Siboglinidae Caullery, 1914

Georgieva, Magdalena N., Little, Crispin T. S., Watson, Jonathan S., Sephton, Mark A., Ball, Alexander D. & Glover, Adrian G., 2019, Identification of fossil worm tubes from Phanerozoic hydrothermal vents and cold seeps, Journal of Systematic Palaeontology 17 (4), pp. 287-329 : 10

Family Siboglinidae Caullery, 1914

(vestimentiferan)

‘Figueroa tubes’

( Fig. 15 A–F, H, I )

1999b Vestimentiferan tube worm Little et al.: 168, fig. 2b–d.

2004 Vestimentiferan tube indeterminate Little et al.: 545, figs 7.3, 8.1–8.7, 11.5

Material. FF-10, FFC-00, FFC-12, FFC-18, FFC-19, FFC-37, blocks of vent sulphides containing fossilized tube fragments, tubes often occurring singly. Collected by C. T. S. Little.

Occurrence. Figueroa massive sulphide deposit, San Rafael Mountains, southern California, USA. Franciscan Complex, Pliensbachian, Lower Jurassic ( Little et al. 1999a, 2004).

Description. Pyritic tubes are 0.3–6.9 mm in diameter, appear to have been originally rigid as they do not exhibit folds or depressions in their walls, and are fairly straight ( Fig. 15A ). One long tube fragment appears to taper along its length ( Fig. 15A ). Tubes possess collars ( Fig. 15B–D ) which are large and flaring in some cases ( Fig. 15B, D ), some tubes showing several collars in short succession ( Fig. 15B ), the collars sometimes oriented obliquely ( Fig. 15C ). The tube walls are ornamented with fine, bifurcating longitudinal and irregular transverse wrinkles ( Fig. 15A–C, E, F ). In section, tube walls are preserved by colloform and framboidal pyrite, and it is unclear whether tubes were originally multi-layered ( Fig. 15H, I ).

Remarks. These tubes group with siboglinids in both PCA and cladistic analyses ( Figs 22 , 24 ). The presence of large, flaring collars suggests that they are unlikely to have been made by chaetopterids. Serpulids and vestimentiferans both produce collars which are large and flaring; however, the pattern of fine longitudinal and irregular transverse wrinkles on tube surfaces suggests that the tubes are more likely to have been made by vestimentiferans, as fine longitudinal wrinkles are not commonly observed in serpulid tubes. The ornamentation of the Figueroa tubes also greatly resembles that of Ridgeia piscesae tubes ( Fig. 15G ). Therefore, we infer that the most likely constructors of the Figueroa tubes were vestimentiferans.

Figures

Figure 15. A–F, H, I, ‘Figueroa tubes’, Pliensbachian, California, USA; A–C, tubes in hand specimen; A, FFC-12, straight, tapering tube with fine longitudinal wrinkles; B, FFC-00-21, tube fragment bearing longitudinal wrinkles and collars; C, FFC-18B, tube with longitudinal wrinkles and a fine, obliquely positioned collar; D, FFC-18, longitudinal section of tube exhibiting long, flaring collars; E, FFC-12, scanning electron microscopy (SEM) image showing details of tube wall ornamentation; F, FFC-12, greater detail of same tube; H, FFC-19, detail of tube transverse section showing preservation of tube walls; I, FFC-19, detail of tube wall in transverse section. G, Ridgeia piscesae (Siboglinidae) tube, JdF317, showing detail of the ornamentation. Scale bars: A, C = 2 mm; B, D, G, H = 1 mm; E = 500 µm; F = 100 µm; I = 300 µm.

Figure 22. Strict consensus cladogram of the three most parsimonious trees of tubes built by a total of 43 modern annelid taxa (best score = 14.344, consistency index = 0.308, retention index = 0.629). The analysis was based on the 48 mostly morphological tube characters and was performed using implied character weighting (k = 3). Numbers on nodes represent groups present/contradicted support values. Symbols/colours indicate taxonomic affinities.

Figure 24. Fourier transform infrared (FTIR) spectroscopy spectra of the organic tubes of vent and seep annelids. Spectra are offset on the absorbance axis, and key spectral absorbance peaks are labelled with the types of chemical bonds they represent: -NH, nitrogenhydrogen; -CH, carbon-hydrogen; -OH, oxygen-hydrogen. The regions of the tube analysed are as follows: Tevnia jerichonana (anterior, inner tube wall); Zenkevitchiana longissimi (middle, outer tube wall); Lamellibrachia anaximandri (posterior, outer tube wall); Sclerolinum contortum (anterior, outer tube wall); Alvinella sp. (middle); Spiochaetopterus izuensis (middle, outer tube wall).