Aricidea sp., from here.

Belongs within: Eumetazoa.
Contains: Machaeridia, Leodicidae, Orthonectida, Cornulitidae, Amphinomida, Phyllodocida, Eunicida, Mesonerilla, Echiura, Aeolosomatida, Clitellata, Scolecida, Polygordius, Saccocirrus, Protodrilus, Spionida, Cirratuliformia, Orbiniidae, Maldanidae, Terebelliformia, Arenicolidae, Sabellida.

The Annelida includes the segmented worms and related taxa. Most members of this clade possess homonomous segmentation, lateral chaetae and a nuchal organ at the posterior end of the prostomium, but these characters have all been modified or lost in some derived subgroups. Many classifications of the annelids have divided them between three classes: the Polychaeta (mostly marine worms which have more or less dense arrays of chaetae inserted on lateral parapodia), Oligochaeta (earthworms and related taxa which have fewer chaetae and lack parapodia) and Hirudinea (leeches). However, recent phylogenetic analyses have indicated that the latter two ‘classes’ (which together form a clade called the Clitellata) are likely to be nested within the paraphyletic ‘polychaetes’. Exact relationships within the annelids remain otherwise much debated. Potential clades include the Canalipalpata, members of which often possess grooved, ciliated palps in association with the prostomium (Parry et al. 2014). Another group, the Aciculata, is characterised by the presence of aciculae, supportive chaetae embedded within the parapodia. Within the Aciculata, the Errantia are mobile, predatory or detritivorous, worms. The Nerillidae are minute, mostly marine polychaetes with the prostomium fused to the peristomium and with setae on most or all segments.

Separating segments
Published 7 March 2008
The marine worm Perinereis amblyodonta, from here).

Annelids have long been victim to a certain chauvinism in systematics. They’ve been treated as kind of the poor cousin to the other major animal phyla*, coupled with an idea that they were in some way “primitive”. A number of other phyla, most notably the arthropods and molluscs, have at various times been explicitly or implicitly regarded as derived from annelid ancestors. It must be stressed that in very few of these cases of proposed annelid ancestry was a direct connection made to any specific annelid subgroup. Annelid ancestry was less of a rigorous hypothesis and more of a vague assertion, in the same vein as suggestions of a “thecodont” ancestry of birds.

*Though they still had the flatworms to look down on, at least.

Christmas tree worm (Serpulidae), from here.

Things changed somewhat with the advent of recent molecular or molecular-influenced phylogenetic studies. Three phyla in particular, the annelids, onychophorans and arthropods, had been united by their metameric segmentation, the regular repetition of separated, similar body segments (this pattern of segmentation has become obscured in many arthropods by specialisation of the separate segments, but is still recognisable in groups such as centipedes and millipedes). More recent analyses have shown the onychophorans and arthropods to have evolved their segmentation separately from annelids, forming a clade with the nematodes and other smaller phyla (the Ecdysozoa) while annelids sit in a clade called the Lophotrochozoa with such phyla as molluscs and brachiopods. Within the trochozoans, metameric segmentation might have been reborn as a defining character of annelids, but the spectre of “ancestral annelids” still didn’t quite go away. For instance, while molluscs are mostly unsegmented, one supposedly basal taxon, the Neopilinida, possesses serial repetition of some organs and was suggested to demonstrate the origin of molluscs from a segmented ancestor, with the implication that “segmented” equaled “annelid” generally not too far behind.

Within the annelids, things have not been much better. Traditionally, annelids have been divided into three classes, the Polychaeta (marine worms), Oligochaeta (earthworms) and Hirudinea (leeches), but it has long been recognised that this is not a satisfactory situation. It is well-established that the earthworms and leeches form a single clade, the Clitellata, but within the Clitellata the “oligochaetes” are united only by the absence of the derived features of leeches. Relationships between the Clitellata and Polychaeta have been even more contentious—authors have differed on whether the polychaetes form a monophyletic group that is sister to the Clitellata, or whether the Clitellata is nested within the polychaetes. The polychaetes in turn have been divided between about 80 families, but relationships between those families have been almost completely unresolved.

Giant tube worms Riftia (Pogonophora), from here.

An influential study in annelid phylogenetics was that of Rouse & Fauchauld (1997) which undertook a morphological analysis of the polychaetes. Rouse & Fauchauld found a monophyletic Polychaeta with Clitellata as sister group, and division of the polychaetes into three major clades, named Aciculata, Canalipalpata and Scolecida. They also found that the worms previously regarded as the separate phylum Pogonophora were actually highly derived annelids, as had been suggested by some authors previously. Unfortunately, support for any of the clades found was relatively low, and homoplasy was rampant. The benefits of hindsight allow us to quibble with their choice of outgroups, as well—Rouse & Fauchauld rooted their tree using the small non-segmented worm clades Sipuncula and Echiura (on which see more below) and the arthropods and onychophorans, for which many of the supposedly shared characters were probably homoplasies. A recent major molecular study (Rousset et al. 2007), despite including some 217 taxa, was unable to even demonstrate annelid monophyly, finding many of the supposed ‘outgroups’, including molluscs, brachiopods and nemerteans, scattered around within the annelids, and recovered almost none of the major clades of Rouse & Fauchauld (1997). However, support over the entire analysis was low, and large chunks of data were missing for many of the taxa included in the analysis.

The echiuran Urechis caupo, from here.

And so we finally get to Struck et al. (2007). While Struck et al. did not cover quite as many taxa as Rousset et al. (2007), they included more genes and more complete data for the taxa included. Outgroup taxa were drawn from a number of other lophotrochozoan phyla, and the first major result of Struck et al. was the resolution of Annelida as a coherent clade, in contrast to earlier molecular studies. Within Annelida, polychaetes were paraphyletic with regard to Clitellata, and the closest relatives of the Clitellata were the Aeolosomatidae, previously suggested as such on morphological grounds. As for the major morphological clades of Rouse & Fauchauld, while none were strictly monophyletic, the conflict between morphological and molecular results was much reduced. Rouse & Fauchauld’s Aciculata was largely monophyletic except for the inclusion of one taxon that had been included with the Scolecida, while the majority of the Scolecida formed two branches of an unresolved trichotomy with the clade including the Clitellata.

(From Struck et al., 2007) ML analysis and BI of Nuc data set with 81 OTUs (-ln L = 66,627.30). 1 of 2 best trees is shown. In the other tree the trichotomy of Nephtyidae, Syllidae, and Pilargidae is resolved with Syllidae being sister of Nephtyidae. OTUs with just the genus names (e.g., Lumbricus) indicate that the sequences from different species of that genus were concatenated. Nuc consisted of 9,482 characters, from which 4,552 (28S rRNA—2,504; 18S rRNA—1,375; EF1α—673) unambiguously aligned and non-saturated ones were included. BS values above 50 shown at the branches on the left; PP’s on the right or alone. The branch leading to Ophryotrocha labronica is reduced by 90%. Ophryotrocha individuals have been sampled from a long time culture, which got bottlenecked several times. For 28S rRNA, Capitella forms a long branch and does not cluster with the two other Capitellidae in the analyses. ML settings: Base frequencies: A = 0.2727, C = 0.2495, G = 0.2586, T = 0.2192; Rate matrix: AC, AT, CG, GT = 1.0000, AG = 2.5097, CT = 3.7263; α = 0.4830; Proportion of invariant sites = 0.3103. Models in BI: 28S rRNA, 18S rRNA, EF1α : GTR+I+Γ. Clitellata, Echiura, Siboglinidae, Sipuncula highlighted with gray and bars indicate polychaete groups: orange = outgroup; A, blue = Aciculata; C, green = Canalipalpata; S, red = Scolecida; Ca = Capitellida; Eu = Eunicida; Ph = Phyllodocida; Sa = Sabellida; Sp = Spionida; Te = Terebelliformia; Aph = Aphroditiformia.

Three small groups of worms previously classified as separate phyla were also included among the annelids. The annelid nature of the Pogonophora (corresponding to the Siboglinidae in the tree above) was confirmed, as was its position in the order Sabellida as proposed by Rouse & Fauchauld. The Echiura had also been previously suggested to be derived annelids—while the adults are non-segmented, echiurans do possess chaetae (bristles) like those of annelids and characters related to segmentation have been demonstrated in their larvae. Struck et al. found a relationship between Echiura and the polychaete family Capitellidae, as had been found in previous molecular studies.

Sipunculans, from here.

Something that is likely to cause more debate, though, is Struck et al.‘s finding the Sipuncula within the annelids. The relationships of the Sipuncula or peanut worms have long been debatable. Some authors have favoured a relationship with annelids, while others have placed them closer to molluscs. Unfortunately, Struck et al. included only one representative of the Sipuncula, and while it was nested well within the annelids its position therein was quite unstable, moving about a lot between analyses. It is worth noting here that the large-scale analysis of animal interrelationships by Dunn et al. available from yesterday as an advance online publication at Nature also positioned Sipuncula within the Annelida. Nevertheless, I can see a lot of further study being done on this result in the future.

A lot remains to be done before we can fully understand the evolution of the annelids, but Struck et al. have certainly made an important contribution. Hopefully, the exorcism of the spectral “ancestral annelid” will encourage the study of annelids not as some relictual halfway-house on the way to somewhere else, but as a specialised and diverse grouping in their own right.

Systematics of Annelida
<==Annelida (see below for synonymy)
    |--Pygocirrus butyricampumPE16, PTV14
    |  |    |--+--Kenostrychus clementsiPE16
    |  |    |  `--AmphinomidaPE16
    |  |    `--ErrantiaPE16
    |  |         |--PhyllodocidaPE16
    |  |         `--EunicidaPE16
    |  `--NerillidaeH-S86
    |       |--MesonerillaPE16
    |       |--Thalassochaetus Ax 1954H-S86
    |       |    `--T. palpifoliaceus Ax 1954TS02
    |       |--Afronerilla Faubel 1978H-S86
    |       |    `--A. hartwigi Faubel 1978H-S86
    |       |--Bathynerilla Faubel 1978H-S86
    |       |    `--B. marina Faubel 1978H-S86
    |       |--Nerillidopsis Jouin 1966H-S86
    |       |    `--N. hyalina Jouin 1966H-S86
    |       |--Psammoriedlia Kirsteuer 1966H-S86
    |       |    `--P. ruperti Kirsteuer 1966H-S86
    |       |--Troglochaetus Delachaux 1921H-S86
    |       |    `--T. beranecki Delachaux 1921H-S86
    |       |--Meganerilla Boaden 1961H-S86
    |       |    |--M. clavata Magagnini 1966H-S86
    |       |    `--M. swedmarki Boaden 1961TS02
    |       |--MicronerillaTS02
    |       |    |--M. brevis Saphonov & Tzetlin 1997TS02
    |       |    `--M. minutaTS02
    |       |--Nerilla Schmidt 1848H-S86
    |       |    |--N. antennata Schmidt 1848H-S86
    |       |    |--N. digitata Wieser 1957H-S86
    |       |    |--N. inopinata Gray 1968H-S86
    |       |    |--N. marginalis Tilzer 1970H-S86
    |       |    |--N. mediterranea Schlieper 1925H-S86
    |       |    |--N. parva Schmidt & Westheide 1977H-S86
    |       |    |--N. sinica Wu, Chen & Sun 1980H-S86
    |       |    `--N. stygicola Ax 1957H-S86
    |       `--Nerillidium Remane 1925H-S86
    |            |--N. gracile Remane 1925H-S86
    |            |--N. levetzovi Remane 1949H-S86
    |            |--N. lothari Schmidt & Westheide 1977H-S86
    |            |--N. macropharyngeum Jouin 1970H-S86
    |            |--N. mediterraneum Remane 1928H-S86
    |            |--N. renaudae Join 1970H-S86
    |            |--N. simplex Levi 1953H-S86
    |            `--N. troglochaetoides Remane 1925H-S86
    `--Canalipalpata [Capitellida, Drilomorpha, Sedentaria, Spiomorpha]PTV14
         |  i. s.: Keilorites Allan 1927Ho62 [=Trachyderma Phillips 1848 non Latreille 1829Ho62; KeiloritidaeW93b]
         |           |--*K. crassituba (Chapman 1910) [=*Trachyderma crassituba]Ho62
         |           |--‘Trachyderma’ antiquissimaH64
         |           |--K. coriacea (Phillips 1848)W93b
         |           `--K. squamosa (Phillips 1848)W93b
         |  |  |  `--+--AeolosomatidaSS07
         |  |  |     `--ClitellataPE16
         |  |  `--+--ScolecidaPE16
         |  |     `--Cossura Webster & Benedict 1887PE16, J56 [Cossuridae]
         |  |          |--*C. longocirrataJ56
         |  |          |--C. candida Hartman 1955J56
         |  |          `--C. pygodactyla Jones 1956J56
         |  `--+--Polygordiidae [Gymnotoma]RP07
         |     |    |--PolygordiusPE16
         |     |    |--Rhamphogordius lacteus Rathke 1843H69
         |     |    |--Linotrypane apogon M’Intosh 1875H69
         |     |    `--Chaetogordius canaliculatus Moore 1904H69
         |     `--+--Protodriloides Jouin 1966PE16, H-S86 [ProtodriloididaeRF98]
         |        |    |--P. chaetifer (Remane 1926)H-S86
         |        |    `--P. symbioticus (Giard 1904)H-S86
         |        `--+--SaccocirrusPE16
         |           `--ProtodrilidaeRP07
         |                |--ProtodrilusPE16
         |                `--Astomus Jouin 1979H-S86
         |                     `--A. taenioides Jouin 1979H-S86
               |  `--+--OrbiniidaePE16
               |     `--ParaonidaeSS07
               |          |--Paraonis lyraPP64
               |          |--Cirrophorus lyra (Southern 1914)RP07
               |          `--AricideaPE16
               |               |--A. cerrutii Laubier 1967 [=Acesta cerrutii]H-S86
               |               `--A. jeffreysiiM62
                  |  `--+--TerebelliformiaPE16
                  |     `--ArenicolidaePE16
                     |    |--MyriocheleRP07
                     |    `--OweniaPE16
                     |         |--O. collaris Hartman 1955SS07
                     |         `--O. fusiformis delle Chiaje 1841SS07
                             |  i. s.: Spiochaetopterus costarum (Claparède 1870)SS07
                             |    |--C. sarsi Boeck in Sars 1851RP07
                             |    `--C. variopedatus (Renier 1804)SS07
                                     |--P. solitariusM62
                                     `--P. verrillii Treadwell 1943H56
Annelida incertae sedis:
  Paranerilla limicolaGO06
  Phyllobranchus Girard 1851BR05
  Eumenia crassaMF02
  Amharete acutifronsGAS03
  Asabelides sibiricaGAS03
  Praxillella praetermissaGAS03
  Chone teresKBC03
  Jugaria quadriangularisKBC03
    |--C. armoricanaKBC03
    `--C. spirillumKBC03
  Hermilepidonotus robustusKBC03
  Genetylli castaneaKBC03
  Polymnia trigonostomaKBC03
  Demonax fulloKBC03
  Neoamphitrite grayiKBC03
  Nicolea gracilibranchisKBC03
  Euthalenessa dendrolepisPP64
  Hermonia histrixM62
  Lagisca extenuata [incl. L. extenuata var. abyssorum]PP64
  Kefersteinia cirrataM62
    |--P. obscuraH56
    `--P. pallidaM62
  Langheransia cornutaM62
  Dialychone acusticaM62
    |--J. candelaM62
    `--J. elegansBBB-S95
  Praegeria remotaM62
  Synelmis albini (Langerhans 1881)H-S86
  Adyte assimilis (McIntosh 1874) [=Hermadion assimile, Scalisetosus assimilis; incl. H. echini Giard 1886]BK77
  Antinoella sarsi [incl. Polynoe cirrata Grube 1876, Harmothoe cirrata]BK77
  Hermadion hyalinusBK77
  Subadyte pellucida (Ehlers 1864-1868) (see below for synonymy)BK77
  Phylo foetida [=Aricia foetida]BK77
  Hesperonoe adventorCH97
  Scolecolepides benhamiHS01
  Hemipodus simplexHS01
  ‘Hedyle’ Malmgren 1865 non Guenée 1857BR05
  Psammodrilidae [Psammodrilida]H-S86
    |--Psammodriloides Swedmark 1961H-S86
    |    `--P. fauveli Swedmark 1961H-S86
    `--Psammodrilus Swedmark 1953H-S86
         |--P. aedificator Kristensen & Nørrevang 1982H-S86
         `--P. balanoglossoides Swedmark 1952TS02
  Steblospio benedictiR96
  Manayunkia speciosaKA01
  Hrabeiella periglandulata Pizl & Chalupsky 1984RP07
    |--D. australis Bretnall 1921F71
    `--D. brazieri Bretnall 1921F71
  Augeneriella lagunariP71
  Theostoma oerstediBBB-S95
    |--Notocirrus attenuatus (Treadwell 1906) [=Arabella attenuata]H56
         |--‘Aracoda’ attenuata Treadwell 1911 [=Drilonereis attenuata]H56
         |--A. iricolor (Montagu 1804) (see below for synonymy)H56
         |--A. iridescens Treadwell 1906H56
         `--A. semimaculata (Moore 1911) [=Aracoda semimaculata; incl. Arab. pacifica Treadwell 1941]H56
    |--L. kroyeriBBB-S95
    `--L. salmacidisBBB-S95
    |--A. filigeraBBB-S95
    `--A. tentaculataBBB-S95
    |--P. lupina (Stimpson 1856)BM88
    |--P. maxillosusM62
    |--P. oculea (Treadwell 1901) [=Panthalis oculea]H56
    `--P. panamensis (Chamberlin 1919) [=Panthalis panamensis; incl. Po. californicus Treadwell 1941]H56
    |--Lumbriconereites Ehlers 1869Ho62
    |    `--*L. deperditus Ehlers 1869Ho62
    `--Lumbriconereis Grube 1840Ho62
         |--*L. quadristriata Grube 1840Ho62
         |--L. coccineaPP64
         `--L. paradoxaPP64
    |--Staurocephalites Hinde 1879Ho62
    |    `--*S. niagarensis Hinde 1879Ho62
    `--Marlenites Eller 1945Ho62
         `--*M. marginatus (Eller 1944) [=Oenonites marginatus]Ho62
  Ebetallites Žebera 1935Ho62
    `--*E. ancoraeformis Žebera 1935Ho62
  Ottawina Wilson 1948Ho62
    `--*O. trentonensis Wilson 1948Ho62
    |--Chloraema Dujardin 1838Ho62
    |    `--*C. edwardsii Dujardin 1838Ho62
    |--Eotrophonia Ulrich 1878Ho62
    |    `--*E. setigera Ulrich 1878Ho62
    `--Siphonostomites Roverto 1904Ho62
         `--*S. hesionoides (Massalongo 1855) [=Nereites hesionoides]Ho62
  Campylites Eichwald 1856Ho62
    `--*C. longissimus (Sowerby 1839) [=Serpulites longissimus]Ho62
  Hammatopsis Hadding 1913Ho62
    `--*H. scanicus Hadding 1913Ho62
  Khemisina Termier & Termier 1951Ho62
    `--*K. annulata Termier & Termier 1951Ho62
  Lockportia Howell 1959 [=Dactylethra Ruedemann 1925 nec Cuvier 1829 nec Meyrick 1906]Ho62
    `--*L. conspicua (Ruedemann 1925) [=*Dactylethra conspicua]Ho62
  Oliveirania Maury 1927Ho62
    `--*O. santacatharinae Maury 1927Ho62
  Ruedemannella Howell 1959 (see below for synonymy)Ho62
    `--*R. obesa (Ruedemann 1925) [=*Bertiella obesa]Ho62
  Tubulella Howell 1949 [incl. Urotheca Matthew 1899 non Cocteau & Bibron 1843]Ho62
    |--*T. flagellum (Matthew 1899)Ho62 (see below for synonymy)
    |--T. pervetus (Matthew 1899)WS93
    `--T. terranovaensis Howell 1963WS93
  Tubulelloides Howell 1949Ho62
    `--*T. gracilis (Ruedemann 1916) [=Serpulites gracilis]Ho62
  Eopolychaetus Ruedemann 1901Ho62
    `--*E. albaniensis Ruedemann 1901Ho62
  Pontobdellopsis Ruedemann 1901Ho62
    `--*P. cometa Ruedemann 1901Ho62
  Lonchosaccus Ruedemann 1925H75
    `--*L. uticanus Ruedemann 1925H75
    |--*L. annae (Syssoiev 1959)D94
    |--L. cylindrica (Grabau 1900)L95
    `--L. sysoievi (Meshkova 1974)W93a
  ‘Hipponyx’ inexpectata Mestayer 1929P61
  Peronochaeta [Peronochaetidae]E-J04
    `--P. dubia (Walcott 1911) [=Canadia dubia]E-J04
  Insolicorypha [Insilicoryphidae]E-J04
    `--I. psygma Conway Morris 1979E-J04
  Stephenoscolex [Stephenoscolecidae]E-J04
    `--S. argutus Conway Morris 1979E-J04
    |--Histriobdella van Beneden 1858 [incl. Histriodrilus Foettinger 1884]H69
    |    `--H. homariH69
    `--Stratiodrilus Haswell 1900H69
         `--S. platensisH69
  Pallasia porrectaPP64
    |--R. intermediaPG98
    `--R. loveni [incl. R. loveni f. gracilior]PP64
  Pontogenia chrysocomaPP64
  Clymene lumbricoidesPP64
  Scolaricia typicaPP64
  Leiocapitella dollfusiPP64
  Nossis Kindberg 1865KM17
  Psyrmobranchus protensusG84
  Facivermis yunnanicus Hou & Chen 1989W93b
  Maotianchaeta fuxianellaC12
  Pharyngocirrus tridentigerSRT18
  Ramesses magnus Schram 1979W93b
  Soris labiosus Schram 1979W93b
  Trophonia plumosaM01
    |--P. evanida (Treadwell 1926) [=Eupanthalis evanida]H56
    |--P. pacifica Treadwell 1914H56
    `--P. pustulata Treadwell 1924 [incl. Acoetes magnifica Treadwell 1929]H56
  Pareulepis [Pareulepidae]H56
    |--P. fimbriata (Treadwell 1901) [=Eulepis fimbriata]H56
    `--P. wyvillei (McIntosh 1885) [incl. Eulepis splendida Treadwell 1901]H56
    |--E. maculosa (Treadwell 1931) [=Macellicephala maculosa]H56
    `--E. mutilata (Treadwell 1906) [=Polynoe mutilata; incl. E. oahuensis Treadwell 1906]H56
  Eupolyodontes elongata (Treadwell 1931) [=Iphionella elongata]H56
  Lysarete [Lysaretidae]H56
    `--L. brasiliensis Kinberg 1865 [incl. Oenone brevimaxillata Treadwell 1931]H56
  Chrysodon alveolatumG20
  Thia rostrataG20
  Eumolpe planaG20
  Levinsenia gracilisHG98
  Lysippe labiataHG98
  Paraprionospio cooraPG98
  Euchone pallidaPG98
  Kinbergonuphis proalopusPG98
  Rhamphobrachium (Spinigerum) averinceviPG98
  Leitoscoloplos kerguelensisPG98
  Vermiforma Cloud in Cloud et al. 1976D78, G79
    `--*V. antiqua Cloud in Cloud et al. 1976G79
  Apomatus similis Marion & Bobretzky 1875C94
Trace fossil: Trachyderma serrata Salter 1864Ha62

Annelida [Amphitrites, Archiannelida, Chaetopoda, Errantida, Naidina, Nereides, Palpata, Pharyngata, Plesiopora, Plesiotheca, Polychaeta, Sedentarida, Terebellida]

Arabella iricolor (Montagu 1804) [=Nereis iricolor; incl. A. dubia Treadwell 1922, Drilonereis pinnata Treadwell 1921, A. setosa Treadwell 1921]H56

Ruedemannella Howell 1959 [=Bertiella Ruedemann 1925 nec (Sacc.) Sacc. & Syd. 1899 (ICBN) nec Stiles & Hassall 1902 nec Kirschst. 1906 (ICBN)]Ho62

Subadyte pellucida (Ehlers 1864-1868) [=Polynoe pellucida, Adyte pellucida, Hermadion pellucidum, Lepidonotus pellucidus, Scalisetosus pellucidus; incl. H. fragile Clarapède 1868, H. fugax Giard 1890, H. sabatieri Darboux 1900]BK77

*Tubulella flagellum (Matthew 1899)Ho62 [=Urotheca flagellumHo62; incl. Selkirkia pennsylvanica Resser & Howell 1938SHB15]

*Type species of generic name indicated


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[BM88] Bieler, R., & P. M. Mikkelsen. 1988. Anatomy and reproductive biology of two western Atlantic species of Vitrinellidae, with a case of protandrous hermaphroditism in the Rissoacea. Nautilus 102 (1): 1–29.

[BBB-S95] Boubezari, K., G. Bitar & D. Bellan-Santini. 1995. Structure et organisation de trois moulières (Mytilus galloprovincialis et Perna perna) de la région d’Alger. Mésogée 54: 63–72.

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[CH97] Castro, P., & M. E. Huber. 1997. Marine Biology 2nd ed. WCB McGraw-Hill: Boston.

Cedhagen, T. 1994. Taxonomy and biology of Hyrrokkin sarcophaga gen. et sp. n., a parasitic foraminiferan (Rosalinidae). Sarsia 79: 65–82.

[C01] Chapman, F. 1901. On some fossils of Wenlock age from Mulde, near Klinteberg, Gotland; with notes by Prof. T. Rupert Jones and Dr. F. A. Bather. Annals and Magazine of Natural History, series 7, 7: 141–160, pl. 3.

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