Claviramus kyushuensis sp. nov. Figs 1, 2, 3

Material examined.

Ariake Sound, Kyushu, Japan, Stn 20D, 32°31.070'N, 130°14.037'E, 20 m depth, sandy mud bottoms, collected by dredge by K. Mori, 17 September 2005. Holotype CBM-ZW 1123, Paratypes CBM-ZW 1124-1126 (three paratypes: two complete, one lacking crown), UANL 8130 (three paratypes: two complete, one lacking crown).

Diagnosis.

Subdistal ends of some radioles with lateral margins extended, thin, as foliaceous flanges (Figs 1 E–G, 2F), some with a short, distal filament or cirrus (Fig. 1G). Glandular ridge on chaetiger 2 present. Abdominal shields well developed (Figs 1B, 2C). Dorsal pockets of collar present exposing large vascular loops (Fig. 1D). Anterior peristomial ring not extending beyond ventral collar margins. Ventral margin of collar with a shallow mid-ventral incision forming two discrete rounded lappets (Figs 1B, C). Thoracic tori not contacting shields (Fig. 1B). Thoracic uncini with tips of main fangs bifid (Fig. 3 C–D).

Description.

Sabellid worm with eight thoracic (eight in all types) and ten abdominal chaetigers (9-16 in paratypes CBM ZW 1124-1126, UANL 8130). Trunk length 2.5 mm (1.6 mm in paratype CBM-ZW 1125, 3.2-4.7 mm in paratypes UANL 8130), body width 0.7 mm (0.3 mm in paratype CBM-ZW 1126, 0.5-1.3 mm in paratypes UANL 8130). Radiolar crown 1.1 mm length (1.3-2.1 mm in paratypes UANL 8130), with seven radioles in each branchial lobe (7-9 in paratypes UANL 8130).

Palmate membrane absent. Subdistal ends of some radioles with lateral margins extended, thin, as foliaceous flanges; overall shape oblong (Figs 1 E–G, 2F) with a mid-ventral incision occupying a quarter of flange length; some tips with a short, distal filament (Fig. 1G). Other radioles with unflanged tips, filiform (Fig. 2D) or with broken tips (Fig. 2E). Largest pinnules located at 3/4 of radiole length (Fig. 2D). Radiolar eyes absent. Two pairs of ventral radiolar appendages, as long as half of radiolar crown length. Dorsal lips narrow, triangular, longer than wide. Ventral lips rounded, low. Dorso-lateral margins of collar fused to faecal groove; dorsal pockets present (Figs 1A, D, 2A); large vascular loops visible on dorsal pockets of collar (Fig. 1D); ventral sacs absent. Ventral margin of anterior peristomial ring as broadly triangular lobe, not extending beyond collar margins. Ventral collar margin with a shallow mid-ventral incision forming two discrete rounded lappets (Figs 1B, C, 2B). Lateral collar margins slightly oblique, with ventral margin slightly higher than dorsal. Thoracic and abdominal shields well developed (Figs 1B, C, 2C). Collar shield divided transversally into three nearly rectangular sections with lateral margins indented (Fig. 2B). A pair of white triangular glandular pads in the ventral side of collar, as lung-shaped. Shields from chaetigers 2 to 8 rectangular, broad, entire (Figs 1B, 2B). Abdominal shields forming two squares divided by faecal groove (Figs 1B, 2C). Narrow glandular ridge on chaetiger 2 present, most notorious laterally (Fig. 1A, D). Thoracic tori not contacting shields (Fig. 1B, C). Thoracic notopodial fascicles in chaetiger 1 as short as rows of narrowly hooded chaetae (collar chaetae) (Fig. 3A). Notopodial fascicles in chaetigers 2-8 with superior group of narrowly hooded chaetae and two inferior rows of broadly hooded chaetae (Figs 2I, 3B). Thoracic neuropodial uncini acicular (Fig. 2G); main fang bifid, surmounted by 5-6 rows of small equal-sized teeth (Fig. 3C, D), breast as a narrow swelling; handles very elongate (Fig. 2G). Abdominal neuropodial fascicles with one or two transverse rows of narrowly hooded chaetae (Fig. 3E). Abdominal notopodia with avicular uncini (Figs 2H, 3F); main fang surmounted by 7-9 rows of small teeth equal in size, occupying a half of the main fang length (Fig. 3F); breast well developed; handles short (Fig. 2H). Pygidium triangular without eyes neither cirrus (Figs 1B, 2C). Anus ventral. Tubes not preserved. Paratypes mature hermaphrodites with full-developed oocytes and sperm in thoracic and abdominal segments.

Etymology.

The specific epithet is named after type locality, Kyushu, Japan.

Remarks .

Among the species currently recognized in Claviramus, C. kyushuensis sp. nov., is unique by having a collar shield rectangular, divided transversally into three nearly equal-sized sections; a glandular ridge on chaetiger 2; abdominal shields well developed; main fang of thoracic uncini with bifid tips and the presence of a short, distal filament in some radioles.

Claviramus grubei has also a glandular ridge on chaetiger 2, a short mid-ventral incision of distal radiolar flanges and radiolar tip filaments, but it differs of C. kyushuensis sp. nov., by lacking abdominal shields (present in C. kyushuensis sp. nov.) (Table 1).

Claviramus kyushuensis sp. nov., differs from C. oculatus and C. candelus mainly by lacking pygidial eyes (present in C. oculatus and C. candelus) and having a collar shield rectangular, divided transversally into three nearly equal-sized sections (entire in C. candelus, divided into two areas in C. oculatus) (Table 1).

In addition, SEM images used in this study reveals that tips of main fangs of thoracic uncini are bifid (Fig. 3C, D). This peculiarity has been only reported in Amphicorina triangulata López & Tena, 1999 by Cepeda and Lattig (2017). However, in A. triangulata, the presence of a large tooth above the main fang in the midline, followed by a third tooth offset from midline, and then followed by series of smaller teeth, is remarkable. In Claviramus kyushuensis sp. nov., all rows of teeth above the main fang are nearly equal-sized (Fig. 3C, D).