Unique occipital articulation with the first vertebra found in pristigasterids, chirocentrids, and clupeids (Teleostei: Clupeiformes: Clupeoidei)

This study recognized a W-shaped occipital articulation associated with the first vertebra in pristigasterids, chirocentrids, and clupeids as a unique character among teleosts, based on an evaluation of 43 species within 40 genera of these three families of the Clupeoidei. This occipital articulation is accompanied by an anterior extension of the neural arch bases, which are autogenous with the first vertebral centrum. In chirocentrids and many of the clupeid species examined, the anterior extension occurs on the second vertebra, and similar occipital articulation is found between the first and second vertebrae. The W-shaped occipital articulation is not found in any other teleosts, including Denticeps (suborder Denticipitoidei), which is thought to be a sister group to the suborder Clupeoidei. The W-shaped occipital articulation is absent in the other family of the Clupeoidei, Engraulidae, based on an evaluation of 11 species in 10 genera. Instead, the convex anterior surface of the first vertebral centrum forms a condyle that articulates with the basioccipital, and the neural arches fuse with the centrum behind this condyle. Therefore, it is unclear whether the anterior extension of the first vertebral neural arch bases, which causes the W-shaped occipital articulation, occurs in engraulids. Based on an evaluation of the osteological development of Konosirus punctatus and Engraulis japonicus, the cartilaginous neural arch bases of the first and second vertebrae extend anteriorly at an early developmental stage in the former, whereas no anterior extension of the first vertebral neural arch bases occurs at any developmental stage in the latter. Therefore, the anterior extension of the neural arch bases, which causes the W-shaped occipital articulation, seems to be a unique character of pristigasterids, chirocentrids, and clupeids among teleosts. Within the recent phylogenetic context, this character may be a synapomorphy of these three families.     

Evidence for extensive cryptic speciation in trematodes of butterflyfishes (Chaetodontidae) of the tropical Indo-West Pacific

Molecular data from the cytochrome c oxidase subunit I (cox1) mitochondrial DNA gene and the second internal transcribed spacer (ITS2) nuclear rDNA region were used to test the current morphologically-based taxonomic hypothesis regarding species of Monorchiidae (Hurleytrematoides) from chaetodontid and tetraodontid fishes from six sites in the tropical Indo-West Pacific (TIWP): Heron and Lizard Islands off the Great Barrier Reef (GBR, Australia), Moorea (French Polynesia), New Caledonia, Ningaloo Reef (Australia) and Palau. The 16 morphospecies analysed differed from each other by a minimum of 55 bp (9.1%) over the mitochondrial cox1 and 8 bp (1.6%) over the ITS2 DNA regions. For two species, Hurleytrematoides loi and Hurleytrematoides sasali, specimens from the same host species in sympatry differed at levels comparable to those between pairs of distinct morphospecies for both cox1 and ITS2 sequences. We take this as evidence of the presence of combinations of cryptic species; however, we do not propose new species for these taxa because we lack identified morphological voucher specimens. For seven species, Hurleytrematoides coronatum, Hurleytrematoides deblocki, Hurleytrematoides faliexae, H. loi, Hurleytrematoides morandi, H. sasali and Hurleytrematoides sp. A, samples from some combinations of localities had base pair differences that were equal to or greater than differences between some pairs of distinct morphospecies for one or both cox1 and ITS2 sequences. For three species, H. coronatum, H. loi and H. morandi, one haplotype differed from every other haplotype by more than the morphospecies benchmark. In these cases morphological specimens could not be distinguished by morphology. These data suggest extensive cryptic richness in this genus. For the present we refrain from dividing any of the morphospecies. This is because there is a continuum of levels of intra- and interspecific genetic variation in this system, so that distinguishing the two would be largely arbitrary.     

Inferring the mode of speciation in Indo-West Pacific Conus (Gastropoda: Conidae)

Aim This study aims to initially explore the mode of speciation in Indo‐West Pacific Conus. Location The Indo‐West Pacific island arc, Indian and Pacific Oceans. Methods Relating evolutionary divergence in a molecular phylogeny [T.F. Duda & S.R. Palumbi (1999) Proceedings of the National Academy of Science USA, 96 , 10272] using node height with modern range extents as a possible measure of allopatric or sympatric speciation following that of T.G. Barraclough, A.P. Vogler & P.H. Harvey [(1999) Evolution of Biological Diversity. Oxford University Press, Oxford] models of sympatric and allopatric speciation. Results The analysis seems to indicate that the relationship of sympatry with node height is not informative. Species that have diverged quite recently show 100% sympatry with the sister species. A clearer signal of recent allopatric speciation is observed in species whose distribution is at the edge of the Indian and Pacific Ocean basins. In the widely distributed Conus ebraeus clade, the relationships of node heights and range extents of the member species support a key prediction of sympatric speciation. In highly ecologically specialized species, there is a smaller degree of sympatry than those species that are less specialized. Main conclusions The modes of speciation models presented in this study are not informative. This suggests that there had been large and possibly rapid changes in range size after speciation in the various clades. This could have been due to the fact that the wide dispersal life‐history strategy in the genus had been largely conserved in Conus evolution. There is evidence of sympatric and parapatric speciation in one Conus clade. Overall, the patterns of phylogeny and range distribution when related to the timing of speciation lend circumstantial support to a Neogene centre of origin hypothesis but not to speciation on the Pacific Plate. Speciation is likely to have been associated with the Tethys Sea closure event, with rapid speciation occurring after closure.     

Sequence and localization of an ultraviolet (sws1) opsin in the retina of the Japanese sardine Sardinops melanostictus (Teleostei: Clupeiformes)

A full‐length complementary (c)DNA encoding ultraviolet (UV)‐sensitive opsin (sws1) was isolated from the retina of the Japanese sardine Sardinops melanostictus. The sws1 phylogenetic tree showed a sister group relationship with the Cypriniformes, following the ray‐finned fish phylogeny. By expressing reconstituted opsin in vitro, it was determined that the maximum absorbance spectrum (λ_max) of sws1 is around 382 nm, being intermediate in position between two subtypes of sws1 pigment that are UV sensitive (λ_max = 355–380 nm) and violet sensitive (λ_max = 388–455 nm), which have been reported to date. The ocular media transmitted >20% transmittance of light in the range of 360–600 nm. In situ hybridization analyses revealed that sws1 messenger (m)RNA is localized in a central single cone surrounded by four double cones in a square mosaic. The square mosaic occupies the ventro‐temporal quadrant of the retina and the in situ hybridization signals were dominant in this area suggesting that the fish may use UV vision when looking upward. Based on these results, considerable significances of potential UV sensitivity, in relation to characteristic habits of S. melanostictus, are discussed.     

Comparative otolith morphology of clupeids from the Iranian brackish and marine resources (Teleostei: Clupeiformes)

The diagnostic features of otolith morphology were provided for the clupeid fishes of the Iranian brackish and marine resources to be used as diagnostic features for the identification of clupeids diversity in these regions. Fish individuals belong to 20 species belong to 13 genera, and four families were collected from the Caspian Sea, the Persian Gulf and the Makran zone of the Oman Sea. Overall, seven otolith morphotypes were distinguished, that is lanceolated (45%), fusiform (20%), boot-like (15%) and clamp-like, pentagonal, elliptic and rectangular (each 5%, respectively). The univariate analysis showed that all variables except shape index [sulcus area (SS)/otolith area (OS)] and ROx (roundness) were significantly different among the clupeid species. The interspecific relationships of the otoliths were analysed based on the data of otolith morphology and otolith shape indices. Both dendrograms showed somehow an obvious separation among the studied species. However, the interspecific relationships in the dendrogram based on the otolith morphology have a better resolution. These phenotypic relationships based on otolith morphology among the studied clupeids are largely consistent with the previous hypothesis on the systematics of these fishes and emphasized that the morphological and morphometric features of the otolith, which are highlighted in this study, could be adequately used as diagnostic features for the identification of clupeids diversity.     

The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Noumea flava colour group

Six species of the genus Noumea are described including four new species. All species are yellow, and four have orange markings as well; one has a white mantle border and the last has red gills and rhinophores. Noumea flava has a widespread distribution in the Indo-West Pacific and two other species are known from the tropical Pacific. The other three species, including a yellow colour form of Noumea haliclona (Burn, 1957), are reported from southern Australia. Aspects of the reproductive system of some species of Noumea strongly indicate that the genus Verconia Pruvot-Fol, 1931 is closely related to that genus.     

Indo-West Pacific species of the genus Stylopoma Levinsen, 1909 (Bryozoa: Cheilostomatida)

Twenty-one species of Stylopoma Levinsen, 1909 are described and illustrated with scanning electron micrographs. S. spongites (Pallas, 1766), the type species, is redescribed from the neotype specimen and included here for completeness. A neotype specimen for S. duboisii (Audouin, 1826) and a lectotype specimen for S. viride (Thornely, 1905) are designated and 14 new species of Stylopoma are described from Indo-West Pacific material in the Recent bryozoan collections of the Natural History Museum, London.     

Revision of the Indo-West Pacific polynemid fish genus <Emphasis Type="Italic">Eleutheronema</Emphasis> (Teleostei: Perciformes)

A taxonomic revision of the polynemid fish genus Eleutheronema, which is redefined, resulted in three species of the genus being regarded as valid: Eleutheronema rhadinum (Jordan and Evermann, 1902), having to date been treated as a junior synonym of E. tetradactylum (Shaw, 1804) and currently known only from East Asia (China and Japan) where it is endemic; E. tetradactylum, a senior synonym of both Polynemus teria Hamilton, 1822 and Polynemus coecus Macleay, 1878, being a widely distributed Indo-West Pacific species, which ranges from the Persian Gulf to Australia; and E. tridactylum (Bleeker, 1845), distributed in Southeast Asia (Thailand, Malaysia, and Indonesia). Eleutheronema tridactylum is easily distinguished from both E. rhadinum and E. tetradactylum owing to the vomer lacking tooth plates in the former [vs. vomer with 2 deciduous tooth plates (in specimens at least over ca. 70 mm SL) in the latter] and lower counts of pectoral filaments (free lower rays, 3 vs. 4) and gill rakers [mode 8 (range 4–10) vs. 12 (10–17) and 13 (6–18) in E. rhadinum and E. tetradactylum, respectively]. Eleutheronema rhadinum clearly differs from E. tetradactylum in having higher counts of pored lateral line scales [mode 95 (range 82–95) vs. 73 (71–80) in the latter] and higher scale counts above and below the lateral line [12 (11–14) and 16 (15–17), respectively, vs. 10 (9–12) and 14 (13–15), respectively]. Furthermore, E. rhadinum is distinguished from E. tetradactylum by having a dense black pectoral fin [vs. vivid yellow in life (except in specimens over ca. 350 mm SL, pectoral fin dusky-yellow) in the latter]. Intraspecific variations and morphological changes with growth of the three species are also discussed. Received: June 13, 2001 / Revised: October 11, 2001 / Accepted: October 17, 2001     

Mitogenomic evidence for the monophyly of elopomorph fishes (Teleostei) and the evolutionary origin of the leptocephalus larva

The monophyly of Elopomorpha (eels and their relatives) has long been one of the most problematic issues in systematic ichthyology. Since established the Elopomorpha based on the existence of the leaf-like larval form, termed a leptocephalus, no one has corroborated their monophyly using character matrices derived from both morphological and molecular data during the last 30 years. We investigated their monophyly and interrelationships at the ordinal level using complete mitochondrial genomic (mitogenomic) data from 33 purposefully chosen species (data for nine species being newly determined during the study) that fully represent the major teleostean and elopomorph lineages. Partitioned Bayesian analyses were conducted with the two data sets that comprised concatenated nucleotide sequences from 12 protein-coding genes (with and without third codon positions), 22 transfer RNA genes, and two ribosomal RNA genes. The resultant trees were well resolved and largely congruent, with most internal branches being supported by high statistical values. Mitogenomic data strongly supported the monophyly of Elopomorpha, indicating the validity of the leptocephalus as an elopomorph synapomorphy. The order Elopiformes occupied the most basal position in the elopomorph phylogeny, with the Albuliformes and a clade comprising the Anguilliformes and the Saccopharyngiformes forming a sister group. The most parsimonious reconstruction of the three previously recognized, distinct larval types of elopomorphs onto the molecular phylogeny revealed that one of the types (fork-tailed type) had originated as the common ancestor of the Elopomorpha, the other two (filament-tailed and round-tailed types) having diversified separately in two more derived major clades.     

The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera

The full anatomy of over fifty species of the Chromodorididae is described including the type species of all but one of the nominal genera. The holotype material of the type species of Ehrenberg's problematic genera Glossodoris, Actinodoris and Pterodoris is described. Sixteen genera are recognized within the family Chromodorididae including four new monotypic genera. Glossodoris is shown to be a senior synonym of Casella , not Chromodoris , and Ceratosoma and Verconia are shown to be members of the Chromodorididae. The separation of Cadlina, Tyrinna and Cadinella into a separate sub-family Cadlininae is considered unnecessary.
A large suite of characters including features of the external shape, mantle glands, gills, foregut, jaw-plates, radula and reproductive system are used to define the genera. A tentative phylogeny of the family is proposed.     

Morphological and mitochondrial-DNA analysis of the Indo-West Pacific rock oysters (Ostreidae: Saccostrea species)

Species of Saccostrea are common oysters on Indo-Pacific rockyshores. The taxonomy of this genus is unclear, however, becauseof morphological plasticity among its constituent species. Oystersamples with distinct morphotypes were collected from shoresexperiencing different degrees of wave exposure in Japan, Taiwan,China, Vietnam, Singapore and Australia. Intraspecific and interspecificvariations in shell characters have been identified. Only S.kegaki could be readily differentiated from S. cucullata-B,S. cucullata-C and S. mordax by multivariate shell allometricanalyses. Phylogenetic analyses using partial mitochondrial16S DNA sequences of approximately 513 base pairs identifiedtwo clades that correspond to superspecies, i.e. putative S.cucullata and putative S. mordax, comprising nine and two lineagesfrom the Indo-West Pacific, respectively. These are S. cucullata-A,B, C, D, E, F, G, S. kegaki and S. glomerata in one clade, andS. mordax-A and B in the other. Interspecific sequence divergence(Kimura-2-parameter values) between lineages ranged from 1.02%to 11.74%. Both S. cucullata-C and S. kegaki are restrictedto the northern hemisphere, whereas S. glomerata seems to bea temperate species from the southern hemisphere. S. cucullata-Doccurs only in Taiwan. Other species, i.e. S. cucullata-A, B,D, E and F and S. mordax-A and B, have a wide range on rockyshores in the tropical and subtropical Western Pacific and inboth northern and southern hemispheres. (Received 7 January 2005; accepted 4 November 2005)     

Epizoanthidae (Hexacorallia: Zoantharia) associated with Granulifusus gastropods (Neogastropoda: Fasciolariidae) from the Indo-West Pacific

Organisms Diversity & Evolution - There have been few detailed studies on the associations between cnidarians and gastropod mollusks. Several hypotheses have been suggested to explain the...     

The genus Rostanga Bergh, 1879 (Nudibranchia: Dorididae) in the Indo-West Pacific

The genus Rostanga Bergh, 1879 is reviewed and ten species, seven of them new, are recognized from the Indo-West Pacific. They are compared with the three species of the genus known from elsewhere in the world. Most species are red or orange-red and the mantle is characterized by a dense covering of spiculate caryophyllidia. Species are characterized on aspects of the buccal armature, rhinophore club, egg-ring, developmental biology and food preferences. Each species has a specialized diet, most species restricted to one or a few sponges of the family Microcionidae.     

Length‐weight and length‐length relationships of the genus Alosa (Clupeoidei: Clupeiformes: Clupeidae) along the southern Caspian Sea coast

Length–weight (LWR) and length–length (LLR) relationships were estimated for four shad species of the genus Alosa, reported from along the southern Caspian Sea coast, north of Iran in a study from March 2014. Two of these species are endemic to the Caspian Sea. The length–weight parameter b for these species ranged from 2.99 to 3.24, with regression coefficients (r²) ranging from 0.91 to 0.99. All LLRs were highly significant (r² > 0.96).