Fig 1.
Geographical map with location of the sampling sites.
For population identification see Table 1.
Table 1.
Geographic coordinates of the 11 sampling sites and estimates of genetic diversity for cytochrome c oxidase subunit I (COI) sequences (493 bp).
Fig 2.
Bayesian phylogenetic tree of the 124 COI Branchiomma sequences obtained (marked in blue and green).
OTUs names consist of the abbreviated location name according to Table 1 and a unique identifier. For Mediterranean populations, dark green indicates samples collected from carbon dioxide vents, light green samples from non-acidified sites. For extra-Mediterranean populations, dark blue indicates samples from sites where the species was introduced, light blue indicates samples from the native range. The tree was rooted using sequences of Bispira manicata, Bispira serrata, Branchiomma sp. and Branchiomma bairdi as outgroups (taxon names followed by GenBank® accession numbers). Only nodes supported by posterior probabilities ≥ 0.95 are reported. **, posterior probability = 1; *, posterior probability ≥ 0.95 and < 1.
Fig 3.
Median-joining network of haplotypes detected from the 11 studied localities.
The area of each circle is proportional to the number of individuals exhibiting that haplotype (Hap). Each line joining haplotypes represents one mutational step, transversal bars show additional steps.
Table 2.
Mean values of total body length, trunk length, crown length and crown/trunk length ratio for each Mediterranean and extra-Mediterranean studied localities.
Table 3.
Results of the ANOVA analysis testing for differences in average crown/trunk length ratio measured in Mediterranean and extra-Mediterranean samples.
Fig 4.
Box-plot graph of the ANOVA results.
The graph shows the values of crown/trunk length ratio reported for Mediterranean and extra-Mediterranean specimens. Differences in these values were tested using crown/trunk length ratio as dependent variable and the geographical origin of the samples (Mediterranean, extra-Mediterranean) as factor.
Fig 5.
Relationship among biometrical measurement in the studied Branchiomma samples.
The graphs show the correlation between individuals’ total body size and number of chaetigers for Mediterranean and extra-Mediterranean populations. (A) Trunk length-number of chaetigers relationship for Mediterranean samples (Taranto population). (B) Trunk length-number of chaetigers relationship for extra-Mediterranean samples (Mazatlán).
Table 4.
Morphological features of Mediterranean (B. boholense) and extra-Mediterranean (B. bairdi) specimens.
Fig 6.
Morphological comparison of Mediterranean (Taranto) and extra-Mediterranean (Mazatlán) Branchiomma samples.
(A) Complete specimens in ventral view; r: Mediterranean specimen, l: extra-Mediterranean specimen. (B) Mediterranean specimen. Basal part of the crown with the detail of the first pair of stylodes. (C) Extra-Mediterranean specimen. Basal part of the crown with the detail of the first pair of stylodes. The arrow indicates eggs masses.
Fig 7.
Morphological features of a Mediterranean specimen.
(A) Detail of the radioles with stylodes, macrostylodes and radiolar eyes. (B) Detail of the radiolar tips. (C) Macrostylodes and microstylodes. (D) Drawn of thoracic avicular uncinus. (E) Dorsal lips. (F) Thoracic avicular uncini. mis: microstylodes, mas: macrostylodes, ce: compound eyes, rt: radiolar tips, dl: dorsal lips.
Fig 8.
Morphological comparisons of branchial radioles for Mediterranean (Taranto) and extra-Mediterranean (Mazatlán) specimens.
Details of radioles with microstylodes, macrostylodes and radiolar eyes from Mediterranean (A, B) and extra-Mediterranean (C, D) samples. mis: microsylodes, mas: macrostylodes, ce: compound eyes. Arrows highlight the different length of microstylodes between Mediterranean and extra-Mediterranean samples. Scale bars: A-D, 500 μm.
Fig 9.
Morphological features of an extra-Mediterranean specimen.
(A) Detail of the radioles with stylodes, macrostylodes and radiolar eyes. (B) Detail of the radiolar tips. (C) Macrostylodes, microstylodes and radiolar eyes. (D) Drawing of thoracic avicular uncinus. (E) Dorsal lips. (F) Thoracic avicular uncini. mis: microstylodes, mas: macrostylodes, ce: compound eyes, rt: radiolar tips, dl: dorsal lips.
Fig 10.
Morphological features of B. boholense specimens from Indonesia.
(A) Branchial lobe showing the unpaired basal stylodes. (B) Detail of microstylodes and macrostylodes along the radiole. (C) Detail of the radiolar tips. (D) Detail of radiole with stylodes (micro and macro) and radiolar eyes. (E) Detail of microstylodes along the radiole. (F) Detail of macrostylodes along the radiole. (G) Detail of thoracic avicular uncini. Scale bars: A-D, F, 500 μm; E, 150 μm; G, 10 μm.