Aricidea (Acmira) pseudoassimilis, Erdoğan-Dereli & Çinar, 2020

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 : 36-43

publication ID

https://doi.org/10.11646/zootaxa.4844.1.1

publication LSID

lsid:zoobank.org:pub:770E285A-3CB3-4649-B70F-631D5AB91EC7

DOI

https://doi.org/10.5281/zenodo.4494308

persistent identifier

https://treatment.plazi.org/id/03EA87B0-FF94-816A-FF18-FD20BA4CFD48

treatment provided by

Plazi

scientific name

Aricidea (Acmira) pseudoassimilis
status

new species

Aricidea (Acmira) pseudoassimilis   new species

( Figures 23–28 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 )

LSIDurn:lsid:zoobank.org:act: FB255513-A520-4155-9A9B-4D85059C5F31

Aricidea assimilis Laubier & Ramos 1974: 1117–1121   , fig. 7 (in part).

Material examined. Holotype: ESFM-POL/2013-1119 , 16 June 2013, station Y23, 40°23’55’’N, 28°09’49’’E, 10 m, mud with shell fragments GoogleMaps   . Paratypes: ESFM-POL/2013-1121 , 10 June 2013, station Y13, 40°45’27’’N, 27°21’24’’E, 100 m, mud, 1 specimen GoogleMaps   ; ESFM-POL/2013-1124 , 9 June 2013, station Y17, 40°39’58’’N, 27°41’08’’E, 50 m, mud with Amphiura   sp., 5 specimens GoogleMaps   ; ESFM-POL/2013-1125 , 16 June 2013, station Y23, 40°23’55’’N, 28°09’49’’E, 10 m, sandy mud with shell fragments, 5 specimens GoogleMaps   ; ESFM-POL/2013-1128 , 16 June 2013, station Y25, 40°24’17’’N, 28°20’50’’E, 10 m, sandy mud with shell fragments, 2 specimens GoogleMaps   ; ESFM-POL/2013-1135 , 16 June 2013, station Y26, 40°22’06’’N, 28°39’55’’E, 10 m, sandy mud with shell fragments, 2 specimens GoogleMaps   .

Additional material examined: ESFM-POL/2015-264 , 12 August 2015, Aegean Sea, Enez , 40°42’40’’N, 26°01’42’’E, 21 m, sand with shell fragments, 1 specimen GoogleMaps   ; ESFM-POL/2016-262 , 13 August 2015, Aegean Sea, Bozcaada , 39°55’05’’N, 26°01’14’’E, 50 m, mud, 2 specimens GoogleMaps   ; ESFM-POL/2016-263 , 30 August 2015, Levantine Sea, Dalaman , 36°41’57’’N, 28°43’39’’E, 70 m, sandy mud with shell fragments, 1 specimen GoogleMaps   ; ESFM-POL/2016- 195 , 15 August 2016, Aegean Sea, Izmir Bay, near the opening of Gediz River , 38º34’82’’N, 26º47’79’’E, 11 m, mud, 2 specimens   ; ESFM-POL/2016-196 , 15 August 2016, Aegean Sea, Aliağa , 38º49’39’’N, 26º57’07’’E, 21 m, mud with shell fragments, 1 specimen GoogleMaps   ; ESFM-POL/2016-197 , 19 August 2016, Aegean Sea, Güllük , 37º14’55’’N, 27º20’30’’E, 38 m, sandy mud, 6 specimens GoogleMaps   ; ESFM-POL/2018-123 , 15 September 2018, Black Sea, Kıyıköy , 41°39’03”N, 28°6’40”E, 27 m, sandy mud with shell fragments, 21 specimens GoogleMaps   ; ESFM-POL/2019-10 , 22 April 2019, Black Sea, Kıyıköy , 41°39’03”N, 28°6’40”E, 27 m, sandy mud with shell fragments, 155 specimens GoogleMaps   .

Description. Holotype incomplete (also all paratypes), 12.65 mm long (9.05–23.60 mm long in paratypes), 0.44 mm wide (0.29–0.53 mm wide in paratypes), with 94 chaetigers (32–128 chaetigers in paratypes). Color of holotype in alcohol yellowish to dull white (also in all paratypes); gamete bearing specimens with distinct red speckles/spots near notopodia and on several dorsal and ventral parts of body ( Fig. 25B, C View FIGURE 25 , E–G); dorso-lateral red spots more conspicuous. Body cylindrical and stout; width of prebranchial and branchial regions nearly same, becoming thick on posterior region ( Figs 23A View FIGURE 23 ; 25 View FIGURE 25 A–C).

Prostomium subtriangular; much longer than wide (ratio length / width: 1.18); anterior margin rounded ( Figs 23A View FIGURE 23 ; 24A View FIGURE 24 ; 27A, C View FIGURE 27 ); eyes absent in all specimens. Crown-like ciliary band (clcb) and a pair of ciliary slits (cs) present on anterior part of prostomium; ciliary slits placed just anterior to nuchal organs, weakly curved ( Figs 23A View FIGURE 23 ; 24A View FIGURE 24 ; 26C View FIGURE 26 , E–F; 27A, C–E). Antenna short, digitiform (0.1 mm in holotype; 0.09–1.3 mm long in paratypes), located in mid-region of prostomium, extending to posterior part of prostomium; densely covered with cilia ( Figs 23A View FIGURE 23 ; 24A View FIGURE 24 ; 27 View FIGURE 27 A–C). A pair of nuchal organs present as narrow, deep, short and slanted slits placed on dorso-lateral sides of posterior prostomium; more or less convex in shape; dense internal ciliation present, cilia not reaching outer margin of slits; light-orange pigmented ( Figs 25A, D View FIGURE 25 ; 26E, F View FIGURE 26 ; 27A, C View FIGURE 27 ). Proboscis with dense cilia ( Figs 26C View FIGURE 26 ; 27F View FIGURE 27 ). Mouth with three buccal lips; two placed anteriorly, one placed posteriorly extending to anterior margin of chaetiger 2, with ten longitudinal folds; an I-shaped gap present between anterior lips (also in all paratypes).

A dense dorsal ciliary band (dcb) present on mid-dorsal transversal line of each prebranchial and branchial chaetigers ( Figs 23A View FIGURE 23 ; 24A View FIGURE 24 ; 26B View FIGURE 26 ). A pair of short dorsal ciliary bands (sdcb) present, as a transversal line, just placed posterior to each branchial base ( Fig. 26A, D View FIGURE 26 ). Ciliary bands absent on ventral side of body ( Fig. 26C View FIGURE 26 ). A short ridge (sr) present on mid-dorsal side of chaetigers in branchial region. A pair of skin folds (sf) present at each dorso-lateral side of chaetigers in pre- and branchial regions ( Figs 25E View FIGURE 25 ; 26 View FIGURE 26 A–B). Irregularly distributed cilia present on body ( Fig. 28 View FIGURE 28 E–F).

Branchiae numbering 16 pairs in holotype, 11–24 pairs in paratypes, starting in chaetiger 4 in all specimens; flattened, foliaceous with a rounded tip; branchial length usually shorter than segment width, becoming longer posteriorly; not elongated ( Figs 23A View FIGURE 23 ; 24A, C View FIGURE 24 ; 25B, C View FIGURE 25 ; 26B View FIGURE 26 ); branchial length / width 3.33–5; 232 μm long in anterior region, 318 μm long in middle region, 396 μm long in posterior region; dense ciliary band on both sides of branchiae.

Interramal lobes present between noto and neuropodia of chaetigers 1–14; as a rudimentary ridge in chaetiger 1, becoming thicker afterwards ( Figs 24 View FIGURE 24 A–C; 27G; 28A).

Notopodial papilla and ventral lobe absent ( Fig. 28A View FIGURE 28 ). Notopodial postchaetal lobes present in all chaetigers; short, digitiform, with a weak enlargement at base in first two chaetigers; stout, long, digitiform, with a weakly asymmetrical basal enlargement in branchial region; long, thin and filiform in posterior region; cilia present on notopodial lobes ( Figs 23A View FIGURE 23 ; 24 View FIGURE 24 A–C; 25D; 26A; 28A–B). Neuropodial postchaetal lobes present in chaetigers 1– 22; as short ridges on anterior chaetigers; getting stronger in branchial region; becoming as short ridges again in chaetigers 19–22 ( Figs 24 View FIGURE 24 A–C; 28A).

Lateral sense organs present between notopodia and neuropodia of all chaetigers, posterior to notopodial postchaetal lobes; with flexible cilia distinctly protruding from opening or embedded into pore ( Fig. 28 View FIGURE 28 C–D); elliptical with irregular clustered pores in prebranchial region to middle part of branchial region; straight lineshaped with regularly clustered pores in posterior part of branchial region to end of body ( Fig. 28 View FIGURE 28 A–F); with 40 pores in prebranchial region (long axis of organ: ca. 6–12 μm), with 40–60 pores (long axis: 12.5–17 μm) in anterior and middle part of branchial region, with 40–70 pores (long axis: 15–20 μm) in posterior part of branchial region, with ca. 60–100 pores (long axis: 25–34 μm) in posterior region.

Three types of chaetae present in chaetigers: limbate, capillary and modified neurochaetae. Limbate chaetae of two types; first type present only on notopodia of chaetigers 1–14, numbering 35–60, arranged in four rows, ca. 191 µm long, thin, and straight with fibrils along edge (hirsute), tapering to tip, ventral to dorsal in fascicle, light-rose in type specimens, dark reddish in Black Sea specimens; second type present only in neuropodia of chaetigers 1–14, numbering 48–60, arranged in three rows, ca. 177 µm µm long, more or less sigmoid shape with fibrils along edge (hirsute), dorsal to ventral in fascicle, light-rose color in type specimens, light reddish in Black Sea specimens ( Figs 23 View FIGURE 23 B–C; 26A–D; 27F–G; 28A–B).

Capillary chaetae starting in noto- and neuropodia of chaetiger 15 and present on all subsequent chaetigers; in middle notopodia numbering 8–10, arranged in 2–3 rows, 273 μm long; in posterior notopodia, numbering 6–9, arranged in one row, ca. 373 μm long; in middle neuropodia, numbering 12–20, arranged in two rows, ca. 230 μm long; in posterior neuropodia numbering 2–4, arranged in one row and ca. 369 μm long.

Modified neuropodial chaetae starting from chaetiger 34 (22–42 in paratypes) to posterior end, numbering 4–8 in each neuropodium, accompanied by capillary chaetae, brownish color in most specimens; hook-shaped, becoming subterminally thinner and with a round tip; pubescence on convex side of terminal and subterminal regions, with a long arista and terminal hairs; superior ones longer (about 169 μm) ( Figs 23 View FIGURE 23 D–E; 25F, H–I; 28G).

Pygidium missing.

Reproduction. Some specimens of Aricidea pseudoassimilis   n. sp. from the Sea of Marmara and Black Sea had sperm packages (two in each segment) within chaetigers from 27–32 to the end of the body. The gamete bearing specimens had red speckles near notopodia as well as two distinct additional red spots on the dorso-lateral sides and two small ones on the ventro-lateral sides of all chaetigers. In addition, a dashed red-line is present on the dorsal side of the chaetigers in the postbranchial region ( Fig. 25B View FIGURE 25 , E–G).

Most of the specimens collected in the Black Sea in 2019 were mature and presented additional reddish speckles on the body. Therefore, this coloration seems to be associated with the reproduction.

Remarks. Aricidea (Acmira) pseudoassimilis   n. sp. is mainly characterized by having a short, thick and digitiform antenna covered with dense cilia; by possessing interramal lobes between notopodia and neuropodia in the pre- and branchial regions; by its branchiae becoming longer towards the posterior part of the branchial region but without elongation of the tip; by the presence of small ridges on the mid-dorsal part of chaetigers; by having a pair of skin folds located in the dorso-lateral sides of each chaetiger; and by its modified neurochaeta with a rounded tip and long arista. The modified neurochaetae are distinctly amber coloured in the specimens of Aricidea pseudoassimilis   n. sp. collected from the Black Sea in 2019 ( Figs 25 View FIGURE 25 B–C, F–G). However, the specimens collected from the same locality in 2018 and from the Sea of Marmara lacked such coloration ( Fig. 25 View FIGURE 25 A–B).

The species morphologically most similar to A. pseudoassimilis   n. sp. are A. assimilis   , A. flava   and A. laubieri   . However, these species differ from each other in terms of the following characters: (1) Antenna: short, stout with a rounded tip, extending barely to the end of the prostomium in A. pseudoassimilis   n. sp.; slender, extending to the chaetiger 3 in A. flava   ; long, thin, with a rounded tip, extending to the mid-line of chaetiger 1 in A. laubieri   ; long, tapering to tip, extending to chaetiger 13 in A. assimilis   ; (2) Interramal lobes: present in A. pseudoassimilis   n. sp. and A. laubieri   ; absent in A. assimilis   and A. flava   ; (3) Branchiae: up to 21 pairs, getting longer but not elongated posteriorly in A. pseudoassimilis   n. sp.; 18 pairs, elongated posteriorly in A. flava   ; up to 27 pairs, last few pairs shorter in A. laubieri   ; 19 pairs and elongated posteriorly in A. assimilis   ; (4) Modified neurochaetae: with distal part becoming slightly thinner, a rounded tip and terminal and subterminal pubescence, bearing a very long arista and terminal hairs on the convex side of the tip in A. pseudoassimilis   n. sp.; with distal part getting slightly thinner, a rounded tip, and pubescence only on the convex side of the terminal part, lacking arista and hairs on the tip in A. flava   ; with distal part getting strongly thinner and bent upward, without pubescence, bearing a very long arista and terminal hairs on the convex side of the tip in A. laubieri   ; with distal part getting slighlty thinner and with undulate tip (curved at nearly 90°), having terminal and subterminal pubescence, bearing long terminal hairs on the tip in A.assimilis   .

Habitat and Distribution. This species was found in soft substrata between 10 and 100 m depths in the Sea of Marmara; between 11 and 70 m depths in the Levantine, Aegean, and Black Seas.

Etymology. The epithet pseudoassimilis   was selected due to morphological and habitat similarity with Aricidea assimilis   .

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Family

Paraonidae

Genus

Aricidea

Loc

Aricidea (Acmira) pseudoassimilis

Erdoğan-Dereli, Deniz & Çinar, Melih Ertan 2020
2020
Loc

Aricidea assimilis Laubier & Ramos 1974: 1117–1121

Laubier, L. & Ramos, J. 1974: 1121
1974