Streblosoma pseudocomatus, Lezzi & Giangrande, 2019

Lezzi, Marco & Giangrande, Adriana, 2019, New species of Streblosoma (Thelepodidae, Annelida) from the Mediterranean Sea: S. pseudocomatus sp. nov., S. nogueirai sp. nov. and S. hutchingsae sp. nov., Journal of Natural History (J. Nat. Hist.) 52 (43 - 44), pp. 2857-2873 : 2861-2865

publication ID	https://doi.org/ 10.1080/00222933.2018.1556357
publication LSID	lsid:zoobank.org:pub:7AE78305-6949-46F3-B61A-D93792038F7A
persistent identifier	https://treatment.plazi.org/id/840E87E6-FFC2-C84D-ABC6-3D420309FBF1
treatment provided by	Felipe
scientific name	Streblosoma pseudocomatus
status	sp. nov.

Treatment

Streblosoma pseudocomatus View in CoL sp. nov.

( Figures 2 View Figure 2 , 3 View Figure 3 , 8c,d View Figure 8 )? Streblosoma comatus Çinar 2009 (not Grube 1856).

Type material

Holotype: Ionian Sea , Mar Grande of Taranto, Italy, 40.440°’N, 17.240°’E, September 2014, artificial substrates, 3 m ( MNCN 16.01 View Materials /17963). Two paratypes, complete specimens, from same locality and date as holotype ( MNCN 16.01 View Materials /17964; MSNP P/4365).

Description

Holotype complete, in two fragments. 19 mm long and 2.7 mm wide, with 71 chaetigers. Paratype (MNCN 16.01/17964) 16 mm long and 2 mm wide, with 52 chaetigers. Paratype (MSNP P/4365) 22 mm long and 2.5 mm wide, with 60 chaetigers.

Transverse prostomium attached to dorsal surface of upper lip; basal part with eyespots irregularly arranged in a single continuous row all around the surface ( Figure 2a,c View Figure 2 ). Relatively thick buccal tentacles. Peristomium forming lips; upper lip hood-like, about as long as wide; lower lip extended around mouth, rectangular, restricted to oral area ( Figure 2b View Figure 2 ). Segments 1 and 2 narrow; segment 3 partially covering segment 2 ventrally ( Figure 2b View Figure 2 ). Three pairs of branchiae, on segments 2–4, segment 2 with about 14 filaments on either side, segment 3 with about 11 filaments on either side and segment 4 with about 11 filaments on either side; branchial filaments thin, originating dorsally to notopodia; filaments of segment 2 laterally extending slightly beyond level of first pair of notopodia, longest filaments about ½ of corresponding body width ( Figure 2a,c View Figure 2 ).

Anterior ventral surface glandular; glandular surfaces progressively more swollen until segments 8–9, then progressively less inflated ( Figure 2b View Figure 2 ), mid-ventral stripe visible from middle to end of specimen.

Notopodia starting from segment 2 (first branchiate segment; Figure 2c View Figure 2 ) and extending until end of body; cylindrical and bilobed notopodia, with flattened rounded lobes of equal size, between which notochaetae arise; first pair about same size as following pairs, then progressively smaller towards posterior body. Notochaetae in two rows, increasing in length from ventral to dorsal position. Anterior notopodia with bilimbate capillaries, those from posterior row with strong wings only on distal third to distal half of chaetae, capillaries from anterior row with slightly narrower limbation ( Figure 3e View Figure 3 ). Posterior notopodia with chaetae from anterior row slightly shorter than those from posterior row, capillaries narrowed, limbate ( Figure 3f View Figure 3 ).

Neuropodia starting from segment 5, swollen and slightly raised from surface of body throughout. Uncini in straight rows until segment 15 ( Figure 2d View Figure 2 ), thereafter conspicuously curved dorsally (C-shaped) until end of body.

Uncini breviavicular with dorsal button conspicuous, terminal, prow short, reduced to small knob, shorter than dorsal button, curved base. Main fang conspicuous, secondary teeth in row of two teeth above main fang and second row with much smaller teeth, larger ones inserted between teeth of first row, surrounded by two smaller teeth at each side in first chaetigers (dental formula: MF: 2:3) ( Figure 3a,b View Figure 3 ) or more in last chaetigers (dental formula: MF:2:3–8) ( Figure 3c,d View Figure 3 ).

Nephridial and genital papillae not visible.

Pygidium distally rounded ( Figure 8c View Figure 8 ). Tubes built with coarse sand and held together by solidified mucus ( Figure 8d View Figure 8 ).

MGS. There is no evident staining pattern; staining homogeneous throughout the body.

Remarks

Steblosoma pseudocomatus sp. nov. is similar to S. comatus sensu Glasby and Hutchings 1987 (not Grube 1856). It differs in the number of branchial filaments (lower in S. pseudocomatus sp. nov.) and the shape of ventral segments (which are narrow in S. pseudocomatus sp. nov. with overlapping structures), and the C-shaped arrangement of uncini is from segment 15 whilst in members of S. comatus sensu Glasby and Hutchings 1987 it is only in the posterior body. Streblosoma pseudocomatus sp. nov. shows the same dental formula as S. comatus sensu Glasby and Hutchings, 1987 , which, however, presents variability of this feature along the body length. In addition, S. pseudocomatus sp. nov. does not have any difference from S. comatus sensu Çinar (2009) , except for the number of branchial filaments, although this author did not give information about variability in dental formula along the body.

Streblosoma comatus , originally named Terebella comata ( Grube 1856) , was considered to belong to the genus Thelepus ( Hessle 1917) for the starting of notopodia from segment 3. That was emended by Glasby and Hutchings (1987), who placed the species back within Streblosoma . These authors analysed an alleged type deposited in the MK museum, which was considered a syntype because it agreed with the type localities given by Grube (Punta Arenas, Chile) and the vial contained a label saying ‘type’. The syntype came from Kröyer’ s collection, which was used by Grube for the description of numerous species, including T. comata in ‘Annulata Örstediana. Enumeratio Annulatorum, quae in itinere Indiam Occidentalem et Americam Centralem annis 1845–1848 suscepto legit cl. A.S. Oersted, adjectis speciebus nonnullis a cl. H. Kroyero in itinere ad Americam meridionalem collecti’. The other syntypes from Valparaiso ( Chile) are not available because all the other types were destroyed during World War II ( Glasby and Hutchings 1987). The authors showed that the analysed syntype material was different from the original description given by Grube (1856). Indeed, Grube described the species as a Thelepus , so with notopodia starting from segment 3: ‘Fasciculi setarum capilarum jam a segment 3° (branchigerorum 2°)’, differently from what has been redescribed by Glasby and Hutchings (1987), as notopodia starting from the second segment (as in Streblosoma ). Moreover, Grube’ s specimens, unlike the one examined by Glasby and Hutchings (1987), have C-shape tori from segment 10 and fewer branchial filaments. It is evident that Grube’ s species belongs to Thelepus , and the alleged syntype analysed by Glasby and Hutchings (1987) was incorrectly associated with Terebella comata .

In the same paper, Glasby and Hutchings (1987) described a new species of Thelepus ( T. ambitus ) from the Chilean coast (unknown locality), from the Dusen collection, the same material attributed to Thelepus comatus by Hessle (1917). Thelepus ambitus , as Grube’ s Terebella comata , is characterised C-shaped tori beginning from segment 10. Therefore, Streblosoma comatus sensu Glasby and Hutchings 1987 , Thelepus comatus Grube 1859 and T. ambitus Glasby and Huchings 1987 are presumably all present along the Chilean coast. Considering the similarity between the original descriptions, Thelepus comatus could be the same as T. ambitus . These hypotheses need, however, to be verified. It is conceivable that specimens belonging to different genera ( Streblosoma and Thelepus ) were associated to a single species by Grube (as Terebella comata ), who did not give enough attention to characters later considered important at the generic level. In our opinion, the original description of Grube’ s species refers to Thelepus comatus , a species missing syntypes and that may be a senior synonym of Thelepus ambitus Glasby and Huchings 1987 . The syntype described by Glasby and Hutchings (1987) as Streblosoma comatus belongs to a different species.

Streblosoma pseudocomatus sp. nov. differs from the other species with uncini in looped rows mainly in the presence of eyes (absent in both S. duplicata and S. chiguensis ). Moreover, it has notopodia to near the pygidium, differing from S. duplicata , S. hesslei , S curvus , S. chiguensis and S. wuchiensis in that regard. Further differences between these species are shown in the synoptic Table 1. Streblosoma pseudocomatus sp. nov. differs from S. nogueirai sp. nov. and S. hutchingsae sp. nov. in having notopodia to near the pygidium. Streblosoma pseudocomatus sp. nov. has similar traits to S. porchatensis which is different in the general aspect of the anterior end: the segments of S. pseudocomatus sp. nov. are narrower with segment 3 partially covering segment 2 ventrally, while in S. porchatensis the anterior end is characterised by segment 1 short, partially covered ventrally by first ventral shield originating from segment 2, and segment 3 does not cover the second segment ( Nogueira et al. 2004, fig. 2b; Nogueira et al. 2017, fig. 5e–g).

Etymology. The specific name pseudocomatus means ‘false’ comatus , because it was confused with the emended Thelepus comatus .

Distribution and ecology. Streblosoma pseudocomatus sp. nov. was considered an alien species for the Mediterranean fauna, first found in shallow waters of the Levantine Sea by Çinar (2009) who referred it to S. comatus . Now this species is also reported from the macrofouling community of Taranto Sea, Ionian Sea. Streblosoma pseudocomatus sp. nov. was found in the fouling community of Taranto, characterised by a great number of non-indigenous species ( Lezzi et al. 2017), which indicates the possibility of it being an introduced species.