Aricidea (Strelzovia) bulbosa Hartley, 1984

Erdoğan-Dereli, Deniz & Çinar, Melih Ertan, 2020, The diversity of the genus Aricidea (Polychaeta: Paraonidae) from the Sea of Marmara, with descriptions of two new species and two new records for the Mediterranean fauna, Zootaxa 4844 (1), pp. 1-73 : 56-60

Aricidea (Strelzovia) bulbosa Hartley, 1984

( Figures 39–41 )

Aricidea (Allia) bulbosa Hartley 1984: 13–17 , fig. 4.

Material examined. ESFM-POL/2013-93 , 09 June 2013, station Y17, 40°39’09’’N, 27°41’14’’E, 25 m, black mud, 5 specimens ; ESFM-POL/2013-998 , 09 June 2013, station Y17, 40°41’03’’N, 27°39’52’’E, 100 m, mud, 1 specimen .

Additional material examined. ESFM-POL/2017-154 , 27 July 2017, Aegean Sea, off Ayvalık, 39°18’1.944”N, 26°33’44.784”E, 35 m, sandy mud with Caulerpa cylindracea , 1 specimen ; ESFM-POL/2017-155 , 07 August 2017, Aegean Sea, off Datça Pennisula, 36° 47’30”N, 27°45’03”E, 49 m, sandy mud with algae, 2 specimens ; ESFM-POL/2017-156, 03 August 2017, Aegean Sea, off Bozburun, 28 m, 36°40’39”N, 27°58’15”E, sandy mud with Halophila stipulacea , 1 specimen.

Description. Largest specimen incomplete, 7.52 mm long, 0.44 mm wide at chaetiger 10, with 53 chaetigers. Color in alcohol yellowish. Body stout, widths of prebranchial and branchial regions nearly the same, getting thicker in posterior region ( Fig. 39 A–C).

Prostomium subtriangular, with two annulations (border of annulations at anterior end of nuchal organs); much wider than long (ratio length / width: 0.94), anterior margin truncated ( Figs 39C ; 40A ), with two intradermal eyes. Crown like ciliary band (clcb) present, but short ciliated slits (cs) above nuchal organs absent ( Fig. 40B ). Antenna short, digitiform, weakly bulbous, with a rounded tip, hardly reaching posterior margin of prostomium, inserted in mid-region of prostomium ( Figs 39C ; 40B ). A pair of nuchal organs as narrow deep, short slits placed on dorsolateral sides of posterior prostomium, more or less convex in shape; dense internal ciliation present, cilia not reaching outer margin of slits; without pigmentation; a pair of ridges located in inner side of nuchal slits ( Figs 39C ; 40B ). Mouth with three buccal lips; two placed anteriorly, one placed posteriorly extending to anterior margin of chaetiger 1, with eight longitudinal folds; a Y-shaped gap present between anterior lips ( Fig. 39B ).

A dense dorsal ciliary (dcb) band present on mid-dorsal transversal line of each prebranchial and branchial chaetigers; cilia ending in a sphaerical plate ( Fig. 40 D–F). A pair of short dorsal ciliary bands (sdcb) present on base of each branchia ( Figs 40A ; 41A ). Ciliary bands absent on ventral side of body.

Branchiae 22 pairs, starting in chaetiger 4, first pair shortest; dorso-ventrally flattened, tapering to tip in first 4–5 pairs, remaining branchiae becoming bulbous and tapering to tip; bases of last 7–8 pairs having asymmetrical enlargement; multiple regular pits located on the anterior side of each branchiae in the middle and posterior part of branchial region; dense ciliary band present on both sides of branchiae, except for distal end; branchiae always shorter than segment width, becoming longer posteriorly ( Figs 39A, C, F ; 40A, D ; 41 A–F); 255 μm long in anterior region, 286 μm long in middle region, 350 μm long in posterior region.

Interramal lobes and notopodial papilla absent. Ventral lobes present on chaetigers 3–19, short, tuberculated ( Fig. 39G ).

Notopodial postchaetal lobes short, digitiform on first two chaetigers; becoming stouter and longer on chaetiger 2; with an asymmetrical basal enlargement in branchial region; long and filiform in posterior region. Neuropodial postchaetal lobes present between chaetiger 1 and chaetiger 20, as short ridges in prebranchial region; becoming cirriform and stouter in branchial region; nearly indistinct in chaetigers 17–20 ( Figs 39C, F ; 40A ; 42 A–D).

Lateral sense organs present on all chaetigers, located between notopodia and neuropodia, posterior to notopodial postchaetal lobes; with cilia distinctly protruding from opening or embedded into pore; elliptical with irregularly clustered pores in prebranchial and in anterior and middle branchial regions; straight line-shaped with regularly clustered pores from posterior part of branchial region to end of body ( Fig. 42 B–F); with 30 pores in prebranchial region (long axis: 5–6 μm), with 40–50 pores (long axis: 9–10 μm) in anterior and middle part of branchial region, with 40–50 pores (length: 12–15 μm) in posterior part of branchial region, with 50–70 pores (length: 22–24 μm) in posterior region.

Three types of chaetae present on chaetigers: limbate, capillary and modified neurochaetae. Limbate chaetae of two types; first type present in notopodia of chaetigers 1–15, numbering 21–24, arranged in three rows, 267–300 µm long, thin and straight with fibrils along edge (hirsute), directed dorsally, light-rose colored; second type present on neuropodia of chaetigers 1–15, arranged in three rows, numbering 24–27, 177– 250 µm long, slightly wider and sigmoid with fibrils along edge (hirsute), directed posterio-ventral side, light rose colored ( Figs 39D ; 40A ; 42A, C ).

Capillary chaetae commencing in noto- and neuropodia of chaetiger 16 and present in all subsequent chaetigers; in middle notopodia numbering 15–18, arranged in two rows, ca. 245 μm long; in posterior notopodia numbering 10–12, arranged in one row, ca.185 μm long; in middle neuropodia numbering 15–21, arranged in two rows, ca.163 μm long; in posterior neuropodia numbering 10–18, arranged in one row, ca.188 μm long.

Strelzovia - type modified neuropodial chaeta (thick at base gradually tapering to tip) from chaetiger 44–52 to posterior end, numbering 1–2 in each neuropodium, accompanied by capillary chaetae, almost 80 μm long, without coloration ( Figs 39E ; 40C ).

Pygidium missing.

Reproduction. Some specimens of A. bulbosa from the Sea of Marmara had eggs in their coelomic cavities after chaetiger 30; four eggs in each chaetiger with a diameter of 119–130 μm.

Remarks. The morphology of the specimens of Aricidea bulbosa from the Sea of Marmara and Aegean Sea coincides with the original description of the species. However, in our specimens, the anterior part of the prostomium is partially truncated (rounded in the original description), the prostomium is longer than wide (equal lengths in the original description) and the limbate chaetae are light rouse-coloured (reddish gold-coloured in the original description).

Hartley (1984) stated that the middle and posterior branchiae were stained heavily when treated with eosin and presented a glandular or vacuolar appearance. We also stained our specimens with Shirlastain-A and saw that most branchiae were pigmented heavily as noted by Hartley (1984) ( Fig. 39A, C, F ). When the specimens were examined under SEM, we observed that the branchiae have regularly arranged pits on their anterior face that absorb stains ( Fig. 41 A–F). Such regular pits have not been previously reported on the branchiae of any paraonid species. These pits might be the external openings of the glands where secretions emerge, but further research is needed to clarify their function on the branchiae.

Habitat and Distribution. This species was found in soft substrata at 25–100 m depths in the Sea of Marmara; in soft substrata with Caulerpa cylindracea and Halophila stipulacea at 28–49 m depths in the Aegean Sea. As this species was previously reported only from the Gulf of Suez, Red Sea ( Hartley 1984), it could have been introduced to the Mediterranean Sea via the Suez Canal and could be regarded as alien species for the region. The paraonids have long lived planktotrophic larvae, so this species might expand its distributional range rapidly in the Mediterranean Sea by natural dispersal or its presence in the Sea of Marmara can be explained by the secondary introduction by ballast water of ships from the eastern Mediterranean. There is a long distance between the localities (south Aegean Sea and Sea of Marmara) where this species was found in the present study, so we need more distributional data of this species to understand if it has a continous or disjunct distribution pattern in the region, which would enable us to assess its type of pathways of introduction.

Figures

FIGURE 39. Aricidea (Strelzovia) bulbosa (ESFM-POL/2013-93). A, General view of body, stained with Shirlastain-A; B, Ventral view of anterior end; C, Dorsal view of anterior end, stained with Shirlastain-A; D, Limbate chaeta of neuropodium of anterior chaetigers; E, Modified neurochaeta of posterior chaetiger; F, Posterior branchiae, stained with Shirlastain-A; arrows indicating the stained pits-like structures; G, Ventral view of branchial chaetigers. Abbreviations: a, annulation; neupcl, neuropodial postchaetal lobes; vl, ventral lobes. Scale bar: A, 572 µm; B, 204 µm; C, 275 µm; D, 11 µm; E, 23 µm; F, 213 µm; G, 211 µm.

FIGURE 40. Aricidea (Strelzovia) bulbosa (ESFM-POL/2013-93). A, Dorsal view of anterior end; B, Dorsal view of prostomium; C, Modified neurochaeta on posterior chaetiger; D, Branchiae; E, Dorsal ciliary band; F, Cilia on dorsal ciliary band.Abbreviations: a, annulation; clcb, crown-like ciliary band; dcb, dorsal ciliary band; no, nuchal organ; pt, pits; sdcb, short dorsal ciliary band. Scale bar: A, 196 µm; B, 33 µm; C, 20 µm; D, 78 µm; E, 30 µm; F, 10 µm.

FIGURE 41. Aricidea (Strelzovia) bulbosa (ESFM-POL/2013-93).A; Posterior branchiae; B, Branchia with sensory pits; C–F Sensory pits. Abbrevation: sdcb, short dorsal ciliary band. Scale Bars: A, 30 µm; B, 10 µm; C, 4 µm; D, 2 µm; E, 1,09 µm; F, 0,62 µm.

FIGURE 42. Aricidea (Strelzovia) bulbosa (ESFM-POL/2013-93).A, Parapodia of chaetigers 3–4; B, Parapodium of a posterior branchial chaetiger; C, Parapodia of mid-branchial chaetiger; D, Notopodial postchaetal lobe of mid-branchial chaetiger; E, F, Lateral sense organ on posterior chaetigers. Abbreviations: bran, branchiae; lso, lateral sense organ; neupcl, neuropodial postchaetal lobes; ntpcl, notopodial postchaetal lob. Scale bar: A, 42 µm; B, 35 µm; C, 57 µm; D, 17 µm; E, 11 µm; F, 7 µm.