Ophryotrocha zitae, Miranda & Rodrigues & Brasil, 2020
|
publication ID |
https://doi.org/ 10.11606/1807-0205/2020.60.13 |
|
publication LSID |
lsid:zoobank.org:pub:C63BE5C4-A213-4E78-82A4-16B22681A888 |
|
DOI |
https://doi.org/10.5281/zenodo.4420257 |
|
persistent identifier |
https://treatment.plazi.org/id/F6B156C2-017C-4B11-9325-006C409A457B |
|
taxon LSID |
lsid:zoobank.org:act:F6B156C2-017C-4B11-9325-006C409A457B |
|
treatment provided by |
Carolina |
|
scientific name |
Ophryotrocha zitae |
| status |
sp. nov. |
Ophryotrocha zitae View in CoL sp. nov. ( Figs. 1‑2 View Figure 1 View Figure 2 )
Type material: Holotype: MNRJP2601 : 1 specimen (adult); 24°21′27ı19″S; 44°13′20ı95″W; 245 mı 27 July 2010; on Lophelia pertusa . Paratypes: MNRJP2602: 10 specimens (adult); 24°21′27ı19″S; 44°13′20ı95″W; 245 mı 27 July 2010; on Lophelia pertusa . MNRJP2603: 4 specimens (3 juveniles and 1 larva); 24°21′27ı19″S; 44°13′20ı95″W; 245 mı 27 July 2010; on Lophelia pertusa .
Non‑type material: MNRJP2604: 59 specimens; 24°21′27ı19″S; 44°13′20ı95″W; 245 mı 27 July 2010; on Lophelia pertusa .
Diagnosis: K‑maxillae comprising a heavily‑sclerotized main fang and seven partially fused plates; P‑maxillae consisting of seven rounded platesı two of them fused and five only partially fused. Uniramous parapodia with a bundle of capillary chaetae occurring only on the supra‑acicular region. Sub‑acicular region possessing a bundle of heterogomph falcigers with slightly serrated blades and single capillary chaeta. Rosette glands from segment eleven on.
DESCRIPTION
Measurements: Holotype: 3.5 mm longı 0.8 mm wide; Paratypes: mean size: 1.8 mm longı 0.5 mm wide (largest specimen 4.20 mm longı 0.9 mm wide; smallest specimen 0.65 mm longı 0ı 22 mm wide).
Body short (holotype with 24 segments)ı stoutı dorsally convexı ventral region flattenedı with longitudinal groove. Both ends are terminally rounded ( Figs. 1 View Figure 1 A‑B). Bundles of cilia present throughout body. On the prostomium these form a frontal bundle with tufts between the antennae and the eyes ( Figs. 1 View Figure 1 A‑C)ı while complete rings of cilia occur on each peristomial segment and on the pygidiumı whereas remaining segments possess a dorsal and a ventral bundle of cilia separated by the parapodia ( Figs. 1 View Figure 1 A‑Bı for dorsal bundle). Fixed specimens with an opaque pale white color ( Fig. 1B View Figure 1 ).
Prostomium wider than longer ( Figs. 1 View Figure 1 A‑C). Anterior border with up to 10 tactile cilia. Cirriform antennae inserted dorsolaterallyı with a tuft of stereocilia on the apex ( Fig. 1C View Figure 1 ). Palps digitiformı stoutı inserted laterally on the prostomium ( Fig. 1C View Figure 1 ). A pair of eyes is located posteriorlyı near the edge of the first peristomial segmentı eyes exhibiting a silver coloration under oblique illumination ( Fig. 1B View Figure 1 ). Nuchal organs consisting of a pair of ciliate tufts located just after and between the eyes. Peristomial segments achaetousı with a translucid region on the dorsum from which it is possible to observe the buccal apparatus (mandible and maxillae) ( Figs. 1 View Figure 1 A‑C). Mouth largeı aperture half the size of segment widthı located anteriorly on the first segment.
The K‑maxillae are fully developedı composed of two black to dark brown forceps with single tipsı united at the posterior end ( Figs. 1 View Figure 1 Dı 2A). The light brown carrier‑like structure is connected to the forceps by narrow ligaments – with basal lateral sheets – that arise from the posterior half of the forceps and connect to the first of the articulated denticles ( Figs. 1 View Figure 1 Dı 2A). This carrier‑like structure is composed of seven spoon‑like denticlesı which become larger from the first to the last; the cutting edges of the first to third denticles are coarsely serratedı with the teeth alternating in size (the larger ones about twice the size of the smaller ones)ı while the cutting edges of the fourth to seventh denticles are finely serrated with all teeth of similar size ( Fig. 2A View Figure 2 ).
Mandibles are elongated sclerotized shaftsı dark brown in color at the center and becoming translucent towards the edgesı located ventrally to the maxillae ( Figs. 1 View Figure 1 Dı 2B). Anterior edges of mandibles representing the cutting plates with about 20 very small and worn teeth; apophysis emerging postero‑ventrally to the cutting plateı three times the width of same at the largest region and becoming narrow posteriorly; shafts longer than wide with posterior apex ending on a bend towards the middle of the body; light brown internal lateral projections present subdistally.
Chaetigerous segments without lobes protruding towards parapodia. Rosette glands occurring from the eleventh segment – in which they occur only on the right side – to the end of the bodyı where they are so small that they are difficult to observe without staining ( Fig. 1A View Figure 1 ). Body tapering posteriorly. Pygidium bearing a pair of ventral cirriı pygidial stylus absent. Anus terminal and located dorsal to the cirri ( Figs. 1 View Figure 1 A‑B).
Parapodia uniramousı with triangular (on anterior segments) to rounded (on posterior segments) pre‑chaetal lobes longer than post‑chaetal onesı with both dorsal and ventral smooth cirri present ( Fig. 2C View Figure 2 ); retractile lobes on the posterior side of parapodia and almost imperceptible in the specimensı supported by a single smooth
Note:since O.lukowensis Szaniawski,1974 is known only by its fossil record and a large amount of data is not available,it has not been included in this comparison.
chaeta.Three groups of chaetae emerge from the parapodia: a bundle of three to four simple chaetae supra‑acicular; and another bundle of three to four heterogomph falcigers emerging right below the acicula( Fig.2C View Figure 2 );below the bundle of compound chaetae there is a single simple chaetaeı similar to those of the supra‑acicular bundle. The shafts of compound chaetae smooth ( Fig. 1E View Figure 1 ); internal border of the blades slightly serrated and presenting a small terminal concavity ( Figs. 1 View Figure 1 E‑Fı 2D‑G)ı which becomes more prominent on posterior segments. Upper compound chaetae ( Figs. 2D and F View Figure 2 ) with blades longer than those below ( Figs. 2E and G View Figure 2 )ı also the blades in the chaetae of the anterior parapodia ( Figs. 2 View Figure 2 D‑E) are longer than those in the posterior parapodia ( Figs. 2 View Figure 2 F‑G).
Juvenile: Specimens resembling adultsı with six chaetigers ( Fig. 1G View Figure 1 ). Prostomium rounded and wider than longı with a tuft of cilia at the anterior border and another tuft – forming a complete ring around the prostomium – posterior to this and anterior to the eyes. Antennae not observed. A pair of digitiform palps emerging laterally to the prostomiumı each with a tuft of three stereocilia at the apex. A pair of light brown eyes situated on the posterior half of the prostomium. Nuchal organs present posteriorly to the eyes. Following the prostomium are two achaetous segmentsı each with a tuft of cilia forming a complete ring around them.
Mouth located at the anterior border of the first peristomial segment. Mandibles are like those in the holotype. Maxillae of P2 typeı with a dark amber color. Forceps with a curved distal fang double the size of oth‑ er teeth; anterior half coarsely serrated; posteriorlyı the forceps are fused forming a shaft ( Fig. 2H View Figure 2 ). Carrier‑like structure composed of seven pairs of partially articulat‑ ed denticlesı the first three pairs of which are coarsely serratedı and the other four pairs finely serrated and with a major fang on the external margin of the serrated border.
Chaetigerous segments as described for the holotype. Pygidium with two long smooth cirriı one on either side of the terminal anus. A bulbous structure (a remaining of pygidial stylus) is present dorsally to the anus ( Fig. 1G View Figure 1 ).
Larva: Among the specimens analyzedı a single larva was found. The specimen has only three achaetous segments (3.01 μm long; 0.5 μm wide) ( Fig. 2I View Figure 2 ). The prostomium is rounded and without palps or antennae but with a pair of dark eyes located posteriorly; two ciliary tufts circle the prostomium (one near the anterior border and another at the middle region) ( Fig. 2I View Figure 2 ). A pair of Y‑like mandibles located on the first segment; cutting edges with 20 prominent teeth (the second external‑most one twice the size of the remaining teeth and this feature was observed only in the larva); teeth located internally curved towards the external margin while those located externally are curved towards the interior; shafts small with narrow lateral expansions ( Fig. 2J View Figure 2 ). P1‑maxillae presentı amber to brown in color and composed of four pairs of plates; first pair longer than the others and with their internal borders coarsely serrated (alternating larger and smaller teeth); remaining plates ovate (in the observed specimenı the second left plate is only half the size of the one on the right)ı internal borders serrated (alternating larger and smaller teeth on second and third platesı but teeth all the same size on the fourth plate). Remaining segments apodousı with two to three capillary chaetae emerging directly from the body wall; ciliary tufts completely encircling the segments ( Fig. 2I View Figure 2 ). Pygidium bearing a pair of terminal pygidial cirrus and a dorsal pygidial stylus – the stylus having an annulation medially and double the size of the cirri – both located anteriorly to the terminal anus and both bearing a tuft of stereocilia at the apex ( Fig. 2I View Figure 2 ).
Etymology: The species name is a tribute to the grandmother of the author A.C.S. Brasilı Maria Teresa dos Santos (known as Dona Zita): a strong womanı who exhibited the same devoted care to her descendants as seen for many species of this genus.
Habitat: The specimens were found in a depth of 245 mı in association with the cold water coral Lophelia pertusa .
Type locality: Southwest Atlanticı Santos Basinı off the state of São Pauloı Brazil.
Remarks: The 75 currently‑assigned species to the genus Ophryotrocha can be divided into three groups according to the morphology of the maxillae in adults: one encompassing the species in which adults bear P‑maxillaeı another in which the adults present K‑maxillae with both fangs of the forceps as single tipsı and a last group that also bear K‑maxillae but with at least one of the fangs being bidentate. Based on this categorizationı O. zitae sp. nov. ı falls into the group in which both fangs are unidentate. The 20 species of the second group of Ophryotrocha that have unidentate forceps are partially compared in Table 1 View Table 1 ı and those that most resemble O. zitae sp. nov. ı are: O. adherens Paavoı Bailey‑Brock & Åkessonı 2000 ı O. eutrophila Wiklund et al., 2009 ı and O. puerilis Claperède & Metschnikowı 1869 .
The morphology and ornamentation of the palps are distinguishing characters among O. zitae and the other three species. In O. zitae the palps are digitate and smoothı while O. adherens and O. puerilis have ovate palps with a tuft of cilia at the apexı and O. eutrophila have digitate palps.
Nuchal organs appear in different numbers among O. zitae , O. adherens and O. puerilis . The former has only a pair of nuchal organs located posteriorly on prostomiumı while the other two species possess two pairs of nuchal organs.
The third pygidial stylus is a character described as present only on juveniles of Ophryotrocha , while adults lacks this structure ( Paavo et al., 2000). However O. adherens , O. puerilis and O. eutrophila are all described as possessing a third stylusı while all mature specimens of O. zitae sp. nov. observed do not possess it. The occurrence of such structure in mature specimens and among the other species of Ophryotrocha needs to be verifiedı in order to confirm the statement of Paavo et al. (2000). Herein we assume that the presence of the third pigidial stylus in mature specimens is a distinguishing character among species of the genus.
In addition to the characters compared in Table 1 View Table 1 ı O. adherens differs from O. zitae sp. nov. ı by having an acicula that may emerge from within the fleshı and by the bifurcation at the tip of the supra‑acicular chaetae. In O. adherens some of the compound chaetae may occur in the ventral setal lobe (which does not occur in O. zitae sp. nov.).
In relation to O. puerilis , we can point out the presence of tactile cilia at the anterior border of the prostomium of this speciesı while cilia at this region is absent in O. zitae sp. nov. Alsoı the absence of a tuft of cilia on the apex of the dorsal and ventral parapodial cirri in O. zitae sp. nov. ı in comparison with the presence of such ciliation in O. puerilis . The number of prostomial ciliary bands differ between both species: O. zitae sp. nov. ı has only a single band of ciliaı while O. puerilis has two bands of cilia.
In relation to O. eutrophila the absence of eyes is a distinguishing characterı while O. zitae sp. nov. ı possesses eyes. Parapodial cirri and retractile lobe contrast between both speciesı in O. eutrophila the cirri (dorsal and ventral) are smallerı while the retractile lobe is longerı in comparison with the same structures in O. zitae sp. nov. Morphology of the teeth in the P‑type maxilla also differ between both species: the teeth in the cutting border of the D1 and D2 of O. eutrophila are longer than those in O. zitae sp. nov. ı also the D3 to D7 plates in O. eutrophila are longer and wider than in O. zitae sp. nov.
Species of Ophryotrocha have been described worldwideı but there are only three records of the genus from the South Atlantic: a non‑identified species from northeastern Brazil ( Cunha et al., 2013)ı and O. claparedei Studerı 1878 and O. notialis (Ehlersı 1908) both from Argentina (Orensanzı 1973ı 1990)ı none of them resembling O. zitae sp. nov. While both Argentinian species have P‑type maxillae onlyı the species described herein changes the P‑type maxilla for a K‑type along its development. Orensanz (pers. comm.) also identified some specimens of O. puerilis from an aquarium at Mar del Plata (Northern Argentina)ı but according to him the specimens present some differences from the original description provided by Claperède & Metschnikow (1869) ı so until these specimens are re‑examined we prefer to avoid comparisons.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.