Arrecifes coralígenos infralitorales: estructura y variabilidad espacial de las comunidades de macroalgas

Coralligenous reefs are calcareous structures edified mostly by coralline algae that characterize the circalittoral zone of the Mediterranean Sea. However, in some cases coralline algae can constitute peculiar infralittoral biogenic reefs which have been studied less than the circalittoral ones. This study aims to contribute to the knowledge of infralittoral coralligenous reefs by describing their macroalgal assemblages on a large rocky platform off the Tuscany coasts, northwestern Mediterranean Sea. To this end, a multifactorial sampling design was used to describe the structure of the assemblages and to evaluate the variability of the system at multiple spatial scales. A total of 71 macroalgal taxa were found on the coralline algae. Macroalgal assemblages were well structured, with high biodiversity values. The dominant taxa included both photophilous and sciaphilous species, guaranteeing peculiar characteristics in these assemblages, above all if compared with the typical infralittoral and circalittoral macroalgal communities of the same geographic area. The assemblages showed greater variability at a small and intermediate spatial scale than at a large scale. Although infralittoral coralligenous outcrops constitute a peculiar system, they are still poorly understood and should not only be the object of specific studies but also be included in monitoring programmes.Los arrecifes coralígenos son estructuras calcáreas edificadas principalmente por algas coralinas que caracterizan la zona circalitoral del Mar Mediterráneo. Sin embargo, en algunos casos las algas coralinas pueden constituir peculiares arrecifes biogénicos infralitorales menos investigados que los circalitorales. El estudio tiene como objetivo contribuir al conocimiento de los arrecifes coralígenos infralitorales describiendo sus comunidades de macroalgas en una gran plataforma rocosa frente a las costas de Toscana, al noroeste del mar Mediterráneo. Un diseño de muestreo multifactorial fue utilizado para describir la estructura de comunidades algales y evaluar la variabilidad del sistema en múltiples escalas espaciales. Se encontró un total de 71 taxones de macroalgas sobre las algas coralinas. Las comunidades de macroalgas estaban bien estructuradas con altos valores de biodiversidad. Los taxones dominantes incluyeron tanto especies fotófilas como esciáfilas, lo que garantizó características peculiares a estas comunidades si se comparan con las típicas comunidades de macroalgas infralitorales y circalitorales de la misma área geográfica. Las comunidades mostraron una variabilidad a pequeña e intermedia escala mayor que a gran escala espacial. Si bien los afloramientos coralígenos infralitorales constituyen un sistema peculiar, aún son poco conocidos y deberían ser objeto no solo de estudios específicos sino también incluidos en programas de monitoreo ambiental

Studio dell’impatto di Caulerpa racemosa var. cylindracea (Forsskål) J. Agardh sul macrobenthos di fondi mobili

Lo scopo di questo progetto era quello di valutare gli effetti sul macrobenthos di fondi mobili dell’invasione di Caulerpa racemosa e di individuare le alterazioni a carico della composizione e struttura dei popolamenti macrobentonici. Per questo scopo è stato effettuato uno studio correlativo con un disegno di campionamento gerarchizzato multi fattoriale per testare ipotesi sulle modalità di distribuzione degli invertebrati bentonici in aree invase e non invase dall’alga Caulerpa racemosa var. cylindracea nell’Arcipelago Toscano a differenti scale spaziali. E’ stato inoltre previsto un disegno di campionamento per valutare l’abbondanza dell’alga nell’area invasa in termini di biomassa e la influenza del substrato (roccioso o mobile) sulla capacità invasiva dell’alga stessa. Successivamente è stato effettuato uno studio manipolativo con un disegno di campionamento gerarchizzato multi fattoriale allo scopo di valutare l’eventuale recupero della comunità bentonica a seguito di una rimozione sperimentale dell’alga. In particolare le ipotesi testate nei vari studi sono: -La composizione e la struttura dei popolamenti macrozoobentonici di fondo mobile differiscono tra aree invase e aree non invase e tali differenze sono dipendenti dalla scala spaziale considerata. -L’abbondanza di C. racemosa su fondo mobile risulta omogenea alle scale spaziali considerate e significatamene differente da quella raggiunta dalla specie su fondo roccioso. -La rimozione dell’alga dalle aree invase causa una modificazione dei popolamenti macrozoobentonici di fondo mobile, la cui composizione e struttura torna ad avvicinarsi a quella delle aree non invase. I risultati dello studio correlativo confermano quanto emerso da altri studi in altre regioni biogeografiche, cioè che l’invasione di Caulerpa racemosa su fondi mobili porta ad un aumento del numero di specie e del numero di individui causando una modificazione nella composizione e nella struttura dei popolamenti macrozoobentonici. Inoltre, lo studio ha investigato per la prima volta gli effetti della rimozione dell’alga sui fondi mobili. I risultati hanno mostrato come la struttura e la composizione dei popolamenti nelle aree dove l’alga è stata rimossa sperimentalmente si è riavvicinata a quella dei controlli. Questo dato conferma che le differenze tra popolamenti invasi e non invasi sono realmente da attribuire all’alga. Dal confronto con altri lavori è emerso inoltre che i popolamenti di fondo mobile hanno capacità di recupero maggiori e più veloci rispetto a quelli di fondi duri. La abbondanza di C. racemosa su fondo mobile risulta omogenea alle due scale spaziali considerate e significatamene differente da quella osservata su fondo roccioso che viene colonizzato più efficacemente formando una struttura complessa e stratificata. Il presente studio ha analizzato più scale spaziali mettendo in evidenza differenti pattern di variabilità tra aree invase e non invase. L’invasione di questa specie modifica il livello di variabilità spaziale nel macrobenthos di fondi molli su piccola scala (decine di metri) dove sembra in grado di indurre una riduzione nella variabilità naturale di questi popolamenti. L’incremento della diversità alpha osservato nelle aree invase deve essere presa con cautela, in quanto molte delle specie presenti in aree colonizzate da C.racemosa sono tipiche di altri habitat come quelli vegetati, e possono contribuire ad una perdita della peculiarità del popolamento naturale. Dal momento che la colonizzazione di questa specie interessa ampie aree dei fondi mobili circalitorali si può ipotizzare che questo processo possa aumentare il rischio di perdere popolamenti tipici di tale habitat. Il presente studio è stato condotto in aree a moderato impatto antropico, fatto che non consente di valutare eventuali interazioni con altre sorgenti di disturbo. Ulteriori studi potrebbero valutare se e come le modalità di invasione possano essere modificate dalle attività umane. Inoltre vista la mancanza di conoscenze sulle modalità di invasione di questa specie sui fondi mobili, ed a causa della correlazione che si pensa possa sussistere tra il livello di invasione e gli effetti sui popolamenti bentonici, sarebbe auspicabile un programma di ricerca che preveda studi a lungo termine sulla distribuzione annuale dell’alga invasiva per comprendere le dinamiche coinvolte ed al fine di intraprendere delle misure gestionali adeguate. Il presente lavoro rappresenta il primo tentativo di analizzare con uno studio correlativo l’impatto di Caulerpa racemosa sul macrobenthos di fondi mobili su più scale spaziali e, pertanto, costituirà un valido punto di riferimento per futuri sviluppi in questo settore di ricerca. Esso rappresenta inoltre il primo tentativo, attraverso la rimozione sperimentale dell’alga, di indagare le modalità ed i tempi di recupero della comunità macrobentonica su fondo molle in seguito alla invasione di questa specie alloctona

Small-spatial scale changes in productivity of suprabenthic and infaunal crustaceans at the continental shelf of Ebro Delta (western Mediterranean)

10 pages, 5 figures, 4 tablesProduction (P) and production/biomass ratio (P/B) were estimated from 21 species of peracarid and eucarid crustaceans belonging to two different compartments (infauna: 10 species and suprabenthos: 11 species) using the Hynes size-frequency method. Calculations were based on 7 cruises performed between December 2002 and November 2003 in the continental shelf of the Ebro river delta (ED, Catalan Sea: northwestern Mediterranean). Within ED, P and P/B were compared between two neighbouring sites, one located on 47 m (S1), the other at 61 m (S2). The possible effects of natural variability on production were considered. Sediments in ED were muddy (%clay between 40 and 65%). No significant trend in production comparing S1 and S2 was detected, with 50% of species showing higher P value in S1, and 50% in S2. A significant trend emerged from P/B estimates, with 18 of 21 species showing higher P/B at S1. Similarly significant trends for infauna and suprabenthos were found after analyzing both compartments separately. It is suggested that the more significant P/B found on S1 both among infauna and suprabenthos could be caused by the higher temperature and organic matter content (%TOC) at S1. In multi-linear regression (MLR) models, differences in P between S1 and S2 were greater with increasing differences in the density of species (RD) between sites. Differences were greater in infauna than in suprabenthos, and greater among rare species (those with low dominance, %D). P/B differences between S1 and S2 were mainly explained by %D and RD, and to a lesser extent by differences between sites in the mean size of species (RW). In other words changes in P and P/B were not explained by removal of large size specimens. Some trawling activity occurred at S2, and it may alter the habitat of small macrofauna. In addition to natural variability, we discussed the possible influence of trawling disturbance on P and P/B, bearing in mind the feeding type, mobility, and dispersal capability of species. We suggest that amphipods of the genus Ampelisca, showing higher P/B on S1, characterized by low mobility (probably tube-dwellers), low trophic level (e.g. filter feeding strategies) and low dispersal capability (not free larvae), could be especially vulnerable to trawling impact. © 2009 Elsevier B.V. All rights reservedThe study is part of the EU project (Q5RS-2002-00787) “Response of benthic communities and sediment to different regimens of fishing disturbance in European coastal waters (RESPONSE)”Peer Reviewe

Efectos de la perturbación crónica por la pesca de arrastre sobre la producción secundaria de las comunidades suprabénticas e infaunales de crustáceos en el Mar Adriático (Mediterráneo NO)

13 pages, 6 figures[EN] Towing gears are known to produce several kinds of effects on benthic ecosystems. As small organisms and benthic species with faster growth rates and shorter life histories can withstand the fishing mortality and benefit from reduced competition or predation, trawl fishing can enhance their proliferation. Thus, trawl fishing can lead to biomass loss and production increase, since smaller specimens are more productive than bigger ones. In the present study we evaluate the effects, if any, of trawling on benthic crustacean macrofaunal production rates. Sampling was carried out in two neighbouring sites in the central Adriatic Sea (central Mediterranean), one affected by fishing activity and one not. Production and production/biomass (P/B) ratio of 13 species of peracarid and eucarid crustaceans were estimated using the Hynes size-frequency method. Estimates measured at both sites were compared in order to test the hypothesis that higher production and P/B values should occur in the fished area rather than in the unfished one. Our results indicated that the effects on the species are more complex than expected in regard to this hypothesis, and that they depend on the ecological and behavioural characteristics of the selected species. [ES] Las artes de pesca de arrastre pueden tener varios tipos de efectos sobre los ecosistemas bénticos. Considerando que los organismos pequeños y las especies bénticas con mayores tasas de crecimiento y menores expectativas de vida pueden soportar la mortalidad por pesca y beneficiarse de una reducción en la competencia o depredación, la pesca de arrastre puede propiciar su proliferación y, por ende, resultar en una pérdida de biomasa y un incremento en producción, ya que las especies de menor talla son más productivas que las de mayor tamaño. En el presente estudio se evalúan los efectos, si es que los hay, de la pesca de arrastre sobre las tasas de producción de la macrofauna béntica. Los muestreos se realizaron en dos sitios adyacentes en la parte central del Mar Adriático (Mediterráneo central), uno impactado por actividad de pesca y otro no. Se estimaron la producción y la razón producción/biomasa (P/B) de 13 especies de crustáceos peracáridos y eucáridos mediante el método de frecuencia de tallas de Hynes. Las estimaciones para ambios sitios se compararon para probar la hipótesis de que los valores de producción y P/B deberían de ser mayores en la zona de pesca que en la zona de exclusión a la pesca. Los resultados indican que los efectos sobre las especies son más complejos que los esperados en relación a esta hipótesis, y que dependen de las características ecológicas y el comportamiento de las especies seleccionadas.[en] This study is part of the EU project (Q5RS-2002-00787) "Response of benthic communities and sediment to different regimens of fishing disturbance in European coastal waters (RESPONSE)". [es] Este estudio es parte del proyecto de la Unión Europea (Q5RS-2002-00787) "Respuesta de diferentes comunidades bénticas y el sedimento a distintos regímenes de perturbaciones pesqueras en aguas costeras europeas (RESPONSE)".Peer reviewe

Changes at very short time scale: An example from the marine benthic communities

XIV Congresso dell'Associazione Italiana di Oceanologia e Limnologia (AIOL), Garda (VR), 25-28 settembre 2000.-- 7 pages, 2 figures, 2 tablesThe present paper reports data obtained from a study carried out in October and November 1998 in a marine area off S. Vincenzo (LI) along the Tuscany coast (South Ligurian Sea, Italy) between 29 and 36 meters depth. The benthic community corresponds to the Biocénose de la Vase Terrigène Côtière (VTC) confirming previous authors who described the VTC biocoenoses as the dominant assemblage in this area. According to nMDS this community showed a well defined temporal gradient which appeared quite clear if a monthly interval is taken into account. Such an interval resulted long enough to record modifications in composition and structure of the benthic community as well as in the textural characteristic of the sediments which showed, in the last sampling date, an increase of the clayed component with a parallel decrease of siltPeer reviewe

Laonice (Laonice) Malmgren 1867

Laonice (Laonice) Malmgren, 1867 Laonice (Laonice): Sikorski, Gunton & Pavlova 2017: 962. Type species: Nerine cirrata M. Sars, 1851. By monotypy. Diagnosis. Prostomium fused with fronto-lateral margin of peristomium. Caruncle long, extending beyond half of branchiate chaetigers. Capillary chaetae on anterior chaetigers arranged in two vertical rows. Hooded hooks with main fang surmounted by paired apical teeth. Hooks absent in notopodia. Remarks. The nominotypical subgenus Laonice (Laonice) was recognized by Sikorski et al. (2017) based on a morphological analysis of Laonice species. Molecular analysis provided in the present study (Fig. 1) supports the monophyly of this group.Published as part of Sikorski, Andrey V., Radashevsky, Vasily I., Castelli, Alberto, Pavlova, Lyudmila V., Nygren, Arne, Malyar, Vasily V., Borisova, Polina B., Mikac, Barbara, Rousou, Maria, Martin, Daniel, Gil, João, Pacciardi, Lorenzo & Langeneck, Joachim, 2021, Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species, pp. 253-283 in Zootaxa 4996 (2) on page 259, DOI: 10.11646/zootaxa.4996.2.2, http://zenodo.org/record/506982

Laonice grimaldii Sikorski, Nygren & Mikac 2021, n. sp.

Laonice grimaldii Sikorski, Nygren & Mikac n. sp. http://zoobank.org:act: D21FC5F2-B9E2-4840-B75F-2D24EBBC2F45 (Figs 10, 11, 12A–C, 13, 14A, 18C, 19B, Table 3) Aonides cirrata: Fauvel, 1909 (Part.): 4–5. Not M. Sars 1851. Laonice cirrata: Fauvel, 1927 (Part.): 37–38, fig. 12a–e. Not M. Sars 1851. Type locality. ITALY, Ligurian Sea, st. GAS 10 ter., 43.6368°N, 10.0983°E, 70–80 m, muddy sand. Type material. MOM INV-0022706 (holotype), INV-0022681–0022693, 0022698, 0022699 (35 paratypes); HUJI NVPOLY-2950 (4 paratypes); MIMB 39037–39039, 39047 (23 paratypes); MNCNM 16.01 /18549–18566 (144 paratypes). Adult morphology. Holotype largest complete specimen 40 mm long, 0.8 mm wide for 109 chaetigers. Smallest complete paratype 13 mm long, 0.26 mm wide for 61 chaetigers. Pigmentation absent on body and palps. Gatherings of glandular cells on branchiae and postchaetal lamellae appearing dark in some formalin-fixed specimens. Prostomium triangular, anteriorly wide, truncate or broadly rounded, fused with anterior margin of peristomium (Figs 10A, B, F, 12A), extending posteriorly to chaetiger 37 (to end of chaetiger 33 in holotype) as a low caruncle (Figs 10A, 12A), shorter in small individuals (Fig. 13A). Posterior end of caruncle flat and often indistinct (Fig. 12B). Nuchal organs U-shaped ciliary bands on sides of caruncle (Fig. 10A). Length of nuchal organs was strongly correlated with individual number of branchiate chaetigers (Fig. 13C, r 2 = 0.8927, n = 30). Occipital antenna present, usually small (Fig. 10A, B, F, 12A). One pair of medium-sized median eyes as transverse short wide bands or oblong oval spots oriented obliquely (Figs 10A, F, 12A). Palps as long as 10–14 chaetigers, with deep frontal longitudinal groove lined with cilia. Chaetiger 1 with short capillaries and moderate sized postchaetal lamellae in both rami. Capillaries in each anterior parapodium arranged in two vertical rows. All notopodia with capillary chaetae only. Notopodial postchaetal lamellae with pointed upper tips usually on 3–4 anterior chaetigers (Fig. 10A), occasionally on 5–9 anterior chaetigers (Fig. 11A–D), with rounded to truncate upper edge on succeeding chaetigers (Fig. 11E, F). Notopodial postchaetal lamellae of chaetiger 3 slightly larger than those of chaetiger 4. Notopodial lamellae and branchiae on anterior chaetigers usually overlapping middorsally, thus obscuring observation of nuchal organs. Notopodial postchaetal lamellae on last branchiate chaetiger and on about seven succeeding postbranchial chaetigers with lower part expanded ventrally (Fig. 11G). Neuropodial postchaetal lamellae until chaetiger 4 with upper part acute (Fig. 11A, B), on succeeding chaetigers with rounded edges (Fig. 11C–G). Branchiae from chaetiger 2 to chaetigers 12–45 (on chaetigers 2–38 in holotype), fewer in smaller individuals (Fig. 13A). Branchiae short on anterior chaetigers, full-sized and slightly longer than notopodial postchaetal lamellae from chaetigers 4–5 onwards (Fig. 11B–F). Individual number of branchiae was strongly correlated with length of nuchal organs (Fig. 13C). Dorsal transverse crests absent on chaetigers with nuchal organs (Fig. 12B). Two dorsal crests usually present on each of 2–3 last branchiate chaetigers (Fig. 10D). Anterior crest on each of those chaetigers appearing as an extension of posterior sides of lateral interneuropodial pouches onto dorsum (Fig. 10C, D), becoming prominent from chaetiger 16 (Fig. 10C) and forming complete dorsal crests on 3–4 last branchiate chaetigers (Fig. 10D). Posterior crests appearing 1–2 chaetigers after first start of anterior crests and interconnecting notopodial postchaetal lamellae (Fig. 10D). Anterior and posterior crests almost equal in maximum height on 2–3 last branchiate chaetigers. Anterior crests reduced in height on succeeding chaetigers and disappearing completely after 2–6 postbranchiate chaetigers. Posterior crests on approximately 20 postbranchiate chaetigers (until chaetiger 57 in holotype) becoming nearly as high as notopodial postchaetal lamellae. Lateral interneuropodial pouches from chaetigers 7–26 (from chaetiger 14 in holotype) to body end. Anterior start of pouches was moderately correlated with individual number of branchiate chaetigers (Fig. 18C, r 2 = 0.5278, n = 29). Sabre chaetae in neuropodia from chaetigers 8–18 (from chaetiger 15 in holotype), from more anterior chaetigers in smaller individuals (Fig. 13B), 1–2 in a tuft below vertical row of capillaries or hooded hooks (Fig. 11F, G). Anterior start of sabre chaetae was weakly correlated with individual number of branchiate chaetigers (Fig. 13D, r 2 = 0.2854, n = 30). Hooded hooks in neuropodia from chaetigers 13–36 (from chaetiger 34 in holotype), from more anterior chaetigers in smaller individuals (Fig. 13B), up to 13 in a series (Fig. 11G). Hooks tri- or quinquedentate, with one or two pairs of small apical teeth above main fang (Figs 11H, 12C); superior pair of teeth tiny and hardly discernible, not developed in some hooks. Anterior start of hooks was strongly correlated with individual number of branchiate chaetigers (Fig. 13D, r 2 = 0.9189, n = 31). Pygidium with one pair of short ventral cirri and up to four pairs of longer and thinner thread-like dorsal cirri with swollen bases (Fig. 10E). Digestive tract without gizzard-like structure. Methylene green staining. Intensely stained narrow band along frontal edge of prostomium and peristomium (Fig. 10F); usually stained as well the posterior surfaces, lateral margins and sometimes frontal surfaces of distal parts of notopodial postchaetal lamellae from chaetiger 4 to chaetiger 9 (rarely up to chaetiger 19), and basal parts of pygidial cirri (Fig. 10F). Characteristic diffused staining on ventral body surface, most intensely from approximately chaetiger 21 to chaetigers 33–35 (Fig. 10G). Remarks. Adult L. grimaldii n. sp. appear similar to L. bahusiensis in having the prostomium fused with the frontal margin of the peristomium, dorsal crests only on postbranchiate chaetigers and a narrow band along the frontal edge of prostomium stained with Methylene Green. They differ from all other species of Laonice in having double dorsal crests on chaetigers near the last branchiate chaetiger. Within the L. bahusiensis complex, L. grimaldii n. sp. differs from the other species in having rounded instead of acute notopodial postchaetal lamellae after chaetigers 4–9, and branchiae being slightly longer instead of considerably longer (from 1.3 to 2 times longer) than notopodial postchaetal lamellae. Moreover, the adults of L. grimaldii n. sp. characteristically have a caruncle flattened and therefore indistinct on its posterior end (Fig. 12B), contrary to adults of most other species, which have distinct caruncles that terminate clearly and abruptly. The adults of L. grimaldii n. sp. are similar to those of L. antipoda Sikorski, 2011 from South Africa in various numeric characteristics, especially in the presence of branchiae and prominent dorsal crests on several chaetigers posterior to nuchal organs. In the original description of L. antipoda, Sikorski (2011) noticed the absence of an occipital antenna in the specimens examined but assumed that it might be due to damage. Recent examinations of additional material of L. antipoda from Angola and Gabon (Sikorski, unpublished), however, confirmed the lack of an occipital antenna in this species (Fig. 12D). Thus, L. grimaldii n. sp. differs from L. antipoda by having smaller adults (maximum body width ≤ 0.8 mm in L. grimaldii n. sp. versus ≥ 1.0 mm in L. antipoda), double dorsal crests on 1–2 last branchiate chaetiger(s), an occipital antenna on the prostomium, and notopodial postchaetal lamellae of chaetiger 4 smaller than those of chaetiger 3 (instead of much bigger as in L. antipoda). Etymology. The name of the species refers to the House of Grimaldi, the princely family of Monaco and, more specifically, it is dedicated to Prince Albert I, who collected some of the specimens used for the present species description. Distribution. Mediterranean Sea (Fig. 14A). At 4–80 m depth.Published as part of Sikorski, Andrey V., Radashevsky, Vasily I., Castelli, Alberto, Pavlova, Lyudmila V., Nygren, Arne, Malyar, Vasily V., Borisova, Polina B., Mikac, Barbara, Rousou, Maria, Martin, Daniel, Gil, João, Pacciardi, Lorenzo & Langeneck, Joachim, 2021, Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species, pp. 253-283 in Zootaxa 4996 (2) on pages 269-273, DOI: 10.11646/zootaxa.4996.2.2, http://zenodo.org/record/506982

Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species

The morphological reexamination of specimens previously identified as Laonice bahusiensis Söderström, 1920 from North European and Mediterranean collections, supported by the molecular analysis of freshly collected material, enabled the recognition of four different species in the region: the genuine L. bahusiensis, L. irinae n. sp. from North European waters, and L. grimaldii n. sp. and L. mediterranea n. sp. from the Mediterranean Sea. The morphology of these species is described and illustrated, and their distributions are clarified based on old and new materials. A key for their identification is also provided. The Bayesian analysis of the COI sequences (483 bp) showed that these four species form a clade, namely the L. bahusiensis species complex, morphologically characterized by the continuous dorsal crests on postbranchiate chaetigers in the adults. The genetic p-distances between the species of the complex ranged from 13.27% to 17.99%, while the intraspecific variability ranged from 0.6% to 1.57%. Together with the sister species Laonice cirrata (Sars, 1851), the L. bahusiensis complex formed the Laonice (Laonice) clade, which is morphologically characterized by the prostomium fused with the anterior peristomial margin. However, the monophyly of the L. bahusiensis complex, as well as that of the clade Laonice (Laonice), needs to be further supported through the analysis of a greater set of genes from a larger number of species

Laonice bahusiensis Soderstrom 1920

Laonice bahusiensis Söderström, 1920 (Figs 2, 3, 4, 5A, 18A, 19A, Table 3) Laonice bahusiensis Söderström, 1920: 4–7, 81–83, 93, 98, 99, 110, 114, 128, 134, 195, 223, figs 78–82. Maciolek 2000: 534- 535, table 1. Jelsing 2003: 244, figs 1H, 3E, F. Sikorski 2003 (Part.): 320–325, figs 3A–I, 4A, B, 5A, B, 6F. Jelsing & Eibye-Jacobsen 2010: 376–377, figs 1–4. Type locality. SWEDEN, Skagerrak, Gullmarfjord, Bohuslän, approximately 58.25°N, 11.00°E, Zool. Stn. 1893. Type material. SMNH 4637 (lectotype), 4636, 4638 (11 paralectotypes); ZMMU Pl 973 (2 paralectotypes); UUZM 153 c, d, f, g (70 paralectotypes). Adult morphology. Up to 60 mm long, 1.2 mm wide for 120 chaetigers. Lectotype complete specimen in three fragments, totally 41 mm long, 1.0 mm wide for 107 chaetigers. Pigmentation on body and palps absent. Prostomium triangular, anteriorly wide, usually broadly rounded, occasionally truncate to slightly concave, fused with fronto-lateral margin of peristomium (Fig. 2A, G), posteriorly extending over 32 chaetigers (to end of chaetiger 26 in lectotype) as a low narrow caruncle, shorter in small individuals (Fig. 4A). Nuchal organs U-shaped ciliary bands on sides of caruncle (Fig. 2A). Length of nuchal organs was strongly correlated with individual number of branchiate chaetigers (Fig. 4C, r 2 = 0.7247, n = 76). Well-developed occipital antenna present in the lectotype (Fig. 3B) and in some specimens (21 of the 69 paralectotypes deposited at the UUZM), but may often be small or even greatly reduced (Fig. 3A). Two pairs of red eyes (appearing very dark red, almost black, in large formalin-fixed specimens) arranged trapezoidally, comprising one pair of large median eyes and one pair of small lateral eyes situated anteriorly and set wider apart; lateral eyes well separated from median pair but often deeply embedded inside epithelium and hardly discernible, especially in large individuals. Palps as long as 5–15 chaetigers, with deep frontal longitudinal groove lined with cilia. Chaetiger 1 with well-developed capillary chaetae and small postchaetal lamellae in both rami; notopodial lamellae triangular; neuropodial lamellae rounded. All notopodia with capillary chaetae only. Low prechaetal lamellae present in noto- and neuropodia on anterior chaetigers after chaetiger 1. Notopodial postchaetal lamellae large, leaf-like on branchiate chaetigers, greatly diminishing in size on posterior abranchiate chaetigers; lamellae on anterior branchiate chaetigers with upper tips pointed (Fig. 2C–E). Neuropodial postchaetal lamellae ear-like on branchiate chaetigers, greatly diminishing in size on posterior abranchiate chaetigers. Branchiae from chaetiger 2, up to 35 pairs (on chaetigers 2–32 in lectotype); first pair shorter or similar in length to notopodial postchaetal lamellae of chaetiger 2; from chaetigers 5–6 branchiae up to twice as long as notopodial postchaetal lamellae (Figs 2E, 3A, B), gradually diminishing in size on succeeding chaetigers, posteriorly present on 0–10 chaetigers after end of nuchal organs (Figs 4A, C, 19A). Branchiae free from lamellae, slightly flattened, with surfaces oriented perpendicular to body axis, with ciliation along inner and outer edges. Afferent and efferent branchial blood vessels forming a loop and interconnected by numerous circular capillaries giving branchiae annulate appearance. Individual number of branchiae was strongly correlated with length of nuchal organs (Fig. 4C). Dorsal transverse crests connecting notopodial postchaetal lamellae present, one per chaetiger, beginning on a chaetiger posterior to caruncle and continuing up to the 21 succeeding chaetigers (Fig. 2B) (on chaetigers 27–47 in lectotype). Lateral interneuropodial pouches from chaetigers 8–25 (from chaetiger 17 in lectotype) to end of the body. Anterior start of pouches was weakly correlated with individual number of branchiate chaetiger (Fig. 18A, r 2 = 0.3928, n = 77). Sabre chaetae in neuropodia from chaetigers 10–20 (from chaetiger 19 in lectotype), from more anterior chaetigers in small individuals (Fig. 4B), 1–3 in a tuft; chaetae with weak granulation on shaft. First appearance of sabre chaetae in neuropodia was weakly correlated with individual number of branchiae (Fig. 4D, r 2 = 0. 2879, n = 76). Hooded hooks in neuropodia from chaetigers 18–32 (from chaetiger 29 in lectotype), from more anterior chaetigers in small individuals (Fig. 4B), up to 14 in a series. Hooks tridentate or quinquedentate, with one or two pairs of upper teeth and a very small median superior tooth above main fang (Fig. 3D). Start of hooks in neuropodia was moderately correlated with the individual number of branchiae (Fig. 4D, r 2 = 0.6559, n = 76). Pygidium with up to seven pairs of cirri arranged around terminal anus, comprising one pair of ventral cirri and up to six pairs of thinner and longer dorsal cirri (Fig. 3C); fewer cirri in small individuals. Digestive tract without gizzard-like structure. Reproduction. Laonice bahusiensis is dioecious. The lectotype is a female with small (apparently not yet fully developed) oocytes. Methylene green staining. Tips of notopodial postchaetal lamellae from chaetigers 4–5 to chaetigers 6–12 usually well stained (Fig. 2G). Narrow bands of light staining present dorsally along anterior edge of prostomium and peristomium (Fig. 2G) and ventrally around mouth (Fig. 2F). Remarks. Most species of Laonice typically have one occipital antenna on the prostomium, inserted between the palp bases. In the L. bahusiensis examined in our study, the length of the occipital antennae varied a great deal, with more than half of the type specimens having neither occipital antenna nor scars to suggest that they were broken. In other type and non-type specimens possessing all the other characteristics of the species, a well-developed antenna was not always present between the palps. Distribution. Norwegian Sea, from Kolvereidvågen (64.9°N) south to Kattegat, Västra, Sweden and off Frederikshavn, Denmark (Fig. 5A). At 14–373 m depth.Published as part of Sikorski, Andrey V., Radashevsky, Vasily I., Castelli, Alberto, Pavlova, Lyudmila V., Nygren, Arne, Malyar, Vasily V., Borisova, Polina B., Mikac, Barbara, Rousou, Maria, Martin, Daniel, Gil, João, Pacciardi, Lorenzo & Langeneck, Joachim, 2021, Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species, pp. 253-283 in Zootaxa 4996 (2) on pages 261-264, DOI: 10.11646/zootaxa.4996.2.2, http://zenodo.org/record/506982