Galapagomystides verenae ( Blake and Hilbig 1990 ) Pearson & Rouse, 2022

Pearson, Kaila A. M. & Rouse, Greg W., 2022, Vampire Worms; A revision of Galapagomystides (Phyllodocidae, Annelida), with the description of three new species, Zootaxa 5128 (4), pp. 451-485 : 466-471

Galapagomystides verenae ( Blake and Hilbig 1990) new combination

Figures 11–14

Bergquist et al. (2007: 53, 62), ( Blake and Hilbig 1990:xx), Chapman et al. (2018: 572, 573), Desbruyères et al. (1997: 82), Desbruyères et al. 2006: 217), Kelly et al. (2007: 6), Lelièvre et al. (2017: 2633, 2637-2639), Milligan and Tunnicliffe (1994: 4781), Tsurumi and Tunnicliffe (2003: 617, 625), Tunnicliffe (1992: 340), Tunnicliffe et al. (1998: 367).

Material Examined. Paratype: SIO-BIC A13575 (transferred from USNM, used for SEM), Magic Mountain , Explorer Ridge, USA, ~ 1,810 m depth . Vouchers: SIO-BIC: A7991 (A–M)*, Axial Seamount ( CASM), Juan de Fuca Ridge, ~ 1,550 m depth ; SIO-BIC: A3263 (A–E)*, A8563(A-D)*, Guaymas Basin , Mexico, ~ 1,650 m depth ; SIO-BIC: A1496A*, A1496B*, A1477A*, A1312*, A1331*, A1918*, Mound 12, Costa Rica, 1,000 m depth ; SIO-BIC: A1830 (A–D)*, A8359*, A8379*, A10044*, Jaco Scar , Costa Rica, ~ 1,800 m depth ; SIO-BIC: A8466 *, A8353*, Parrita Seep , Costa Rica, ~ 1,400 –1,800 m depth . For locality details see Table 1 . * indicates sequenced specimens.

Diagnosis. First segment not fused to prostomium. Trapezoidal prostomium that is dorsally “ V ” shaped posteriorly. Elongated dorsal cirri on segments 1, 2 and 3. Elongated ventral cirri on segment 2.

Description. Up to 25 mm long, 1 mm wide at segment 10 for ~60 segments. Body red longitudinal stripe in life, semi-translucent white/pink at parapodial lobes. Dorsal and ventral cirri, elongated cirri, pygidial cirri, prostomium and pygidium also white/pink ( Figs 11 , 14 ). Trapezoidal prostomium, “V” shaped posteriorly ( Figs 12A, C , 13A ); nuchal organs not visible. Anterior dorsal edge of prostomium with paired cylindrical antennae ~ 0.25 mm long ( Fig. 12B ). Paired palps ventral to antennae, similar in shape, slightly shorter ( Fig. 12B ). Segment one distinct from prostomium, following segments also clearly demarcated ( Fig. 12A, C ). Pair of elongated dorsal cirri [tentacular cirri] on each of segments 1 (~ 0.4 mm long), 2 (~ 0.5 mm long), 3 (~ 0.4 mm long) ( Fig. 12A, C ). All elongated dorsal cirri cirriform, tapering distally. Pair of elongated ventral cirri on segment 2 (~ 0.2 mm long) ( Fig. 11B ). Bulbous, rounded dorsal cirri (~ 0.15 mm long) begin on segment 4 continuing posteriorly ( Fig. 12A, D ). Dorsal cirri larger than ventral cirri. Conical, tapering ventral cirri (~ 0.1 mm long) begin on segment 3 continuing posteriorly ( Fig. 12B ). Ventral cilia bands present ( Fig. 12B ). Parapodia uniramous, notopodial chaetae absent; neuropodium with central fascicle containing ~5–8 compound chaetae; one simple emergent acicula ( Figs 11G , 12F, G ). Compound chaetal shaft cylindrical; thin, flattened pointed curled blade extended from curved joint ( Figs 11G , 12F, G ). Pygidium with one pair of cirriform pygidial cirri tapering distally (~ 0.2 mm long) ( Fig. 11B, D, F ).

Variation. Material examined in this study largely matches the original description ( Blake and Hilbig 1990). The largest SIO-BIC specimen was 25 mm long (SIO-BIC A7991, Axial seamount vents, JDF), slightly shorter than the original description at 27 mm long ( Blake and Hilbig 1990). Galapagomystides verenae n. comb. specimens collected from Costa Rica and Guaymas had the similar lengths reported from the type locality.

Remarks. Blake and Hilbig (1990) argued that Galapagomystides verenae n. comb. was a member of Protomystides owing to the absence of fusion between the prostomium and segment 1, the position and orientation of the elongated dorsal and ventral cirri, and its lobed pygidial cirri. While these observations are correct, the phylogenetic position based on DNA means that it should be moved to Galapagomystides . Observations of living G. verenae n. comb. are reported for the first time and its red color is like other species of Galapagomystides ( Figs 11 , 14 ). Also, images of Galapagomystides verenae n. comb., on top of juvenile Escarpia spicata (Vestimentifera) tubes from Costa Rica seeps supports the hypothesis that these worms may be blood feeders ( Fig. 14 ).

Unique features for G. verenae n. comb. include a trapezoidal prostomium that is dorsally “V” shaped posteriorly ( Figs 12A and 13A ), chaetal blade length and curl ( Figs 12G and 13D ), and the conical shape of ventral cirri ( Figs 12B and 13C ). The total range of G. verenae spans from ~ 9°N, to ~ 46°N, from the seeps of Guaymas Basin and Costa Rica margin to the hydrothermal vents of the Juan de Fuca Ridge. Galapagomystides verenae n. comb. is unique among Galapagomystides for being present at both seeps and vents and appears to have occupied vents from a seep ancestry ( Fig. 6 ). Galapagomystides verenae n. comb. is morphologically most like G. patricki n. sp., with both species showing no fusion of anterior segments with the prostomium. However, in the phylogenetic analyses, G. verenae n. comb. was found to be the sister taxon to G. kathyae n. sp. ( Fig. 2 ).

Figures

FIGURE 2. Maximum Likelihood (ML) tree generated from the concatenation of mitochondrial (COI 16rRNA) and nuclear genes (18S rRNA, 28S rRNA). Numbers on nodes represent ML bootstrap values (above node) and Bayesian posterior probabilities (below node). Values below 50% for ML and 0.70 for posterior probabilities are not shown. ‘*’ indicates G. aristata as the type species of Galapagomystides.

FIGURE 6. Most parsimonious reconstruction for habit of Galapagomystides. The ancestral state for the clade is ambiguous and could have been seep or vent. Galapagomystides verenae n. comb. is found at both vents and seeps and appears to have colonized seeps from a vent ancestral habitat.

FIGURE 11. Light microscopy (LM) images of live Galapagomystides verenae n. comb.from different regions.A—dorsal view of anterior (SIO-BIC A7991, Juan de Fuca Ridge). B—dorsal view of the whole worm (SIO-BIC A7991, Juan de Fuca Ridge). C—dorsal view of anterior (SIO-BIC A3263, Guaymas Basin). D—dorsal view of the whole worm (SIO-BIC A3263, Guaymas Basin). E—dorsal view of anterior (SIO-BIC A10044, Costa Rica). F—dorsal view of whole worm (SIO-BIC A10044, Costa Rica). G—compound chaetae (SIO-BIC A1830, Costa Rica). H—dorsal view of the whole worm (SIO-BICA8466, Costa Rica). I—dorsal view of whole worms (SIO-BIC A8466, Costa Rica).

FIGURE 12. Scanning electron microscopy (SEM) of Galapagomystides verenae n. comb. (SIO-BIC A7991, Juan de Fuca Ridge). A—dorsal view of anterior. B—ventral view of anterior. C—dorsal view of anterior. D—parapodia, dorsal cirri and chaetae. E—ventral/lateral view of pygidium. F—parapodia. G—compound chaetae. Abbreviations: a, antennae; bo, buccal organ; ci, cilia; dc, dorsal cirri; edc, elongated dorsal cirri; evc, elongated ventral cirri; vc, ventral cirri; p, palps; pro, prostomium; pyg, pygidium.

FIGURE 13. Scanning electron microscopy (SEM) of Galapagomystides verenae n. comb., paratype from the type locality (SIO-BIC A13575).A—dorsal view of anterior. B—ventral view of anterior. C—lateral view of parapodia and chaetae fascicles. D—detail of compound chaetae. Abbreviations: a, antennae; bo, buccal organ; dc, dorsal cirri; edc, elongated dorsal cirri; p, palps; pro, prostomium.

FIGURE 14. A & B—in situ dorsal-view images of Galapagomystides verenae n. comb. associated with juvenile Escarpia spicata tubes at Parrita Seep off Costa Rica.