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Lovenella assimilis (Browne, 1905), morphological specifications. Female, oral view (A); Female, lateral view, (B); Young specimens (C); Marginal bulb, and statocyst with 3 statoliths (D); Sequence of marginal bulbs and statocysts in an interradial quadrant (E); Longitudinally divided female gonad, tentacular bulb with black spot, and lateral clusters of tentacular cirri (F); Male gonad exceeding the edge of the umbrella (G); Medusal buds on the place of gonad (H). g, gonad; m, manubrium; mb, medusal bud; B, marginal bulb; s, statolith; T, radial tentacle; tb, radial tentacular bulb; c, tentacular cirri; V, marginal vesicle. Scale bar: A, B, C: 1 mm; H: 100 µm. Photomicrographs by Jean-Michel Brylinski.
Source publication
Hydromedusae, morphologically resembling the Indo-Pacific leptomedusa Lovenella assimilis (Browne, 1905) (Cnidaria: Hydrozoa: Lovenellidae), are reported for the first time in both the eastern English Channel and the southern bight of the North Sea. Analyses of past zooplankton samples from a long-term monitoring program suggest that this non-indig...
Contexts in source publication
Context 1
... Leptomedusa Lovenella assimilis (Browne, 1905) (Cnidaria: Hydrozoa: Lovenellidae) has been reported from tropical to temperate regions in Indo-Pacific waters (Kramp, 1968, cf. in Pires-Miranda et al. 2013; Figure 2) such as Sri- Lanka (Browne 1905; original description), the Bay of Bengal (Navas- Pereira and Vannucci 1991), China and Philippines (Chow and Huang 1958;Kramp 1961;Xu et al. 2008), Papua New Guinea (Bouillon 1984), New Zealand (Bouillon 1995), Japan (Hirano and Yamada 1985) and Red Sea (Schmidt 1973). Lovenella assimilis was never been reported outside the Indo-Pacific Oceans until a first citation in Europe, in the Bay of Biscay (Altuna 2010). ...
Context 2
... under parsimony criteria was performed with 1,000 replicates. (Figure 2) Based on pigment distribution, gonad shape, number of marginal bulbs, occurrence of cirri, number of statocysts and their concretions, and the cnidome, all studied specimens were identified as Lovenella assimilis. ...
Context 3
... Umbrella fairly thick, 2.5 mm wide (1 to 3 mm for fixed specimens, Figure 2A to 2C), a little broader than high. Velum narrow. ...
Context 4
... marginal bulbs (4 interradial and 8 adradial bulbs) without cirri. 16 marginal vesicles (statocysts), most of them with 3 concretions (1-3 statoliths, Figure 2D, Table S2). Hence, in each quadrant, between 2 tentacles (T), there are 3 marginal bulbs (B) alternating with 5 marginal vesicles (V) ( Figure 2E). ...
Context 5
... marginal vesicles (statocysts), most of them with 3 concretions (1-3 statoliths, Figure 2D, Table S2). Hence, in each quadrant, between 2 tentacles (T), there are 3 marginal bulbs (B) alternating with 5 marginal vesicles (V) ( Figure 2E). The formula TVBVBVBVT, with homogeneity between the four quadrants, can be considered as a standard formula. ...
Context 6
... form large oval sacs along the outer half of the radial canals. Each gonad more or less divided into two by a median longitudinal line ( Figure 2F). Gonads poorly developed in the small specimens (< 1 mm) but well developed in the large specimen (> 2.5 mm) and female gonads distinguished by spherical gametes (50 µm in diameter). ...
Context 7
... gonads were slightly narrower than those of females and contained indistinguishable gametes. At maximum development, gonads protruded from the umbrella (e.g., Figure 2B and 2G). This phenomenon had never been reported in the literature and did not seem to only correspond to a preservation artifact because the external extension was as long as the fixed part of the gonad attached to the radial canal. ...
Context 8
... phenomenon had never been reported in the literature and did not seem to only correspond to a preservation artifact because the external extension was as long as the fixed part of the gonad attached to the radial canal. Medusa buds located occasionally at the place of the gonads for asexual reproduction ( Figure 2H) (Chow and Huang 1958;Bouillon 1984). ...
Context 9
... species occurred in low densities (< 1.5 ind.m -3 ). In Gravelines (August 2008), as well as at the Belgian stations (October and November 2011), we observed some individuals with medusal buds instead of gonads ( Figure 2H). ...
Context 10
... original description of Browne (1905) (he provisionally placed the specimen in the genus Mitrocomium) must cautiously be interpreted, as it was based on a single male specimen. Browne (1905), using a specimen from Type locality: Cheval Parr Bank, Sri Lanka, described about 5 marginal vesicles in each inter-radial quadrant and 5 to 7 marginal bulbs, "the central, interradial, bulb being much larger than others", as in Altuna (2009 - Figure 2). Kramp (1961; adjusted the description by limiting the number of bulbs to approximately 5, and noted "the median one the largest", using Browne's figure. ...
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Citations
... Because Eucheilota and Lovenella have a history of confusing taxonomy with some evidence that species assigned to the two genera may belong to the same species (see [25]), the two datasets were merged and analysed as one. The resulting dataset comprised 25 sequences (9 sequences identified as E. maculata and 16 as L. assimilis), 573 sites, of which 171 (29.84%) were phylogenetically informative. ...
... Despite the sampling efforts in the GoM, sequences available for E. maculata are scarce (both in the GoM and worldwide). Thus, similarly to L. assimilis, more sequences are needed to clarify the status of the three clades represented in figure 4. Eucheilota and Lovenella have a long and complicated taxonomic history, being historically put in different families based on morphology [29,30], but with more recent accounts showing minimal genetic distance between the two genera [31], and some evidence that species assigned to the two genera belong to the same species [25]. When combined, the two species dataset shows little resolution in the relationship between clades but clear indication that the two species are not reciprocally monophyletic ( figure 5). ...
Sampling in multiple localities, coupled with molecular barcoding, has shown that nominal species with wide geographical distribution often harbour local cryptic species in allopatry. Cryptic species in sympatry, however, can be easily missed if they have different seasonality, because they can be identified only through long-term frequent sampling (i.e. sampling through time of the same species in the same location). This is especially true in planktonic invertebrates that exhibit strong seasonality. By integrating mitochondrial 16S sequences of eight species of Hydrozoa (Cnidaria) collected weekly for a year in one Gulf of Mexico region, with sequences gathered globally, we investigate the presence of cryptic species within a temporal gradient (regionally) and on a spatial (worldwide) scale. We find that eight species of Hydrozoa are composed of 28 cryptic species, with 16 of them appearing in sympatry but with non-overlapping seasonality. The high number of sympatric cryptic species could only be discovered through extensive and prolonged regional sampling efforts. The bi-dimensional cryptic diversity (in time and space) highlighted in this study is essential for understanding processes of evolution, biogeography dispersal in the sea, and for more realistic biodiversity assessments.
... Velum width ca 1/6 of bell radius. Manubrium short, cruciform cross-section, base quadrangular, only slightly larger than oral end, mouth cruciform, simple, four perradial, slightly recurved (Altuna, 2009), perhaps introduced in the north-eastern Atlantic (Altuna, 2009;Brylinski et al., 2016). Type locality: Nancowry Harbour, Nicobar Islands. ...
... The material from New Zealand was identifi ed as E. menoni because DNA sequences of part of the present material have already been published under this name and also because it mostly matched the diagnosis given in Bouillon & Barnett (1999). However, the identity is not entirely clear and it could as well be attributed to Lovenella assimilis (Browne, 1905) as has been argued in detail by Brylinski et al. (2016). Eucheilota menoni and Lovenella assimilis are indeed rather diffi cult to separate (Bouillon, 1984). ...
... Bouillon also observed medusa buds in both morphotypes, something never observed by other authors. To conclude, the present material is not unambiguously attributable to either E. menoni or L. assimilis and this is also the case for the European material described by Altuna (2009) andBrylinski et al. (2016). As already concluded by the latter authors, it is likely that both nominal species as used today are in fact conspecifi c. ...
This work reports upon observations and identifications of 18 leptomedusae, mostly documenting specimens which have been used for previous molecular phylogenetic studies. All species are illustrated, for some of them links to electronically archived photos are provided. The taxonomy of some genera and species is discussed. The diagnosis of the genus Neotima Petersen, 1962 is modified to accommodate the new species Neotima galeai, the only member of the genus with subdivided gonads. Eutima sapinhoa Narchi & Hebling, 1975 is transferred to the genus Neotima as Neotima sapinhoa (Narchi & Hebling, 1975) n. comb. Helgicirrha schulzii Hartlaub, 1909 and Tima plana Neppi, 1910 are both regarded as junior synonyms of Helgicirrha cari (Haeckel, 1864). Eirene octonemalis Guo, Xu & Huang, 2008 is a new junior synonym of Eirene hexanemalis (Goette, 1886).
... Two non-indigenous hydrozoans, Lovenella assimilis (Browne, 1905) and Eucheilota menoni (Kramp 1959), have had their presence in the Eastern part of the English Channel and North Sea confirmed since 2007 (Brylinski et al., 2015). Their taxonomy is under review, and their vectors of introduction have been identified as ballast water and ship fouling. ...
