The Nereididae (Annelida) - diagnoses, descriptions, and a key to the genera

Abstract

Nereididae is among the most familiar of marine annelid families, common and well-studied in most marine environments but paradoxically no recent key or identification guide exists to the world's genera. Here updated generic descriptions, a list of characters, a linear key to genera, and minimal diagnoses that distinguish each genus from all others in the family are provided. This information is generated from a Delta database of 186 morphological characters and a link is provided to downloadable software allowing the same data to be interrogated using the open-source Delta program Intkey - a nonlinear multiple entry point computerised interactive key. For each genus the recent literature is also summarised, comments on taxonomic status provided, and published keys to species cited. Nexus format matrices are provided for all 45 genera and 158 Nereididae species, representing all genera, scored for 146 multistate characters from the same character list to facilitate future phylogenetic studies.

Keywords: Computer taxonomy; Taxonomic Information System; diagnosis; identification tools; natural language descriptions; polychaete; taxonomic verification.

Figure 1.

Prostomium, pharynx A barrel-shaped palps (orange dashed outline) and palpophore surface with a single transverse groove (open arrow) Namalycastisabiuma LNG M16Q3 B subconical palps (orange dashed outline) and palpophore surface with several oblique grooves (filled arrows) Neanthesglandicincta MD165 anterior C caecal glands (filled arrows) in ventral dissection of PerinereisvallataNMV F108784 D spherical palpostyles (filled arrow) and prostomium with longitudinal groove (open arrow) NamalycastisabiumaE acutely conical palpostyles (filled arrow) and indented prostomium (open arrow) GymnonereisminyamiF prostomium anterior margin entire Nereis sp. G prostomium anterior margin indented (open arrow) Ceratonereis sp. H dentate jaws (filled arrow) PlatynereisbicanaliculataNTM W17252 I smooth/crenulate jaws (white arrow) LeonnatescrinitusNTM W3330 J everted pharynx a truncate cone with greatest width at margin of tentacular belt (= “frustrum-shaped”) Alitta sp. NMV F94547 K everted pharynx cylindrical SimplisetiaaequisetisNMV F94248 L ventral peristomial flap (filled arrows) and palpostyles subconical to oval-shaped (open arrow) CheilonereisperistomialisM ventrum of anterior chaetigers with rows of tubercles extending to the base of each neuropodium (filled arrows) AustralonereisehlersiN ventrum of anterior chaetigers smooth Neanthes sp. NMV F182608 O dorsal view pharynx with numbering following Kinberg PerinereisvallataP ventral view pharynx with numbering following Kinberg Perinereisvallata. Sources: A, B, F, H, I, M C. Glasby photographs C, J, K, N R. Wilson photographs D modified after C. Glasby (1999)E modified after Hutchings and Reid (1990)G Leon Altoff photograph L, O, P R. Wilson drawings. Not to scale; body widths of these example specimens are in the range 2–5 mm wide excluding parapodia.

Figure 2.

Paragnaths A P-bar paragnaths PseudonereisanomalaB conical paragnaths PseudonereistrimaculataC rod-like paragnaths PlatynereispolyscalmaD smooth bar paragnaths PerinereisvancauricaE pyramidal paragnaths PerinereisakunaF crown paragnaths MicronereispiccolaG shield-shaped paragnaths Pseudonereistrimaculata. Sources: A–E, G emended from Bakken et al. (2009: figs 2–5) F emended from Paxton (1983: fig. 4). Scale bars: 0.1 mm (A–E, G); 200 μm (F).

Figure 3.

Parapodia A transverse dorsal lamellae (filled arrows) CeratocephalesetosaB flattened post-chaetal neuropodial lobe (filled arrow), accessory ventral cirrus (open arrow) anterior parapodium anterior view CeratocephalesetosaC cirrophore of dorsal cirrus enlarged and vascularised (filled arrow), acicular notopodial ligule present (open arrow) posterior parapodium anterior view CeratocephalesetosaD dorsal notopodial ligule (= accessory dorsal cirrus of some authors) (filled arrow) ventral neuropodial ligule (open arrow) Gymnonereisminyami chaetiger 34 anterior view E notopodial acicular process (open arrow) digitiform neuropodial postchaetal lobe (filled arrow) Neanthestasmani chaetiger 30 anterior view (ventral cirrus missing) F notopodial prechaetal lobe (open arrow) digitiform neuropodial postchaetal lobe (filled arrow) Neanthestasmani chaetiger 30 anterior view G dorsal notopodial ligule markedly broader on posterior chaetigers (filled arrow) chaetiger 78 Alittasuccinea USNM 27799 H dorsal notopodial ligule divided into branchiae (filled arrow) dorsal cirrus (open arrow) Dendronereidesheteropoda chaetiger 19 anterior view I dorsal cirrus divided into branchial filaments (filled arrow) Dendronereis sp chaetiger 14 anterior view. Sources: A–DHutchings and Reid (1990)E, F modified after Bakken (2002)G R. Wilson drawing H, I C. Glasby photographs. Abbreviations: anl, acicular notopodial ligule; dc, dorsal cirrus; dnl, dorsal notopodial ligule; pnl, prechaetal notopodial ligule; vnl, ventral neuropodial ligule; vc, ventral cirrus. Not to scale; maximum body width excluding parapodia of 3A specimen ~ 1.2 mm; for remaining figures acicula lengths in the range 0.1–0.4 mm.

Figure 4.

Chaetae A chaetal shaft homogomph articulation Perinereisvallata spiniger NMV F53971 B chaetal shaft heterogomph articulation Perinereisvallata falciger NMV F53971 (= long-bossed heterogomph sensu Conde-Vela (2021) filled arrow points to boss C chaetal shaft sesquigomph articulation Ceratonereismirabilis (= short-bossed heterogomph sensu Conde-Vela (2021) filled arrow points to boss D heterogomph falcigers with long blades (a < b; = Type 0 of Bakken and Wilson (2005)) E heterogomph falcigers with extra-long blades (2× a < b; = Type 1 of Bakken and Wilson (2005)) F heterogomph falcigers with short blades (a ≥ b; = Type 2 of Bakken and Wilson (2005)) G heterogomph falciger blade with straight margin H heterogomph falciger blade with bowed margin I fused heterogomph falciger chaetiger 70 Hedistediversicolor complex AHF, Gilleleje, Denmark J fused falciger chaetiger 40 SimplisetiaaequisetisNMV F53970 K homogomph falciger with terminal tendon (filled arrow) and with terminal secondary tooth (open arrow; = bifid) Platynereisantipoda notopodial falciger chaetiger 66 NMV F50116 L sesquigomph falciger with terminal tendon absent but bifid with secondary terminal tooth (open arrow) and boss (filled arrow) Ceratonereismirabilis median chaetiger M homogomph falciger with smooth blade Nereiscirriseta chaetiger 74 N homogomph falcigers with bidentate blade and large adjacent terminal and subterminal teeth Nereisbifida chaetiger 71 O homogomph falciger with bidentate blade and large widely-separated terminal and subterminal teeth Nereistriangularis chaetiger 24 P homogomph falciger with multidentate blade with ≥ 2 large lateral teeth, first lateral tooth subequal to terminal tooth, subsequent teeth decreasing in size Nereisdenhamensis anterior chaetiger Q homogomph falciger with multidentate blade with ≥ 2 small lateral teeth, first and subsequent lateral teeth much smaller than terminal tooth Nereisapalie chaetiger 74. Sources: A–F, I–K, M–J R. Wilson drawings G, H edited after Villalobos-Guerrero et al. (2021: fig. 1e, f) L after Perkins (1980: fig. 1d) M–P redrawn after Hutchings and Turvey (1982)Q after Wilson (1985: fig. 1E). Not to scale; maximum widths of chaetal shafts (at articulation) are in the range 0.01–0.03 mm.