Eliberidens Wolf, 1986
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publication ID |
https://doi.org/ 10.1016/j.jcz.2022.09.006 |
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persistent identifier |
https://treatment.plazi.org/id/8D45878E-FF82-193C-FF28-E630FC30871F |
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treatment provided by |
Felipe |
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scientific name |
Eliberidens Wolf, 1986 |
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Genus Eliberidens Wolf, 1986 View in CoL (amended description).
Type species: Eliberidens forceps Wolf, 1986
28. Tip of the blade of compound 0: unidentate, 1: bidentate chaetae
Maxillae in four rows, each row with superior and inferior basal plates only, free maxillary plates entirely lacking. Maxillary rows fused posteriorly to very small and thin maxillary carries apparently fused to a posteriorly directed ligament. Palps and antennae similar to each other in size and shape, all simple, smooth and clavate/digitiform. Notopodia absent. Supra-acicular chaetae include simple, serrate, tapering capillary; geniculate with short distal end developing in a furcate chaetae with serration below the shorter prong. Sub-acicular chaetae compound, unidentate falcigers and occasional cultriforms replacing the ventralmost in last chaetigers.
29. Thin guard in the tip of compound 0: absent, 1: present chaetae
30. Distal end of shafts of compound 0: smooth, 1: serrated chaetae
31. Cultriform or simple chaeta 0: no, 1: yes replacing the ventralmost compound in last chaetigers
32. Fused teeth in the anterior margin of 0: absent, 1: present mandibles
33. Free teeth in the anterior margin of 0: absent, 1: present mandibles
34. Carriers (or carrier-like structures) 0: absent, 1: present
Comments: The specimens analyzed from MDBio ZUEC-POL are very similar to the type series deposited at the Smithsonian Institution and to the original descriptions ( E. forceps : Wolf, 1986a and Eliberidens hartmannchroederae : Hilbig, 1995). This study clarified the morphology of the geniculate chaeta with short distal end present in first parapodia, which develops in a furcate chaeta in the following parapodia and towards the posterior region; its morphology and development is not clearly mentioned in the original descriptions. The occasional presence of a cultriform chaeta replacing the ventralmost compound in last chaetigers was not mentioned in the original description, but it was observed in some paratypes and specimens from MDBio of both species; this characteristic is common in some genera of Dorvilleidae , such as
35. Margin of carriers (or carrier-like 0: smooth, 1: serrated structures)
36. Shape of superior basal plate 0: straight, 1: pincer-like shape, 2: L shape 37. Dentition on the margin of superior 0: absent, 1: present plate
38. Inferior basal plate 0: absent, 1: present
39. Shape of inferior basal plate 0: straight, 1: pincer-like shape, 2: L shape 40. Superior row of maxillary plates 0: absent, 1: present
41. Number of maxillary plates in 0: thirteen or less, 1: more than thirteen superior row
42. Inferior row of maxillary plates 0: absent, 1: present
43. Number of maxillary plates in 0: thirteen or less, 1: more than thirteen inferior row
Meiodorvillea ( de Oliveira Bonaldo et al., 2022) . These two characters were amended to the diagnosis of the genus.
3.1.1. Eliberidens forceps Wolf, 1986 ( Figs. 1 View Fig and 2 View Fig ).
3.1.1.1. Type locality. Cape Romano , Florida, United States of America, Atlantic Ocean. 25 ◦ 40 ′ N, 83 ◦ 50 ′ W. 120 m, mid fine sand. Aug 1977 GoogleMaps .
3.1.1.2. Type material examined. USNM 89575 About USNM (holotype) ; USNM 89574 About USNM (one paratype) .
3.1.1.3. Additional material examined. ZUEC-POL 21442 (1 spec) 22 ◦ 8 ′ 9331 ′′ S 40 ◦ 27 ′ 27,877 ′′ W, 65 m, 04 Jul 2009 ; ZUEC-POL 21443 (1 spec) 21 ◦ 9 ′ 9286 ′′ S 40 ◦ 16 ′ 7457 ′′ W, 103 m, 21 Jul 2009 ; ZUEC-POL 21444 (1 spec) 21 ◦ 23 ′ 2933 ′′ S 40 ◦ 15 ′ 9568 ′′ W, 140 m, 21 Jul 2009 .
3.1.1.4. Description of specimens from MDBio (ZUEC-POL). Complete specimens 2.5–6. 7 mm long, maximum width 0.27 mm and 41 to 71 chaetigers. Color in ethanol pale yellow. Width measurement usually uniform along the body.
Prostomium pear-shaped, as long as wide, anterior half depressed and rounded; posterior half wider and globular ( Fig. 1B and C View Fig ). Eyes absent. One pair of clavate antennae inserted dorsolaterally on the middle or posterior half of prostomium, 2/3 the length of prostomium ( Fig. 1B and C View Fig ). Pair of small and clavate palps inserted laterally in the posterior base of prostomium, 2/3 the length of antennae ( Fig. 1B and C View Fig ).
Two peristomial rings; posterior ring wider and longer than anterior, 2/3 length of prostomium ( Fig. 1C View Fig ).
Cylindrical parapodia, shorter and robust in anterior region ( Fig. 2A–C View Fig ). Dorsal cirrus absent. Small papiliform ventral cirrus, inserted medially in the parapodium, present in all parapodia, absent in the first ( Fig. 2A–C View Fig ).
Four classes of chaetae ( Fig. 2D and E View Fig ): Supra-acicular: (1) one long and serrated capillary, (2) one geniculate with small serrated distal end, resembling a furcate in development, present in the first three to five parapodia ( Fig. 2D.a View Fig ), (3) one thin and long furcate with asymmetrical prongs in shape and size replacing the geniculate; serrations along the shaft below the shorter prong ( Fig. 2D.b View Fig ). Sub-acicular: (4) three compound heterogomphs; dorsalmost with longer shaft and blades and ventralmost shorter; blade of dorsalmost falciger or spiniger; median and ventral falcigers; blades unidentate with serrated cutting edge; distal end of shafts serrated on one side ( Fig. 2E View Fig ). One internal thick acicula present ( Fig. 2B and C View Fig ).
Pygidium rounded and narrower than previous chaetigers. Two pairs of clavate pygidial cirri; dorsal pair longer than ventral.
3.1.1.5. Occurrence. Cape Romano , Florida, United States of America 08/ 1977, 120 m ; St. Petesburg , Florida, United States of America, Jun 1976, 189 m , very fine sand and lime ( Wolf 1986a). Southwest Atlantic Ocean , States of Espírito Santo and Rio de Janeiro, Brazil, 65–103 m.
3.1.2. Eliberidens hartmannschroederae Hilbig, 1995 ( Figs. 3–7 View Fig View Fig View Fig View Fig View Fig ).
3.1.2.1. Type locality. South of Cape Cod , Massachusetts, United States of America, Atlantic Ocean. 39 ◦ 54,32 ′ N, 70 ◦ 55,09 ′ W. 550 m. Jul 1986 GoogleMaps .
3.1.2.2. Type material examined. USNM 170558 About USNM (holotype) ; USNM 170559 About USNM (five paratypes) ; USNM 170560 About USNM (one paratype) .
3.1.2.3. Additional material examined. USNM 170577 About USNM (2 spec) 39 ◦ 54 ′ 16,920 ′′ N, 70 ◦ 55 ′ 1920 ′′ W, 554 m, 04 May 1985 ; ZUEC-POL 21431 (2 spec) 21 ◦ 55 ′ 7349 ′′ S, 39 ◦ 54 ′ 31,683 ′′ W, 996 m, 08 Feb 2009 ; ZUEC-POL 21432 (1 spec) 22 ◦ 19 ′ 2381 ′′ S, 40 ◦ 5 ′ 27,062 ′′ W, 383,8 m, 30 Jan 2009 ; ZUEC-POL 21433 (1 spec) 21 ◦ 45 ′ 54,791 ′′ S 39 ◦ 59 ′ 27,498 ′′ W, 1023.3 m, 26 Jun 2008 GoogleMaps ; ZUEC-POL 21434 (1 spec) 20 ◦ 14 ′ 17,95 ′′ S 39 ◦ 48 ′ 34,35 ′′ W, 395 m, mud, 19 Jun 2013 GoogleMaps ; ZUEC-POL 21435 (1 spec) 22 ◦ 19 ′ 10,211 ′′ S, 40 ◦ 5 ′ 42,884 ′′ W, 400 m, 10 Feb 2009 GoogleMaps ; ZUEC-POL 21436 (1 spec) 23 ◦ 37 ′ 57,453 ′′ S, 41 ◦ 19 ′ 41,936 ′′ W, 390,7 m, 01 Feb 2009 GoogleMaps ; ZUEC-POL 21437 (1 spec) 23 ◦ 39 ′ 20,559 ′′ S 41 ◦ 18 ′ 28,196 ′′ W, 701 m, 28 Jan 2009 GoogleMaps ; ZUEC-POL 21438 (2 spec) 21 ◦ 4 ′ 4,67 ′′ S, 40 ◦ 13 ′ 6,06 ′′ W, 415 m, mud, 08 Jun 2013 GoogleMaps ; ZUEC-POL 21439 (3 spec) 19 ◦ 45 ′ 55,39 ′′ S, 39 ◦ 30 ′ 25,74 ′′ W, 149 m, muddy, 15 Jan 2012 GoogleMaps ; ZUEC-POL 21440 (3 spec) 20 ◦ 35 ′ 15,33 ′′ S, 39 ◦ 53 ′ 45,22 ′′ W, 415 m, mud, 18 Jun 2013 GoogleMaps .
3.1.2.4. SEM material. ZUEC-POL 21441 (3 spec) (1 spec) 19 ◦ 45 ′ 55,39 ′′ S, 39 ◦ 30 ′ 25,74 ′′ W, 149 m, muddy, 15 Jan 2012; (1 spec) GoogleMaps 20 ◦ 14 ′ 17,95 ′′ S, 39 ◦ 48 ′ 34,35 ′′ W, 395 m, mud, 19 Jun 2013; (1 spec) 21 ◦ 11 ′ 12,228 ′′ S, 40 ◦ 12 ′ 51,745 ′′ W, 683 m, 04 Feb 2009.
3.1.2.5. Description of specimens from MDBio (ZUEC-POL). Complete specimens 1.4–5. 3 mm long, maximum width 0.25 mm and 24 to 50 chaetigers. Color in ethanol pale yellow. Width measurement usually uniform ( Fig. 3A View Fig ).
Prostomium pear-shaped, as long as wide, anterior half depressed and rounded, posterior half wider and globular ( Figs. 3B View Fig and 4A, B View Fig ). Eyes absent. Pair of clavate antennae inserted dorsolaterally in the posterior half of prostomium, 1/3 to 1/2 the length of prostomium. Pair of clavate palps inserted laterally in the posterior base of prostomium, 1/ 2 to 2/3 the length of antennae ( Figs. 3B View Fig and 4A, B View Fig ).
Two short apodous peristomial rings; posterior ring wider and longer than anterior and sometimes covering it up in dorsal view ( Figs. 3B View Fig and 4A, B View Fig ).
Cylindrical parapodia ( Figs. 3C View Fig and 5 View Fig ); shorter and stouter in the anterior region. Dorsal and ventral cirri absent ( Fig. 5 View Fig ).
Five classes of chaetae ( Fig. 6 View Fig ): Supra-acicular: (1) one long and serrated capillary, (2) one geniculate chaeta with small serrated distal end, resembling a furcate in development present in the first five parapodia ( Fig. 6A, E View Fig ), (3) one thin and long furcate with asymmetrical prongs in shape and size replacing the geniculate; serrations along the shaft below the shorter prong ( Fig. 6B, E View Fig ). Sub-acicular: (4) three compound heterogomph; dorsalmost compound with longer shaft and blades and ventralmost shorter; blade of dorsalmost falciger or spiniger; blades unidentade with serrated cutting edge, distal end of shafts serrated on one side ( Fig. 6D, F View Fig ) and (5) cultriform chaeta with serrated cutting edge replacing the shorter and ventralmost compound chaeta in last chaetigers ( Fig. 6C View Fig ). One internal thick acicula present ( Fig. 5B and C View Fig ).
Pygidium rounded and narrower than previous chaetigers. Two pairs of clavate pygidial cirri; one dorsal pair up to 2x the length of pygidium; ventral pair the length of pygidium ( Fig. 3A, D View Fig , 4C, D View Fig ).
Ventral mandible in butterfly shape without free or fused dentition in anterior and cutting edge; anterior region broad and rounded; posterior region slender; distal part weakly sclerotized; proximal inner region strong sclerotized ( Fig. 7 View Fig ). Maxillae composed by denticulated basal plates in L shape fused in a posterior ligament; maxillary plates absent ( Fig. 7 View Fig ).
3.1.2.6. Remarks. Eliberidens hartmannschroederae differs from its congener by the total absence of ventral cirrus.
3.1.2.7. Occurrence. Atlantic Ocean, South of Cape Cod , Cape Fear and Cope Lookout (USA), 255–1550 m deep, Jul 1984 to Jul 1986 ( Hilbig 1995). Southwestern Atlantic Ocean, States of Espírito Santo and Rio de Janeiro ( Brazil), 103–1023. 3 m, mud, muddy, muddy sandy .
3.2. Cladistic analysis
The phylogenetic study resulted in one most parsimonious cladogram, through 47,139 rearrangements examined, with length of 74 steps, consistency index (ci) of 77% and retention index (ri) of 88% ( Fig. 8 View Fig ). The genus Eliberidens resulted as monophyletic supported by two synapomorphies: the presence of a geniculate chaeta with short distal end in the first parapodia (character 21) and the absence of maxillary plates of superior row (character 40).
The genus Meiodorvillea resulted as monophyletic supported by the synapomorphy of the absence of dentition on the basal plate (character 37), while the monophyly of Pettiboneia was supported by two synapomorphies: long digitiform dorsal cirri (character 11) and the absence of maxillary carrier-like structure (character 34). Protodorvillea also resulted as monophyletic group supported by three synapomorphies; i) palps longer than the second chaetiger (character 7), ii) the presence of dorsal cirrus in the first parapodium (character 8) and the iii) dorsal cirrus positioned distally in the parapodium (character 13). The monophyly of Dorvillea was also supported by three synapomorphies, among them the presence of only capillary chaeta in the supra-acicular fascicle
(character 21 and 23). Schistomeringos was the only genus in which the monophyly was not recovered.
The presence of antennae and palps (characters 3 and 5, respectively) are the two synapomorphies placing Eliberidens as a sister group of all other species of dorvilleids presented in this study, except Gymnodorvillea floridana . Schistomeringos and Dorvillea form a clade supported by the biarticulated shape of dorsal cirri (character 11). Protodorvillea form a clade with Schistomeringos and Dorvillea which is supported by five synapomorphies, among them: presence of dorsal cirrus in following parapodia in median and posterior region (character 10), blades of compound chaetae with bidentate tip (character 28), presence of free teeth in the anterior margin of mandibles (character 33) and the presence of inferior row of maxillary plates (character 42).
The two Pettiboneia species, that originally were included in the outgroup, fell into the ingroup and as sister group of the clade formed by Protodorvillea , Schistomeringos and Dorvillea . Furthermore, the monotypic genus Marycarmenia was placed as a sister group of the clade formed by Pettiboneia , Protodorvillea , Schistomeringos and Dorvillea by sharing two synapomorphies, biarticulated shape of palps (character 6) and the presence of fused teeth in the anterior margin of the mandible (character 32). Meiodorvillea was placed as the sister group of the clade composed by Marycarmenia , Pettiboneia , Protodorvillea , Schistomeringos and Dorvillea .
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