Laubieriopsis brevis ( Hartman, 1965 )
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publication ID |
https://doi.org/ 10.1080/00222933.2020.1757170 |
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persistent identifier |
https://treatment.plazi.org/id/EE1B9519-FF87-FFF9-FE6E-FF789C04FC7E |
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treatment provided by |
Carolina |
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scientific name |
Laubieriopsis brevis ( Hartman, 1965 ) |
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Laubieriopsis brevis ( Hartman, 1965) View in CoL
( Figures 1 View Figure 1 (c), 2(b), and 3(d–f); Table 1)
Material examined
4,023 specimens (45.81% of the total) collected in 77 samples ( Figure 1 View Figure 1 (c); Table 1).
Description of BIOICE specimens
Body elongated, blunt at each end, circular in transversal section ( Figure 3 View Figure 3 (d)); prostomium and peristomium usually retracted within CH 1–4. Specimens 2.0–8.0 mm long, 0.4–0.5 mm wide, with 16 chaetigers. Cuticle thin, transparent, with micropapillae mostly behind parapodia; intestine and oocytes visible by transparency. Three body regions: 1) anterior comprising prostomium, peristomium and CH 1–4, segments short and well delimited, with four unidentate aciculars per parapodium ( Figure 3 View Figure 3 (e)), two of them thick, straight, and two thinner, elongated and recurved (bidentate chaetae observed in smaller specimens); 2) median: CH 5–15, segments longer than in other body regions; each parapodial ramus provided with one thin, elongated capillary and one thicker acicular, notopodial chaetae longer than neuropodial ones ( Figure 3 View Figure 3 (f)); 3) posterior region comprising only CH 16 and pygidium, CH 16 bearing same chaetae as in middle region but acicular longer and bent backwards, surpassing posterior end; pygidium with three papillae only visible under SEM accompanied by a number of micropapillae. Intersegmental grooves gradually less conspicuous and eventually disappearing from CH 4 backwards. Parapodia biramous, lobes hardly developed. One interramal papilla in all chaetigers, spherical and hardly visible under stereomicroscope ( Figure 3 View Figure 3 (f)); papillae of similar size across body and slightly displaced towards notopodium. One pair of globose to verrucose genital papillae, located latero-dorsally at each side of CH 6 near posterior border ( Figure 3 View Figure 3 (d)).
Habitat and distribution
BIOICE material was collected in a wide range of depths (256–2,709 m) and bottom temperature (2.07–7.08ºC) ( Figure 2 View Figure 2 (b)). Most specimens were found in samples around southern Iceland ( Figure 1 View Figure 1 (c)) but their geographic distribution also reaches Westernfjords at NW Iceland and the southeast coasts. The shallowest samples were located from Reykjanes Peninsula and Vik to Vestman and Surtsey islands, while the deepest ones were found off the coast at SE and SW Iceland.
This species is apparently widespread in the Atlantic Ocean. In the North Atlantic, it has been reported from New England ( Hartman 1965; Hartman and Fauchald 1971) to the Gulf of Biscay ( Katzmann and Laubier 1974; Martínez and Adarraga 2012) and into the Mediterranean Sea ( Laubier 1972); there are also records from the Southern Hemisphere at abyssal depths ( Fiege et al. 2010; Thiel et al. 2011, as cf.) including the Sandwich Islands ( Levenstein 1975). Reports by Hartman (1978) in the Antarctic Ocean and Blake and Petersen (2000) from California need confirmation.
Remarks
Identification of BIOICE specimens followed descriptions and characters considered in Petersen (2000), Martínez and Adarraga (2012) and Salazar-Vallejo et al. (2019). Our observations confirmed the presence of one pair of genital papillae in CH 6. This supports the idea that L. hartmanae ( Levenstein, 1970) , traditionally considered a junior synonym of L. brevis , should be considered a valid species because it bears only an impaired papilla in that chaetiger. In fact, Thiel et al. (2011) and Salazar-Vallejo et al. (2019), these last reinstating the validity of this species, pointed out that L. hartmanae also differs from L. brevis in lacking bidentate acicular chaetae, and the last segment is provided with acicular chaetae not extending beyond pygidium when retracted.
BIOICE specimens showed a wide range of sizes but all had 16 chaetigers. However, Thiel et al. (2011) reported juvenile stages of 7–9 chaetigers, but such specimens were not found among our material. On the other hand, Zhadan and Salazar-Vallejo (2019) pointed out that L. brevis has a smooth cuticle and bears aciculars; on the contrary, BIOICE specimens have micropapillae behind the parapodia while bidentate chaetae are only present in small-sized individuals whereas larger specimens bear instead unidentate chaetae.
Petersen (2000) considered that L. brevis might correspond to a species complex after taking into account the discrepancies between available descriptions of type series and other material attributed to this species. However, Salazar-Vallejo et al. (2019) did not consider such possibility and characterised L. brevis against L. hartmanae according to the shape and number of genital papillae, and whether acicular chaetae are bidentate or not. In our opinion, further taxonomic morphological studies coupled with a molecular approach are needed to clarify this.
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