Nereis riisei Grube & Örsted

Salazar-Vallejo, Sergio I., León-González, Jesús Angel De & Conde-Vela, Víctor M., 2021, Revision of the species confused with “ Nereis falsa ” de Quatrefages, 1866 (Annelida, Nereididae), European Journal of Taxonomy 779, pp. 1-70 : 28-38

Nereis riisei Grube & Örsted in Grube, 1857

Figs 10–13

Nereis (Nereis) riisei Grube & Örsted in Grube, 1857: 162–163.

Nereis albipes Grube & Müller in Grube, 1874: 60 (groups), 73 (description) syn. nov.

Nereis glandulata Hoagland, 1919: 575 , pl. 30 figs 1–6.

Nereis (Nereis) riisei – Augener 1922: 42; 1925: 6 (redescription). — Monro 1933: 43–44 (synonymy). — Allen 1957: 51–52 (reproduction). — Rullier 1974: 38. – Fauchald 1977b: 31, fig. 8c–e (partim, only Caribbean specimens). — Liñero-Arana & Reyes-Vázquez 1979: 6, pl. 4 figs 1–11. — Taylor 1984: 31.38–31.40, figs 31.35, 31.36a–g. — de León-González et al. 1999: 676. — Salazar-Vallejo & Eibye-Jacobsen 2012: 1396.

Diagnosis

Nereis with posterior eyes completely exposed; tentacular belt 2 × as long as first chaetiger; pharyngeal areas VII–VIII with a single row of large denticles; median and posterior parapodia with ventral ligules surpassing neuracicular ligule tips.

Material examined

Holotype UNITED STATES VIRGIN ISLANDS • atoke; Saint Croix; Kröyer leg.; NHMD 109270 (previously ZMUC POL-1487).

Syntypes of Nereis albipes Grube & Müller in Grube, 1874 BRAZIL • 5 syntypes; “Desterro” [now Santa Catarina Island]; Fr. Müller leg.; ZMB Q3441 .

Holotype of Nereis glandulata Hoagland, 1919

PUERTO RICO • holotype (posteriorly incomplete, 8.5 mm long, 1.2 mm wide at chaetiger 10, 26 chaetigers; pharyngeal formula: I: 1; II:12–14 cones; III: 9 cones; IV: 17–? cones; V: 0; VI: 5–5 cones; VII–VIII: 7); rocks off Guanica Harbor; 1915; AMNH 1211 .

Other material

ANTIGUA AND BARBUDA • 1 spec.; N Antigua; R/V Pillsbury, Cruise 6806, stn 968; 17°18′ N, 61°52′ W; 18 m depth; 20 Jul. 1969; UMML 0000 • 1 spec.; SW Barbuda; R/V Pillsbury, Cruise 6802, stn 975; 17°29′ N, 61°55′ W; 29 m depth; 21 Jul. 1969; UMML 22.1169 .

COLOMBIA • 1 spec.; W San Bernardo Archipelago; 9°46′ N, 76°10′ W; R/V Pillsbury, Cruise 6607, stn 372; 91 m depth; 13 Jul. 1966; UMML 22.1170 .

FRENCH GUIANA • 1 spec.; NE French Guiana; 6°07′ N, 52°19′ W; R/V Pillsbury, Cruise 6806, stn 650; 87 m depth; 8 Jul. 1968; UMML 22.1172 .

HONDURAS • 1 spec.; Omoa Bay ; 15°36′ N, 88°04′ W; R/V Pillsbury, Cruise 7101, stn 1362; 24 m depth; 1 Feb. 1971; UMML 22.1167 .

JAMAICA • 2 specs; S Jamaica; 17°47′ N, 77°41′ W; 28 m depth; R/V Pillsbury, Cruise 7006, stn 1223; 6 Jul. 1970; ECOSUR P3115 .

MEXICAN CARIBBEAN (Smithsonian Breeding Expedition) • 23 specs; Ascension Bay , Nicchehabin Reef , behind center of reef, E of Allen Point; stn 52-60; 10 Apr. 1960; E.L. Bousfield and H.A. Rehder leg.; USNM 174874 • 19 specs; Ascension Bay, Central Nicchehabin Reef ; stn 67-60; 13 Apr. 1960; E.L. Bousfield and H.A. Rehder leg.; USNM 174835 • 46 specs; behind central part of Nicchehabin Reef; stn 72-60; 14 Apr. 1960; E.L. Bousfield and H.A. Rehder leg.; USNM 174836 • 5 specs; N end of Ascension Bay, shore just E of Halfway Point, turtle grass flats off point to sandy beach and mangrove roots; stn 77-60; 15 Apr. 1960; E.L. Bousfield and H.A. Rehder leg.; USNM 174837 • 9 specs; behind central part of Nicchehabin Reef; stn 82-60; 16 Apr. 1960; W.L. Schmitt, E.L. Bousfield and H.A. Rehder leg.; USNM 174838 • 1 spec.; Ascension Bay , mangrove inlet behind Allen Point Light; stn 83-60; 16 April 1960; USNM 174839 • 1 spec.; Ascencion Bay , 180–270 m off SW of Suliman Point; stn 87-60; 17 Apr. 1960; E.L. Bousfield, F.C. Daiber and H.A. Rehder leg.; USNM 174840 • 1 spec.; Nicchehabin Reef; stn 91-60; 18 Apr. 1960; USNM 174841 • 10 specs; Ascension Bay , Suliman Point to 270 m to SW shore, reef flats and sand flats; stn 95-60; 19 Apr. 1960; W.L. Schmitt, F.C. Daiber, E.L. Bousfield, J.F. Clarke, H.A. Rehder, Haynes and Harvey leg.; USNM 174842 • 3 specs; S end of Cozumel Island, N of Santa Maria Point, shore and sand; stn 100-60; 21 Apr. 1960; H.A Rehder, E.L. Bousfield and F.C. Daiber leg.; USNM 174843 • 1 spec.; Cozumel Island , San Miguel , along shore 400 m NE of pier, in front of barracks (military reservation); stn 118-60; 30 Apr. 1960; W.L. Schmitt and H.A. Rehder leg.; USNM 174844 .

MEXICO – Veracruz • 3 specs; La Gallega Reef; M.L. Chavez leg.; ICMyL • 1 spec.; La Gallega Reef ; May 1957; 3 Jun. 1979; B. Galván leg.; ICMyL • 3 specs; La Gallega Reef ; 14 Nov. 1992; J.A. de León- González leg; UANL 8145 . – Campeche • 1 spec.; Perez Island ; 18 Apr. 1955; F. Bonet leg.; ICMyL • 1 spec.; Bonita Beach, Playa del Carmen ; 28 May 1957; M.E. Caso leg.; ICMyL • 1 spec.; Bahamita Beach; 1 Aug. 1972; M.E. Caso leg.; ICMyL . – Quintana Roo • 1 atoke; Punta Allen, Bahía Ascensión ; sponge on wood pole, intertidal; 11 Jun. 1986; E. Donath leg.; ECOSUR P1114 • 2 specs; Punta Allen, Bahía Ascensión ; 11 Jun. 1986; E. Donath leg.; ECOSUR P1126 • 1 atoke; Xcacel ; coral stone; 1 m depth; 3 Apr. 1992; SI Salazar-Vallejo leg.; ECOSUR P1130 • 3 specs; Playa Aventuras ; coral rock; 1 m depth; 22 Mar. 1992; SISV leg.; ECOSUR P1131 • 2 specs; Banco Chinchorro ; 3 Oct. 1983; ECOSUR P1134 • 2 spec.; Xahyayxol ; coral rock; 2 m depth; 26 Sep. 1996; L.F. Carrera-Parra and SISV leg.; ECOSUR P1138 • 5 specs; Buenavista, Xahuayxol ; coral rock; 2 m depth; 27 Sep. 1996; L.F. Carrera- Parra and SISV leg.; ECOSUR P1139 • 1 spec.; E Arrowsmith Bank; 21°04′ N, 86°19′ W; R/V Gerda , Cruise 6717, stn 898; 352 m depth; 10 Sep. 1967; ECOSUR P3123 • 1 spec.; Arrowsmith Bank ; 21°06′ N, 86°28′ W; R/V Pillsbury, Cruise 7028, stn 1286; 280 m depth; 23 Aug. 1970; UMML 22.1166 .

PANAMA • 2 specs; Manzanillo Bay ; 9°21′ N, 79°57′ W; 0 m depth; R/V Pillsbury, Cruise 6607, stn 321; 5 Jul. 1966; UMML 22.1171 .

SAINT KITTS AND NEVIS • 2 specs; NW of Saint Christopher; 17°27′ N, 62°54′ W; R/V Pillsbury, Cruise 6907, stn 960; 32 m depth; 19 Jul. 1969; ECOSUR P3116 .

UNITED STATES • 1 spec.; E Gulf of Mexico; 25°05′ N, 86°28′ W; R/V Gerda , Cruise 6717, stn 887; 97 m depth; 9 Sep. 1967; ECOSUR P3114 .

VENEZUELA • 1 atoke (broken in two fragments, used for variation); Isla Margarita , Islote Los Frailes; in seagrasses; 7 Jun. 1961; ECOSUR P2256 .

Description

Holotype of Nereis riisei ( NHMD 109270 )

BODY. Atoke, incomplete posteriorly, 70 mm long, 3.5 mm wide including parapodia, 88 chaetigers. Body pale, median parapodia with dark red glands in dorsal, median and ventral ligules, posterior parapodia with glandular areas only in dorsal and median ligules.

PROSTOMIUM. Pyriform, longer than wide, dorsal groove present. Eyes in trapezoidal arrangement, anterior ones small, rounded, with lens, posterior ones oval, with lens. Antennae thin, terminal, with a small gap between them ( Fig. 10A ). Palpophores globose, directed downward, 3× as long as wide, palpostyles rounded.

TENTACULAR BELT. 2× as long as first chaetiger, anterior margin not covering posterior eyes. Tentacular cirri smooth, longest pair reaching anterior margin of chaetiger 2 ( Fig. 10A ).

PHARYNX. Previously removed, now lost.

PATTERN OF PARAPODIAL LIGULES. Anterior chaetigers with dorsal ligules tapered, blunt, median ligules rounded; median and posterior chaetigers with ligules subconical. Ligules with contorted glandular tubules.

CHAETIGERS 1–2. With neuraciculae only, with both noto- and neuraciculae thereafter.

ANTERIOR PARAPODIA ( Fig. 10B ). With dorsal cirrus 1.5× as long as ventral one, basally inserted ( Fig. 10B ); dorsal ligule subconical, blunt, as long as median ligule; median ligule triangular, blunt, 2× as long as neuracicular ligule; prechaetal lobe absent. Neuracicular ligule subconical, 1.5 × as long as ventral ligule; postchaetal lobe subconical, shorter than neuracicular ligule; ventral ligule subconical, 1.5 × as long as ventral cirrus. Notochaetae 15 homogomph spinigers. Supracicular neurochaetae: 14 homogomph spinigers and 5 heterogomph falcigers with blades 5.6 × as long as wide, slightly denticulate, with apical tooth incurved, fused to blade; subacicular neurochaetae: 26 heterogomph spinigers, blades 35 × as long as wide and 8 other heterogomph spinigers with blades 9× as long as wide, heterogomph falcigers absent.

MEDIAN PARAPODIA ( Fig. 10C ). With dorsal cirrus thin, 3× as long as ventral ones; dorsal and median ligules subequal, subconical, 1.5× as long as neuracicular ligule, dorsal one 2× as wide as medial one; prechaetal lobe absent. Neuracicular ligule subconical, as long as ventral ligule; postchaetal lobe subconical, shorter than neuracicular ligule; ventral ligule subconical, 4× as long as ventral cirrus. Notochaetae: 6 homogomph spinigers and 2 homogomph falcigers with blades 6.5× as long as wide, teeth minute, distal thin tooth incurved. Supracicular neurochaetae: 14 homogomph spinigers and 2 heterogomph falcigers with blades 6.2× as long as wide, several long teeth, distal thin tooth incurved; subacicular neurochaetae: 4 heterogomph spinigers and 4 heterogomph falcigers with blades 4 × as long as wide, several long teeth, distal thin tooth incurved.

POSTERIOR PARAPODIA ( Fig. 10D ). With dorsal cirrus about 2 × as long as ventral one; dorsal and median ligules subconical, subequal, 2 × as long as neuracicular ligule, dorsal one 1.5× as wide as medial one. Neuracicular ligule subconical; ventral ligule digitiform, 2× as long as neuracicular ligule, 4× as long as ventral cirrus. Notochaetae: homogomph spinigers and 2 homogomph falcigers, blades 5.8× as long as wide, similar in shape to those of median parapodia ( Fig. 10G ). Supracicular neurochaetae: 5 homogomph spinigers and 2 heterogomph falcigers, blades 5× as long as wide, both chaetae similar in shape to those of median parapodia ( Fig. 10F ); subacicular neurochaetae: 3 heterogomph spinigers and 5 heterogomph falcigers, 5.8× as long as wide, both chaetae resembling those of median parapodia ( Fig. 10H ).

POSTERIOR REGION. Unknown. Pygidium unknown.

Holotype of Nereis glandulata (AMNH 1211)

The holotype of Nereis glandulata Hoagland, 1919 ( Fig. 11A ) consists of an anterior fragment 8.5 mm long, 1.2 mm wide at chaetiger 10, with 26 chaetigers; a posterior end of a non - nereidid polychaete was found in the same vial. The tentacular belt is projected anteriorly middorsally ( Fig. 11B ). The pharynx was previously dissected, and is damaged, with the following paragnath formula: I: 1; II:12–14; III: 9; IV: 17; V: 0; VI: 5–5; VII–VIII:? (5–7 fide Hoagland 1919). Hoagland (1919) described notopodial and supracicular neuropodial heterogomph spinigers, but they were not found in the holotype. First two chaetigers with parapodia only with neuraciculae ( Fig. 11C ), dorsal and ventral cirri conical, of similar length; ventral ligules blunt conical, with large brownish glands, dorsal ligule more pigmented than ventral one. Anterior chaetigers with noto- and neuraciculae ( Fig. 11D ); notopodial fascicle with spinigers with blades of varying length; neurochaetae with supracicular and subacicular fascicles with spinigers and heterogomph falcigers ( Fig. 11E–F ). The size of the eyes and antennae, the length of the tentacular cirri, the paragnath formula, and the shape of both parapodia and chaetae, agree with those of N. riisei , so the synonymy proposed by Monro (1933) is maintained.

Atokes

BODY.Atoke specimen (ECOSUR P2256) from Venezuela:with body soft, pale ( Fig. 12A ), subcylindrical, depressed in posterior region; complete, 101 mm long (43 + 58 mm), 6 mm wide, with 187 chaetigers (66+121). Pre-epitokal specimen (UMML 22.1171) from Panama: body pale, muscle being replaced by irregular undifferentiated gonads throughout body ( Fig. 13A–B ); complete, 65 mm long, 2.5 mm wide, with 123 chaetigers.

PROSTOMIUM. Slightly longer than wide, dorsal groove present. Eyes black ( Fig. 12A–B ), larger in preepitoke ( Fig. 16A ), or reddish, of similar size, anterior eyes oval, directed anteroventrally, about ⅒ of prostomial width, slightly more separated than posterior eyes. Antennae terminal, without gap between them, tips surpassing tips of palpophores, not surpassing palpostyles, half as long as prostomium. Palpophores conical, truncate, 2 × as long as wide; left palpostyle longer than wide, right one as long as wide.

TENTACULAR BELT. 2× as long as chaetiger 1; anterior margin projected anteriorly middorsally, not covering posterior eyes or nuchal organs. Tentacular cirri regularly corrugated, twisted over anterior end; longest tentacular cirri reach chaetigers 4 or 5 ( Figs 12A–B , 13A ).

PHARYNX. Not exposed, observed by dissection. Jaws brown, with 7–8 teeth. Paragnath formula (ECOSUR P2256): I: 1; II: 16–17 in rows; III: 20; IV: 28–30; V: 0; VI: 8–9; VII–VIII: 3 in a single band. Paragnath formula (UMML 22.1171): I: 4; II: 7–11; III: 9; IV: 10–12 cones; V: 0; VI: 3–3; VII–VIII: 3 in a single band.

PATTERN OF PARAPODIAL LIGULES. On first few chaetigers, as well as on medial and posterior ones, with ligules tapered, blunt, about 2× as long as wide, with massive dark glands, projected beyond ligular bases; anterior chaetigers with ligules massive, shorter, slightly tapered. First chaetigers with ligules granulose or verrucose, in a small area, progressively larger in anterior chaetigers, but missing in medial and posterior chaetigers. Glandular masses leave apical ligular spaces empty in medial and posterior chaetigers.

CHAETIGERS 1–2. With neuraciculae only ( Figs 12C , 13C ), with both noto- and neuraciculae thereafter. Dorsal cirrus longer and slightly wider than ventral one, longer than parapodial ligules. Dorsal ligule about 2× as long as wide, as long as ventral one, both blunt. Neuracicular ligule slightly longer than wide, projected into a small acicular lobe. Supracicular neurachaetae: 10 homogomph spinigers and 2 heterogomph falcigers with blades spinulose, 6–7× as long as wide, tips incurved, tendon well defined;

subacicular neurochaetae: 8 heterogomph spinigers and 5 heterogomph falcigers with blades spinulose, 8–9 × as long as wide, tips incurved, tendons well defined.

ANTERIOR CHAETIGERS ( Figs 12D , 13D ). With ligules massive, integument verrucose. Dorsal cirrus tapered, about 2 × as long as ventral one. Dorsal and median ligules subconical, blunt, as long as wide, dorsal one wider. Neuracicular ligule subconical, about 2× as long as wide, slightly projected into an acicular lobe, as long as postchaetal one; postchaetal lobe digitiform; ventral ligule digitiform, as long as neuracicular one. Notochaetae 9 homogomph spinigers. Supracicular neurochaetae: 10 homogomph spinigers and 4 large heterogomph falcigers with blades spinulose, 3× as long as wide, tips incurved, tendons well defined; subacicular neurochaetae: 5 heterogomph spinigers and 8 heterogomph falcigers with blades spinulose, 5–6 × as long as wide, tips incurved, tendons well defined.

POSTERIOR CHAETIGERS ( Figs 12E , 13E–F ). With dorsal and ventral cirri 5–7 × as long as wide, dorsal cirrus 1.5× as long as dorsal ligule. Dorsal and median ligules digitate to subconical, blunt, slightly longer than wide or 2× as long as wide; glandular areas not invading central apical regions. Neuracicular ligule subconical, about 2 × as long as wide, with a small acicular lobe, as long as ventral ligule or slightly longer. Notochaetae: 2 homogomph spinigers and 1 homogomph falciger with blade spinulose, 3 × as long as wide, tip incurved, tendon well defined. Supracicular neurochaetae: 12 homogomph spinigers ( Fig. 13I ) and 2 large heterogomph falcigers with blades spinulose, 2× as long as wide, tips incurved, tendons well defined ( Fig. 13K ); subacicular neurochaetae: 4 homogomph spinigers ( Fig. 12J ) and 4 heterogomph falcigers with blades spinulose, 3–4 × as long as wide, tips incurved, tendons well defined.

SUBTERMINAL CHAETIGERS. With dorsal cirrus 2× as long as dorsal ligules ( Figs 12F , 13G ). Dorsal ligule subconical, tapered, slightly longer than wide, as long as digititiform ventral ligule; central apical regions without glands. Neuracicular ligule subconical, tapered, slightly longer than wide; postchaetal lobe absent; ventral ligule digitate, basally swollen, glands barely visible, 1.5× as long as neuracicular ligule. Notochaetae: 1 homogomph spiniger and 2 homogomph falcigers with blades spinulose, 3 × as long as wide, tips incurved, tendon well developed. Supracicular neurochaetae: 2 homogomph spinigers and 1 large heterogomph falciger with blade spinulose, about 2× as long as wide, tip incurved, tendon well developed; subacicular neurochaetae: 2 homogomph spinigers and 3 heterogomph falcigers with blades spinulose, about 2× as long as wide, tips incurved, tendons well defined.

POSTERIOR REGION. Tapered into a blunt cone ( Figs 12G , 13B ). Pygidium truncate, anus terminal, anal cirri as long as last 12 chaetigers.

VARIATION. Some specimens from Quintana Roo, Mexico show some variatons in their paragnath formula and a tendency for it to change with body size. I: 1–4 (increasing with size); II: 12–24 (more or less stable); III: 20–36 (decreasing with size); IV: 33–40 (more or less stable); V: 0 (unchanged); VI: 4–18 (decreasing with size); VII–VIII: 3–7 in a row (decreasing with size).

Remarks

Salazar-Vallejo & Eibye-Jacobsen (2012) incorrectly indicated Puntarenas, Costa Rica (Pacific Ocean) as the type locality of Nereis riisei . Rather, St Croix is the correct type locality as indicated both in the description ( Grube 1857: 163) and the index for the series ( Grube 1858: 119). The label in the holotype material deposited in NHMD indicates that the type locality is St Croix and the collector was Kröyer (Danny Eibye-Jacobsen, pers. comm.).

Although it is a relatively easy species to identify, Nereis riisei has a largely confused taxonomic history and has been widely reported for both coasts of America in temperate to tropical waters. It is likely that the confusion regarding the type locality has given this species its current amphiamerican status. The first amphiamerican report was made by Monro (1933), synonymizing several species with N. riisei , and Hartman followed this conclusion in subsequent papers ( Hartman 1938, 1940, 1944, 1954). This decision has been widely followed, except for some species such as N. glandulata Hoagland, 1919 (e.g., Treadwell 1924, 1928). We disagree and regard N. ambigua Treadwell, 1937 as a distinct species (see below).

Day (1973) and Gardiner (1976) recorded Nereis (Nereis) riisei from North Carolina, but their specimens differ from Caribbean ones by having tentacular cirri reaching chaetiger 6, ventral ligules as long as neuracicular ligules in posterior chaetigers, and notopodial homogomph falcigers with longer blades. Furthermore, Day (1973) described the dorsal cirri of anterior parapodia as being 3× as long as dorsal ligules and the dorsal ligules as half as long as median ones, subconical instead of rounded.

On the other hand, N. riisei resembles N. ambigua Treadwell, 1937 by having the posterior eyes completely exposed and pharyngeal areas VII–VIII with a single row of paragnaths (the latter characterized in Dean 2001). These two species differ because in N. riisei the ventral ligules in median and posterior parapodia surpass the neuracicular ligules, and fresh specimens have a blackish tentacular belt, whereas in N. ambigua the ventral ligules reach the neuracicular ligule tips in median and posterior parapodia, and fresh specimens have a pale tentacular belt. However, these differences must be taken as preliminary pending the collection of topotype specimens of N. ambigua and confirming these diagnostic features.

Nereis (Nereis) puncturata Grube & Örsted in Grube, 1857 was described based on specimens from two distinct localities. Salazar-Vallejo & Eibye-Jacobsen (2012) located the type material in two museums: a specimen from St Croix is deposited in the Natural History Museum of Denmark (NHMD), while specimens from Valparaiso are deposited in the Zoological Museum, Berlin (ZMB 4040). Grube did not include type localities in the descriptions. but included them for the index to species ( Grube 1858). One syntype of N. puncturata (NHMD 109269, previously ZMUC POL-1486) was studied and within it a label by Kröyer was found indicating that this species is similar to N. riisei ; the syntype is in poor condition, the body being crystallized, but morphological characters could be observed that place it closer to Platynereis dumerilii (Audouin & Milne Edwards, 1833) . The species requires the proposition of lectotypes to separate the Atlantic from the Pacific forms.

The syntypes of Nereis albipes (ZMB Q3441) are similar to N. riisei , and they are herein regarded as snynonyms. This southern Brazilian species has the same pattern of black glandular spots in the parapodial ligules; however, a slight variation is observed in the paragnath formula: I: 1; II: 11– 20 in two rows; III: 11–23 in oval group; IV: 18–28 in a crescent-shaped patch; V: 0; VI: 4–10 in a rounded patch; VII–VIII: 5 in a single band. Incidentally, this species name was indicated, on the same page ( Grube 1874: 60), as “ N. albipes Gr. ” and 20 lines below as “ albipes Gr. Müll. ” We are following the latter because Fritz Müller provided some identifications to the specimens sent to Grube.

Other species have been referred to as synonyms of N. riisei , but the material needed to corroborate their status were not examined. These species deserve to be studied in further detail to clarify their affinities, but that is beyond our objectives for this contribution. The species are the following ones (in chronological order):

Heteronereis fasciata Schmarda, 1861 . Schmarda (1861) described this species based on epitokes from Jamaica, preventing an adequate comparison with atoke specimens of N. riisei . Augener (1925) revised the type material and based upon the paragnaths on pharyngeal areas VII–VIII and the chaetae, he concluded that it was identical to N. riisei . Diagnostic features include jaws with five teeth, areas VII– VIII with few paragnaths in one band, neuropodial heterogomph falcigers with short blades and natatory region starting at chaetiger 22–23. Several specimens of this species (with labels V900 and V901), supposed to be the type material observed by Augener, are deposited at the Natural History Museum in Vienna (H. Sattmann, pers. comm.).

Nereis nigripes Ehlers, 1868 . Ehlers (1868) described this species based on specimens from Haiti and Florida. Augener (1925) regarded N. nigripes as identical to N. riisei , and Monro (1933) synonymized it with N. riisei without further explanation. Hartman (1938), based on Monro’s decision, synonymized this species and N. bicruciata Augener, 1906 (see below) with N. riisei . The database of the Museum of Comparative Zoology (Harvard University, Cambridge, MA) indicates they have the specimen from Haiti (ANNa-54). Ehlers (1868) detailed the following paragnath formula: I: irregular patch; II: arc patch; III: transverse patch; IV: arc patch; V: 0; VI: 8–13; VII–VIII: 5. Based on the original description, N. nigripes differs from N. riisei by having the antennae as long as the prostomium, tentacular cirri reaching chaetiger 9 and dorsal ligules longer than median ones in posterior chaetigers.

Nereis (Lycoris) trifasciata Grube, 1878 . Grube (1878) described this species from Bohol, Philippines. He provided the following paragnath formula: I: 0; II: 11 in two rows; III: 8 in two rows; IV: 15 in two rows; V: 0 or 1; VI: 5–6; VII–VIII: a single band. The original description is succinct and prevents any further comparison between N. trifasciata and N. riisei . Monro (1933) regarded this species as a synonym of N. riisei without further explanation, but this conclusion must be evaluated based upon topotype specimens because of the different type localities for these species. The species was transferred to Neanthes Kinberg, 1865 by Villalobos-Guerrero & Idris (2021).

Nereis lata Hansen, 1882 . Hansen (1882) described this species based on one specimen from Rio de Janeiro, Brazil. Augener (1934) concluded that this species must be regarded as a synonym of N. riisei because of the presence of ligules with dark glands in middle and posterior chaetigers and the presence in pharyngeal areas VII–VIII of 4 paragnaths in a single band. The original description and Augener’s redescription were very short, preventing further comparisons with N. riisei . Records of Nereis sp. by Nonato & Luna (1970) and of N. riisei by Santos & Lana (2003) might belong to N. lata if they are shown to be different from N. riisei .

Nereis scolopendroides Hansen, 1882 . This species was also described based on specimens from Rio de Janeiro ( Hansen 1882). According to Augener (1934), the type material contains two species, one of them very similar to N. lata and therefore, in his opinion, probably conspecific with N. riisei . Augener (1934) detailed the following paragnaths in the oral pharyngeal ring: V: 0; VI: 11–15; VII–VIII: 4 in a single band. Based on the original description, N. scolopendroides differs from N. riisei by having shorter antennae, dorsal and median ligules shorter than neuracicular ligules and heterogomph falcigers with shorter blades.

Nereis unifasciata Willey, 1905 . Willey (1905) described this species from Sri Lanka (formerly Ceylon) and provided the following paragnath formula: I–IV: unknown; V: 0; VI: small patch; VII–VIII: a single band. Fauvel (1919) thought that this species differed from N. trifasciata only in its pigmentation. Monro (1933) regarded N. unifasciata as a synonym of N. riisei without further explanation. Based on the original description, N. unifasciata differs from N. riisei by having tentacular cirri reaching chaetiger 7 and lacking notopodial homogomph falcigers. This explains why Day (1967: 318) regarded it as belonging in Neanthes . Pamungkas & Glasby (2015) provided an account of this species.

Nereis bicruciata Augener, 1906 species inquirenda. Augener (1906) described this species based on an incomplete specimen from St Croix, Virgin Islands, dredged from sediments at a depth of 210 m. Hartman (1938) examined the type specimen and determined that N. bicruciata and N. nigripes Ehlers, 1868 were synonyms of N. riisei , although she identified some differences in jaw dentition and paragnath numbers. The type material was supposedly deposited in the Museum of Comparative Zoology, Harvard University (MCZ ANNc-2277) but has been lost since 1983, requiring the proposal of a neotype. Augener (1906) detailed the following paragnath formula: 1: 1; II: several rows; III: 7; IV: triangular patch; V: 0; VI: 4–5; VII–VIII: 3 in a single band. Based on the original description, N. bicruciata differs from N. riisei by having tentacular cirri reaching chaetigers 10–11 and fewer paragnaths in pharyngeal area III.

Nereis decora Treadwell, 1932 . Hartman (1938: 14; 1956: 255) synonymized this species from Ilha de São Sebastião, Brazil, with N. riisei , but made no comments about this decision. Treadwell (1932) detailed the following paragnath formula: I: 1; II: about 15 in two rows; III: oblong patch; IV: oval patch smaller than in III; V: 0; VI: 6–8; VII–VIII: 4–5 in a single band. Based on the original description, N. decora differs from N. riisei mainly by having antennae as long as the prostomium and tentacular cirri reaching chaetiger 7, while the parapodia are very similar in both species.

Neanthes varia Treadwell, 1941 (replacement name for Nereis (Neanthes) paucidentata Treadwell, 1939 ). Hartman (1956) synonymized this species with N. riisei , notwithstanding the fact that she detailed clear differences between them, such as the presence in N. varia of paragnaths in area V, a single paragnath in areas VI and two rows of paragnaths in areas VII–VIII. Moreover, in the middle parapodia of N. varia , the dorsal cirri are half as long as the dorsal ligules, and the dorsal ligules are 2× as long as the median ligules; in N. riisei , the dorsal cirri are longer than the dorsal ligules, and the dorsal and median ligules are subequal. Finally, notopodial homogomph falcigers were not noticed for N. varia . All these mentioned features are enough to separate it from N. riisei .

Distribution

Western Atlantic from North Carolina ( USA) to Florianópolis (Desterro), Brazil.

Figures

Fig. 10. Nereis riisei Grube & Örsted in Grube, 1857, holotype (NHMD 109270). A. Anterior end, dorsal view. B. Chaetiger 10, right parapodium, anterior view. C. Chaetiger 40, right parapodium, anterior view. D. Chaetiger 60, right parapodium, anterior view. E. Chaetiger 10, heterogomph falcigers. F. Chaetiger 40, heterogomph spiniger. G. Chaetiger 60, homogomph falciger, tip slightly eroded. H. Chaetiger 60, heterogomph falciger.

Fig. 11. Nereis riisei Grube & Örsted in Grube, 1857, holotype of Nereis glandulata Hoagland, 1919 (AMNH 1211). A. Anterior fragment, dorsal view. B. Anterior end, dorsal view. C. Chaetiger 2, right parapodium, anterior view. D. Chaetiger 9, right parapodium, anterior view. E. Same, neuropodial supracicular heterogomph falciger. F. Same, neuropodial subacicular heterogomph falciger.

Fig. 12. Nereis riisei Grube & Örsted in Grube, 1857, non-type specimen (ECOSUR P2256). A. Anterior region, dorsal view. B. Anterior end, dorsal view. C. Chaetiger 2, left parapodium, anterior view. D. Chaetiger 30, left parapodium, anterior view. E. Chaetiger 90, left parapodium, anterior view. F. Chaetiger 168, left parapodium, anterior view. G. Posterior region, dorsal view, after Shirlastain-A staining.

Fig. 13. Nereis riisei Grube & Örsted in Grube, 1857, non-type, pre-epitokal specimen (UMML 22.1171). A. Anterior region, dorsal view. B. Posterior end, dorsal view. C. Chaetiger 1, right parapodium, anterior view. D. Chaetiger 11, right parapodium, anterior view. E. Chaetiger 49, right parapodium, anterior view. F. Chaetiger 88, right parapodium, anterior view. G. Chaetiger 113, right parapodium, anterior view. H. Chaetiger 88, notopodial homogomph falciger. I. Same, neuropodial supracicular homogomph spiniger. J. Same, neuropodial subacicular heterogomph falciger. K. Same, neuropodial supracicular heterogomph falciger.

Fig. 16. Nereis lucipeta Ehlers, 1908, reinstated, non-type specimens (MNHN 83-52), anterior region in dorsal view. A. 0.9 mm wide. B. 1.2 mm wide, after Shirlastain-A staining. C. 1.4 mm wide, after methyl green. D. 2.0 mm wide. E. Largest fragment, chaetiger 2, right parapodium, anterior view. F. Same, chaetiger 15, right parapodium, anterior view. G. Same, chaetiger 28, right parapodium. H. Complete specimen, chaetiger 65, left parapodium, anterior view (inset: homogomph falciger).