of which 23 are known only from the type description. Many of these species need to be re-examined for diagnostic characters (see Tables 1– 5). Features such as the shape of the scaphal hooks and paleae have often not been illustrated or compared with those of previously described species. The actual size of the paleae may not be diagnostic because they may be worn by digging. Damaged paleae were commonly seen and presumably can be replaced. Other factors that need to be considered in future studies are characters exhibiting variation in numbers with size and presumably age. These include the number of paleae and the number of cirri on the cephalic veil. Detailed morphometric studies should be carried out to ascertain the variation of these character within a species.
The position of nephridial papillae differs between Amphictene favona and P. antipoda but whether this represents a consistent generic difference is unclear. In all the other species that we examined, the position of these structures could not be determined and has rarely been reported in the literature. Further work is needed to clarify this.
Of the five described genera, four occur worldwide and one, Cistenides , has a restricted distribution. Three genera, Cistenides , Petta and Lagis , do not occur in Australian waters. The diagnostic characters of the species recorded in the Tables 1–5 are based mainly on the literature. We have moved species that obviously belong in another genus, but other species may also need to be reassigned once they are re-examined. Variation in characters described from nontype material has been included in brackets in these tables, and some additional records of species may prove to be misidentifications.
ACKNOWLEDGMENTS. We thank Kristian Fauchald for his thoughts on the validity of the manuscript prepared by Savigny. We are also grateful to Miranda Lowe (BMNH), Hilke Ruhberg (HZM) and Birger Neuhaus (ZMB), for the loan of material, and to the Collection Managers at various Australian State Museums for the loan of their pectinariid material. Alex Muir provided us with information about the collector of the neotype of P. antipoda , and Tom Miura provided us with a copy of a Japanese paper. Anna Murray prepared some figures and Kate Attwood prepared the plates (both AM). The Australian Bureau of Flora and Fauna provided the salary of one of us (RP).
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