Two new species of Caulleriella ( Polychaeta , Cirratulidae ) from Argentina

Caulleriella bremecae and C. galeanoi (Polychaeta: Cirratulidae) are newly described from Mar del Plata, Argentina (38oS, 57oW). Both species have small, red-pigmented nuchal organs (lateral “eyes”) on the prostomium. Caulleriella bremecae sp. nov. is further characterized by a peristomium without annulations except for a narrow anterior dorsal fold, posterior part of peristomium extending posterodorsally over chaetiger 1, latter extending posterodorsally over chaetiger 2 and with slightly separated grooved palps arising middorsally; notochaetae of chaetigers 1-23 all smooth capillaries, thereafter with six bidentate sigmoid hooks and 3-4 capillaries, both types fewer on last 4-5 chaetigers; neurochaetae of chaetigers 1-2 comprised of 8 bidentate hooks and 1-2 capillaries, thereafter only bidentate hooks, decreasing in number posteriorly. The species is frequent and abundant throughout the year in the intertidal mussel beds situated 200-700m from the sewage outfall of Mar del Plata city. Caulleriella galeanoi sp. nov. is characterized by a peristomium with three annulations dorsally, with grooved palps arising from annulus 3, and by smooth capillary chaetae in notoand neuropodia of chaetigers 1-2. Bidentate hooks are present in neuropodia from chaetiger 3, numbering 5-6 in anterior and middle chaetigers, 1-3 in posterior ones. Notopodia have 3-6 pairs of smooth capillary chaetae, decreasing in number posteriorly. From chaetiger 13-20, notopodia with 1-2 capillary chaetae and 1-2 bidentate hooks. Specimens held in aquaria supplied with water and the green alga Vaucheria sp. (Vaucheriaceae) from the intertidal zone reproduced asexually by fission. Gametes were not observed in any specimens.

Although several faunistic and other studies on polychaetes have been published during the last half century, many regions still lack taxonomic knowledge about the local fauna.This is particularly true for Argentina, whose extensive coastline spans more than 4,000km.The first characterization of macrobenthic communities from the extensive Argentine shelf did not include polychaetes due to "insufficient taxonomic knowledge, although [Polychaeta] is a relatively abundant group" (BASTIDA et al., 1992).Among Argentine polychaetes, members of Cirratulidae Ryckholt, 1851 are particularly undocumented.
Cirratulids belong to the subclass Palpata, order Canalipalpata, suborder Terebellida.The family includes organisms with cylindrical body, with a blunt or conical prostomium, and reduced parapodia.Feeding palps arise dorsally in many species, but others have only tentacular cirri.Slender filiform branchiae are present on at least some chaetigers.Chaetae are mostly capillary, but curved or excavate hooks are characteristic of some genera (FAUCHALD, 1977).Chaetal morphology is the main diagnostic character at the generic and specific levels (HARTMAN, 1961;BLAKE, 1996), but chaetal morphology may vary throughout ontogeny, requiring special care in taxonomic identification (GEORGE & PETERSEN, 1991).This is the first of a planned series of contributions destined to elucidate the taxonomic status and diversity of Argentine cirratulids.Starting in 1996, and at the request of the Mar del Plata city water management authority (Obras Sanitarias Sociedad de Estado, OSSE), a series of benthic studies were conducted in intertidal and subtidal areas affected by sewage discharge.These studies were performed in order to obtain baseline information before the construction of a new sewer that will discharge wastes up to 3km offshore (11m depth), replacing the current one that discharges in the intertidal zone.These ecological studies have improved the knowledge of the regional polychaete fauna (e. g., ELÍAS & BREMEC, 1997, 2003;ELÍAS et al., 2001ELÍAS et al., , 2003a, b;, b;ELIAS, 2002;VALLARINO et al., 2002;RIVERO et al., 2005).

ELÍAS & RIVERO
We describe herein two new species of the genus Caulleriella Chamberlin, 1919, one of which was previously identified as Caulleriella alata (Southern, 1914).

MATERIAL AND METHODS
The study area, around Mar del Plata (Buenos Aires Province, 38ºS, 57ºW), is located within the boundaries of the Argentine Biogeographic Province (warm-temperate region of the southwestern Atlantic) (BOSCHI, 2000).
During a series of laboratory experiments, one aquarium, supplied with seawater from the intertidal zone, developed an algal cover of Vaucheria sp.Associated with the latter we observed specimens of Caulleriella.Observations with light microscopes and scanning electron microscope (SEM) showed it to be different from the one collected in the mussel beds.
Specimens of both species were examined with a JEOL (JSM -6460 LV) scanning electron microscope.Materials for SEM were fixed for 24h with glutaraldehyde 3% in a buffer solution of sodium cacadylate 0.1 mol, pH between 7.2-7.4,then dehydrated in ETOH (50,70,80,90,95 and 100%).Samples were dried in hexamethyldisilazane (HMDS), mounted on aluminum discs and coated with Au-Pd (Gold-Palladium).Small specimens were mounted on slides with a Grey & Wess Medium (PVA: polyvinyl alcohol) for optical observation.
All materials were deposited in the Museo de Ciencias Naturales de La Plata (MCNLP), Argentina.
The genus Caulleriella is characterized by an elongated prostomium, and a short or long peristomium; two grooved tentacules anterior to chaetiger 1; middle segments not beaded; noto-and neuropodia widely separated, with a large gap between them.Chaetae include capillaries and bidentate, crotchetlike hooks, not arranged in cinctures (BLAKE, 1996).
The species of Caulleriella are still very incompletely known.Caulleriella alata, originally described from Ireland, has been reported from southern Argentina (ORENSANZ, 1974), southeast Brazil (BOLIVAR, 1990), Chile (including a subspecies C. alata chilensis Carrasco, 1977) to Gulf of Mexico and Florida (WOLF, 1984), Massachusetts (HARTMAN, 1965) and California (HARTMAN, 1961) in USA.This distribution is not coherent, and further studies will very likely show that this "group" consists of several species.Most Southern Hemisphere cirratulid species should be reviewed.
Etymology.The species is dedicated to Dr. Claudia S. Bremec, polychaetologist who shares our passion for the study of worms from the Argentine sea.
Description.A moderate-size species.Body elliptical; chaetigers widest at mid-body, roughly square in cross section throughout; ventral surface concave to pygidium (Fig. 1).Color in alcohol yellowish-tan.
Prostomium triangular in dorsal and lateral views, as wide as long and with very irregular epidermis, appearing glandular.Prostomium with lateral "red eyespots", which under SEM look like vertical depressions; these are in fact ciliated nuchal organs (Fig. 2) (DONER & BLAKE, 2006).Peristomium achaetous, lacking annulations, except for a narrow dorsal annulus.Dorsal part of peristomium extending over half of chaetiger 1 and forming slightly raised crest (Figs. 1, 4); grooved palps slightly separated, arising medially from posterior part of chaetiger 1; latter overlapping anterior half of chaetiger 2. First pair of filiform branchiae present on chaetiger 1, anterior and lateral to palps; subsequent pairs of branchiae on each following segment slightly dorsal to notochaetae (Fig. 3), frequent and long in anterior segments, shorter and less frequent in middle ones, absent on posterior ones.
Remarks.Caulleriella bremecae differs from C. alata in the position of the eyespots, which are dorsal, versus lateral in our material.Caulleriella alata has a simple peristomium not overlapping chaetiger 1, and with first pair of branchiae lateral to palps and on posterior part of peristomium, while in C. bremecae the peristomium forms a slight crest and overlaps chaetiger 1; the first pair of branchiae arises anterolaterally with respect to the palps, with both arising from posterior part of chaetiger 1. Caulleriella alata has long and short capillaries to the last notopodium, with the shorter capillaries being distinctly flattened, while C. bremecae lacks notochaetae in posteriormost chaetigers.Neuropodia bear hooks and capillaries on all segments in C. alata, while only a few capillaries are present on the first two (rarely three) neuropodia in C. bremecae.Caulleriella alata has bidentate hooks with a distinct wing on the convex side of the shaft above the constriction and only a slight bend distally; whereas hooks of C. bremecae have no wing (or hood), lack the constriction and are bent at a nearly right angle (Fig. 5).
DEAN & BLAKE (2007) described C. moralesensis and also compared it with C. alata.The former species is larger and with more segments than C. bremecae, and only the anterior region is flattened dorsoventrally, while in C. bremecae all the body is flattened dorsoventrally.The peristomium of C. moralesensis is triannulated, with Two new species of Caulleriella (Polychaeta, Cirratulidae)...
Description.Very small species (Fig. 7).Body short; noto-and neuropodia widely separated (Fig. 9); ventral surface grooved from chaetiger 1, dorsum grooved from chaetiger 4-5.Color in life yellowish-tan with brown dots, latter denser on the dorsal surface, palps and some branchiae; pygidium densely pigmented, almost black.Color pattern remains after organisms are fixed in formaldehyde solution and transferred to ETOH.Specimens fixed in ETOH turn green, becoming gray shortly after.
Prostomium short and rounded, with irregular epidermis; laterally, with a pair of rounded red spots resembling eyes (Fig. 9).Close SEM examination revealed that those structures are nuchal organs (Fig. 8).Peristomium slightly annulated dorsally; first two annuli wide, but third annulus narrow and bearing a pair of long, grooved palps; first pair of branchiae lateral to dorsal tentacles and anterior to chaetiger 1; branchiae long and thin, present through most of body length, only absent on posteriormost chaetigers; dorsal tentacles thick and grooved.
Methyl Green Staining Pattern.There is no clear staining pattern.Only palps and some branchiae stained slightly.Parts that are in the process of schizometamery stained darker, as well as the pygidium.
Remarks.Caulleriella galeanoi is closely similar to C. bioculata (Keferstein, 1862) but differs markedly in having a simple pygidium instead of the bilobed pygdium present in C. bioculata.Since the two lobes are not anal cirri, which may be lost, they will be present on any but incomplete specimens.Both species have a rounded prostomium, and are similar in the shape of the peristomium and position of palps and branchiae; they have notopodial capillaries all along the body, notopodial bidentate hooks are absent from a variable number of anterior chaetigers, neuropodial capillaries are present on chaetigers 1-2, and neuropodial bidentate hooks from chaetiger 3 to the posterior end.An interesting feature of C. galeanoi and C. bremecae is the presence of nuchal organs resembling red eyespots.According to DONER & BLAKE (2006), in Caulleriella species the nuchal organs are a longitudinal slit, whereas in examined Chaetozone species it is circular.These authors suggest that location and shape of nuchal organs may be important generic-level characters in some cirratulids.This generalization is not valid for the South American C. bremecae, as nuchal organs here are as vertical slits.A comparative SEM study of cirratulid "eyes" is needed to reveal the real nature of these red-or black-pigmented structures (DONER & BLAKE, 2006).
Distribution.Only known from the Mar del Plata area, in aquaria.
Ecology.This species was not recorded in natural habitats.Specimens were found in aquaria supplied with seawater from the intertidal zone.The aquaria developed mats of the alga Vaucheria sp., and the organisms preferred this habitat rather than the sediment of the bottom.The fact that specimens fixed in ETOH turn green suggests that they can be feeding on the algae, in spite of the deposit-feeding typical of cirratulids (FAUCHALD & JUMARS, 1979).In the course of our study, C. galeanoi reproduced only asexually, by schizometamery.
The two species differ in that the capillaries are simple in C. galeanoi but limbate and pectinate in C. bioculata; the peristomium is slightly triannulate dorsally in C. galeanoi but not in C. bioculata; notopodial hooks start on chaetiger 8-22 in C. galeanoi and in chaetiger 6-9 in C. bioculata.Complete specimens of C. galeanoi are quite short, 5mm long for about 50 chaetigers, while C. bioculata can have more than 140 chaetigers and reach a length of 40mm.Pigmentation in C. galeanoi is clearly different due to the presence of granules of dark pigment.Another similar species is C. minuta Dean & Blake, 2007 (also confused with C. bioculata).Caulleriella galeanoi is similar to C. minuta in having small body size, small number of chaetigers, triannulate peristomium, neuropodium with capillaries in first chaetigers and hooks with no accompanying capillaries.However, in C. galeanoi the peristomium has a different annulation shape; neuropodia 1-2 have capillaries (three in C. minuta); and hooks have no capillaries; they are accompanied by capillaries in the anterior 4-9 chaetigers in C. minuta.Capillaries are laterally fimbriated in C. minuta and smooth in C. galeanoi, and the pattern of notopodial capillaries and hooks differs, as does the pigmentation.