Aricidea (Aricidea) wassi Pettibone, 1965

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 : 52-56

Aricidea (Aricidea) wassi Pettibone, 1965

( Figures 36–38 )

Aricidea (Aricidea) wassi Pettibone 1965: 135–138 , figs. 9 A–D, 10 A–D, 11 A–C; Imajima 1973: 265–267, fig. 6 a–i; Strelzov 1973: 62–64, figs. 17(2)–23 C–E; Katzmann & Laubier 1975: 582–584, fig. 5 A–E; Blake 1996: 44–45, fig. 2.7 A–F; Jung et al. 1996: 319, 328, fig. 6; Selim 2007: 174–176, fig. g–m; Aguirrezabalaga 2012: 229–231, figs. 98 A–C, 99 A–B.

Material examined. ESFM-POL/2013-1278 , 06 June 2013, station Y1, 40°01’08’’N, 26°13’00’’E, 50 m, mud, 1 specimen ; ESFM-POL/2013-1276 , 09 June 2013, station Y17, 40°39’58’’N, 27°41’08’’E, 50 m, mud, 5 specimens ; ESFM-POL/2013-1295 , 17 June 2013, station Y28, 40°29’59’’N, 28°51’30’’E, 10 m, mud with shell fragment, 1 specimen .

Description. Largest specimen incomplete, 7.28 mm, 0.35 mm wide, with 54 chaetigers. Color in alcohol usually white and light yellow; with dense pink or red pigmentations on anterior and branchial region in large specimens ( Fig. 36A ). Body long and slender, anterior part slightly swollen, branchial and posterior part similar in thickness ( Fig. 37A ).

Prostomium conical, much longer than wide (ratio length / width: 1.56); anterior margin rounded, without eyes. Crown like ciliary band (clcb) and a pair of ciliary slits (cs) present ( Fig. 37C ). Antenna long, with four joints and a central insertion, extending to anterior margin of chaetiger 2 ( Figs 36 A–B; 37B). A pair of nuchal organs as narrow, short slits placed on posterio-dorsal part of prostomium, more or less convex in shape, dense internal ciliation not reaching to outer margin of slits; without pigmentation. Mouth with three lips; two placed anteriorly, one placed posteriorly extending to anterior margin of chaetiger 1, with six longitudinal folds; a Y-shaped gap present between anterior lips.

A dorsal ciliary band (dcb) present on mid-dorsal transverse line of each prebranchial and branchial chaetiger. A pair of short dorsal ciliary bands (sdcb) present posterior to each branchial base ( Fig. 38B ). Ciliary bands absent on ventral side of body.

Branchiae ten pairs, starting in chaetiger 4, last pair rudimentary; anterior branchiae short and cylindro-conical, with distal end abruptly tapering and with a rounded tip; middle and posterior branchiae narrow, tapering with a rounded tip; ciliary bands on both sides of branchiae not reaching the tip ( Figs 36A, D ; 37 A–B; 38E); branchiae always shorter than segment width; 196 μm long in anterior region, 204 μm long in middle region and 172 μm long in posterior region.

Lateral sense organs present on all chaetigers, located between notopodia and neuropodia, posterior to notopodial postchaetal lobes, except in branchial region where lateral sense organ locate on the base of notopodial postchaetal lobes; with flexible cilia distinctly protruding from opening or embedded into pore ( Fig. 38 A–D); oval-shaped with irregularly clustered pores from prebranchial to mid-branchial region; straight line-shaped with regularly clustered pores from mid-branchial region to end of body; 20–24 pores in prebranchial region (long axis of organ: 4 μm), with 35–40 pores (long axis: 5–7 μm) in mid-branchial region; with 42–45 pores (long axis: 13–14 μm) in posterior part of branchial region and with 50–55 pores (long axis: 14–15 μm) in posterior region.

Interramal lobes present between noto and neuropodia of chaetigers 3–15 as a rudimentary ridge ( Fig. 36D ). Notopodial papillae and ventral lobes absent.

Notopodial postchaetal lobes short and cirriform on first two chaetigers; thick, long and digitiform with basal symmetrical enlargement between chaetiger 3–13; thin, long and filiform on posterior chaetigers. Neuropodial postchaetal lobes absent ( Figs 36 C–D; 37B; 38A–B, E).

Three types of chaetae present on chaetigers: limbate, capillary and modified neurochaetae. Limbate chaetae of two types; first type present in notopodia of chaetigers 1–13, numbering 12–20, arranged in three rows, ca. 223 µm long, thin and straight with fibrils along edge (hirsute), dorsally directed, light-rose colored; second type present in neuropodia of chaetigers 1–13, numbering 36–38, arranged in four rows, ca. 190 µm long, slightly wider and sigmoid with fibrils along edge (hirsute), directed ventrally, light-rose colored. ( Figs 36 C–D; 37C; 38A–B, E).

Capillary chaetae starting in noto- and neuropodia of chaetiger 15 and present on all subsequent chaetigers; in middle notopodia numbering 8–10, arranged in two rows, ca. 264 μm long; in posterior notopodia numbering 3–5, arranged in one row, ca. 192 μm long; in middle neuropodia numbering 15–20, arranged in 2–3 rows, ca. 200 μm long; in posterior neuropodia, numbering 4–8, arranged in one row, ca. 225 μm long.

Modified neuropodial chaetae from chaetiger 22–28 to end of body, numbering 5–6 in each neuropodium and accompanied by capillary chaetae, superior ones longer (about 229 μm long, without considering arista); hookshaped; subterminal region slightly curved towards concave side; with a very long arista arising subterminally from concave side; without hood ( Figs 36E ; 38F ); without coloration.

Pygidium missing.

Remarks. The specimens of A. wassi from the Sea of Marmara differ from the original description of the species in terms of the following characters: (1) antenna has four distal joints and reaching up to chaetiger 4 in the Sea of Marmara’s specimens, whereas antenna has 3–6 distal joints and reaches up to chaetiger 3–5 in the original description; (2) the interramal lobes are present in the specimens from the Sea of Marmara, whereas they are absent in the original description; (3) the base of notopodial postchaetal lobes has a symmetrical enlargement in the specimens from the Sea of Marmara, whereas it was absent in the original description (however, Pettibone drew it in Fig. 9 C–D). However, some characters are overlapping and the interramal lobe is very hard to see on specimens without SEM examination.

Habitat and Distribution. Aricidea wassi was found in soft substrata between 10 and 50 m depths in the Sea of Marmara. According to the previous studies, this species was reported from similar habitats in 10–1480 m depth range in the Pacific Ocean ( Hobson 1972; Imajima 1973; Blake 1996; Jung et al. 1996; Aguado & López 2003), the western ( Pettibone 1965; Hobson 1971) and eastern (Gil & Sard 1999; Aguirrezabalaga & Gil 2008) Atlantic Ocean, and the western ( Katzmann & Laubier 1975) and eastern ( Selim 2007; Çinar et al. 2014) Mediterranean Sea.

Subgenus Strelzovia, Aguirrezabalaga, 2012

Figures

FIGURE 36. Aricidea (Aricidea) wassi. A, Lateral view of anterior end (ESFM-POL/2013-1295); B, Antero-lateral view of prostomium (ESFM-POL/2013-1295); C, Lateral view of parapodia of chaetigers 3–6 (ESFM-POL/2013-1276); D, Cross section of chaetiger 7 (ESFM-POL/2013-1276); E, Modified neurochaeta on chaetiger 45 (ESFM-POL/2013-1295). Abbreviations: bran, branchia; irl, interramal lobe; ntpcl, notopodial postchaetal lobe. Scale bar: A, 333 µm; B, 111 µm; C, 59 µm; D, 150 µm; E, 37 µm.

FIGURE 37. Aricidea (Aricidea) wassi (ESFM-POL/2013-1276). A, Dorsal view of anterior end; B, Dorsal view of anterior end; C, Lateral view of anterior end. Abbreviations: clcb, crown-like ciliary band; cs, ciliary slits. Scale bar: A, 140 µm; B, 63 µm; C, 34 µm.

FIGURE 38. Aricidea (Aricidea) wassi (ESFM-POL/2013-1278). A, Notopodium of chaetiger 1; B, Lateral view of parapodia of mid-branchial chaetigers; C, Lateral sense organ on posterior chaetiger; D, Lateral sense organ of posterior chaetiger; E, Dorsal view of posterior branchial chaetigers; F, Modified neurochaetae of posterior chaetiger. Abbreviations: bran, branchia; irl: interramal lobe; lso, lateral sense organ; ntpcl, notopodial postchaetal lobe; sdcb, short dorsal ciliary band. Scale bar: A, 15 µm; B, 22 µm; C, 19 µm; D, 20 µm; E, 66 µm; F, 15 µm.

FIGURE9. Aricidea(Acmira) catherinae.A, Lateralsenseorgan on a parapodiuminanteriorbranchial region(ESFM-POL/2013- 956); B, Lateral sense organ on a parapodium in posterior branchial region (ESFM-POL/2013-956); C,A notopodium of posterior chaetiger (ESFM-POL/2013-956); D, Dorso-lateral view of anterior end, short dorsal ciliary bands (ESFM-POL/2013-1077). Abbreviations: bran, branchia; lso, lateral sense organ; neupcl, neuropodial postchaetal lobe; ntpcl, notopodial postchaetal lobe; sdcb, short dorsal ciliary band. Scale bar: A, 26 µm; B, 18 µm; C, 27 µm; D, 118 µm.