Spirobranchus lirianeae, Brandão & Brasil, 2020

Brandão, Ivison Cordeiro & Brasil, Ana Claudia dos Santos, 2020, On a new species of Spirobranchus Blainville, 1818 (Annelida: Serpulidae) and considerations on the genus along the Brazilian coast, Papéis Avulsos de Zoologia 60, pp. 1-17 : 3-7

publication ID	https://doi.org/ 10.11606/1807-0205/2020.60.51
publication LSID	lsid:zoobank.org:pub:C598BF30-2A01-467A-B4F1-42032F448100
DOI	https://doi.org/10.5281/zenodo.4975227
persistent identifier	https://treatment.plazi.org/id/025CD000-880A-9C68-FC7F-44CAFC2EFD3E
treatment provided by	Carolina
scientific name	Spirobranchus lirianeae
status	sp. nov.

Treatment

Spirobranchus lirianeae View in CoL sp. nov.

( Figs. 2-4 View Figure 2 View Figure 3 View Figure 4 , 9 View Figure 9 )

Examined material: Rio de Janeiro state, Ilha Grande Bay, Angra dos Reis Municipality: Machado Beach: 23°00′11.21″S, 44°15′24.82″W, intertidal, MNRJP-002777 (1 specimen). Cataguases Island: 23°01′28.57″S, 44°17′06.52″W, intertidal, MNRJP-002774, MNRJP-002775, MNRJP-002776 (10 specimens, including holotype). Holotype: MNRJP-002774 – Cataguases Island, preserved entire, with tube, 16 May 2019, under rocks. Paratypes: MNRJP-002775, MNRJP-002776, MNRJP-002777, 10 specimens.

Diagnosis: Tubes solitary with one longitudinal pointed keel and transverse ridges. Operculum and calcareous endplate funnel-shaped, without thorns or spines. Paired reddish ocellar clusters along aboral face of radioles. Collar chaetae absent.Tonguelets bilobed, one lobe bearing finger-like processes.

Description

Tube: Opaque, white purplish or blueish, internally blueish. Triangular in cross-section, lumen circular. One longitudinal keel along the tube, extending over the opening forming a pointed tip. Transversal ridges present on tube surface ( Fig. 2C View Figure 2 ). Tubes solitary.

Radiolar Crown: Live and preserved specimens with dark brown base of crown, then alternating bands of white, iridescent pigmentation and light brown pigmentation, in a “zebra-like” pattern ( Fig. 2A View Figure 2 ). Coloration faded after preservation. Crown composed of two lobes arranged in a complete circle, each with around 15 radioles, basally joined by inter-radiolar membrane for one third of their length, dorsally hidden by collar lobes and operculum ( Fig. 2B View Figure 2 ). Radioles rectangular in cross-section, the inner side with two rows of filiform pinnules, distally shorter, with naked tips.Tips filiform and about same size as distal pinnules. Dorsal radioles longer than ventral ones. Paired red spots present, 3 to 6 pairs per radiole ( Figs. 2D, 2E View Figure 2 ), with ocellar clusters ( Fig. 2E View Figure 2 ).

Mouth Parts: Two thin, smooth lips. Dorsal lips with median notch and forming a pair of lateral filiform palps, often colored in brown, about as long as proximal pinnules. Ventral lips rectangular, as semicircular lap along inner sides of bases of radiolar lobes.

Peduncle: Smooth, triangular in cross-section, inserted slightly left to mid-dorsal line. Pair of smooth lateral wings, triangular with rounded tip, not reaching tip of operculum. “zebra-like” coloration pattern present, extending into the lateral wings ( Figs. 2B, 2G View Figure 2 ). Constriction between peduncle and opercular base absent.

Operculum: Continuous with the peduncle ( Fig. 2G View Figure 2 ). Opercular ampulla funnel-shaped, with calcareous opercular endplate, deeply concave, without ornamentation, white, circular in top view ( Figs. 2A, 2F, 2G View Figure 2 , 3A, 3D View Figure 3 , 4A, 4B, 4C View Figure 4 ).Talon embedded in opercular ampulla,basally ending in five rounded teeth, unequal in size ( Fig. 2G View Figure 2 ).

Collar and Thoracic Membranes: High, three-lobed collar extending to margin of inter-radiolar membrane. Dorso-lateral lobes long, circular with entire edges, reaching near distal region of crown; continuous with thoracic membranes, forming ventral apron covering 1 to 2 abdominal chaetigers. Mid-ventral lobe reniform, laterally as long as dorsolateral lobes, shorter medially, often folded, inserted between crown lobes ( Fig. 2A, 2H View Figure 2 ). Tonguelets present between lateral and ventral lobes; bilobed, outer lobe and inner lobe leaf-shaped, the former twice as long, with fringed rim ( Fig. 9A, 9B View Figure 9 ). Collar light brown or darker, purplish brown, extending through entire thorax, iridescent inclusions present in median-ventral lobe ( Fig. 3B View Figure 3 ).

Thorax: Six chaetigers. Collar chaetae absent in adults ( Fig. 3C View Figure 3 ), juveniles not observed. Notopodial lobes conical, emerging between thoracic membranes and neuropodia. Thoracic chetae limbate, in two fascicles of different lengths per notopodium ( Fig. 4D View Figure 4 ). Neuropodial lobes rectangular, overlapping subsequent neuropodia, all bearing straight tori of similar size along the thorax. Thoracic uncini saw-shaped, with 9-10 curved teeth, plus the anterior-most peg,flat,spatulated( Fig.4E View Figure 4 ).Parapodial lobes approaching each other posteriorly, forming a ventral triangular depression. Glandular clusters covering the ventral portion of mid-ventral collar lobe, as a rectangle; glandular rectangles also present basally to thoracic neuropodial tori and in ventral depression, as 3 to 4 pairs of ventral glandular shields ( Fig. 3D View Figure 3 ).

Abdomen: Largest analyzed specimen with 46 abdominal segments, at least the first one achaetous. Abdomen usually three times longer than thorax, with larger anterior chaetigers ( Fig. 3E View Figure 3 ),the final third with densely packed, much shorter chaetigers ( Fig. 3F View Figure 3 ). Notopodial uncini smaller than thoracic ones, saw-shaped,with 10-13 teeth plus gouged anterior peg ( Fig. 4F View Figure 4 ). Neuropodial chaetae true trumpet-shaped, abruptly bent, with 2 distal rows of denticles separated by groove and lateral filiform projection, serrated with minute teeth ( Fig. 4G View Figure 4 ). Color equal to thorax, possibly darker or reddish on dorsum, and beige to brown on venter,with squared ventral shields anteriorly and rectangular posteriorly. Glandular clusters present basally to tori and on posterior abdomen, near fecal sulcus rim ( Fig. 3G View Figure 3 ). Pygidium bilobed, with terminal anus.

Remarks: Bastida-Zavala (2008) studied specimens of Panama’s Pacific coast and mentioned a possible different species (“ Pomatoleios sp.”), with a prominent opercular talon.This species,although never formally described, presents only a longitudinal keel in the tube, differing from S.lirianeae sp. nov. because the specimens analyzed for the present study do not possess thoracic ocelli as the individuals studied by Bastida-Zavala (2008) do.

Although the S. cf. kraussii specimens reported from Costa Rica are possibly a different species within the S. kraussii -complex, they share many morphological similarities with S. lirianeae sp. nov., but they are distinguished by having flattened projection of the dual tube keels, while members of Spirobranchus lirianeae sp. nov. possess a tube with a single sharp longitudinal keel. Moreover, S. cf. kraussii and S. kraussii are gregarious, belt-forming species, whereas animals belonging to S. lirianeae sp. nov. exhibited a low density of individuals in the sampled areas. Both S.kraussii and the Costa Rican morphospecies present dark brown paired spots on the radioles, associated with photoreceptor structures, whereas those of members of S.lirianeae sp. nov. are red. The funnel-like calcareous endplate of the operculum of individuals of S. lirianeae sp. nov. exhibits a deeper concavity than those of other members of the other species within the S. kraussii complex. The opercular talon is short in members of S. cf. kraussii and S. kraussii , and long in S. lirianeae sp. nov., almost fully immersed within the basal opercular ampulla. The opercular talon of specimens of S. lirianeae sp. nov. ends in five round and unequal teeth, similar to those reported for members of S. kraussii , in the redescription by Simon et al. (2019). The tonguelets of members S. cf. kraussii and S. lirianeae sp.nov. are different, being pyriform in the former and bilobed, with fringed outer lobe in the latter. Furthermore, members of S. cf. kraussii have six pairs of thoracic ventral shields, whereas in those of S. lirianeae sp. nov. there are only three or four pairs. The shape of the tonguelets and the ventral shields of members of S. kraussii were not defined in the redescription of Simon et al. (2019), although the images in that report show the tonguelets are not fringed.

Members of S. lirianeae sp. nov. differ from those belonging to the recently described S. sinuspersicus in having an operculum with a concavity as a deep funnel, with a talon formed by five protuberances, while in individuals of S. sinuspersicus the operculum is flattened (though slightly concave) and the talon has two or three protuberances. The compound ocellar clusters of members of S. sinuspersicus are dark brown, whereas in S. lirianeae sp. nov. they are red, notwithstanding the brown bands on the crown. Animals belonging to S. sinuspersicus present bilobed tonguelets with smooth lobes (not described, but see Pazoki et al., 2020, fig. 4E), unlike the unique fringed outer lobe of members of S. lirianeae sp. nov. Moreover, S. sinuspersicus was indicated as invasive in potential ( Pazoki et al., 2020), since individuals were found forming aggregates on artificial substrates,which also differentiates it from S.kraussii , another gregarious species. We only observed individuals of S. lirianeae sp. nov. on natural substrates, despite sampling artificial substrates in the type locality, including buoys, small boats, metal pipes, and wooden piers. Since Simon et al. (2019) established that species belonging to the S. kraussii complex are regionally distributed species, given the morphological differences between our specimens and members of the other species assigned to that species complex (in addition to the morphotype S. cf. kraussii , reported from Costa Rica), we assert that the material described herein corresponds to a new species.

The concave and tapered calcareous operculum, the presence of paired compound ocellar clusters along the radioles, the tonguelets with a fringed lobe, and the absence of collar chaetae render S.lirianeae sp. nov. unique among Brazilian species of Spirobranchus . Although the operculum of S. minutus also lacks endplate ornamentation, the structure is convex and bilobed, not tapered as in members of S. lirianeae sp. nov. Moreover, specimens of S. minutus do not present radiolar photoreceptor structures, such as those of members of S. lirianeae sp. nov., and their tubes are multi-keeled and ornamented by alveoli, whereas the tube of members of S. lirianeae sp. nov. is single-keeled and lacks alveoli. The tube of members of S. giganteus is also single-keeled, but their operculum is elaborately ornamented with spined thorns. Individuals of S. giganteus have single compound ocellar clusters, which are located only at the base of the two dorsal-most radioles. Members of S. tetraceros have fringed interradiolar processes and collar chaetae, both characters absent among members of S. lirianeae sp. nov. The operculum of specimens of S. tetraceros also presents complex ornamentation and the ocelli of those animals are simple.

Type-locality: Cataguases Island, Ilha Grande Bay, Rio de Janeiro, Brazil (Atlantic Ocean).

Habitat: Intertidal: Under rocks; not found in artificial substrates.

Etymology: The specific epithet is a tribute to Professor Liriane Monte Freitas, from the Universidade Federal de Alagoas (Federal University of Alagoas), responsible for the formation of numerous biologists, including the first author.

Distribution: Atlantic Ocean: Brazil, State of Rio de Janeiro, in Cataguases Island and Angra dos Reis ( Ilha Grande Bay).