Orbinia camposiensis, Leão, Luciana Sanches Dourado & Santos, Cinthya Simone Gomes, 2016

Leão, Luciana Sanches Dourado & Santos, Cinthya Simone Gomes, 2016, Orbinia (Polychaeta: Orbiniidae) from the Brazilian coast: two new species and two new records, Zootaxa 4105 (2), pp. 145-158 : 150-152

Orbinia camposiensis n. sp.

Figures 4 A–E; 5 A–E

Type material. Total: 5 specimens. Holotype: Hab. 11; PLAT. F 1; Rep. 0 3 (MNR/JP 767), 22 º 40 ′S 41 º 20 ″W. Depth: 50 m. Paratypes: Hab. 13; FOZ 12; Rep. 2 (1 spec., MNRJ /P 768), 22 o 40 ′S 40 o 40 ″W. Depth: 25 m; Hab. 11; PLAT. E 2; Rep. 0 2 (2 spec., MNRJ /P 765), 22 o 40 ′S 40 o 40 ″W. Depth: 25 m; Hab. 13; PLAT. H 1; Rep. 0 1 (1 spec., MNRJ /P 766), 22 º 0′S 40 º 40 ″W. Depth: 25 m.

Diagnosis. Prostomium conical and pointed; 15–19 thoracic chaetigers. Branchiae from chaetigers 9–13. Papillae present in posterior thoracic and first two abdominal parapodia. Subpodial lobes present. Flail-tipped chaetae present. Furcate chaetae absent.

Description. All specimens incomplete, ranging from 3.7 to 13 mm in total length and with 33 to 62 chaetigers. Holotype 13 mm long, with 62 chaetigers. Prostomium conical and pointed ( Fig. 4 A), width 0.15 mm and height 0.1 mm. Peristomium with one ring. Anterior thoracic region (chaetigers 1–3) 0.75 mm long. First abdominal chaetiger 1 mm wide.

Thorax dorsoventrally compressed, with 19 chaetigers. Branchiae from chaetiger 12 ( Fig. 4 A), abdominal branchiae twice as long as thoracic branchiae. Single post-chaetal lobe of thoracic notopodia, elongate and present from chaetiger 1 ( Fig. 5 B). Thoracic neuropodia with one papilliform lobe from chaetiger 12 ( Fig. 4 B). One subpodial papilla on chaetiger 18 ( Fig. 4 B) and two on chaetiger 19. Abdomen cylindrical. Abdominal notopodia with one postchaetal lobe ( Fig. 4 C); abdominal neuropodia bilobate, with dorsal lobe longer than ventral one ( Figs. 4 E; 5 C); four ventral papillae only on the first two abdominal chaetigers ( Fig. 4 C). Long subpodial lobe on the remaining parapodia.

Thoracic notochaetae with crenulated capillaries (10–15); abdominal notochaetae with crenulated capillaries (5–7). Thoracic neurochaetae with three rows of smooth uncinate spines accompanied by 3–4 crenulated capillaries; abdominal neurochaetae with crenulated capillaries (4–5) and flail-tipped chaetae (1–2) ( Fig. 4 D).

Etymology. The specific name ″ camposiensis ″ refers to the type locality.

Occurrence. Southeast Brazil. Depths: 25 and 50 m.

Remarks. Among all the species recorded for the Brazilian coast Orbinia camposiensis n.sp. most resembles Orbinia latreiili ( Audouin & Milne Edwards 1833) , reported from La Rochelle ( France) and Gulf of Naples ( Italy), based on the presence of papillae extending from the thorax to the abdomen and subpodial lobes. However, they differ in the number of thoracic chaetigers (19 and 36 for O camposiensis n.sp. and O. latreilli , respectively), and distribution of ventral papillae, which in O. latreilli form a continuous row of papillae on the thoracic region. Orbinia camposiensis n. sp. is also similar to Orbinia hartmanae ( Day 1977) , described from the coasts of Australia, in the number of thoracic chaetigers, the position of the first pair of branchiae, the arrangement of the papillae and the presence of subpodial lobes. However, O. camposiensis n.sp. does not have abdominal furcate chaetae as found in O. hartmanae . Orbinia camposiensis n.sp. is also similar to Orbinia johnsoni ( Moore 1909) , recorded from California and Campos Basin, in the number of thoracic chaetigers (15–19) and the distribution of papillae, but O. johnsoni has furcated chaetae. The depth occurrence range for O. camposiensis n. sp. was between 25 and 50 m. Orbinia camposiensis n.sp. was recorded at greater depths than O. latreilli and O. johnsoni ( Fauvel, 1927, Hartman, 1944), but similar to records for O. hartmanae (60 m; Day, 1977).