Branchiosyllis belchiori, Nascimento & Fukuda & Paiva, 2019

Nascimento, Rodolfo Leandro, Fukuda, Marcelo Veronesi & Paiva, Paulo Cesar De, 2019, Two new sponge-associated Branchiosyllis (Annelida: Syllidae: Syllinae) from Northeastern Brazil, Zootaxa 4568 (2), pp. 307-322 : 309-313

Branchiosyllis belchiori sp. nov.

Figures 2–5 ; Table 1

Type series. Holotype: Atlantic Ocean, Brazil, state of Bahia, Todos os Santos Bay , Ilha dos Frades (12°46’47”S, 38°37’11”W), 3 m depth, associated with Haliclona caerulea : ( MNRJP1430 ) . Paratypes: Atlantic Ocean, Brazil, state of Bahia, Todos os Santos Bay , Ilha dos Frades (12°46’47”S, 38°37’11”W), 3 m depth, associated with Haliclona caerulea : four paratypes ( MNRJP1431 – MNRJP1434 ) coll. R. Dias, 16. Nov. 2015. Morphological data from specimens of the type series provided in Table 1 .

Additional Material. Atlantic Ocean, Brazil, state of Bahia, Todos os Santos Bay, Ilha dos Frades (12°46’47”S, 38°37’11”W), 3 m depth, associated with Haliclona caerulea : 6 specimens (MNRJP1436), coll. R. Dias, 16. Nov. 2015; state of Pernambuco , Fernando de Noronha Island, Buraco da Raquel (3°50’11”S, 32°20’34”W), 0.5 m depth, associated with Haliclona caerulea : 2 specimens ( MNRJP1437 ), coll. R. Nascimento, 21. April . 2016.

Description. Holotype complete, 4 mm long, 0.32 mm wide, with 42 segments ( Figs 2 A–B; 3A; Table 1). Longest specimen analysed paratype 1, 5 mm long, 0.3 mm wide, with 48 segments ( Table 1). Body subcylindrical ( Figs. 2 A–B; 3A). Live specimens pigmented, dorsally with brownish spots on prostomium and alternating chaetigers with no pigmentation and chaetigers with brown transverse stripes interrupted in the center, forming dark spots on each side ( Figs 2 A–B, D–E; 3A); orange colored in ventral view, organized in thin bands more concentrated in the mouth region and becoming sparser and clearer towards proventricle ( Fig. 2C ). Color pattern preserved in specimens maintained in 92% ethanol. Distally rounded palps, fused only at bases ( Figs 2 A–C; 3A). Prostomium subpentagonal to ovate, with two pairs of eyes in trapezoidal arrangement ( Figs 2B ; 3A ). Lateral antennae inserted on anterior margin of prostomium, with 10–11 articles each; median antenna inserted between and slightly anteriorly to anterior pair of eyes, slightly posteriorly to lateral ones, of similar size as lateral antennae, longer than combined length of prostomium and palps, with 9–12 articles ( Figs 2B ; 3A ). Peristomium dorsally inconspicuous, covered by chaetiger 1 ( Fig. 3A ); dorsal peristomial cirri longer than median antenna, with 19–23 articles each ( Figs 2 A–B; 3A), proportionally longer in juveniles ( Fig. 2E ); ventral peristomial cirri shorter than dorsal ones, with 10–12 articles each ( Fig. 3A ; Table 1). Chaetiger 1 with a mid-dorsal projection over peristomium and prostomium ( Fig. 3A ). Dorsal cirri on chaetiger 1 with 15–17 articles each; on chaetiger 2 with 12–15, on chaetiger 3 with 17–20 articles, on chaetiger 4 with 10–13 articles, and on chaetiger 5 with 13–16 articles each ( Fig. 3A ); dorsal cirri slightly alternating in length in remaining chaetigers, longer cirri with 17 articles, shorter cirri with 12 articles ( Figs 2 A–B; 3A; 5A). Ventral cirri digitiform, inserted at midlength of parapodial lobes, extending until tip of parapodial lobes or slightly beyond ( Fig. 3C ). Parapodia distally bilobed, pre-chetal lobe larger than post-chaetal one, both digitiform ( Figs 3B, C ; 5D ). Single branchia per parapodium, dorsally inserted close to base of parapodial lobes, well developed; ovate to pyriform, slightly flattened ( Figs 3 B–C; 4A–B; 5A). Compound chaetae as ungulae only, regular falcigers absent; anterior body with 3–4 ungulae per parapodium; midbody with 3–5, posterior body with 2–3 ungulae per parapodium ( Table 1); ungulae with shafts subdistally slightly spinulated ( Fig. 5 C–D), shafts progressively thicker ventralwards throughout body ( Fig. 3 D–F); blades unidentate with dorsoventral gradation in length, ventralmost ungulae larger and slightly thicker than dorsalmost ones throughout ( Figs 3 D–F; 5B–D). Parapodia with only one acicula each, straight, slightly inflated and oblique subdistally, with acute, rounded tip slightly protruding from parapodial lobes; aciculae progressively thicker towards posterior body ( Fig. 3 G–I). Pygidium semicircular, with two articulated anal cirri slightly longer than posterior dorsal cirri ( Fig. 2D,E ), lost in most examined specimens. Pharynx slightly thinner than proventricle, through 3.5 segments ( Table 1); conical pharyngeal tooth close to anterior border ( Fig. 3A ). Proventricle through three segments, with 24–26 rows of muscle cells ( Figs 2 A–C; 3B; Table 1).

Reproduction. One specimen with 40 chaetigers was found with attached pigmented acephalous stolon, 0.61 mm long, 0.25 mm wide, with 6–7 chaetigers ( Fig. 2D ). In addition, some juveniles were found ( Fig. 2E ), suggesting that the species completes its life cycle, or spends most of it, within the sponge.

Remarks. Branchiosyllis belchiori sp. nov. resembles B. australis Hartmann-Schröder, 1981 , B. lamellifera Verrill, 1900 , B. oculata Ehlers, 1887 , B. pacifica Rioja, 1941 , and B. tamandarensis by the presence of branchiae and only ungulae as compound chaetae throughout the body. Branchiosyllis australis has been reported from Western Australia and the Philippines; B. pacifica has been reported from the Eastern Tropical Pacific ( Mexico), whereas both B. lamellifera and B. oculata occur in the North Atlantic region, in the Gulf of Mexico, and in the Caribbean Sea, respectively ( Table 2). Branchiosyllis tamandarensis is the only of those species described from the South Atlantic, specifically from the states of Paraíba and Pernambuco, Northeastern Brazil, and to date is only known from the original description.

Branchiosyllis belchiori sp. nov. differs from all species mentioned above in the characteristic color pattern, in the size and shape of body, length of pharynx and proventricle, in the unique shape of branchiae, and the number of ungulae per parapodium ( Table 2). Branchiosyllis pacifica lacks distinctive color pattern, B. oculata , B. tamandarensis , B. lamellifera and B. australis have uniform color pattern; in contrast, B. belchiori sp. nov. has brownish spots dorsally on the prostomium, and alternates chaetigers with no pigmentation and chaetigers with brown transverse stripes interrupted in the center, forming dark spots on each side ( Table 2). Specimens of B. australis , B. lamellifera , B. oculata , B. pacifica , and B. tamandarensis have longer and wider bodies than B. belchiori sp. nov., including larger pharynx and proventricle ( Table 2). Branchiosyllis lamellifera , B. pacifica , and B. tamandarensis have multilobed branchiae with up to three, four, and six lobes, respectively; B. oculata branchiae are dome-shaped or slightly flattened, and in B. australis , branchiae are small, nearly inconspicuous.

Branchiosyllis Branchiosyllis belchiori Branchiosyllis gonzaguinhai Branchiosyllis Branchiosyllis Branchiosyllis Branchiosyllis australis sp. nov. sp. nov. lamellifera oculata pacifica tamandarensis Hartmann-Schröder, Paresque et al. Original description This paper This paper Verrill, 1900 Ehlers, 1887 Rioja, 1941 1981 2016 Pawlik, (1983) (as B. Rioja (1941) and Additional San Martín et al. oculata ) and none none Uebelacker Capa (2003) none descriptions (2008) Álvarez-Campos et (1984) al. (2012) Holotype with brownish spots Alternating chaetigers on prostomium and dark spots with brown transversal Yellowish, brown, on each side of the segments, Uniformly light stripes interrupted in the purple, depending on Uniformly dark Yellowish to Color pattern in the base of the cirrophores. Absent brown center, with dark spots on the sponge in which (brown to black) orange Other specimens less each side and the specimens dwell pigmented or without unpigmented chaetigers pigmentation Length (mm) 100 5 4.6 20 21 8.5 5.5 Width (mm) 0.8 0.3 0.40 2 2.8 1.5 0.8 Peristomium Dorsally reduced Dorsally reduced Dorsally reduced Dorsally reduced Dorsally reduced Dorsally reduced Dorsally reduced Number of 92 (+11 stolon) 48 52 140 112 71 52 chaetigers Very small and Dome or slightly Shape of branchiae Ovate to piriform Up to five lobes Up to three lobes Up to four lobes Up to six lobes without pigment flattened Number of anterior/posterior 4–6 / 3–2 3–6 / 2–3 4–5 / 4–6 3 / 3 3–5 / 3–5 2–4 / 2–4 4–6 / 2–3 ungulae Pharynx length (number of 5 3.5 5 9 6 5–7 5 segments) Proventricle length (number of 6–7 3 4 9 8 4–5 3.5–5 segments) Number of muscle cell rows in 26–30 24–27 24 30 22 22 25–30 proventricle Associated with the Sponges, algae, On and within Sand, algae, Coral rubble, On and within Habitat sponge Haliclona On and within sponges coral rubble sponges coral rubble algae sponges caerulea Only known Caribbean Sea from type Brazil (Todos os Santos Eastern Tropical Western Australia, Brazil (Fernando de Noronha Bermuda, Gulf of (Florida, Cuba, locality. South Distribution Bay, Fernando de Pacific ( Mexico, Philippines Island and Rocas Atoll) Mexico Mexico, Atlantic (states Noronha Island) Panama) Venezuela) of Paraíba and Pernambuco)

Habitat. Species found in association with the sponge Haliclona caerulea ( Hechtel, 1965) . Infestation was accomplished by few specimens in a small sponge fragment (2–5 cm ³ in volume). The collection methods prevented us to confirm whether this association is species-specific.

Distribution. South Atlantic, Brazil: states of Bahia (Todos os Santos Bay) and Pernambuco (Fernando de Noronha Island).

Etymology. Named after Antônio Carlos Belchior (stage name Belchior), a remarkable Brazilian popular singer and songwriter (02.Oct.1946 — 30.April.2017) who has amazed and inspired generations with his talent, and who is the first author’s favorite artist.

Figures

FIGURE 2. Branchiosyllis belchiori sp. nov. A, complete specimen, dorsal view; B, anterior body, dorsal view; C, anterior body, ventral view; D, acephalous stolon, dorsal view; E, juvenile specimen, dorsal view. Scale bars: A, B, D, 0.5 mm; C and E, 0.2 mm.

FIGURE 3. Branchiosyllis belchiori sp. nov. A, anterior body, dorsal view; B, anterior parapodium, dorsal view; C, midbody parapodium, lateral view; D, E, F, ungulae, anterior, mid-, and posterior body, respectively; G, H, I, aciculae, anterior, mid-, and posterior body, respectively. Scale bars: A, 0.28 mm; B and C, 28 µm; D–I, 10 µm.

FIGURE 4. Branchiosyllis belchiori sp. nov. A, dorsal, and B, dorso-lateral view of branchiae. dc—dorsal cirrus; pd— parapodium; brc—branchia. Scale bar: A, B, 30 µm.

FIGURE 5. Branchiosyllis belchiori sp. nov. A, midbody parapodia, dorsal view; B, C, ungulae anterior body; D, E, ungulae mid- and posterior body, respectively. Scale bars: A, 50 µm; B, 10 µm; C, 2 µm; D, 10 µm; E, 5 µm.