Galapagomystides bobpearsoni, 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 : 471

Galapagomystides bobpearsoni n. sp.

Figures 15 , 16

Diagnosis. First segment fused dorsally to prostomium. Elongated dorsal cirri on segments 1, 2 and 3. The elongated dorsal cirri on segments 2 and 3 are the longest of all Galapagomystides species. Elongated ventral cirri on segment 2.

Material Examined. Holotype: SIO-BIC A4588 * (prepared for SEM), Tow Cam vent, Lau Back-arc Basin, Tonga, ~ 2720 m depth, May 19, 2005, ROV Jason II. [Genbank COI = MZ 711262 ] Paratype: SIO-BIC A4590 collected from Tui Malila , Lau Back-arc Basin, Tonga, ~ 1890 m depth. For locality details see Table 1 . * indicates sequenced specimen .

Description. Holotype length unknown (incomplete- missing posterior end used for DNA sequencing). Body width 0.8 mm at segment 10 ( Figs 15A , 16C ). Body light pink in life ( Fig. 15C ). Body brown/orange with numerous dark pigmentation speckles in preserved (formalin/ethanol) state ( Fig. 15A, B ). Prostomium slightly wider than long; nuchal organs not visible ( Fig. 16A, D ). Anterior dorsal edge of prostomium with paired cylindrical antennae ~ 0.25 mm long ( Fig. 16A ). Paired palps ventral to antennae, similar in shape and length to antennae ( Fig. 16D ). Segment 1 fused to prostomium, following segments clearly demarcated ( Fig. 16A ). Pair of elongated dorsal cirri [tentacular cirri] on each of segments 1 (~ 0.3 mm long), 2 (~ 0.42 mm long) and 3 (~ 0.44 mm long) ( Fig. 16A, D ). All elongated dorsal cirri cirriform, tapering distally. Ventral cirri absent from segment 1 ( Fig. 16D ). Pair of elongated ventral cirri on segment 2 ~ 0.3 mm long ( Fig. 16D ). Bulbous, rounded dorsal cirri ~ 0.1 mm long begin on segment 3 continuing posteriorly ( Fig. 16C ). Cylindrical, tapering ventral cirri ~ 0.1 mm long begin on segment 3 continuing posteriorly ( Fig. 16D ). Parapodia uniramous, notopodial chaetae absent; neuropodium with central fascicle containing ~5–9 compound chaetae; one simple emergent acicula ( Figs 15D, E, F, G , 16E, F ). Compound chaetal shaft cylindrical; thin, flattened pointed blade extended from curved joint ( Fig. 15E ).

Variation. Only two specimens were collected. The paratype matches the holotype, but is also complete with a pygidium, which has a pair of small lobed cirri ~ 0.2 mm long, rounded distally.

Remarks. Galapagomystides bobpearsoni n. sp. is morphologically like G. aristata and G. kathyae n. sp. in having segment 1 dorsally fused to the prostomium. However, in the phylogenetic analyses G. bobpearsoni n. sp. was found to be the sister group to a clade comprising G. aristata , G. kathyae n. sp. and G. verenae n. comb. ( Fig. 2 ) Galapagomystides bobpearsoni n. sp. is restricted to Lau Back-arc Basin between 1890–2720 m depth. An obvious morphological feature distinguishing G. bobpearsoni n. sp. is the very long cirriform elongated dorsal cirri originating from the first three segments, the longest projecting from segments two and three. The chaetal blades of G. bobpearsoni n. sp. are also notable for being the longest of all Galapagomystides species.

A Etymology. Galapagomystides bobpearsoni n. sp. is named after the lead author’s father, Bob Pearson, for his invaluable love and support, and who inspired the lead author’s passion and curiosity for the ocean.

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 15. Light microscopy (LM) images of Galapagomystides bobpearsoni n. sp. holotype (SIO-BIC A4588). A—dorsal view. B—ventral view. C—dorsal view of anterior, live. D—parapodia. E—drawing of compound chaetae. F—compound chaetae. G—compound chaetae. Abbreviations: a, antennae; dc, dorsal cirri; edc, elongated dorsal cirri; evc, elongated ventral cirri; vc, ventral cirri; p, palps; pro, prostomium.

FIGURE 16. Scanning electron microscopy (SEM) of Galapagomystides bobpearsoni n. sp.A—close-up dorsal view of anterior and prostomium, holotype (SIO-BIC A4588). B—ventral view of pygidium (pygidial cirri broke off, two scars seen at distal end), paratype (SIO-BIC A4590). C—dorsal view of anterior, holotype (SIO-BIC A4588). D—ventral view of anterior (tips of antennae and palps broken off), holotype (SIO-BIC A4588). E—compound chaetae, holotype (SIO-BIC A4588). F—parapodia, holotype (SIO-BIC A4588). Abbreviations: a, antennae; bo, buccal organ; dc, dorsal cirri; edc, elongated dorsal cirri; evc, elongated ventral cirri; vc, ventral cirri; p, palps; pro, prostomium; pyg, pygidium.