Anamobaea orstedii Kroyer , 1856

Tovar-Hernandez, Maria Ana Ana, Garcia-Garza, Maria Elena & de Leon-Gonzalez, Jesus Angel, 2020, Sclerozoan and fouling sabellid worms (Annelida: Sabellidae) from Mexico with the establishment of two new species, Biodiversity Data Journal 8, pp. 57471-57471 : 57471

Anamobaea orstedii Kroyer, 1856

Anamobaea orstedii Anamöbæa Ørstedii

Anamobaea orstedi. - Humman and Deloach 2001: 155; San Martín et al. 1994: 556, fig. 1A-I; Tovar-Hernández and Salazar-Vallejo 2006: 27-30, figs. 1-2.

Materials

Type status: Other material. Occurrence: catalogNumber: UANL 8133 ; recordedBy: Luis Fernando Carrera-Parra, Isabel Cristina Molina-Acevedo, Tulio Fabio Villalobos-Guerrero, Sergio I. Salazar-Vallejo; individualCount: 8; sex: Hermaphrodite; lifeStage: Adult; reproductiveCondition: Ripe; Taxon: phylum: Annelida; class: Polychaeta; order: Sabellida Levinsen, 1883; family: Sabellidae Latreille, 1825; genus: Anamobaea Krøyer, 1856; specificEpithet: orstedii Krøyer, 1856; Location: higherGeography: Atlantic Ocean; continent: America; waterBody: Gulf of Mexico; islandGroup: Sistema Arrecifal Veracruzano; country: México; countryCode: MX; stateProvince: Veracruz de Ignacio de la Llave; municipality: Veracruz; locality: Isla Verde ; maximumDepthInMeters: 1 m; decimalLatitude: 19.201191; decimalLongitude: -96.065768; Identification: identifiedBy: María Ana Tovar-Hernández; Event: samplingProtocol: By hand; eventDate: 27March 2015; year: 2015; month: 03; day: 27; habitat: Dead coral; Record Level: language: Spanish; institutionID: Universidad Autónoma de Nuevo León; collectionID: Colección Poliquetológica, Universidad Autónoma de Nuevo León; institutionCode: UANL; collectionCode: UANL, NL INV 0002-05-09

Description

Figures 1-5

Body shape and size. Specimens fairly large and plump on thorax, flattened dorso-ventrally in thorax (Fig. 2 B), pyriform abdomen in transversal section (Fig. 3 K). Body length 10-42 mm (n = 5, all lacking posterior abdomen), width 1.5-4 mm.

Radiolar crown. Length 6-17 mm with 15-20 pairs of radioles. Base of radiolar crown (basal lamina) smooth, long, as long as the length of eight thoracic segments in largest specimens. Erect, prominent dorsal and ventral flanges (Fig. 2 A-F and Fig. 3 A-B). Dorsal flanges forming a broad and deep canal from the base of dorsalmost radioles until base of posterior peristomial ring collar (Fig. 2 C and Fig. 3 B). Ventral flanges with an anterior digitiform lobe overlapped (Fig. 2 A) and exposing the base of parallel lamellae. Radioles united by a palmate membrane as long as two times the length of base of crown or basal lamina (Fig. 2 F). Radiolar skeleton composed of 12-16 cells in cross section at the base (Fig. 3 F), then decreasing in number towards mid-radiolar length (Fig. 3 J). Longest pinnules located at three quarters of the radiolar crown length. Radiolar tips filiform, occupying the space of 5-8 pinnules, without flanges (Fig. 4 H). Ocelli in both sides of the outside of radioles (Fig. 3 G-I). Dorsal most radioles with ocelli in groups of 15-22: basal ocelli distributed in two irregular rows (Fig. 3 H), distal ocelli forms only one row (Fig. 3 I). Ventral radioles with 5-10 ocelli in a single row. Dorsal lips long, erect, triangular (Fig. 3 E) with mid-rib (radiolar appendage). Dorsal pinnular appendages present, short. Dorsal lips longer than palmate membrane, reaching the basalmost radiolar ocelli. Ventral lips small, folded and joining radiolar lobes near origin of first ventral radiole. Ventral radiolar appendages absent.

Peristomium . Anterior peristomial ring high, as long as the length of three thoracic segments, with rounded margin (Fig. 4 A-B, crown removed). Posterior peristomial ring collar: dorsal margins shallow, not fused to faecal groove (Fig. 3 B); ventral margins forming two nearly triangular lappets (Fig. 2 A and D), not overlapped (whereas relaxed or contracted). Parallel lamellae and ventral sacs present (Fig. 3 D). Ventral sacs rounded, inflated and exposed outside ventral basal flanges of crown, in some specimens full of sand (Fig. 3 A and D). Dorsal margin of anterior peristomial ring exposed above collar margin (posterior peristomial ring), triangular, divided by faecal groove (Fig. 3 B).

Thorax. Chaetigers very numerous (20-54 chaetigers). Ventral shield of collar rectangular, longer and broader than following shields (Fig. 2 A). Collar chaetae arranged in a bunch (Fig. 4 A) of short, spine-like with symmetrical hoods (Fig. 4 D). Ventral shields of chaetigers 2-8 rectangular, swollen (Fig. 2 A). Superior notochaetae spine-like, short, 3-4 per group (Fig. 5 A). Inferior notochaetae paleate, symmetrical (Fig. 4 E) or asymmetrical (Fig. 5 B), arranged in two transverse rows, each row with 3-4 chaetae (Fig. 5 A). Tori not contacting ventrals shields (Fig. 2 A). Uncini avicular, with minute, equal-size teeth covering half of the crest (Fig. 5 E), breast well developed, handle as long as two times the length of crest (Fig. 4 I). Companion chaetae with symmetrical tips as teardrop-shaped membranes (Fig. 4 I, Fig. 5 D), shaft not longer than uncini. Posterior segments with brown blood vessels dorsally, forming rectangular, sinuous nets seen in both alive and fixed material (Fig. 3 C).

Abdomen. Number of chaetigers not fully determined (incomplete specimens, the longest with 124 segments). Segments with brown blood vessels dorsally, forming rectangular, sinuous nets (Fig. 3 C). Neurochaetal fascicles in two transverse rows. Anterior abdominal segments with anterior and posterior rows of paleate chaetae with dentate mucros (Fig. 4 G and Fig. 5 C), mucros short (as long as paleae width) being fragile and broken in many paleae (Fig. 5 C) and modified, elongate, narrowly-hooded chaetae (Fig. 4 K). Posterior abdominal segments with paleae with long mucros (more than three times the width of paleae) (Fig. 4 G) and modified, elongate, narrowly-hooded chaetae. Uncini avicular, with 30-37 rows of equal-sized teeth covering 3/4 of the crest length (Fig. 5 F), breast well developed (Fig. 4 J), handles as long as crest. Pygidium not examined (specimens lacking the last segments of abdomen, near pygidium).

Variation. One large specimen (44 thoracic chaetigers, 3.5 mm width) with a regenerating radiolar crown: it is short, measuring only 6 mm in length with 18 pairs of radioles, all unequal in length. This regenerating crown has a palmate membrane well developed and dorsal radioles with rows of 8-14 ocelli, whereas ventral radioles have 5-6 ocelli.

Colour in live specimens. Radiolar crown with red and white bands in situ (Fig. 1 ). Under light microscopy, base of radiolar crown translucent. Basal half of radiolar crown red with a translucent palmate membrane and red radiolar ocelli. Distal half of radiolar crown with alternate white and red bands. Ventral lappets of posterior peristomial ring collar and lateral margin of anterior peristomial ring red. Body yellow with ventral shields and lateral margins of the body whitish. Anterior thoracic segments with narrow, red, transversal lines between each torus.

Colour in preserved specimens. Palmate membrane white. Basal half of crown with radioles brown to orange containing rows of brown ocelli. Distal half of crown with whitish radioles. Radiolar tips white. Ventral lappets with large, orange spots each. Whitish ventral sacs. Segments from mid-thorax with two brown, sinuous blood vessels dorsally forming a nearly-rectangular shape. Some abdominal segments with brown, sinuous blood vessels forming a rectangular shape dorsally.

Tubes. Tubes embedded in dead coral seem like wooden trunks with a strong consistency, composed of an external wide bark-like layer and several thin, golden internal layers.

Diagnosis

Base of the radiolar crown smooth (basal lamina) with prominent, erect, dorsal and ventral flanges. Collar chaetae arranged in a bunch. Ocelli in both sides of the outer margin of radioles. Dorsal-most radioles with ocelli in groups of 15-22 (basal ocelli distributed in two rows, distal ocelli forms only one row). Ventral radioles with 5-10 ocelli in a single row. Simultaneous hermaphrodite.

Biology

Ripe simultaneous hermaphrodites were found with female and male gametes within the coelom of abdominal segments and also attached to the internal tube layer (Fig. 4 K-L). Oocytes are equal in size and spermatozoa with spherical nucleus and rounded cap-like acrosome.

Taxon discussion

According to Fitzhugh (1989), members of Anamobaea , Hypsicomus and Notaulax , have a low anterior margin of the anterior peristomial ring, of even height all around. However, in the description provided here for Anamobaea , this feature is interpreted as high (as long as three thoracic segments), with distal margin rounded once crowns were removed to properly examine the peristomium (Fig. 4 B-C). In addition, Perkins (1984) [figs. 25E-F and 35E-F], illustrates anterior peristomial rings of Notaulax bahamensis Perkins, 1984 ( Perkins 1984) and N. nudicollis ( Krøyer, 1856) ( Krøyer 1856) similar to that described here for Anamobaea . Consequently, a re-examination of this feature is needed in Hypsicomus , as well as in other members of Notaulax .

Tovar-Hernández and Salazar-Vallejo (2006) reported a radiolar skeleton composed of 6-7 cells in cross-section and thorax with 32-55 chaetigers. In the present study, a small variation was found: 12-16 cells at the base of radioles and then decreasing in number towards medium radiole length. Specimens here reported have 20-54 thoracic chaetigers. Ventral lips were incorrectly shown by Tovar-Hernández and Salazar-Vallejo (2006) in their figure 1B (as vl). These structures correspond to ventral sacs, not ventral lips. The ventral lips are small, folded and joining radiolar lobes near the origin of first ventral radiole.

In addition, it should be noted that the spelling of the species name orstedii has previously been incorrect in a number of publications (misspelled as " orstedi " instead the original " orstedii ") in Fitzhugh (1989) [p. 74], San Martín et al. (1994) [p. 556], Tovar-Hernández and Salazar-Vallejo (2006) [p. 27], Dean (2012) [p. 65] and Capa et al. (2019) [p. 191].

Detailed information about eye and ocelli types found in A. orstedii was provided by Bok et al. (2016): eye type S (scattered ocelli on both sides of each radiole) and ocelli type 4 (four-cell forming the ocellus).

Reproductive information is absent for Anamobaea . In this study, the presence of simultaneous hermaphroditism is confirmed in A. orstedii. Brooding within the tube of the radiolar crown was not observed. Broadcast spawning is supported by sperm morphology (spherical heads).

Most of the sabellid species present a thorax consisting typically of eight chaetigers ( Fitzhugh 1989), but there is a remarkable exception in Anamobaea , where a long thorax consisting of 20-54 chaetigerous segments in Anamobaea orstedii (this study) or 74 in A. phyllisae has been reported, being the highest number of thoracic segments reported nowadays in Sabellidae ( Tovar-Hernández and Salazar-Vallejo 2006). Other exceptions are represented by members of Perkinsiana , which may have 19 thoracic segments as in P. anodina or 24 in P. longa ( Capa 2007).

Perhaps the presence of a long thorax in Anamobaea and some species of Perkinsiana is related to their mode of life in corals. Perkinsiana anodina was described as sclerozoan of dead coral from Western Australia, where there were large granite boulders with small colonies of live and dead corals on them ( Capa 2007). It was also found in Tiger Island (Indonesia) surrounded by tissue of a mushroom coral where their tubes form straight protuberances on the scleractinian coral surface ( Tovar-Hernández et al. 2020). As corals provided refuge to worms in addition to that provided by their own tubes, it is probable that worms present a high growth and longevity as demonstrated in other infaunal, tube worms of corals such as the serpulid Spirobranchus corniculatus (Grube, 1862) ( Grube 1862) with an estimated longevity of 15-20 years or the sabellariid Idanthyrsus sp., with eight years of longevity ( Nishi and Nishihira 1999, also see their fig. 1 where a boring Notaulax was sketched). The tube ultrastructure of A. orstedii has a regular plywood microstructure which is lamellar in cross-section ( Vinn et al. 2018), whereas the tube wall of Perkinsiana anodina is dense, non porous, with sparsely spaced three different sets of fibres ( Tovar-Hernández et al. 2020). This indicates that inhabiting with coral has had no effect on the tube microstructure of the species, possibly because P. anodina did not communicate with the host coral through its tube wall.

Figures

Figure 1. Anamobaea orstedii in coral reefs from southern Gulf of Mexico.

Figure 2. Selected features of Anamobaea orstedii. A-C) Thoracic segments and base of radiolar crown, D-F) base of radiolar crown and radioles. A) Ventral view, B, D-F) lateral views, C) dorsal view. Abbreviations: adl) anterior digitiform lobe, df) dorsal flange, pm) palmate membrane, vf) ventral flange. Scale bars: A) 4 mm, B-C) 2 mm, D-F) 1.5 mm. A-C) UANL 8133.

Figure 3. Selected features of Anamobaea orstedii. A-B) Base of radiolar crown, C) thoracic segments, dorsal view, D) radiolar crown internal structures, E) dorsal and ventral lip, F) base of radioles showing skeletal cells, cross section, G) radiolar ocelli, H) detail of basal ocelli, I) detail of distal ocelli, J) cross section of radiole at mid-radiole length, K) abdomen, transversal section. Abbreviations: d) dorsum, df) dorsal flange, dl) dorsal lip, v) ventrum, vf) ventral flange, vl) ventral lip, vs) ventral sacs. Scale bars: A-B) 0.5 mm, C) 1.75 mm, D) 1 mm, E) 0.75 mm, F-G) 0.25 mm, H-J) not scaled, K) 0.4 mm. A-K) UANL 8133.

Figure 4. Selected features of Anamobaea orstedii. A) Collar chaetiger and dorsal flange, B) anterior peristomial ring, crown removed, dorso-lateral view, C) same, dorsal view, D) spine-like chaeta from collar, E) thoracic paleate chaeta, F) paleate chaeta from anterior half of abdomen, G) paleate chaetae from posterior abdominal segments, H) radiolar tip, I) thoracic uncinus and companion chaetae, J) abdominal uncini, K) elongate, modified narrowly-hooded chaetae from abdomen, L) oocytes and sperm attached to the internal layer of tube, M) oocytes and spermatozoa indicated with arrows. Abbreviations: apr) anterior peristomial ring, df) dorsal flange. Scale bars: A) 1 mm, B-C) 0.8 mm, D-G, K) 30 μm, H) 0.6 mm, I-J) 24 μm, L) not scaled, M) 1000 x magnification. A-M) UANL 8133.

Figure 5. Chaetae of Anamobaea orstedii under Scanning Electron Microscopy. A) Thoracic chaetiger: superior group of spinelike chaetae; posterior group with two rows of paleae; B) thoracic paleae, C) abdominal paleae, D) thoracic companion chaetae, E) thoracic uncini, F) abdominal uncini. Abbreviation: sc) scar. Scale bars: A-B) 66.6 μm, C) 50 μm, D-F) 20 μm.