Inermonephtys inermis Ehlers 1887

Inermonephtys inermis (Ehlers, 1887)

Figure 6 (A–D); Figure 9 (D −F)

Nephthys (Aglaophamus) inermis Ehlers, 1887: 125, pl. 38, Figures 1–6. Inermonephtys inermis; Fauchald 1968, 16–17, pl. 4, Figures 31–35; Day 1973, 42; Taylor 1984: 35 –19–35–20, Figures 35–15, 16a–c.

Material examined. 4 specimens: AMBES: Continental shelf: UERJ 4553 (1 spec., 20º34’53.05’’S and 040º6’27.68’’W, AMB.14 B3 R1), UERJ 4554 (2 spec., 20º34’53.05’’S and 040º6’27.68’’W, AMB.14 B3 R2), UERJ 4568 (1 spec., 19º40’25.46’’S and 039º36’20.57’’W, AMB.14 D2 R3).

Type locality. Florida, United States of America (from synonym).

Diagnosis. Interramal branchiae from parapodium 3, two pairs of eyes, bristly chaetae with few coarse teeth on cutting edge.

Description. Based on complete specimen (UERJ 4554) measuring 30.2 mm long and 2 mm wide (excluding chaetae), with 99 chaetigers. Remaining specimens measure 0.7–18.6 mm long, 0.2–1.1 mm wide, with 9–84 chaetigers; only one specimen incomplete (UERJ 4553). Body rectangular and wider in anterior region.

Prostomium long (when the proboscis is not everted) with straight anterior edge, rounded upper corners, and Ushaped posterior margin (Figure 6 A). Two pairs of eyes positioned on posterior margin of prostomium, one pair on right margin, and another pair on left margin (Figure 6 A). Pair of long digitiform nuchal organs located on upper margin of first chaetiger (Figure 6 A). One pair of ventral palps bent ventrally, each palp with short digitiform papilla. Interramal branchiae from parapodium 3, curved inward (Figure 6 B–D); basal papillae start from parapodium 4 and are located on upper part of each branchia, as a short digitiform process, sometimes difficult to see. First parapodia inserted frontally (Figure 6 A), notopodia and neuropodia little developed; dorsal and ventral cirri short and digitiform. Notopodial preacicular lobe rounded and undeveloped; acicular lobe conical and larger than preacicular lobe; postacicular lobe well developed, rounded and translucent (Figure 6 B–D). Neuropodial preacicular lobe rudimentary; acicular lobe conical and larger than other lobes; postacicular lobe rudimentary (Figure 6 B–D). Dorsal and ventral cirri long and digitiform (Figure 6 B–D). Notopodial postacicular lobe becoming slightly narrower and elongated from middle region. Anterior region with notopodial and neuropodial preacicular chaetae barred (Figure 9 D), some short bristly chaetae with few coarse teeth on cutting edge also present (Figure 9 F); postacicular chaetae denticulate, and a few lyrate (Figure 9 E). Barred chaetae decreasing in number and lyrate chaetae increasing in number from middle region. Pygidium rounded, without appendix and with dorsal anal opening.

Remarks. The species is a new record for the Brazilian coast. Inermonephtys inermis (Ehlers, 1887) resembles Inermonephtys tetrophthalmos Rainer & Kaly, 1988 from Australia, in that both have two pairs of eyes and are the only members of the genus with this characteristic, and also have a pair of digitiform nuchal organs and a conical notopodial acicular lobe. However, in I. tetrophthalmos the interramal branchiae start from parapodium 2, barred preacicular chaetae are absent, and the species lacks digitiform papillae on the ventral palps, among other characteristics. According to Nateewathana & Hylleberg (1986), the branchiae arise from chaetiger 4 in I. inermis, as well as in a specimen examined in this study. In another specimen, the branchiae start from chaetiger 3, as in the material examined by Martin et al. (2009), differing from other species in other characteristics.

Distribution. Atlantic Ocean—North Atlantic Ocean, North Carolina and Florida (USA), Gulf of Mexico, Brazil (Campos Basin), Mediterranean, Spanish Exclusive Economic Zone, West Africa from Morocco to Angola; Indian Ocean – Red Sea, Gulf of Suez, Gulf of Aden, Mozambique, Maldives, Vietnam; Pacific Ocean—California (USA) (Taylor 1984). Records distant from the type locality require confirmation, since I. foretmontardoi Ravara, Cunha & Pleijel, 2010, for example, was erected for specimens from northern Europe.