Neanthes galetae Fauchald, 1977

Villalobos-Guerrero, Tulio F., Kara, Jyothi & Idris, Izwandy, 2021, Redescriptions of Neanthes Kinberg, 1865 (Annelida: Errantia: Nereididae) species from worldwide regions, European Journal of Taxonomy 760 (1), pp. 101-135 : 109-114

Neanthes galetae Fauchald, 1977

Fig. 2

Neanthes galetae Fauchald, 1977: 26–27 , fig. 6a–b [type locality: Galeta Island, Colón, Panama].

Neanthes galetae – Wilson 1984: 225 (species list, group IIB). — de León-González et al. 2020: 19 (key). — Villalobos-Guerrero & Idris 2021: 559 (table 1), 561 (table 2).

Type material

Holotype PANAMA • atokous; Caribbean Sea , Colón, Canal Zone, Galeta Island Reef ; 23 Oct. 1970; Smithsonian Tropical Research Institute and A.A. Reimer leg.; intertidal, Laurencia or Acanthophora zones; USNM 53088 .

Paratypes PANAMA • 2 atokous; same collection data as for holotype; USNM 53089 • 1 atokous; same collection data as for holotype; 9°24′18″ N, 79°51′48.5″ W; Laurencia zone; LACM-AHF Poly 1132 .

Description

COLOUR AND MEASUREMENTS. Holotype atokous, complete, in good condition, 7 (9–14) mm TL, 2.4 (2.5– 4) mm L15, 0.6 (0.6–0.9) mm W15, with 52 (56–58) chaetigers. Body colour yellowish, with greyish pigmentation on distal half of prostomium, cirrophores of anal cirri, and present throughout dorsally and ventrally as a transverse, thin line in anterior margin of segments ( Fig. 2A–B ).

PROSTOMIUM. Pear-shaped, as long as wide ( Fig. 2B ); anterior end narrow, distally complete; anterolateral gap beside palpophore narrow, three-quarters as wide as antennal diameter; dorsal groove distinct, shallow, running mid-subdistally. Nuchal organs deeply embedded.

PALPOPHORES. Ovoid, 1.6 times wider than long ( Fig. 2B ), as long as half of entire prostomium; with inconspicuous sub-distal transverse groove. Palpostyles ovoid, thick, with diameter as wide as half of palpophore ( Fig. 2B ).

ANTENNAE. Tapered, slender, short, extending forwards to tip of palpophore ( Fig. 2B ) and posteriorly to one-third length of prostomium; antennae close together, with gap one-quarter as wide as basal diameter of antennae.

EYES. Paired eyes blackish, arranged in a trapezoid form; gap between both pairs one-quarter as wide as diameter of posterior pair of eyes ( Fig. 2B ); anterior pair of eyes rounded, twice as wide as basal diameter of antennae, gap between both eyes 2.5 times as wide as diameter of eyes, with lens distinct, purplish, covering 30% of eye; posterior pair of eyes rounded, twice as wide as basal diameter of antennae, with lens distinct, purplish, placed posterolaterally on eye and covering 40% of it.

APODOUS ANTERIOR SEGMENT. Segment 2.5 times wider than long, as long as chaetiger 1, with flattening anterior margin, dorsum without marked transverse wrinkle ( Fig. 2B ).

TENTACULAR CIRRI. Slender, multi-articulated ( Fig. 2B ); postero-dorsal cirri extending posteriorly to chaetiger 4 (3), 1.6 times as long as antero-dorsal cirri; antero-dorsal cirri extending posteriorly to between chaetigers 1 and 2 (1–2); postero-ventral cirri extended over half of prostomium; antero-ventral cirri 1.5 times as long as postero-ventral cirri and extending beyond 1.3 times length of palpophore; dorsal cirrophores cylindrical, ventral cirrophores ring-shaped, postero-dorsal cirrophores 1.5 times as long as antero-dorsal cirrophores, antero-ventral cirrophores 1.5 times as wide as postero-ventral cirrophores.

PHARYNX. Non-everted, previously dissected. Jaws with distal quarter brownish, remaining yellow amber, 10 well-developed and sharp denticles; pulp cavity with two canals ( Fig. 2C–D , paratype). Reddish-brown paragnaths on maxillary and oral rings ( Fig. 2C ), consisting of conical, p-bars, and merged paragnaths; plate-like basements absent. Area I: 0 (0–1) ( Fig. 2C ); areas IIa: 9 (9–12) and IIb: 9 (8–14), two slightly regular rows of uneven cones in eyebrow-shaped patch, cones in outer row larger ( Fig. 2C ); area III: unknown but one paratype with 12 (5–12) paragnaths in two slightly regular rows of uneven cones in rectangular patch, without distinct laterally-isolated cones, distal row with larger cones; areas IVa: 11 (13–14) and IVb: 13 (11–17), crescent-shaped patch with two slightly regular transverse rows of uneven cones located proximally and four long and slender merged paragnaths (2–4 times longer than wide; Fig. 2C ) located distally; area V: 0 (0) ( Fig. 2C ); areas VIa: 9 (9–11) and VIb: 9 (9–10), one rounded patch of uneven cones, closely together ( Fig. 2C ); areas VII–VIII: 5 (13–15), one band of uneven cones consisting of two transversely aligned rows ( Fig. 2C ). Areas VI–V–VI ridge pattern, π- shaped ( Fig. 2C ). Gap between area VI and areas VII–VIII narrow, as wide as palpostyle.

PAIRED OESOPHAGEAL CAECA. Present.

PARAPODIA. With one massive, dorsal, sub-spherical gland present from chaetiger 13 towards posterior end, becoming larger, reaching maximum size from chaetiger 36 ( Fig. 2A, H–I ). Notopodia consisting of dorsal cirrus, dorsal ligule (distal and proximal), and median ligule in biramous parapodia; notopodial prechaetal lobe absent throughout but as notoacicular process in some parapodia. Neuropodia consisting of neuroacicular ligule, ventral ligule, and ventral cirrus; lobes absent throughout.

DORSAL CIRRI. Cirriform, thick, medium-sized, extending beyond distal region of dorsal ligule throughout ( Fig. 2E, I ); dorsal cirri 3–3.5 times as long as proximal region of dorsal ligule in anteriormost and posteriormost parapodia ( Fig. 2E, I ), 2–2.5 times as long as in remaining parapodia ( Fig. 2F–H ); attached basally to dorsal ligule in anteriormost parapodia ( Fig. 2E ), medially in following parapodia ( Fig. 2F–I ).

DORSAL LIGULE. Proximal region even towards posterior end, except faintly humped in middle and posterior parapodia ( Fig. 2H–I ); shorter than distal region of dorsal ligule in anteriormost parapodia ( Fig. 2E ), as long as that in following parapodia ( Fig. 2F–I ); two irregular glandular patches covering partially proximal region of dorsal ligule in anterior parapodia and entirely covering that in following parapodia ( Fig. 2G–I ). Distal region well developed, becoming narrower towards posterior end; digitiform in anteriormost parapodia ( Fig. 2E ), bluntly rounded in anterior parapodia ( Fig. 2F ), conical in following parapodia ( Fig. 2G–I ), slightly smaller than median ligule throughout; projecting beyond notoacicula throughout; one irregular glandular patch covering entire distal region of dorsal ligule ( Fig. 2F–I ).

NOTOACICULAR PROCESS. Present from parapodia 5 to parapodia 20 ( Fig. 2F–G ), small, blunt.

MEDIAN LIGULE. Digitiform in anteriormost parapodia, bluntly rounded in anterior parapodia ( Fig. 2F ), conical in following parapodia ( Fig. 2G–I ), becoming narrower from middle parapodia towards posterior end.

NEUROACICULAR LIGULE. Smaller than ventral ligule in anteriormost parapodia ( Fig. 2E ), as long as in following parapodia ( Fig. 2F–I ), 1.5 times as wide as ventral ligule throughout.

VENTRAL LIGULE. Well developed throughout; bluntly conical, thick in anteriormost and anterior parapodia ( Fig. 2E–F ), conical and slender in following chaetigers; smaller than median ligule throughout; as long as distal region of dorsal ligule in parapodia 1 and 2 ( Fig. 2E ).

VENTRAL CIRRI. Cirriform, slender; two-quarters as long as ventral ligule in anteriormost and anterior parapodia ( Fig. 2E–F ), half as long as in following chaetigers ( Fig. 2G–I ).

ACICULAE. Reddish, with basal end uncoloured. Notoaciculae absent in first two chaetigers ( Fig. 2E ). Neuroaciculae extending slightly beyond distal end of notoaciculae throughout, with proximal half 1.4– 1.7 times as wide as notoaciculae.

NOTOCHAETAE. All homogomph spinigers; 8–9 spinigers present in anterior parapodia, 6–7 spinigers in middle parapodia, 4–5 spinigers in posterior parapodia and 2 spinigers in posteriormost parapodia.

SUPRACICULAR NEUROCHAETAE. Consisting of homogomph spinigers ( Fig. 2J–K ), heterogomph spinigers ( Fig. 2J ) and heterogomph falcigers ( Fig. 2L ). Homogomph spinigers present throughout; 1 spiniger present in anteriormost parapodia, 2–4 spinigers in anterior and middle parapodia, 3–4 spinigers in posterior parapodia, 2 spinigers in posteriormost parapodia. Heterogomph spinigers present in first seven parapodia, with 3 spinigers. Heterogomph falcigers present from parapodia 8 to end of body; 2 falcigers present in anterior parapodia, 1–2 falcigers in middle parapodia, 2 falcigers in posterior parapodia, 1 falciger in posteriormost parapodia.

SUBACICULAR NEUROCHAETAE. Consisting of heterogomph spinigers ( Fig. 2J ) and heterogomph falcigers ( Fig. 2M ). Heterogomph spinigers present throughout; 4–5 spinigers present in anteriormost and anterior parapodia, 1–2 spinigers in middle parapodia, 1 spiniger in posterior and posteriormost parapodia. Heterogomph falcigers present from parapodia 5 (5–6) to end of body, with 4–5 falcigers in parapodia throughout.

BLADES. Both homogomph ( Fig. 2J–K ) and heterogomph ( Fig. 2J ) spinigers with blades of medium and long size (B/A ratio 3.8–9.1), finely serrated towards toothed edge, evenly spaced in anteriormost and anterior parapodia, coarse proximal teeth and notoriously separated in following parapodia ( Fig. 2K ). Blades of heterogomph falcigers in anterior parapodia slender, convex, medium size (B/A ratio 1.3–1.7), terminal tooth blunt with inconspicuous tendon, serrations present in about half to one-third (0.35–0.46) of total blade length; blades in following parapodia thicker, convex, short (B/A ratio 0.9–1.1), terminal tooth incurved with distinct tendon, serrations present in about one-quarter to one-third (0.25–0.34) of total blade length ( Fig. 2L–M ). Shaft of supracicular falcigers thicker than subacicular ones in posterior parapodia; camerated, with cavity divided sub-distally into two longitudinal partitions.

PYGIDIUM. Distinctly projected, bluntly conical, as long as wide, with anal cirri as long as last 4 (3–6) chaetigers; cirrophores of anal cirri barely developed.

Remarks

Among all the currently known species of Neanthes , N. galetae from Galeta Island, Panama, resembles N. dawydovi (Fauvel, 1937) from Vietnam, N. egregicirrata (Treadwell, 1924) from Antigua in Lesser Antilles, N. hondoensis Khlebovich, 1996 from Japan, N. maculata Wu, Sun & Yang, 1981 from China, N. mexicana Fauchald, 1972 from the Mexican Pacific, N. papillosa (Day, 1963) from South Africa, and N. vandersandei (Horst, 1924) from Indonesia. These eight species share proximal region of the dorsal ligules of similar size across the body (or slightly enlarged in posterior parapodia), absence of notopodial prechaetal, neuropodial postchaetal and superior lobes and subacicular homogomph spinigers, areas VII–VIII with one well-defined band of fewer than 20 paragnaths, area III with less than 20 paragnaths, and the area I with no more than two paragnaths (see Villalobos-Guerrero & Idris 2021: table 2). Additionally, they are all similar as they possess a pear-shaped prostomium and ovoid palpophores.

Nonetheless, N. galetae is easily distinguishable from them all by the following diagnostic features: (I) rounded patch of 9–11 paragnaths on area VI, in contrast to transverse row of up to four paragnaths in N. dawydovi , N. egregicirrata , N. maculata , N. papillosa and N. vandersandei , one paragnath in N. mexicana , and none in N. hondoensis ; (II) the paired eyes of similar size, in contrast to the anterior pair markedly larger than the posterior pair in N. mexicana and N. papillosa ; (III) the ventral ligule welldeveloped throughout, in contrast to that markedly reduced in posterior parapodia of N. dawydovi ; (IV) the dorsum of all segments with transverse pigmentations, in comparison to its absence in chaetiger 2 in N. dawydovi ; and (V) dorsal cirri with regular size, in contrast to it being markedly elongated on parapodia 6 in N. egregicirrata .

Likewise, N. galetae can also be differentiated from N. vandersandei in the following features based on its recent redescription ( Villalobos-Guerrero & Idris 2021): (I) the multi-articulated tentacular cirri, in contrast to those smooth in N. vandersandei ; (II) the presence of merged paragnaths on area IV, in comparison to its absence in N. vandersandei ; (III) the presence of paired oesophageal caeca, in contrast to its absence in N. vandersandei ; (IV) the presence of heterogomph spinigers in a few anterior supracicular neurochaetae, in comparison to its absence throughout in N. vandersandei ; and (V) the blade of heterogomph falcigers with incurved terminal tooth and distinct tendon in middle and posterior parapodia, in contrast to those with blunt terminal tooth and inconspicuous tendon throughout in N. vandersandei .

The species was described by Fauchald (1977) using eight immature specimens collected from the Panama side of the Caribbean Sea among red algae, although only six of those collected in the Acanthophora and Laurencia zones correspond to the type series. At present, only four types remain (holotype and three paratypes). The type material examined here partially matches the barely-illustrated original description, which was seemingly based on the holotype. Neanthes galetae was described with a higher number of paragnaths in the areas of the maxillary ring (I: 2; II: 20; III: 18; IV: 25) when compared with specimens from the type series (I: 0–1; II: 8–14; III: 5–12; IV: 11–17). The dorsal cirri were mentioned as attached basally throughout in the original description, although it is attached medially in the middle and posterior parapodia of the type series. The replacement of homogomph spinigers by heterogomph spinigers in supracicular neurochaetae of posteriormost parapodia stated in the description was not observed in the type material. However, the heterogomph spinigers were observed in a few anteriormost parapodia, which were replaced by heterogomph falcigers in the following parapodia.

Neanthes galetae was not characterised or redescribed previously until this study. The original description includes a short, implicit comparison with four taxa of Neanthes in having a few paragnaths on area VII–VIII: Neanthes agulhana (Day, 1963) from South Africa, N. dawydovi , N. kerguelensis (Mclntosh, 1885) from the Kerguelen Islands, and N. kerguelensis oligodonta (Augener, 1913) from Australia. They were distinguished by paragnaths occurring on area I, although variations overlap in the species (see Villalobos-Guerrero & Idris 2021; this study). The subspecies is not considered valid presently ( Wilson 1984), and the differences with N. dawydovi were mentioned above. Neanthes galetae is easily distinguished from both N. agulhana and N. kerguelensis by the lack of notopodial prechaetal lobe (present in those species) and the rounded patch of 9–11 paragnaths on area VI (transverse row of up to 4 paragnaths in N. agulhana and 0–1 paragnath in N. kerguelensis ). Neanthes galetae is also different from N. kerguelensis by the lack of neuropodial postchaetal lobe and subacicular homogomph spinigers (both present in N. kerguelensis ).

The species has also been recorded from the Pacific part of El Salvador ( Planas et al. 2013) and Colombia ( Jaime et al. 1999) in ecological studies. However, they are considered doubtful until a re-examination of the voucher material is performed.

Distribution

Panama: Galeta Island, Colón (Caribbean Sea).

Ecology

Intertidal among red algae of the genera Acanthophora J.V.Lamour. and Laurencia J.V.Lamour. and present among the seagrass Thalassia Banks ex König ( Fauchald 1977) and Halodule Endl. ( Vásquez Montoya & Thomassin 1983).

Reproduction

Unknown.

Figures

Fig. 2. Neanthes galetae Fauchald, 1977. A–B, E–M. Holotype (USNM 53088) from Galeta Reef, Panama, atokous. C–D. Paratype (USNM 53089) from Galeta Reef, Panama, atokous. A. Entire body in dorsal view.B. Anterior end in dorsal view.C. Non-everted pharynx in ventral view, black arrow indicates merged paragnaths. D. Right jaw in dorsal view, white arrow indicates canals. E. Right parapodium from chaetiger 2 in anterior view. F. Right parapodium from chaetiger 8 in anterior view. G. Right parapodium from chaetiger 16 in anterior view. H. Right parapodium from chaetiger 33 in anterior view. I. Right parapodium from chaetiger 47 in anterior view. J. Supracicular (Sp) and subacicular (Sb) neurochaetae (chaetiger 1). K. Homogomph spiniger from supracicular neurochaetae (chaetiger 47). L. Heterogomph falciger from supracicular neurochaetae (chaetiger 47). M. Heterogomph falciger from subacicular neurochaetae (chaetiger 47). Roman numerals refer to the areas and Arabic numbers to chaetigers. Scale bars: A = 0.5 mm; B = 0.2 mm; C–I = 0.1 mm; J = 20 µm; K–M = 10 µm.