Anobothrus dayi Imajima, Reuscher & Fiege, 2013

Reuscher, Michael G. & Fiege, Dieter, 2016, Ampharetidae (Annelida: Polychaeta) from cold seeps off Pakistan and hydrothermal vents off Taiwan, with the description of three new species, Zootaxa 4139 (2), pp. 197-208 : 200

Anobothrus dayi Imajima, Reuscher & Fiege, 2013

( Fig 2 A, B)

Specimens examined. SMF 24135, Yonaguni Knoll IV Hydrothermal Field, sampling site not affected by CO2 seepage, Okinawa Trough, 24°50.355’N 122°41.736’E, 1324 m, SO 196, Station 65, TV-MUC, 18 March 2008 (1 af).

Description. Anterior fragment including ten thoracic uncinigers. Length 1.2 mm, width 0.35 mm. Prostomium with middle lobe delimited by incision from surrounding lobe, without glandular ridges or eyes. Buccal tentacles with ventral groove, smooth. Three pairs of cirriform branchiae in fused segments II + III, arranged in transverse row; groups of branchiae separated by wide median gap ( Fig. 2 A); segmental origin of outermost and second outermost branchiae not determinable; branchiae of segment IV inserted in innermost position of transverse row. Chaetae in fused segments II + III longer and slightly thicker than following capillaries, pointing forwards. Notopodia with limbate capillary notochaetae from segment IV, present to end of fragment. Notopodia in thoracic unciniger 8 slightly elevated, connected by dorsal ridge ( Fig. 2 A); notochaetae of thoracic unciniger 8 broken, shape indeterminable. Neuropodial tori with uncini from segment VI, present to end of fragment. Cirri and papillae in thoracic parapodia absent. Circular glandular band absent. Continuous ventral shields present to thoracic unciniger 9. Intermediate and abdominal uncinigers missing. Nephridial papillae absent. Thoracic uncini with 9 teeth in 2 alternating rows above rostral tooth and basal prow ( Fig. 2 B).

Distribution. Anobothrus dayi has been found along the coast of Japan, in depths of 30–125 m ( Imajima et al. 2013). The finding at the Yonaguni Knoll Hydrothermal Field is the species’ second record. It was found in an area that is not directly affected by the hydrothermal vent’s CO2 seepage. It is the deepest and southernmost record of the species.

Figures

FIGURE 2. Anobothrus dayi: (A) entire specimen, dorsal view; (B) thoracic uncinus, fronto-lateral view.