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Cryptic bivalves with descriptions of new species from the Rodrigues lagoon
Journal of Natural History
Abstract
This paper describes a number of new taxa in the Arcidae, Philobryidae, Mytilidae, Galeommatidae, Kelliidae, Cyamiidae, Carditidae, Thraciidae and Clavagellidae. A further 17 species are included as new to the malacofauna of Rodrigues. Most of the species included came from cryptic habitats, of which the most interesting are apparently cavernicolous and similar to those described from southern Japan. Other species were described from crevice or algal turf communities. The most understudied group is the Galeommatoidea with four species described as new and a further five with as yet unresolved taxonomy.
... He also noted that one specimen "gave birth to a single young […] which was approximately 300 microns in length (and) immediately began to burrow", thus suggesting brooding up to the juvenile stage. Brooding was also recorded for a few other species from different genera, and some data on the soft parts were provided along conchological observations in faunistic or taxonomic studies (Bernard, 1896a;Bernard, 1896b, Bernard, 1898Waller, 1973;Salas & Rolán, 1990;Salas & von Cosel, 1991;Middelfart, 2002a;Middelfart, 2002b;Oliver & Holmes, 2004;Güller & Zelaya, 2013;Malchus & Sartori, 2013). ...
... In a small species of Astartidae (Goodallia triangularis (Montagu, 1803), with a maximum shell size of four mm), only a single demibranch (the inner) is present (Saleuddin, 1965); this condition also occurs in species of Crassinella (Crassatellidae) (Harry, 1966;Allen, 1968). For species classified as condylocardiids, reduction to a single demibranch was recorded by Middelfart (2002aMiddelfart ( , 2002b, Oliver & Holmes (2004) and Güller & Zelaya (2013) (in this latter work, a species of the Carditopsis was reported as having a single demibranch, whereas two species of Carditella were recorded as bearing both demibranchs, with the outer strongly reduced). Reduction of ctenidial elements such as demibranchs or filaments is a recurrent phenomenon in Bivalvia, occurring independently in many groups (e.g., Purchon, 1939;Bieler et al., 2014, MorphoBank matrix), and frequently associated with small size (as discussed for species classified as condylocardiids by Güller & Zelaya, 2013). ...
... For the condylocardiids, observations are mainly restricted to the information provided by Bernard (1896aBernard ( , 1896b, Moore (1961), Waller (1973), Salas & Rolán (1990), Salas & von Cosel (1991) and Middelfart (2002aMiddelfart ( , 2002b. Moore (1961) was the only author to record ovoviviparity in a living condylocardiid, and Salas & von Cosel (1991), Middelfart (2002a) and Oliver & Holmes (2004) observed chemically fixed animals with brooded juveniles, albeit in different places of the parent's body: in two specimens of Carditopsis gofasi Salas & von Cosel, 1991, the young appeared to be held among the gill filaments (Salas & von Cosel, 1991;figs. 42-47). ...
‘Miniaturization’ is a widespread phenomenon among the Metazoa. In the molluscan class Bivalvia, records of miniaturization are numerous. Among the Archiheterodonta, Warrana besnardi (Klappenbach, 1963) has attracted attention for its tiny size, which does not exceed 1.5 mm in shell length, and because it belongs to a group with limited anatomical information and often-debated status, the “Condylocardiidae” (which recent molecular studies place deeply nested within the family Carditidae). All species of Warrana Laseron, 1953 are small-bodied, and so miniaturization presumably occurred from a large-bodied ancestor within the Carditidae sensu lato. South American W. besnardi is here studied in detail. Its small size and the enlargement of the anterodorsal region during growth, reflects (and
likely led) to infaunal habit, living as a burrowing bivalve that passively feeds on deposit particles entering the pallial cavity anteriorly. Mantle glands, previously reported as a common feature of other archiheterodonts, are missing in W. besnardi, but spongiform tissue in the antero-ventral portion of the mantle lobes presumably represents a blood sinus that might compensate for the great reduction of the
ctenidia. Lecithotrophy is reported, with yolky oocytes bearing a thick non-cellular capsule layer; brooding was not observed, and it is here hypothesized that the extreme miniaturization, with the great reduction of ctenidia, is responsible for a shift in the reproductive mode of condylocardiids, contrasting with the commonly reported ovoviviparity of the carditids.
... The underlying processes are not understood. However, there is sufficient evidence to correlate these growth patterns with extended brooding (hayaMi & kase, 1993;MiddelFart, 2002a;oliver & holMes, 2004;this study). Because the distinction of shell stages is important for homology hypotheses and for a morphologybased classification, shells with indistinct boundaries (or where a clear boundary could represent either P-1/P-2 or P/N) are presently called cryptoconch rather than prodissoconch or metaconch. ...
... 2;MiddelFart, 2002aMiddelFart, , 2002b. Larger pits and ridges may be traced on the shell interior ( Fig. 15-16 liNse, 2002;MoraN, 2004a;oliver & holMes, 2004). Conical elevations often possess distinct sculptural characteristics ( Fig. 15.2), and the underlying microstructure is antimarginal granular-prismatic. ...
... Examples include numerous arcoids (e.g., Philobryidae, Barbatia Gray, 1842); Cyclochlamydidae (Cyclochlamys FiNlay, 1926, right valves);and Condylocardiidae (Austrocardiella MiddelFart, 2002a;Benthocardiella PoWell, 1930), among others (Fig. 37.3-37.8;dell, 1964MiddelFart, 2002a;oliver & holMes, 2004;Malchus, 2006). chaParro and others (2011) illustrated a cryptoconch (probably P-1) of Gaimardia bahamondei osorio & arNaud, 1984, which represents a transitional shell type between ST-2D (overall outline) and ST-3B (domed central portion with distinct microsculpture and differentiation of ears). ...
This chapter provides a state-of-the-art review (as of 2013) of the ontogeny of the early shell in bivalve molluscs written for a revised Bivalve Treatise.
All bivalves go through a succession of two or more shell-forming phases before the
adult valves take shape. These early, larval to juvenile portions of the shell, and their
morphology, morphogenetic patterns, taxonomic distribution, and evolutionary interpretations are the subjects of this chapter.
Some aspects of the processes of shell formation at the level of cell lineages and control
genes are briefly summarized. Most research conducted on these topics focuses on phases preceding the veliger and pericalymma larvae. However, from a morphological
perspective, the most instructive modifications occur around the metamorphic window, where shell features are most diverse and record differences in reproductive modes
and heterochronic changes. These changes provide clues to the evolution of autobranchs
and protobranchs. The following sections are dedicated to establishing a theoretical
framework for interpretation and defining the essential terms.
... The underlying processes are not understood. However, there is sufficient evidence to correlate these growth patterns with extended brooding (hayaMi & kase, 1993;MiddelFart, 2002a;oliver & holMes, 2004;this study). Because the distinction of shell stages is important for homology hypotheses and for a morphologybased classification, shells with indistinct boundaries (or where a clear boundary could represent either P-1/P-2 or P/N) are presently called cryptoconch rather than prodissoconch or metaconch. ...
... 2;MiddelFart, 2002aMiddelFart, , 2002b. Larger pits and ridges may be traced on the shell interior ( Fig. 15-16 liNse, 2002;MoraN, 2004a;oliver & holMes, 2004). Conical elevations often possess distinct sculptural characteristics ( Fig. 15.2), and the underlying microstructure is antimarginal granular-prismatic. ...
... Examples include numerous arcoids (e.g., Philobryidae, Barbatia Gray, 1842); Cyclochlamydidae (Cyclochlamys FiNlay, 1926, right valves);and Condylocardiidae (Austrocardiella MiddelFart, 2002a;Benthocardiella PoWell, 1930), among others (Fig. 37.3-37.8;dell, 1964MiddelFart, 2002a;oliver & holMes, 2004;Malchus, 2006). chaParro and others (2011) illustrated a cryptoconch (probably P-1) of Gaimardia bahamondei osorio & arNaud, 1984, which represents a transitional shell type between ST-2D (overall outline) and ST-3B (domed central portion with distinct microsculpture and differentiation of ears). ...
... The same is not true of the free-living 'gastropodlike' species with ornate/colourful mantles. Many presumably freeliving species with this probable general appearance were described in the 19th century by, for example, Deshayes (1856) who named no fewer than 39 species of ' Scintilla ' based on empty shells collected by Cuming in the Philippines and elsewhere in the tropical Pacific, an impediment also lamented by Oliver & Holmes (2004) . Deshayes emphasized ' animal ignotum ' and many of these nominal species have never been treated in the recent literature or, when they have, in a manner that does not add to the original description. ...
Galeommatoidea are bivalves with small (usually 1–15 mm), fragile, sometimes vestigial, shells, occurring free-living or in association with other benthic invertebrates from the intertidal to depths in excess of 7,000 m. They are the most diverse but least studied and most underrepresented group of bivalves in biodiversity surveys and museum collections. The majority of commensal species of Galeommatoidea have dull, frequently uncoloured, unsculptured shells, but free-living species have papillate, sometimes coloured, mantles; they can be gregarious, and superficially resemble crawling gastropods. Many species of Galeommatoidea remain to be discovered, and we argue that future descriptions of free-living new species should ideally include photos of living animals, while many of the historically known species described based on their shells will probably be best treated as nomina dubia.
... Condylocuna tricosa Middelfart, 2002 ( Figure 5C) was described from Qld and synonymised with Condylocuna io (Barsch, 1915) by Graham and Holmes (2004) despite Middelfart (2002) comparing C. tricosa with the South African type of C. io (United States National Museum (USNM 251043) and stating the dissimilarity. Oliver and Holmes (2004) did not examine the type of C. io, and compared it only to material from Rodrigues Island, which is C. tricosa and not C. io. Hence, the synonymy is here revoked and the distribution of C. tricosa is extended across the tropical Indo-Pacific region from Qld to Rodrigues Island and the Kimberley region. ...
... However, A. plicata may comprise a complex of species (Oliver and Holmes, 2004). The holotype of B. ...
The bivalve molluscan fauna of Jeju Island (Jeju-do), the largest island of Korea, is reviewed based on original and literature data. An annotated and illustrated catalogue of species with indication of local distribution and taxonomic comments is prepared, supplemented also with data on general distribution, habitats, and primary synonyms. This
first part of the paper includes 105 species belonging to 21 families (Nuculidae through Limidae). The history of Jeju molluscan research, a bibliography on all aspects of mollusk biology, and the general ecology of Jeju bivalves in various habitats are also included. Five species are reported as new for Jeju Island, two species as new for Korea, and 11 species have been reported in literature but were not included in the first bivalve catalogue of Jeju
by Noseworthy et al. (2007); in total 16 species are added to the fauna.
... A study of H. strangei by Morton (2002b), however, has shown to the contrary that Humphreyia is most closely linked to the Brechites (or Penicillus) "lineage" (as Savazzi, 1999 and2005 puts it). Moreover, Dianadema multangularis (Tate, 1887) has hitherto been placed in the genus Clavagella (B.J. Smith, 1971(B.J. Smith, , 1976 but Morton (2003a) has shown that it is distinct in that it possesses a crown of tubules arising from the apex of the crypt, as also seen in the Indian Ocean D. mascarenensis recently described by Oliver and Holmes (2004) and the fossil Ascaulocardium armatum (Pojeta and Soh!, 1987). 3. Morton (2005Morton ( , 2006a has studied the structure and method of formation of the adventitious tubes of the fossil clavagellid Stirpulina coronata (Deshayes, 1824) and the extant Stirpulina ramosa and showed that the process involved is fundamentally different from that of the penicillid Brechites vaginiferus, as elucidated by Harper and Morton (2004). ...
Dead coral rocks are prevalent hard substrates in shallow warm waters, providing habitat for various infaunal and boring invertebrates. Despite this, the nature of species interactions, especially symbiotic relationships, among them remains poorly understood. Bonellia (Annelida: Thalassematidae: Bonelliinae) is a group of greenish echiuran worms commonly inhabiting cavities inside dead coral rocks. Although echiuran burrows in marine sediments are known to harbour various host-specific macrosymbionts, it remains unclear whether such associations also occur in hard substrates. To address this, we investigated the diversity of macrosymbionts associated with the burrows of Bonellia sp. aff. minor in the warm-temperate coast of the Kii Peninsula, Japan, and the evolutionary origins of those symbionts. The host’s burrow morphology was also examined using micro-computed tomography (CT) scanning. Our field survey revealed that the burrows of Bo. sp. aff. minor hosted three commensal species including a polychaete, Oxydromus fauveli, and two new species, a bivalve (Basterotia bonelliphila sp. nov.) and an amphipod (Leucothoe bonelliae sp. nov.). Our molecular phylogenetic analyses showed that each symbiont species belongs to a clade comprising commensal species specific to echiurans or annelids. Overall, our findings contribute to a better understanding of symbiotic associations in marine hard substrates.
Twenty species of Pectinoidea (12 Propeamussiidae, three Cyclochlamydidae, five Pectinidae) are herein listed. Six new species of Pectinoidea (three Propeamussiidae, three Cyclochlamydidae) are from littoral and bathyal depths of the western and southwestern Pacific, sampled by various expeditions and cruises to Papua New Guinea and the South China Sea, viz. Propeamussium regillum n. sp. from the bathyal Bismarck and Solomon Seas, Parvamussium minusculum n. sp. from the lower bathyal South China Sea, Cyclopecten inoculatus n. sp. from the bathyal Bismarck Sea, Cyclochlamys corrugata n. sp., Cyclochlamys barbatula n. sp. and Micropecten reticulatus n. sp. from shallow coastal waters of Papua New Guinea. Fourteen species of Pectinoidea (nine Propeamussiidae, five Pectinidae) are new records for the Bismarck Sea (five), for the Solomon Sea (four), and for the South China Sea (seven). © Publications scientifiques du Muséum national d'Histoire naturelle, Paris.
The genus Lampeia was previously represented in the Chukchi Sea and the northwestern Bering Sea by only one species, Lampeia adamsi (MacGinitie, 1959). We found L. adamsi in the Sea of Okhotsk at depths of 65-85 m. Additionally, we described two new species from this genus. Lampeia triangula was found in the Sea of Okhotsk off the west coast of Kamchatka at a depth of 144-214 m, Lampeia posteroresecta off the Kurile Islands near Iturup Island at 180 m and in the Fourth Kurile Strait at 500 m. An expanded description of L. adamsi, including some additional data on shell morphology, geographic distribution, and habitat is also given.
A new subgenus, Pseudoasthenothaerus, of the genus Parvithracia Finlay, 1927, and two new species, Parvithracia (Pseudoasthenothaerus) lukini and P. (Pseudoasthenothaerus) sirenkoi, are described from the Pacific seas of Russia. Previously representatives of the genus Parvithracia, with the type species Parvithracia suteri Finlay, 1927, were found only off New Zealand. Study of thraciid genera showed that Japanese species assigned to the genus Asthenothaerus Carpenter, 1864, should be placed in the genus Parvithracia. For Asthenothaerus sematana (Yokoyama, 1922) and A. isaotakii Okutani, 1964, new combinations are suggested: Parvithracia (Pseudoasthenothaerus) sematana (Yokoyama, 1922) and P. (Pseudoasthenothaerus) isaotakii (Okutani, 1964). The main morphological characteristics of the new subgenus are the presence of conspicuous lateral teeth in both valves and a subumbonal plate for the attachment of the lithodesma that is supported by pillars. Expanded descriptions of P. suteri, P. (Pseudoasthenothaerus) sematana, and P. (Pseudoasthenothaerus) isaotakii are given.
Twenty-two species of galeommatacean bivalves from four families and nine genera are described, compared and illustrated. The invertebrate hosts of many of these commensal species are reported for
the first time. Six new species are described, belonging to the genera Pseudopythina (4), Barrimysia
(1) and Scintillona (1). Of the known species, eleven have been recorded previously from Japan, two
from the Philippines, Ephippondonta oedipus only from Hong Kong and Lasaea rubra from shores
virtually world-wide. The generic and familial placement of many of the species discussed are revised.
Species of the genus Dacrydium are ubiquitous, mostly at bathyal and abyssal depths within the world's oceans. Here, 11 species are described from the Atlantic at depths greater than 500 m, and of these six are described for the first time. In addition, a bibliography of the world's species described to date is appended. The Dacrydiinae are neotenous mytilids, many being associated with sponges to which they are byssally attached. Multiple fine byssal threads are produced, which may form a nest. The shells are small, rarely more than 4 mm total length, fragile, and transluscent, white or pale cream in colour. Ornamentation, when present, consists of fine concentric striae, sometimes with very fine radial lines and occasionally a scattering of tiny shell granules. The hinge is narrow, with fine, multiple, nepioconch teeth retained throughout life. The ligament is small, internal, and amphidetic. Ventral to the posterior hinge plate is a shell buttress parallel to the dorsal shell margin, which probably provides necessary strength to an extremely fragile shell at times subject to adduction. The viscera occupy the dorsal-most third of the mantle cavity, the organs within being arranged parallel to the dorsal shell margin. Sexes are separate. The palps and gills are reduced in size. The outer demibranch, if present, develops late in life at the time the gonads are begining to mature. At most, it occupies a third of the gill axis and acts as a repository for sperm or eggs when they are first released. At the same time, the fused inner folds of the posterior mantle edge, ventral to the point of the attachment of the gill axis, enlarge and form an aperture that is probably related to the release of sperm or eggs, or spat in the case of those species that brood.
Ten mytilid species are described as new, viz. Modiolus (Modiolus?) nicklesi (tropical W. Africa), M. (M.) pseudobarbatus (tropical W. Africa), M. (M.) thorsoni (tropical W. Africa), Musculus (Musculus) koreanus (Sea of Japan), Rhomboidella obesa (tropical W. Africa), R. malaccana (W. coast of Thailand), Xenostrobus mangle (W. coast of Malaysia), X. balani (W. coast of Thailand), Dacrydium angulare (S. Atlantic), and D. viviparum (Reykjanes Ridge). The latter species has suprabranchial protection of embryos as does the Mediterranean D. hyalinum (Monterosato). Modiolus lulat (Dautzenberg, 1891) is regarded synonymous with M. martorelli (Hidalgo, 1877), and Vignadula Kuroda & Habe, 1971, with Xenostrobus Wilson, 1967. — The descriptions include anatomical and biological notes for several of the species. — The so-called ‘periostracal’ hairs of mytilids are concluded to be secretions of byssus glands, shaped and applied to the shell exterior by the foot of these bivalves. — It is pointed out that the opisthodetic, parivincular ligament of mytilids is separate and secondary in ontogeny. — Species of the Dacrydiinae n. subfam. are characterized by a non-nacreous shell which is homologous with the nepioconch of other mytilids, by functional persistence of the primary ligament and absence or ontogenetically late formation of a weak secondary ligament, by simplification and, in part, reduction of the soft parts. They are thus neoteneous in several respects. The group is briefly discussed and a survey of taxobases is given.