Nereis lucipeta Ehlers, 1908

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 : 43-46

Nereis lucipeta Ehlers, 1908 reinstated

Fig. 16

Nereis lucipeta Ehlers, 1908: 69–71 , pl. 8 figs 7–13.

Nereis splendida – Ehlers 1913: 496 (non Grube, 1840).

Nereis falsa – Fauvel 1919: 398 (non de Quatrefages, 1866).

Nereis lucipeta – Hartman 1959: 262 (synonymy).

Nereis (Nereis) falsa – Day 1967: 317, fig. 14.7k–o (non de Quatrefages, 1866).

Diagnosis

Nereis with posterior eyes completely exposed; tentacular belt 2× as long as first chaetiger; tentacular cirri short, reaching chaetiger 3; jaws with 7 denticles; pharyngeal area II with 18–20 paragnaths in crescent-shaped group, areas VII–VIII with 30–46 paragnaths in 2–3 transverse rows; anterior chaetigers with notopodial ligules short, globose; ventral ligules in median and posterior chaetigers markedly longer than neuracicular ligules.

Material examined

Syntypes ANGOLA • many syntypes (fide Hartwich 1993: 114); Big-Fish Bay ; ZMB Verm. 4440 • 2 syntypes; same collection data as for preceding; ZMF 1660 • 2 syntypes; University of Marburg (fide Fiege & Wehe 2004). Not seen .

Other material

MADAGASCAR • 4 specs; “Tuléar” [Toliara]; stn 52; 1906; Mission F. Geay leg.; MNHN 83-52 .

Description (MNHN 83-52)

BODY. Atoke specimens; two complete, and two anterior fragments; complete specimens 18–29 mm long, 0.9–1.4 mm wide, with 64–72 chaetigers; anterior fragments 6–18 mm long, 1.2–2.0 mm wide, with 18–30 chaetigers (largest one broken in two pieces). Body pale, subcylindrical, depressed along posterior region.

PROSTOMIUM. Slightly longer than wide, dorsal groove present ( Fig. 16A–D ). Eyes blackish, of similar size, anterior eyes oval, directed anteroventrally, diameter about ⅙–⅐ of prostomial width, slightly more separated than posterior eyes ( Fig. 16A–D ). Antennae half as long as prostomium, without gap between them, tips surpassing palpophore tips, sometimes reaching palpostyle tips ( Fig. 4C ). Palpophores subconical, 2× as long as wide; palpostyles projected, blunt, slightly longer than wide ( Fig. 16A–D ).

TENTACULAR BELT. 2 × as long as first chaetiger, anterior margin projected anteriorly middorsally, not covering posterior eyes or nuchal organs. Tentacular cirri smooth, barely contracted distally; smallest complete specimen with longest tentacular cirri reaching chaetiger 3 ( Fig. 16A ), in largest complete specimen reaching chaetiger 3.

PHARYNX. Not everted, observed by previous dissection of largest specimen. Jaws brown, with 7 denticles. Paragnath formula: I: 2 in tandem; II: 18–20 in crescent-shaped group; III: 30 in oval group; IV: 28–30 in oval groups; V: 0; VI: 4 in diamond; VII–VIII: 30-46 paragnaths in 2–3 rows (size dependent).

PATTERN OF PARAPODIAL LIGULES. Anterior chaetigers with ligules blunt, slightly longer than wide, becoming blunt subconical to digitiform in median and posterior chaetigers; ventral ligules thinner, 3–4 × as long as wide.

CHAETIGERS 1–2. With neuraciculae only ( Fig. 16E ); with both noto- and neuraciculae thereafter. Dorsal cirrus slightly longer and wider than ventral one, 2 × as long as parapodial ligules. Dorsal ligule longer than wide, blunt, as long as tapered median one. Neuracicular ligule subconical, blunt, as long as wide. Supracicular neurochaetae: barely exposed, 5 homogomph spinigers and 3 heterogomph falcigers with blades spinulose, 5–6× as long as wide, distal tooth incurved, tendons not visible; subacicular neurochaetae: 5 heterogomph spinigers and 6 heterogomph falcigers with blades spinulose, 6–7× as long as wide, distal tooth incurved, tendons not visible.

MEDIAN PARAPODIA ( Fig. 16F ). With dorsal cirrus 2 × as long as dorsal ligule, slightly longer than ventral cirrus. Dorsal ligule as long as wide, subconical, blunt; median ligule rounded; both ligules subequal, 2.5 × as long as neuracicular ligule, with glandular areas unpigmented, extended along ligular bases. Neuracicular ligule subconical, blunt, wider than long; ventral ligule digitiform, slightly longer than wide, 2× as long as neuracicular ligule. Notochaetae 9 heterogomph spinigers. Supracicular neurochaetae: 4 homogomph spinigers and 3 heterogomph falcigers with blades spinulose, 3× as long as wide, distal tooth incurved, tendons barely visible; subacicular neurochaetae: 3 heterogomph spinigers and 7 heterogomph falcigers with blades spinulose, 3–5× as long as wide, distal tooth incurved, tendons barely visible.

POSTERIOR PARAPODIA ( Fig. 16G ). With dorsal and ventral cirri 5–6 × as long as wide, dorsal cirrus about 2 × as long as dorsal ligule, ventral cirrus shorter than ventral ligule. Dorsal and median ligules subequal, blunt, subconical to digitiform, 2 × as long as wide, glandular areas unpigmented, darker along ligular bases. Neuracicular ligule subconical, 2× as wide as long; ventral ligule digitiform, 2 × as long as wide, 2× as long as neuracicular ligule. Notochaetae: 4 homogomph spinigers and 1–2 homogomph falcigers with blades spinulose, 4× as long as wide, tip incurved, tendon visible. Supracicular neurochaetae: 5 homogomph spinigers and 2 heterogomph falcigers with blades spinulose, 2× as long as wide, distal tooth incurved, fused to blade; subacicular neurochaetae: 2 heterogomph spinigers and 3 heterogomph falcigers with blades spinulose, 2× as long as wide, distal tooth incurved, fused to blade.

SUBTERMINAL CHAETIGERS ( Fig. 16H ). With dorsal cirrus 2.3× as long as dorsal ligule, almost 2× as long as ventral cirrus. Dorsal notopodial ligule digitiform, 2.5 × as long as wide, slightly longer than median one; median ligule digitiform, 2× as long as wide, 2× as long as neuracicular ligule. Neuracicular ligule truncate, slightly wider than long; ventral ligule digitiform, 2 × as long as neuracicular ligule. Notochaetae: 3 homogomph spinigers and 1 homogomph falciger, blade spinulose, about 3× as long as wide, distal tooth incurved and fused to blade. Supracicular neurochaetae: 5 homogomph spinigers and 2 heterogomph falcigers with blades spinulose, almost 2× as long as wide, distal tooth incurved, fused to blade; subacicular neurochaetae: 4 heterogomph spinigers and 3 heterogomph falcigers with blades spinulose, 3× as long as wide, distal tooth incurved, fused to blade.

POSTERIOR REGION. Tapered into a blunt cone. Pygidium with anus terminal, anal cirri as long as last 6–8 chaetigers.

Remarks

Nereis lucipeta Ehlers, 1908 was described based on prenatatory male epitokes dredged in Big-Fish Bay, Angola ( Valdivia , stn 76, 16°33′ S, 11°46′ E; 14 m). Ehlers (1913: 496) recorded atoke specimens but regarded this species as a junior synonym of N. splendida Grube, 1840 . This latter record was regarded as a synonym of “ N. falsa ” by Fauvel (1919), after finding it in Madagascar. This same conclusion was followed by Hartman (1959) and Day (1967). However, N. lucipeta must be reinstated.

The main difference between the male epitokes of N. lucipeta and those of N. splendida is in the number of chaetigers in the non-natatory region, as indicated in the key below. In N. lucipeta the anterior region includes 20 chaetigers, whereas in N. splendida , it has 27. An additional difference is in the shape of the prostomium and the size of the palpophores. In N. lucipeta the anterior prostomial region is longer than the posterior, ocular one, and the palpophores are markedly swollen, projected laterally beyond the level of the lateral eyes, whereas in N. splendida the anterior prostomial region is as long as, or shorter than, the posterior ocular one, and the palpophores are not so markedly swollen.

The atokes of what could be regarded as N. lucipeta were briefly characterized by Day (1962: 639), under the name of N. falsa , based on some specimens from Natal, and later he keyed out the atokes and provided an extended diagnosis ( Day 1967: 317). These records are herein regarded as N. lucipeta because of the similarities in parapodial and pharyngeal features, although the anterior end of an atoke has not been illustrated before.

As indicated in the key below, by having short tentacular cirri N. lucipeta resembles N. callaona and N. callaona sensu Augener 1918 from Western Africa. However, typical N. callaona can be separated from the two other species because its jaws only have 4 denticles, whereas the two other species have 6–7 denticles. The main difference between N. lucipeta and N. callaona from Western Africa are in the pharyngeal areas II and III, because N. lucipeta has 18–20 paragnaths in II and about 30 paragnaths in III, whereas N. callaona sensu Augener has 28 paragnaths in II and about 50 in III.

Distribution

From Angola to Madagascar, in shallow water.

Figures

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).

Fig. 4. Nereis splendida Grube, 1840, non-type, largest male epitoke (MNHN A83), after Shirlastain-A staining. A. Anterior region, dorsal view.B. Anterior end, ventral view.C. Chaetiger 2, right parapodium, anterior view. D. Chaetiger 15, right parapodium, anterior view. E. Chaetiger 30, right parapodium, anterior view. F. Chaetiger 74, right parapodium, posterior view (chaetae omitted). G. Posterior region, dorsal view.