Labrorostratus prolificus Amaral, 1977
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publication ID |
https://doi.org/ 10.1080/00222930903219988 |
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persistent identifier |
https://treatment.plazi.org/id/625387E4-6C1A-FFAC-95FD-CE260935FF08 |
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treatment provided by |
Felipe |
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scientific name |
Labrorostratus prolificus Amaral, 1977 |
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Labrorostratus prolificus Amaral, 1977 View in CoL
( Figures 1–2 View Figure 1 View Figure 2 ; Table 1)
Labrorostratus prolificus Amaral, 1977, p. 285 View in CoL , figures 1–8.
Material examined
Araçá Beach , São Sebastião Channel, State of São Paulo, Brazil, 45°24′28″W; 23°48′55″S, August 1996, intertidal; 1–10 setigers: ZUEC-POL-1886 (4 specimens), ZUEC-POL-1887 (4 specimens), ZUEC-POL-1888 (4 specimens), ZUEC-POL-1889 (4 specimens), ZUEC-POL-1890 (8 specimens); 11–30 setigers: ZUEC-POL- 1891 (4 specimens), ZUEC-POL-1892 (5 specimens); 31–45 setigers: ZUEC-POL-1893 (3 specimens), ZUEC-POL-1894 (4 specimens). Slides: ZUEC-POL-2174 (14 specimens, in different stages), ZUEC-POL-2173 (3 specimens, 11–30 setigers), ZUEC-POL-2172 (1 specimen, 3 setigers) GoogleMaps .
Material used for SEM: (2 specimens, in different stages). Additional material: 3 slides with jaws (ZUEC-POL-2174A1, ZUEC-POL-2174A2, ZUEC-POL-2174A3), 2 slides with parapodia (ZUEC-POL-2174A4, ZUEC-POL-2174A5).
Host: Perinereis cultrifera (Grube 1840) – ZUEC-POL-824. Complete female specimen, 46 mm long, 3 mm wide, 105 setigers.
Description
Body without evident pigmentation. Smallest specimen 285 µm long, 122 µm wide, three setigers ( Figure 1A View Figure 1 ). Largest specimen 3330 µm long, 495 µm wide, 45 setigers.
Stage 1 (1–10 setigers). Eyes, jaws, aciculae and setae absent. Prostomium compressed dorsoventrally, with rounded anterior end in specimens with three setigers ( Figure 1A View Figure 1 ), and others with a triangular shape ( Figure 1B and C View Figure 1 ). First peristomial ring fused to prostomium ( Figure 1D View Figure 1 ); second ring well-defined, shorter than (in specimens with more than four setigers) or as long as (in specimens with three to four setigers) the first setigers. Body slightly flattened dorsoventrally, wider in setigers where parapodia are larger. Setigers with one pair of broad triangular parapodia, without distinct pre- and post-setal lobules ( Figure 1D View Figure 1 , arrow), well developed in the first setigers and reduced near the pygidial region. Cylindrical pygidium, as long as the prostomium, without pygidial cirri.
The only distinguishable peristomial ring is the second; the first peristomial ring is fused to the prostomium ( Figure 1D View Figure 1 ). At the end of this stage, while new setigers are added in the pre-pygidial zone, only the parapodia of the first setigers grow, and it is possible to observe the beginning of the differentiation between the pre- and post-setal lobules. Aciculae of the first setigers begin its development at the end of this stage.
Stage 2 (11–20 setigers). Anterior end cylindrical, with the posterior third of the body without evident parapodia, tapering abruptly ( Figure 2D View Figure 2 ). Prostomium triangular; eyes and setae not evident. First peristomial ring well defined, distinct from prostomium in specimens with more than 15 setigers, being as long as the second ring. A rudimentary jaw is present ( Figure 2D View Figure 2 ). Specimens with 18–20 setigers with one aciculum only on the first 3 pairs of parapodia.
The post-setal lobe is developed in the first setigers, but is inconspicuous in the posterior region. The median parapodia are well developed, but aciculae are absent. The last 5–10 setigers are very short and narrow, and without apparent parapodia. In general, the body is narrow where there are no well-developed parapodia.
Stage 3 (21–30 setigers). Anterior end of the prostomium rounded, inflated dorsoventrally. Beginning of formation of lateral pair of eyes. Setae apparently absent.
At the beginning of this stage, the aciculae of median and posterior parapodia appear more rapidly, and most of the parapodia already have evident acicula.
Stage 4 (31–40 setigers). Second pair of eyes (inner pair) well developed ( Figure 2E View Figure 2 ). Maxillae and mandibles easily visible and well formed. Parapodia of anterior region uniform in size; post-setal lobule conical, and pre-setal lobule truncate. One neuropodial aciculum and one short, simple, limbate geniculate seta present on each parapodium of the first 5–15 setigers.
Stage 5 (41–45 setigers). Prostomium as wide as long. Two pairs of reddish eyes, inner pair shorter and more superficially located. Peristomial rings as long as the following setigers ( Figure 1E View Figure 1 ). Body uniform in width, tapering near pygidial region. Sub-biramous parapodia, notopodium with a very short papilla and one internal aciculum. Neuropodium of the first setigers with rounded pre-setal and conical postsetal lobule ( Figure 2A View Figure 2 ), with one aciculum and one to two simple limbate capillary setae with a serrated blade ( Figure 2B View Figure 2 ). Jaws amber-coloured, with flat and slender paired mandibles. Maxillae with one pair of broad maxillary plates, attached to a single, elongated basal support, almost twice as long as the maxillae ( Figure 2E View Figure 2 ).
Remarks
Some specimens with about 30–40 setigers have eyes, whereas others with the same number of setigers have none. Some individuals with three to 30 setigers have a clearly delimited longitudinal area in the median portion of the prostomium, which can be seen under SEM observation ( Figure 1D View Figure 1 ).
A peculiar characteristic in specimens with three to 15 setigers is the fusion of the first peristomial ring with the prostomium. This aspect has not been described previously in oenonids. In these specimens, the parapodia of the anterior region are a simple triangular projection, without differentiation into pre- and post-setal lobules ( Figure 1D View Figure 1 , arrow). The lobules begin to appear together with the arising of the aciculum; that is, lobules are present where aciculae are being formed.
Discussion
Information on length and width variation of specimens in their different stages is given in Table 1. In this study we found individuals with up to 45 setigers, and more than 50% had between three and 10 setigers. The specimens collected by Amaral (1977) had between 17 and 65 segments, which indicates that the host was in a more advanced stage of infection ( Figure 3 View Figure 3 ).
Amaral (1977) found stolons only in specimens with about 65 setigers. In this study we found specimens in different stages with stolons, with the highest frequency in individuals with 21–40 setigers ( Table 1). Because of this, and considering that the pygidium of these polychaetes is a simple cylinder, it is possible that the specimens with fewer than 65 setigers that were studied by Amaral (1977) also had stolons beginning to form, as in Figures 2D and E View Figure 2 .
Even though there is no pygidial cirrus in worms with up 45 setigers, one pair of small cirri is present in longer individuals, as in Figure 2C. View Figure 2
A large number of gametes (possibly oocytes) 240 µm in diameter was found in the coelomic cavity, mainly in the posterior half of the host’s body. Emerson (1974) described a species of the genus Arabella in the coelomic cavity of Diopatra ornata , which was completely full of eggs. According to the author, the parasites feed on the eggs to grow, and consequently come to occupy less space in the coelom. The youngest worms, without developed jaws, feed on coelomic fluid.
In this study, both young and adults occupied the anterior half of the host’s body, and no specific location was noted for each stage, as mentioned by Amaral (1977), who found young specimens (with about 17 setigers) in the anterior region and adults (with 50 setigers) in the median region.
Distribution
Atlantic Ocean: Brazil (State of São Paulo).
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.
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Labrorostratus prolificus Amaral, 1977
| Steiner, Tatiana M. & Amaral, Antonia Cecília Z. 2009 |
Labrorostratus prolificus
| Amaral ACZ 1977: 285 |