Genus Namalycastis Hartman, 1959

Diagnosis (emended). Long body, usually with more than 150 chaetigers; prostomium trapezoidal; antennae short and subconical; two pairs of eyes (rarely, eyes absent), usually with posterior pair slightly smaller; four pairs of tentacular cirri; dorsal cirri usually increasing in size posteriorly showing cylindrical cirrophores in the anterior region and flattened cirrophores in the posterior region; notochaetae present in most species; preacicular neurochaetae as heterogomph falcigers (rarely sesquigomph or heterogomph spinigers); postacicular neurochaetae as sesquigomph spinigers in the supra-acicular fascicle and heterogomph spinigers (rarely heterogomph elongated falcigers) in the sub-acicular fascicle; pygidium button-shaped.

Type species: Namalycastis abiuma (Grube, 1871)

(1) Number of chaetigers: 0, Less than 130; 1, More than 130.

(2) Body width: 0, Body width uniform anteriorly, tapering posteriorly; 1, Body widest mid-anteriorly, tapering anteriorly and posteriorly.

(3) Epidermal pigment: 0, Absent; 1, Present.

(4) Prostomium anterior end: 0, Smooth; 1, Prostomium with an anterior cleft.

(5) Prostomium lateral indentation: 0, Absent; 1, Present.

(6) Antennae length: 0, Short, maximum extent level with anterior edge of prostomium; 1, Long, extending beyond anterior edge of prostomium.

(7) Antennae insertion: 0, Anteriorly inserted, over inner edge of palps; 1, Laterally inserted, over mid-palps.

(8) Eyes: 0, Absent; 1, Present.

(9) Eye insertion angle: 0, Transversal; 1, Oblique; 2, Longitudinal.

(10) Eye pair relative size: 0, Both pairs of same size; 1, Posterior/anterior pair smaller.

(11) Eye lens: 0, Indistinct/absent; 1, Distinct.

(12) Jaws structure: 0, With bifid terminal teeth; 1, Serrated, with single terminal tooth.

(13) Posterodorsal tentacular cirri extending posteriorly to: 0, chaetiger 1–2; 1, chaetiger 3–4; 2, beyond chaetiger 4.

(14) Tentacular cirrophores: 0, Indistinct; 1, Distinct.

(15) Neuropodial acicular ligule: 0, Globular; 1, Subconical; 2, Bilobed.

(16) Dorsal cirri length: 0, Same size throughout body or increasing slightly posteriorly; 1, Dorsal cirri greatly increasing for posterior parapodia.

(17) Cirrophores in dorsal cirri: 0, Indistinct; 1, Distinct.

(18) Notochaetae: 0, Absent; 1, Present.

(19) Falcigers in posterior parapodia: 0, Falcigers replaced by spinigers in preacicular fascicle of posterior podia; 1, Falcigers present in preacicular fascicle in all chaetigers.

(20) Sub-acicular falciger blades: 0, Smooth; 1, Finely serrated; 2, Coarsely serrated.

(21) Sub-acicular, postacicular spinigers: 0, Absent; 1, Present.

(22) Sub-acicular spiniger blades in posterior podia: 0, Finely serrated; 1, Increasingly coarsely serrated proximally.

(23) Preacicular Elongated falcigers (Pseudospinigers): 0, Absent; 1, Present.

(24) Postacicular Elongated falcigers (Pseudospinigers): 0, Absent; 1, Present.

(25) Pygidium shape: 0, Tripartite; 1, Button-shaped, multi-incised rim.

(26) Anus position: 0, Terminal; 1, Dorsoterminal.

(27) Anal cirri rising: 0, Ventrally; 1, Ventrolaterally; 2, Laterally.