Psamathe Johnston, 1836

Salazar-Vallejo, Sergio I., 2022, New species of hesionid and phyllodocid polychaetes (Annelida, Errantia) from Clipperton Island, Zoosystema 44 (1), pp. 1-26 : 3

Genus Psamathe Johnston, 1836

Psamathe Johnston, 1836: 14-16 . — Pleijel 1998: 122 (syn., diagnosis). — Parapar et al. 2004: 232.

TYPE SPECIES. — Psamathe fusca Johnston, 1836 , by monotypy.

DIAGNOSIS. — Psamathinae with two lateral antennae, without median antenna; no frontal tubercle; eyes present; nuchal organs separate; palpostyles ovoid, as long as palpophores; 8 pairs of tentacular cirri; without notochaetae; neurochaetae with simple and compound falcigers; pharynx without jaws, with marginal papillae.

DISTRIBUTION. — The species of Psamathe are only known from temperate localities in the Atlantic and Pacific and from the Antarctic, in shallow water, rocky or mixed bottoms. A new species, P. charpyi n. sp., is described from the Eastern tropical Pacific. The confusion in the identification of the species and their rarity might explain these sporadic records.

KEY TO SPECIES OF PSAMATHE JOHNSTON, 1836

REMARKS

Psamathe cirrhata Keferstein, 1862 might need a modification in the specific epithet. As usual for those times, etymology was not explained, but the h letter modifies the meaning ( Brown 1954: 206) from having filaments, or provided with cirri, which is typical for most hesionids (L. cirrus), to being orange-colored (Gr. cirrho, kirrhos). However, the term was derived from the German noun for cirri, used several times along the original description and must be corrected for indicating cirri ( ICZN 1999, Art. 32.5.1). Psamathe fusca hibernica was originally described as Castalia Savigny, 1822 (accepted as Nereimyra de Blainville, 1828 ), but in the brief diagnosis, Southern (1914: 49) regarded it as very similar to P. fusca ; Hartman (1959: 183) included it as a subspecies. The Western Atlantic records of P. cirrata by Uebelacker (1984) differ from the Eastern Atlantic forms, and might belong to an undescribed species, because they have smaller eyes, positioned on the posterior prostomial half, and by having neurochaetae with blades 6-20× longer than wide.

1. Dorsal cirri longer than body width ........................................................................................................ 2

— Dorsal cirri shorter than body width; ventral cirri reaching tips of neurochaetal lobes; all neurochaetae compound; neurochaetal blades 11-21× longer than wide; anterior eyes 2× larger than posterior ones; tentacular cirri as long as body width (pale) .................................................... P. fauveli ( Averincev, 1972) Antarctic.

2(1) Ventral cirri reaching tips of neurochaetal lobes ...................................................................................... 3

— Ventral cirri not reaching tips of neurochaetal lobes ................................................................................ 6

3(2) All neurochaetae compound ................................................................................................................... 4

— Neurochaetae with single capillary chaetae; compound neurochaetal blades 7-15 longer than wide; anterior eyes 3× larger than posterior ones .................. P. haploseta ( Perkins, 1984) Gulf of Mexico, subtidal sands.

4(3) Neurochaetal blades all unidentate; eyes blackish; neurochaetal blades 3-10× longer than wide .............. 5

— Neurochaetal blades unidentate and bidentate; eyes reddish; neurochaetal blades 5-6 longer than wide ..... .................................................................... P. fusca hibernica ( Southern, 1914) Western Ireland, subtidal.

5(4) Anterior eyes 2-3× larger than posterior ones ... P. cirrata Keferstein, 1862 English Channel , France, intertidal.

— Anterior eyes slightly larger than posterior ones ..................... P. charpyi n. sp. Clipperton Island, subtidal.

6(2) Ventral cirri tapered; neurochaetal blades of grading size (5-12× longer than wide); anterior eyes 4× larger than posterior ones (dorsum with 1-2 transverse dark, thin bands per segment) ......................................... .......................................................................... P. fusca Johnston, 1836 English Channel , intertidal rocks.

— Ventral cirri blunt; all neurochaetal blades of similar size (12× longer than wide); anterior eyes twice larger than posterior ones ................................................................... P. ancuda (Wesenberg-Lund, 1962) Chile

REMARKS

Pleijel (1998: 122-124) reinstated Psamathe Johnston, 1836 , clarified its taxonomic history, and provided a list of species, including some new combinations ( Pleijel 1998: 162- 163). There are currently five species in Psamathe : P. ancuda (Wesenberg-Lund, 1962) from Chile, P. cirrata Keferstein, 1862 from Normandy, France, P. fauveli ( Averincev, 1972) from Antarctica, P. fusca Johnston, 1836 from the British coast in the English Channel, and P. haploseta ( Perkins, 1984) from Florida, United States. On the other hand, Pleijel (1998) also regarded P. fusca and P. cirrata as synonyms, and Parapar et al. (2004: 232) followed it. However, despite the proximity of the type localities for these two species, both in the English Channel, there is no type material and topotype specimens for both species should be compared to corroborate this conclusion. There is one apparent difference regarding the length of ventral cirri according to the original descriptions, and some later illustrations ( McIntosh 1908: pl. 69, fig. 16; Hartmann-Schröder 1996: 133, fig. 5b). In P. fusca it is short, not reaching the tip of neurochaetal lobes, whereas in P. cirrata it is longer, reaching the tip of neurochaetal lobes. The key below regards them as different species based on this feature.