Streblosoma nogueirai, 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 : 2865-2868

Streblosoma nogueirai sp. nov.

( Figures 4 , 5 , 8a )

Type material

Holotype: Torre Guaceto , Adriatic Sea, Italy, 40.722°’N, 17.792°’E, July 2000, hard bottom, 3 m ( MNCN 16.01 /17965). Four paratypes, complete specimens, from same locality and date as holotype ( MNCN 16.01 /17966; MNCN 16.01 /17967; MSNP P/4366; MSNP P/4367).

Description

Holotype complete, 9 mm long, 0.5 wide, with 49 chaetigers. Paratypes complete, 7– 9 mm long, 0.4–0.6 mm wide, 35–46 chaetigers.

Transverse prostomium attached to dorsal surface of upper lip; basal part with eyespots irregularly arranged in a single row all around the surface, more concentrated laterally ( Figure 4a,c ). Long and annelated buccal tentacles. Peristomium forming lips; upper lip hood-like, expanded about as long as wide; lower lip button-like, restricted to oral area ( Figure 4b ). Segment 1 expanded, segment 2 shortest ( Figure 4b ). Three pairs of branchiae, on segments 2–4, segment 2 with two filaments on either side, segment 3 with about two filaments on either side and segment 4 with two filaments on either side; branchial filaments originating dorsally to notopodia, longest filaments about 1/3 of corresponding body width ( Figure 4a,c ).

Anterior ventral surface glandular until segment 19; glandular surfaces progressively more swollen until segments 9–10, mid-ventral stripe visible from segment 14 to end of specimen ( Figure 4a ).

Notopodia starting from segment 2 (first branchiate segment; Figure 4c ) and extending until 22nd segment; bilobed notopodia, with flattened rounded lobes. Notochaetae arranged in two rows. Posterior row notochaetae as bilimbate capillaries slightly wider distally, and tapering to tip; notochaetae of anterior row shorter than those of posterior row, wings broader on one margin, basally bulbous, tapering to tip ( Figure 5a ).

Neuropodia starting from segment 5, slightly raised from surface of body throughout. Uncini in straight rows until segment 14, then conspicuously curved (C-shaped) until posterior end, all with openings towards the dorsal side.

Uncini breviavicular with dorsal button conspicuous, terminal, prow shorter than dorsal button with deep notch ( Figure 5d ); curved base, main fang conspicuous, secondary teeth in row of two teeth above main fang and a second row with much smaller teeth, one larger one inserted between teeth of first row, surrounded by several (4–6 or more, not clearly visible at 1000× magnification) smaller teeth at each side (dental formula: MF: 2:4–6). Unicini similar throughout body, including dental formula ( Figure 5b,c,e ).

Nephridial and genital papillae not visible.

Pygidium distally rounded, without papillae.

MGS. There is no evident staining pattern; there are scattered white spots on the dorsal surface of posterior body ( Figure 4d ).

Remarks

Streblosoma nogueirai sp. nov. is similar to S. duplicata and S. curvus with which it shares the absence of a lateral extension of branchiae on chaetiger 1 and a similar pattern of notopodial distribution, with chaetae not reaching the posterior end of the body. Streblosoma nogueirai sp. nov. differs from S. duplicata in having eyespots in the peristomium, and from S. curvus in the general aspect of the anterior end (which appears swollen in S. curvus ) and the shape of the uncinal prow (which is more conspicuous in S. curvus ). The other species of Streblosoma with tori arranged in C-shaped rows have a lateral extension of branchiae on chaetiger 1 ( Table 1).

Streblosoma nogueirai sp. nov. is probably the species of Streblosoma identified by Giangrande et al. (1981) as S. hesslei , from Ischia (Naples), because of a similar general aspect of the anterior end (i.e. number of branchial filaments, upper lip shape), the presence of eyes and a similar dental formula. However, no further speculation can be made because the authors did not describe the torus arrangement and the material from the Ischia Port has been lost.

Distribution and ecology

Endemic for the Mediterraena Sea. From shallow hard-bottom substrates.

Etymology

The new species is named in honour of Dr João Miguel De Matos Nogueira, who contributed to the understanding of Terebellidae systematics.

Figures

Figure 4. Streblosoma nogueirai sp. nov. Holotype (MNCN 16.01/17965): (a) entire specimen; (b) anterior end, ventral view; (c) anterior end, dorsal view; (d) methyl green staining (MGS) evidencing white spots on posterior end.

Figure 5. Streblosoma nogueirai sp. nov. Holotype (MNCN 16.01/17965): (a) notochaetae from anterior notopodia; (b) frontal view of uncini, anterior segment; (c) frontal view of uncini, posterior segment; (d) lateral view of uncini, anterior segment; (e) frontal view of uncini, posterior segment showing Cshape arrangement.

Figure 8. (a) Streblosoma nogueirai sp. nov. holotype; (b) Streblosoma hutchingsae sp. nov. holotype; (c) Streblosoma pseudocomatus sp. nov.; (d) tube of Streblosoma pseudocomatus sp. nov.