Molecular evidence for cryptic species in <i>Pteroclava krempfi</i> (Hydrozoa, Cladocorynidae) living in association with alcyonaceans

<p>Hydrozoans are able to establish intimate relationships with several other organisms. The hydroid <i>Pteroclava krempfi</i> lives in association with different alcyonacean taxa from Indo-Pacific and Atlantic coral reefs, growing partially embedded within host tissues. In this study, we found <i>P. krempfi</i> associated with four alcyonacean hosts from the Maldives, namely <i>Sinularia</i>, <i>Sarcophyton</i>, <i>Lobophytum</i> and <i>Paraplexaura</i>, the latter representing a new record. We provided the first molecular phylogenetic evaluation of the genus <i>Pteroclava</i>. <i>Pteroclava krempfi</i> clustered with <i>Cladocoryne floccosa</i>, confirming its position into the family Cladocorynidae. We also performed the first morpho-molecular assessment of <i>P. krempfi</i> diversity. All the colonies growing on different hosts revealed polyps and medusae matching published descriptions of <i>P. krempfi</i>, showing no morphological differences. However, analysing both nuclear and mitochondrial DNA, two highly supported molecular lineages were identified. These two clades were highly divergent and were specifically associated with hosts belonging to different families (Alcyoniidae and Plexauridae). Therefore, our results suggest that <i>P. krempfi</i> from the Maldives is a complex of cryptic species in which the main diagnostic feature between different species could be the host specificity.</p

Description of <i>Turritopsoides marhei</i> sp. nov. (Hydrozoa, Anthoathecata) from the Maldives and its phylogenetic position

<p><i>Turritopsoides marhei</i>, a new species of the hydrozoan family Oceaniidae, is described from the Maldives. This species can be distinguished from the only other member of the genus by the presence of more branched colonies, branches not being adnate to pedicels, longer pedicels, larger nematocysts, nematocyst-rich nematophore-like outgrowths from pedicels, smaller male gonophores, and a different geographic distribution. This finding represents the first record of the genus outside the type locality of its type species, in Belize. Molecular phylogenetic analyses show that, as expected, <i>T. marhei</i> belongs to the clade Filifera IV. However, the phylogenetic hypothesis based on both mitochondrial and nuclear DNA sequences reveals that most of the families of this group are polyphyletic, including Oceaniidae, and suggests that the morphological characters used to discriminate among filiferan families need to be revised thoroughly.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:CE901E0D-B125-4A87-BB97-8020C0658B5D" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:CE901E0D-B125-4A87-BB97-8020C0658B5D</a></p

List of specimens.

<p><b>Boldface</b> indicates newly obtained sequences.</p><p>List of specimens included in the analysis, with specimen code, locality and GenBank accession numbers, when available.</p

Relationship between fish species extent of occurrence (EOO) and area of occupancy (AOO).

<p>Both variables are logarithmically transformed (A: freshwater dataset; B: marine dataset).</p

Morphological differences among clades.

<p>^a present study;</p><p>^b Fontana et al. 2012;</p><p>^c Montano et al. 2015.</p><p>Morphological characters of the clades resulted from the molecular analyses.</p

Frequency distribution plots of both maximum latitudinal (A and B) and longitudinal (C and D) ranges for freshwater (A and C) and marine (B and D) fishes.

<p>Frequency distribution plots of both maximum latitudinal (A and B) and longitudinal (C and D) ranges for freshwater (A and C) and marine (B and D) fishes.</p

<i>In situ</i> photographs and microphotographs of living <i>Zanclea</i> hydroids associated with scleractinians.

<p><b>A</b>) <i>Goniastrea</i>; <b>B</b>) <i>Porites</i>; <b>C</b>) <i>Montipora</i>; <b>D</b>) <i>Acropora</i>; <b>E</b>) <i>Pavona</i>; <b>F</b>) <i>Favites</i>; <b>G</b>) <i>Dipsastrea</i>; <b>H</b>) <i>Echinopora</i>; <b>I</b>) <i>Platygyra</i>. (Scale bars: ~ 500 μm)</p

Global-Scale Relationships between Colonization Ability and Range Size in Marine and Freshwater Fish

<div><p>Although fish range sizes are expected to be associated with species dispersal ability, several studies failed to find a clear relationship between range size and duration of larval stage as a measure of dispersal potential. We investigated how six characteristics of the adult phase of fishes (maximum body length, growth rate, age at first maturity, life span, trophic level and frequency of occurrence) possibly associated with colonization ability correlate with range size in both freshwater and marine species at global scale. We used more than 12 million point records to estimate range size of 1829 freshwater species and 10068 marine species. As measures of range size we used both area of occupancy and extent of occurrence. Relationships between range size and species traits were assessed using Canonical Correlation Analysis. We found that frequency of occurrence and maximum body length had a strong influence on range size measures, which is consistent with patterns previously found (at smaller scales) in several other taxa. Freshwater and marine fishes showed striking similarities, suggesting the existence of common mechanisms regulating fish biogeography in the marine and freshwater realms.</p> </div

Frequency distribution plots of geographic range sizes expressed as area of occupancy (AOO, Number of occupied 1×1° Lat/Lon grid cells) in freshwater (A) and marine (B) fishes.

<p>Frequency distribution plots of geographic range sizes expressed as area of occupancy (AOO, Number of occupied 1×1° Lat/Lon grid cells) in freshwater (A) and marine (B) fishes.</p

Canonical loadings for the first two dimensions of CANCORs for freshwater and marine fish species.

<p>CANCORs were conducted accounting for phylogenetic non indepence. AOO: area of occupancy (number of 1×1° grid cells from which a species was recorded); EOO: extent of occurrence (latitudinal range longitudinal range); K: growth rate; L: maximum length; T: trophic level; Ym: age at first maturity; Y: life span; W: frequency of occurrence. D1: Dimension 1, D2: Dimension 2.</p