Thelepodidae Hessle, 1917
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publication ID |
https://doi.org/ 10.5852/ejt.2021.782.1593 |
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publication LSID |
lsid:zoobank.org:pub:510DE23F-4CE5-4DDF-B1E7-CA8346AA4F5F |
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DOI |
https://doi.org/10.5281/zenodo.5784398 |
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persistent identifier |
https://treatment.plazi.org/id/03A4A269-792D-610C-1B63-F9248A6D6064 |
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Felipe |
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Thelepodidae Hessle, 1917 |
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Family Thelepodidae Hessle, 1917
Figs 1F View Fig , 3–4 View Fig View Fig
Diagnosis (after Hutchings et al. 2021a, most important diagnostic characters highlighted in bold)
Transverse prostomium attached to dorsal surface of upper lip; basal part as thick crest, eyespots frequently present, in short lateral rows, or extending transversely across basal part of prostomium, usually progressively more spaced towards dorsal mid-line, with mid-dorsal gap or not; distal part of base of upper lip short, from nearly indistinct to shelf-like. Buccal tentacles all uniformly thin and cylindrical, to slightly spatulate distally ( Figs 3D, F View Fig , 4B View Fig ). Peristomium forming lips, sometimes also complete annulation, with dorso-lateral nuchal organs as ciliated grooves; lips expanded, relatively short upper lip, hood-like, about as long as wide; swollen, button-like, mid-ventral lower lip ( Figs 3D, F View Fig , 4B–C View Fig ). Segment 1 usually present all around, frequently with ventral lobe marginal to mouth ( Figs 3D, F View Fig , 4B–C View Fig ); SG II typically with anterior margin as protruding crest, at least ventrally ( Figs 3D–E View Fig , 4B–C View Fig ); lobes on following anterior segments sometimes present. Anterior segments highly glandular ventrally, smooth to highly corrugated between neuropodia within pairs, discrete shields absent ( Figs 3D F View Fig , 4B View Fig ); mid-ventral groove frequently extending from anterior segments with notopodia. Two to three pairs of branchiae, on SG II–III or II–IV, each pair with simple thin, curled and relatively short filaments progressively tapering to tips ( Figs 3C, E View Fig , 4C View Fig ), leaving mid-dorsal gap or not between filaments within pairs; branchial filaments originating directly from the body wall or from specialised dorsolateral cushion-like pads. Notopodia beginning on SG II–III, usually extending to mid-body, at least, sometimes until near posterior end; cylindrical to rectangular, distally bilobed notopodia, notochaetae originating between lobes; most taxa with winged notochaetae only, with wings of variable width ( Fig. 4D View Fig ), distally serrated notochaetae sometimes also present; bayonet-like and pinnate chaetae both absent. Neuropodia beginning posteriorly to notopodia, on SG IV–VI, typically on SG V; neuropodia in conjunction with notopodia as fleshy, swollen ridges, as raised rectangular to cylindrical pinnules after notopodia terminate; neurochaetae as avicular uncini frequently longer than high, with short triangular heel directed posteriorly, distinctly curved and wide base, and dorsal button near anterior margin of uncini, or within anterior third of distance between anterior margin of uncini and base of main fang ( Fig. 4F View Fig ). Nephridial and genital papillae usually present, on SG IV–VII, posterior to bases of notopodia or between parapodial lobes ( Fig. 3C View Fig ).
Remarks
A comprehensive phylogenetic analysis conducted by Nogueira et al. (2013) permitted the elevation of the previous Thelepodinae subfamily to Thelepodidae family level, as they represented a separate clade from other terebellids. This family is represented in European waters by three genera Euthelepus McIntosh, 1885 (a single species), Streblosoma Sars, 1872 (seven species) and Thelepus Leuckart, 1849 (nine species) ( Table 1 View Table 1 ). Among these species, Thelepus japonicus Marenzeller, 1884 , native from Japan, is considered as a non-indigeneous species in French waters, probably introduced with oyster transfers ( Lavesque et al. 2020a) ( Fig. 3C View Fig ).
Main morphological characters of European species
BRANCHIAE. Both in Thelepus and Streblosoma genera, the number of pairs of branchiae varies between two (e.g., Streblosoma lindsayae or Thelepus nucleolata ) and three (e.g., Streblosoma hutchingsae or Thelepus setosus ). Branchiae in Thelepodidae are always cirriform ( Figs 3C, E View Fig , 4C View Fig ) but the number of branchial filaments varies among the species with for example 5–10 filaments on the second and third pairs of branchiae for Streblosoma cabiochi ( Fig. 3E View Fig ) and only three or less filaments for Streblosoma intestinale . Finally, the size of the medial dorsal gap separating the pairs of branchiae is a good diagnostic character. This gap is for example inconspicuous for T. parapari and wide for Thelepus cincinnatus ( Nogueira 2019) .
PRESENCE OF EYESPOTS. The eyespots are very useful in differentiating species of Streblosoma and Thelepus for which they can be absent (e.g., Thelepus davehalli or Streblosoma hutchingsae ) or present (e.g.m Thelepus corsicanus or Streblosoma nogueirai ). Also, the arrangement of the eyespots, if in a continuous line, or leaving a medial gap is of taxonomic importance ( Nogueira et al. 2010).
START AND EXTENSION OF NOTOPODIA. The segment with the first appearance of notopodia permits the discrimination between the genus Streblosoma , for which notopodia begin on the second segment, and Euthelepus and Thelepus for which it begins on the third segment. These notopodia also extend for a variable number of segments, sometimes present only on the anterior half of the body (e.g., T. corsicanus ) or present until the end of the body ( T. japonicus ).
SHAPE OF NEUROPODIA AND UNCINI. In most of the species, the uncini start on SGV which could correspond to CH 3 (as in Thelepus ) or CH 4 (as in Streblosoma ). The uncini are arranged habitually in single rows but some have uncini forming loops (C-shaped arrangement) from mid thorax onwards. This last character is found for example in S. nogueirai . Between species, the uncini differ in the development of the prow (e.g., well developed in T. triserialis ), the shape of the base (e.g., strongly curved in S. cabiochi ), the position of the dorsal button (e.g., far from anterior margin in S. bairdi or in a terminal position for T. japonicus ( Fig. 1F View Fig ) and number of secondary of teeth.
CREST AND LATERAL LOBES. The presence of lateral lobes on SG II–IV allows the separation of the genus Euthelepus from other genera of the family. The presence of lateral crests on SG II (= thick anterior margin) is an important character within the Streblosoma genus. For example, S. cabiochi has a very low crest on SG II ( Fig. 4C View Fig ) while S. bairdi has a protruding crest ( Nogueira 2019).
Key to European species of Thelopodidae (after Lavesque et al. 2020a)
1. Notopodia from SG II (i.e., first branchiferous segment), start of uncini from CH 4 ......................... ....................................................................................................................................2 ( Streblosoma View in CoL )
– Notopodia from SG III (i.e., second branchiferous segment), start of uncini from CH 3.................. 8
2. Two pairs of branchiae ........................................................................................................................ ........................................ Streblosoma lindsayae Lavesque, Londoño-Mesa, Daffe & Hutchings, 2020 View in CoL
– Three pairs of branchiae .................................................................................................................... 3
3. Uncini arranged in C-shaped loops from mid thorax ....................................................................... 4
– Uncini always in straight rows ......................................................................................................... 6
4. Notopodia not extending to posterior body ...................................................................................... 5
– Notopodia until posterior body ................. Streblosoma pseudocomatus Lezzi & Giangrande, 2019 View in CoL
5. Eyespots absent .............................................. Streblosoma hutchingsae Lezzi & Giangrande, 2019 View in CoL
– Eyespots present ................................................. Streblosoma nogueirai Lezzi & Giangrande, 2019 View in CoL
6- Branchiae on SG III and SG IV with 3 or less filaments on each side ............................................... ........................................................................... Streblosoma intestinale M. Sars View in CoL in G.O. Sars, 1872
– Branchiae on SG III and SG IV with 5–10 filaments on each side .................................................. 7
7. Absence of prostomial process, presence of lateral crest on SG II, absence of branchial cushion .... ......................................... Streblosoma cabiochi Lavesque, Londoño-Mesa, Daffe & Hutchings, 2020 View in CoL
– Presence of prostomial process, absence of lateral crest on SG II, presence of branchial cushion ................................................................................... Streblosoma bairdi ( Malmgren, 1866) View in CoL
8. Lateral lobes on SG II–IV ................................................. Euthelepus setubalensis McIntosh, 1885 View in CoL
– Lateral lobes on SG I only .............................................................................................. 9 ( Thelepus View in CoL )
9. Two pairs of branchiae .................................................................................................................... 10
– Three pairs of branchiae ................................................................................................................. 15
10. Uncini in a single row throughout ...................................................................................................11
– Uncini in loops from SG XIV .............................................. Thelepus nucleolata ( Claparède, 1870) View in CoL
11. Notopodia present on 50–66% of body length ............................................................................... 12
– Notopodia present on at least 90% of body length ......................................................................... 13
12. Eyespots absent ................................................................................ Thelepus davehalli Jirkov, 2018 View in CoL
– Eyespots present .............. Thelepus corsicanus Lavesque, Londoño-Mesa, Daffe & Hutchings, 2020 View in CoL
13. Uncini of CH 1 with one tooth above main fang ............................................................................ 14
– Uncini of CH 1 with two teeth above main fang ............................. Thelepus parapari Jirkov, 2018 View in CoL
14. Eyespots present ................................................................. Thelepus cincinnatus ( Fabricius, 1780) View in CoL
– Eyespots absent ................................................................................. Thelepus marthae Jirkov, 2018 View in CoL
15. Prow of uncini well developed; notch between the prow and dorsal button of the uncini well marked ......................................................................................... Thelepus triserialis ( Grube, 1855) View in CoL
– Prow of uncini poorly developed; notch between the prow and dorsal button of the uncini poorly marked ............................................................................................................................................ 16
16. Notopodia present on about 60% of the body length ............. Thelepus setosus ( Quatrefages, 1866) View in CoL
– Notopodia present until end of the body length .................... Thelepus japonicus Marenzeller, 1884 View in CoL
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