Order
Nudibranchia Cuvier
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in Blainville, 1814, restricted
Diagnosis: Notum primarily present, often reduced. Shell in adult state absent. Rhinophores primarily separated, secondarily united, initially rhinophores connected to broad oral veil that replaces anterior notum, often reduced, or oral tentacles formed. True gill absent, often various secondary structures (branched outgrowths, cerata, etc.) arranged latero-dorsally on both sides of the body. Anal opening initially remains in ventro-lateral position, secondarily may shift dorsally. Jaws entire, radula initially multiserial, with hooked teeth, often reduced to one tooth per row, central teeth usually present. Digestive gland initially entire, usually branched to varying degrees, in many taxa branches penetrate dorsal processes. Reproductive system usually considered to be diaulic, but triaulic also present.
Suborders included: (See Remarks below for details) suborder
Arminacea Odhner, 1934
, restricted, reinstated; suborder
Tritoniacea Lamarck, 1809
, reinstated; suborder
Dendronotacea Odhner, 1934
, restricted, reinstated; suborder
Janolacea Minichev and Starobogatov, 1979
, amended, reinstated; suborder
Aeolidacea Odhner, 1934
, reinstated.
Remarks: To reinstate the suborder status for the
Aeolidacea
, first the higher order-level systematics of ‘nudibranchs’, which has an intricate history, needs to be clarified. Initially, the separate order
Nudibranchia
was for the first time introduced in the same work of Blainville (1814) on the same page, but under two different names—Polybranches (Blainville 1814: 177, not to be confused with the subsequent misapplication for sacoglossans), and Nudibranches (Cuvier inBlainville 1814: 177). The original diagnosis for Blainville’s order
Polybranchia
clearly reads ‘respiratory processes subdivided into numerous small branches’, and further, importantly, placed ‘at two sides of the whole body’ as ‘a main distinguishing character’. Simultaneously, for dorids Blainville (1814: 178) introduced the separate order
Cyclobranches
(not to be confused with the subsequent misapplication of the name ‘Cyclobranches’ for patellids and chitons by Cuvier 1817: 451). Dorids immediately differ from ‘Nudibranchia’ by the presence of the predominantly dorsal gill, modified into a circle, at least in part homological to the lateral gill of the order
Pleurobranchida ( Wägele and Willan 2000)
, by ontogenetic patterns (Martynov 2011, Martynov and Korshunova 2015, Martynov et al. 2022), and, regardless of its sister-position to
Nudibranchia
, forms a robustly supported, separate clade, according to the molecular phylogenetic analyses ( Korshunova et al. 2020a, Knutson 2021). Evidently, under the name
Cyclobranches
(
Cyclobranchia
), Blainville implied precisely the circular gill of dorids, whereas included the ‘addition’, onchidiids, possess different secondary dorsal respiratory structures. Unfortunately, the proposal by Blainville, which is strongly supported by modern multisource data, has been historically diminished under the sweeping name ‘Nudibranchia’ (Cuvier in Blainville 1814: 177, Cuvier 1817: 389), although the ordinal status for dorids has been persistently attempted to be resurrected under several different names ( Wägele and Willan 2000). Thus, despite the fundamental differences between
Nudibranchia
and
Doridida
, explicitly indicated at the ordinal ranks very early in the history of sea slug classification, currently dorids are considered just a ‘suborder’ of ‘Nudibranchia’ s.l., whereas
Nudibranchia
in the original sense was renamed significantly later as ‘Cladobranchia Willan and Morton, 1984 ’ ( Wägele and Willan 2000).
Importantly, in Blainville (1814: 177, our italics), it is unequivocally stated that ‘ Mr. de Blainville gives the fourth order the name Polybranches [
Polybranchia
], intending to indicate that the organs of respiration are subdivided into a fairly large number of small gills, but its principal characteristic is actually that these organs arranged in two rows, on each side of the animal’s body and completely exposed, what Mr. Cuvier designated under the name Nudibranches [
Nudibranchia
], which could even be preserved without inconvenience.…’, and on the same page it is unambiguously stated that ‘…the genus
Doris Mr. Blainville
places in particular order [which on the page 178 is designated as the order
Cyclobranches
]’. Thus, regardless of the implied taxonomic content of
Nudibranchia
by Cuvier, Blainville immediately distinguished these two major body plans at the order level, not just as suborders or families. In a further work, Blainville (1816: 51–53) explicitly listed in the details for his order
Polybranchia
several core genera, including
Glaucus, Tergipe
s,
Eolidia
,
Scyllaea
,
Tritonia
, and
Thetys
, thus undoubtedly covering the major diversity of the
Nudibranchia
without dorids. Cuvier (1817: 389), instead, further reinforced the lumped classification by the unexplained complete omission of Blainville’s two ordinal system, and furthermore, by the incorrect usage of Blainville’s dorid’s order
Cyclobranchia
, for very different and distantly related patellids and chitons ( Cuvier 1817: 451). Therefore, the original diagnosis for
Nudibranchia
, with the initial explicit removal of the dorids (Blainville 1814: 177, not subsequent diagnosis byCuvier 1817: 389), almost ideally fits into the 170-year later concept of ‘Cladobranchia Willan and Morton, 1984 ’, which unambiguously implied the same diagnosis of the possession of numerous secondary respiratory processes on both sides of the body, either branched or not, but not a true dorid’s gill. Wägele and Willan (2000: 89) also clearly indicated that
Nudibranchia
has been renamed to Cladobranchia by Willan and Morton (1984) for the traditional suborders
Dendronotacea
,
Arminacea
, and
Aeolidacea
, exactly to accommodate the two-order system by Minichev (1970: 176), who explicitly used order
Anthobranchia
for dorids, and order
Nudibranchia
for traditional aeolidaceans, dendronotaceans, and arminaceans: ‘Minichev called his clades
Anthobranchia
(for the dorids) and
Nudibranchia
( renamed Cladobranchia by Willan and Morton 1984) for the aeolids, arminids and dendronotaceans’.
Given the enormity of hidden diversity at a very fine scale ( Martynov and Korshunova 2022, Korshunova and Martynov 2024) worldwide that still awaits description in all organismal group, it is especially important to accurately separate drastically different patterns of major organizations at a higher scale, such as
Nudibranchia
and
Doridida
. This separation was performed at the initial ‘joined’ description of the orders
Nudibranchia (Polybranchia)
and
Doridida
(
Cyclobranchia
) in Blainville (1814), and there are no historical, morphological, or phylogenetic reasons to dismiss that insightful initial designation. Herein, therefore, the order
Nudibranchia
is restricted (= Cladobranchia Willan and Morton, 1984) to the taxa without a true gill, thus restoring the original designation by Blainville (1814) without dorids. Respectively, the full ordinal status for the order
Doridida
is reinstated. Pelseneer (1894) was probably the first to clearly apply the name with the stem ‘Dorid-’ as a taxon above the family group (as a taxon ‘Doridiens’, yet within ‘Nudibranches’ s.l.). Therefore the authorship of the order
Doridida
, ordinal status restored, is assigned to Pelseneer (1894). For morphological diagnoses, and a list of included families for the order
Doridida
, see Martynov (2011), Korshunova et al. 2020a, and Martynov and Korshunova (2025). According to ontogenetic data (Martynov 2011, Martynov et al. 2022), the order
Nudibranchia
is well differentiated from the order
Doridida
initially by separated rhinophores, which in the course of subsequent evolution may be secondarily united [for a comparison of patterns of the families
Doridoxidae
and
Arminidae
, see details in Korshunova and Martynov (2020)]. We have consistently applied the two-order system of nudibranchs, order
Nudibranchia
and order
Doridida
, respectively, throughout a series of our works (e.g. Martynov and Korshunova 2011, 2012, Martynov et al. 2022), including molecular phylogenetic analyses, Korshunova et al. 2017a, 2020a).
The reinstated, monophyletic suborder
Aeolidacea
( Figs 1, 2) belongs to the restricted order
Nudibranchia
, along with the traditional suborders
Arminacea Odhner, 1934
and
Dendronotacea Odhner, 1934
, both are definitely heterogeneous and paraphyletic ( Goodheart et al. 2018, Korshunova and Martynov 2020, Karmeinski et al. 2021, Knutson 2021). Therefore, to further properly delineate the suborder
Aeolidacea
, the following suborders need to be restricted and reinstated within the proper
Nudibranchia
:
Suborder
Arminacea Odhner, 1934
, restricted, reinstated, with the main diagnosis being the presence of a well-defined notum, moderately tuberculated or striated, without distinct or branched appendages, secondary branchial lamellae may be present under the notum, rhinophores and oral veil connected in various degrees, rhinophores initially separated, secondarily united, digestive gland externally unbranched to moderately branched, and radula multiserial. Includes the superfamily
Doridoxoidea Bergh, 1899
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with the families
Doridoxidae Bergh, 1899
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,
Heterodorididae Verrill and Emerton, 1882
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,
Doridomorphidae Er.Marcus and Ev. Marcus, 1960
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, and the superfamily
Arminoidea Iredale and O’Donoghue, 1923
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, with the family
Arminidae Iredale and O’Donoghue, 1923
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[see molecular phylogenetic analysis in Korshunova and Martynov (2020)].
Suborder
Tritoniacea Lamarck, 1809 sensu Minichev and Starobogatov, 1979
, reinstated. Lamarck’s original (1809) order-level name ‘Tritoniens’, despite being based on the stem-genus name ‘Tritonia’, in its initial taxonomic composition ( Lamarck 1809) was equal to both orders
Nudibranchia
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and
Doridida
and, therefore, unsuitable for the narrow diagnosis of the suborder
Tritoniacea
. Minichev and Starobogatov (1979) instead proposed the amended name ‘Tritoniina’, as part of the reformation of traditional ‘Dendronotacea’ in the rank of a separate suborder. The main diagnosis of
Tritoniacea
is the well-defined, broad, to reduced notum with commonly a various number of branched appendages (secondary gills) dorso-laterally on both sides of the body, rhinophores and oral veil originally connected in various degrees, but the connection is less evident in a majority of taxa, rhinophores initially separate, digestive gland externally not considerably branched, rather compact and does not penetrate into the dorsal appendages, radula multiserial to oligoserial. For details on the included superfamily
Tritonioidea Lamarck, 1809
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, with a single family
Tritoniidae Lamarck, 1809
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, see the molecular phylogenetic analysis in Korshunova and Martynov (2020).
Suborder
Dendronotacea Odhner, 1934
, reinstated, restricted to exclude
Tritoniidae
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, with the main diagnosis being the possession of a considerably reduced to completely absent notum with commonly various branched appendages, rhinophores and oral veil not evidently connected in a majority of taxa, the initial separation of rhinophores is also less evident, digestive gland externally usually considerably branched, and partly penetrates into the dorsal appendages, but definite aeolidacean-like cnidosacs are never formed, radula multiserial to more commonly oligoserial. Included is the superfamily
Dendronotoidea Allman, 1845
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with the families
Bornellidae Bergh, 1874
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,
Dendronotidae Allman, 1845
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,
Dotidae Gray, 1853
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,
Hancockiidae MacFarland, 1923
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,
Lomanotidae Bergh, 1890
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,
Phylliroidae Menke, 1830
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,
Scyllaeidae Alder and Hancock, 1855
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, and
Tethydidae Rafinesque, 1815
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; more superfamilies need to be recognized.
Suborder
Janolacea Minichev and Starobogatov, 1979
, amended, reinstated. The restoration and separation of this suborder is necessary to repair the paraphyletic traditional arminaceans (e.g. Wägele and Willan 2000, Goodheart et al. 2018, Korshunova and Martynov 2020)— because there is a group of arminacean-like nudibranchs of the superfamily
Proctonotoidea Gray, 1853
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(the family list is below), which are only distantly related to the true
Arminacea
in a restricted sense (e.g. including
Arminidae
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and
Doridoxidae
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, see references above). The main diagnosis for the suborder
Janolacea
ranges from a well-defined notum without dorsal appendages to a completely reduced notum with dorsal unbranched appendages, rhinophores and oral veil are evidently connected only in two families, but not in a majority of taxa, digestive gland from not considerably branched externally to strongly branched, and commonly may penetrate into the dorsal appendages, but definite cnidosacs are never formed, radula multiserial to triserial. Includes the superfamily
Proctonotoidea Gray, 1853
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, with the families
Curnonidae d’Udekem d’Acoz, 2017
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,
Lemindidae Griffiths, 1985
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,
Dironidae Eliot, 1910
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,
Madrellidae Preston, 1911
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,
Proctonotidae Gray, 1853
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,
Janolidae Pruvot-Fol, 1933
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, and possibly also Goniaeolidiidae Odhner, 1907; more superfamilies need to be recognized. The genus
Trivettea Bertsch, 2014
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and the family
Heroidae Gray, 1857
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remained incertae sedis regarding suborder placement within
Nudibranchia
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; the genus
Bathydevius Robison and Haddock, 2024
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remains incertae sedis regarding ordinal placement.
ThesuborderJanolaceaisanimportantevolutionaryprecursor for the further formation of the definite cnidosac-bearing suborder
Aeolidacea
, since it represents its sister-group according to the molecular phylogenetic analyses ( Goodheart et al. 2018, Karmeinski et al. 2021, Knutson 2021, present study, Figs 1, 2), and, therefore, the refined diagnosis for the order
Nudibranchia
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proper and discussion of its suborders’ composition presented above is immediately relevant for the major theme of the present study of the high morphological diversity and the numerous distinct molecular lineages, revealed in the suborder
Aeolidacea
( Figs 1, 2).
Suborder
Aeolidacea Odhner, 1934
, reinstated
( Figs 1, 2)
Diagnosis: Body bears dorsal cerata (papillae) of various lengths, number and pattern of placement, but basically in two sets of commonly numerous, partly crowded or, rarely, few in number, separately placed cerata dorso-laterally across almost the entire body length. The initial connection of separated rhinophores with broad oral veil almost completely reduced; rhinophores in adult state commonly closely placed. In an absolute majority of superfamilies, a fully functional single cnidosac (a storage area for nematocysts, which are stinging cells ingested for self-defence from cnidarian prey) is present in the apical part of the cerata. Very rarely the cnidosac is secondarily reduced. Branched appendages or gill-like structures are absent. Digestive gland in all superfamilies is branched in various degrees and patterns, including regular, simple rows. Anal opening may found on the right lateral side of the body (pleuroproctic), in between the anterior and posterior digestive gland branches on the right side of the body (acleioproctic), or between the branches of the posterior digestive gland on the right side of the body (cleioproctic), or very rarely placed toward the posterior extreme of the body. There are also some mixed states of anal opening placement. Jaws are found as a pair of whole, strong plates placed inside of each lateral side of the pharynx. Masticatory edges of the jaws bear various denticle-like structures in various patterns, or, more rarely, smooth. Radula formula falls into three main patterns: oligoserial (commonly more than one and less than 10 longitudinal rows of lateral teeth flank central teeth from each side), triserial (one longitudinal row of lateral teeth on each side of central teeth), and uniserial (lateral teeth completely reduced). Oligoserial is a very rare pattern within
Aeolidacea
, the majority of superfamilies possess either triserial or uniseral radula. Central (= rachidian) teeth usually with central cusp and various numbers and shapes of lateral denticles. In some families central teeth become pectinate, where the central cusp is reduced and may become almost indistinguishable. In a unique case, uniserial radular teeth are fused together in a continuous ribbon-like pattern. So far, there are no known cases within
Aeolidacea
where the radula is completely reduced. Reproductive system described as commonly diaulic, but there are patterns in various superfamilies that can be similar to a triaulic condition. Both distal and proximal seminal receptaculums, or only a single, distal or proximal receptaculum, present. If a single receptaculum is present, it is more commonly a distal receptaculum. Prostate rarely elaborate, evidently granulated, more commonly forms a prostatic vas deferens, but vas deferens and prostate itself in many cases remain relatively distinct. Copulative apparatus commonly includes entire, contractable, but usually non-evertable, penis of various shapes and lengths. Extremely rarely (in at least one taxon of the family
Notaeolidiidae
and in the genus
Paracoryphella
of the family
Paracoryphellidae
) the penis is directly attached to the external body wall. In different families, the penis may bear various hard structures, such as single or multiple stylets, or soft structures, such as warts, tubercles, or folds. Copulative apparatus may also include various glands, which form, in one particular superfamily, a special supplementary gland inserted to the vas deferens or penis, whereas in others form different accessory glands.
Remarks: As a main result of the present study what follows is an updated system of the aeolidacean superfamilies and a Synopsis of all the aeolidacean families so far known, derived from the molecular phylogenetic analysis, which included all the families so far known, and two newly described aeolidacean families ( Figs 1, 2). In a tight connection with the reliable comparison of the two new families from different aeolidacean lineages ( Fig. 2) with all other aeolidacean family-level taxa, it needs to be specially highlighted that the current system of superfamilies of aeolidacean nudibranchs employed in the World Register of Marine Species (WoRMS 2024) is inconsistent with existing morphological and molecular data (see Results, and Synopsis below, including diagnoses of the new families; Figs 1, 2; Tables 1, 2). One of the major inconsistencies is that a number of families that belong to respective phylogenetically clearly distinct clades and correspond to morphological aeolidacean supergroups, such as
Fionoidea
,
Flabellinoidea
, and
Aeolidioidea
( Fig. 2), currently are chaotically scattered among the only two currently recognized superfamilies,
Aeolidioidea
and
Fionoidea
. For example, the core flabellinoideans of the families
Coryphellidae
and
Paracoryphellidae
(see Results andFigs 1, 2), for some reason are currently placed in WoRMS (2024) within a completely different morphological and molecular superfamily
Fionoidea
. Whereas, simultaneously, the actual
Flabellinidae
are definitely closer to the above-mentioned
Coryphellidae
and
Paracoryphellidae
than to any aeolidioidean families ( Fig. 2), but for some equally unexplained reason they are placed instead into a very different molecular and morphological superfamily
Aeolidioidea (WoRMS 2024)
.
To counter this synonymization, over the past seven years we have presented several comprehensive aeolidacean phylogenies, which included all previously known and newly described families ( Korshunova et al. 2017a, 2019b, Martynov et al. 2020, present study; Figs 1, 2). Therefore, we now have a sufficient basis for a superfamilies-based classification of
Aeolidacea
. In those previous, and these present, phylogenies, no representatives of the core of the main superfamilies
Flabellinoidea
,
Aeolidioidea
, and
Fionoidea
have been mixed with each other and all three major supergroups are monophyletic with high support ( Figs 1, 2). The genus
Edmundsella
, which previously has shown some paraphyly with regard to other families ( Goodheart et al. 2018), is invariably placed as an integral part of the monophyletic family
Flabellinidae
with the inclusion of the family stem-genus
Flabellina
( Korshunova et al. 2017a, present study; Figs 1, 2) and consistently nested within other flabellinoids, but not with any other
Fionoidea
( Figs 1, 2). In turn,
Flabellinopsidae
are invariably placed as sister to the majority of core
Flabellinoidea
, but never with the family
Notaeolidiidae
( Korshunova et al. 2017a, present study; Figs 1, 2).
Therefore, the load of accumulated inconsistencies in the superfamily-based classification of the suborder
Aeolidacea
is currently so high that while we have separated two new taxa at the family-level (see below) in the present study, further progress in aeolidacean nudibranch phylogeny and classification is impossible without proper resolution of the above-mentioned serious objective contradiction in the superfamily-based classification of aeolidacean nudibranchs. Thus, before further comparison of the
Hantazuidae
fam. nov. and
Chudidae
fam. nov. (which are definitely distinctly different from any aeolidacean families—see diagnoses and descriptions in the Synopsis below; Figs 1, 2; Tables 1, 2) can be presented, we need to clarify the superfamily system of the suborder
Aeolidacea
. Fortunately, separation of the superfamilies is a nomenclaturally relatively easy action because according to ICZN (1999, article 36), and to the principle of coordination, a taxon of any rank in the family group, including superfamily, ‘is deemed to have been simultaneously established for nominal taxa at all other ranks in the family group’, with the same genus-derived stem family-group name and, importantly, the same authorship. Thus, using the accumulated comprehensive morphological and phylogenetic data on aeolidacean nudibranchs, we may now refine the aeolidacean superfamily system.
First, we separate and consider valid three major aeolidacean superfamilies, all of them having been previously supported for a sufficiently long time ( Bouchet et al. 2005, 2017; even with considerable reservations for the position of several families, see below) and in all of them, consistent morphological data align with evidently distinct phylogenetic clades ( Korshunova et al. 2017a, present study; Fig. 2):
Flabellinoidea Bergh, 1889
,
Aeolidioidea Gray, 1827
, and
Fionoidea Gray, 1857
. The triserial superfamily
Flabellinoidea Bergh, 1889
, reinstated, contains exclusively triserial families without a special supplementary gland in the male part of the hermaphroditic reproductive system (with the exception of a partly similar accessory gland in the coryphellid genus
Occidenthella
, but clearly independently evolved from fionoideans and aeolidioideans, see below)—
Coryphellidae
,
Paracoryphellidae
, and
Flabellinidae
. In turn, the uniserial superfamily
Aeolidioidea Gray, 1827
contains a majority of the exclusively uniserial families without a special supplementary gland (some taxa with additional glandular formations associated with the copulative apparatus, independently evolved from fionoids)—
Aeolidiidae
,
Myrrhinidae
,
Facelinidae
,
Favorinidae
,
Glaucidae
,
Babakinidae
, and
Pleurolidiidae
. The triserial family
Chudidae
fam. nov., discovered through our present work, shows some relation to
Aeolidioidea
, but also aligns as a sister-taxon to several other Aeolidacean superfamilies ( Figs 1, 2), and thus cannot be unambiguously placed into any of the known or aeolidacean superfamilies ( Fig. 2; see detailed discussion below) established here; therefore, is placed in a separate superfamily
Chudoidea
superfam. nov. ( Figs 1, 2). Finally, the third largest aeolidacean superfamily, the predominantly uniserial superfamily
Fionoidea Gray, 1857
contains a majority of the exclusively uniserial families with a special supplementary gland in the copulative apparatus (inserted more commonly into the penis or, more rarely, into the vas deferens)—
Abronicidae
,
Murmaniidae
,
Xenocratenidae
,
Cuthonellidae
,
Calmidae
,
Cuthonidae
,
Tergipedidae
, and
Trinchesiidae
. Paradoxically, within
Fionoidea
there is only a single family without a special supplementary gland and, notably, with a uniserial radula— the family
Fionidae
(the superfamily stem-genus
Fiona
bearing its name), but only a single triserial family,
Eubranchidae
( Figs 1, 2).
However, apart from these three major aeolidacean superfamilies, there are several family-level taxa that cannot be included in any of these three major supergroups according to morphological and molecular data ( Figs 1, 2). The classificatory placement of these families according to their current superfamily position in WoRMS (2024) is also highly inconsistent. For example, two of the most basally placed aeolidacean triserial families,
Apataidae
and
Samlidae
—with disparate ceratal placement morphology and differing details of their reproductive systems—for some inexplicable reason are placed within the predominantly uniserial
Fionoidea
whose phylogenetic position is obviously very distant to
Apataidae
and
Samlidae
( Figs 1, 2). The same is true for the triserial
Cumanotidae
, whose phylogenetic position, together with their paedomorphic sister-family
Pseudovermidae ( Martynov et al. 2020)
, do not show a definite relationship to any main aeolidacean superfamily or other family ( Fig. 2) according to all available analyses ( Martynov et al. 2020, present study; Fig. 1), but for some equally inexplicable reason are currently placed within the predominantly uniserial
Fionoidea
, which are obviously not directly related to the superfamily
Cumanotidae
. Furthermore, the triserial family
Flabellinopsidae
, together with the robustly morphologically and molecular confirmed ( Fig. 2) uniserial family
Hantazuidae
fam. nov. ( Fig. 2, see below), align as sister to the superfamily,
Flabellinoidea
, but without significant support ( Fig. 1).
Externally both the triserial
Flabellinopsidae
and the uniserial
Hantazuidae
fam. nov. are partly similar in the possession of a flap-like—rather than only discontinuous—notal edge or stalk-like ceratal peduncles of
Flabellinoidea
. But partly similar flaps may occur in core species of the otherwise distantly related ( Figs 1, 2)
Notaeolidiidae ( Wägele 1990)
family with an oligoserial radula. That external feature may not indicate a close relationship, but instead may have very ancient evolutionary roots for
Aeolidacea
, so that feature must be considered in the
Aeolidacea
superfamily classification. Additionally, the family
Flabellinopsidae
obviously shows a more distantly-related position compared to the core
Flabellinoidea
family,
Flabellinidae
, according to phylogenomic analysis (e.g. Karmeinski et al. 2021), and this provides additional justification of the more significant separation between core
Flabellinoidea
(
Paracoryphellidae
,
Flabellinidae
, and
Coryphellidae
) species and
Flabellinopsidae
. Therefore, taking into consideration the molecularly robust support between the triserial
Flabellinopsidae
and the uniserial
Hantazuidae
fam. nov. ( Figs 1, 2), the morphological disparity between
Flabellinopsidae
and
Hantazuidae
fam. nov. on the one hand, and the core triserial families
Paracoryphellidae
,
Flabellinidae
, and
Coryphellidae
(superfamily
Flabellinoidea
) on the other hand, we have established the separate superfamily
Flabellinopsoidea Korshunova et al., 2017
for the families
Flabellinopsidae
and
Hantazuidae
fam. nov. ( Fig. 1).
Ultimately, one of the most basal aeolidacean families, the family
Notaeolidiidae
(which aligns as sister to the family
Samlidae
, and together with
Apataidae
is sister to all other Aeolidacean families; Fig. 2), has the pattern of an oligoserial radula with more than one and less than 10 regular longitudinal rows of lateral teeth per each side, which is unknown in any other aeolidaceanfamily (seeTables 1,2). Nevertheless,
Notaeolidiidae
are currently placed in the drastically morphologically different, exclusively uniserial superfamily
Aeolidioidea
in WoRMS (2024). Considering all these obvious morphological and molecular inconsistencies, along with the above-outlined three major aeolidacean superfamilies, we recognize the following ‘lesser’ aeolidacean superfamilies:
Notaeolidioidea Eliot, 1910
,
Samloidea Korshunova et al., 2017
,
Apataoidea Korshunova et al., 2017
,
Unidentioidea Millen and Hermosillo, 2012
,
Cumanotoidea Odhner, 1907
(apart from
Cumanotidae
also to include its paedomorphic close relatives
Pseudovermidae
, see: Martynov et al. 2020), and
Flabellinopsoidea Korshunova et al., 2017
. The position of two smaller families with long-discussed uncertain positions such as
Embletoniidae (Karmienski et al. 2021)
and ‘Piseinotecidae’ ( Korshunova et al. 2017a), plus a few more uncertain taxa, are considered further in the present study (see Synopsis of all aeolidacean superfamilies and families below).
The separation of several ‘lesser’ superfamilies within
Aeolidacea
is not pursued to perform classic ‘classificatory division’, but clearly aims to maximally reflect the extremely complex, genuine evolutionary patterns within
Aeolidacea
( Fig. 1), uncovered in all the performed analyses up to this point. Nearly all families are traditionally assessed as having strict distinct correspondence to particular family-level taxa features, such as patterns of the notal edge, position of the anus, a triserial or uniserial radula (e.g. Odhner 1934, Odhner in Franc 1968), and other characters that are distributed over family-level aeolidacean groups in a highly intricate, sometimes counter-intuitive pattern, forming an evolutionary-fuelled morphological and molecular immensely complicated picture ( Figs 1, 2). This complexity must be correspondingly reflected in the respective family- and superfamily-based revised Aeolidacean taxonomy. The family
Embletoniidae Pruvot-Fol, 1954
shows a somewhat unsettled phylogenetic relationship to
Aeolidacea
(see: Martynov et al. 2020, Karmeinski et al. 2021) and is included in the present Synopsis as a separate superfamily addition, after all other aeolidacean superfamilies.
The updated Synopsis with the diagnoses of all of the abovediscussed valid aeolidacean superfamilies and families of the suborder
Aeolidacea
is, therefore, presented below and throughout the text. Further data may potentially correct some aspects of this classification of superfamilies, but according to the currently available extensive morphological data and robustly supported numerous aeolidacean phylogenetic superfamily clades ( Fig. 1), this classification scheme has a reliable evolutionary basis. In the future, more detailed genomic data may add further details to some of these clades and respective groups, but it is unlikely that it will change the major patterns of aeolidacean phylogeny. For example, the later phylogenomic study of Karmeinski et al. (2021) largely confirmed the major aeolidacean family-level clades originally revealed in Korshunova et al. (2017a).
Superfamilies included:
Notaeolidioidea Eliot, 1910
, reinstated;
Samloidea Korshunova et al., 2017
, herein established;
Apataoidea Korshunova et al., 2017
, herein established;
Unidentioidea Millen and Hermosillo, 2012
, herein established;
Fionoidea Gray, 1857
, restricted;
Cumanotoidea Odhner, 1907
, herein established;
Chudoidea
superfam. nov.;
Aeolidioidea Gray, 1827
, restricted;
Flabellinopsoidea Korshunova et al., 2017
, herein established;
Flabellinoidea Bergh, 1889
, reinstated.
Synopsis of the suborder
Aeolidacea